local Generic = require("device/generic/device")
local Geom = require("ui/geometry")
local UIManager -- Updated on UIManager init
local WakeupMgr = require("device/wakeupmgr")
local time = require("ui/time")
local ffiUtil = require("ffi/util")
local lfs = require("libs/libkoreader-lfs")
local logger = require("logger")
local util = require("util")
local _ = require("gettext")

-- We're going to need a few <linux/fb.h> & <linux/input.h> constants...
local ffi = require("ffi")
local C = ffi.C
require("ffi/linux_fb_h")
require("ffi/linux_input_h")
require("ffi/posix_h")

local function yes() return true end
local function no() return false end
local function NOP() return end

local function koboEnableWifi(toggle)
    if toggle == true then
        logger.info("Kobo Wi-Fi: enabling Wi-Fi")
        os.execute("./enable-wifi.sh")
    else
        logger.info("Kobo Wi-Fi: disabling Wi-Fi")
        os.execute("./disable-wifi.sh")
    end
end

-- NOTE: Cheap-ass way of checking if Wi-Fi seems to be enabled...
--       Since the crux of the issues lies in race-y module unloading, this is perfectly fine for our usage.
local function koboIsWifiOn()
    local needle = os.getenv("WIFI_MODULE") or "sdio_wifi_pwr"
    local nlen = #needle
    -- /proc/modules is usually empty, unless Wi-Fi or USB is enabled
    -- We could alternatively check if lfs.attributes("/proc/sys/net/ipv4/conf/" .. os.getenv("INTERFACE"), "mode") == "directory"
    -- c.f., also what Cervantes does via /sys/class/net/eth0/carrier to check if the interface is up.
    -- That said, since we only care about whether *modules* are loaded, this does the job nicely.
    local f = io.open("/proc/modules", "re")
    if not f then
        return false
    end

    local found = false
    for haystack in f:lines() do
        if haystack:sub(1, nlen) == needle then
            found = true
            break
        end
    end
    f:close()
    return found
end

-- checks if standby is available on the device
local function checkStandby()
    logger.dbg("Kobo: checking if standby is possible ...")
    local f = io.open("/sys/power/state")
    if not f then
        return no
    end
    local mode = f:read()
    logger.dbg("Kobo: available power states:", mode)
    if mode and mode:find("standby") then
        logger.dbg("Kobo: standby state is supported")
        return yes
    end
    logger.dbg("Kobo: standby state is unsupported")
    return no
end

local function writeToSys(val, file)
    -- NOTE: We do things by hand via ffi, because io.write uses fwrite,
    --       which isn't a great fit for procfs/sysfs (e.g., we lose failure cases like EBUSY,
    --       as it only reports failures to write to the *stream*, not to the disk/file!).
    local fd = C.open(file, bit.bor(C.O_WRONLY, C.O_CLOEXEC)) -- procfs/sysfs, we shouldn't need O_TRUNC
    if fd == -1 then
        logger.err("Cannot open file `" .. file .. "`:", ffi.string(C.strerror(ffi.errno())))
        return
    end
    local bytes = #val
    local nw = C.write(fd, val, bytes)
    if nw == -1 then
        logger.err("Cannot write `" .. val .. "` to file `" .. file .. "`:", ffi.string(C.strerror(ffi.errno())))
    end
    C.close(fd)
    -- NOTE: Allows the caller to possibly handle short writes (not that these should ever happen here).
    return nw == bytes
end

-- Return the highest core number
local function getCPUCount()
    local fd = io.open("/sys/devices/system/cpu/possible", "re")
    if fd then
        local str = fd:read("*line")
        fd:close()

        -- Format is n-N, where n is the first core, and N the last (e.g., 0-3)
        return tonumber(str:match("%d+$")) or 1
    else
        return 1
    end
end

local function getCPUGovernor(knob)
    local fd = io.open(knob, "re")
    if fd then
        local str = fd:read("*line")
        fd:close()
        -- If we're currently using the userspace governor, fudge that to conservative, as we won't ever standby with Wi-Fi on.
        -- (userspace is only used on i.MX5 for DVFS shenanigans when Wi-Fi is enabled)
        if str == "userspace" then
            str = "conservative"
        end
        return str
    else
        return nil
    end
end

local function getRTCName()
    local fd = io.open("/sys/class/rtc/rtc0/name", "re")
    if fd then
        local str = fd:read("*line")
        fd:close()
        return str
    else
        return nil
    end
end

local Kobo = Generic:extend{
    model = "Kobo",
    isKobo = yes,
    isTouchDevice = yes, -- all of them are
    hasOTAUpdates = yes,
    hasFastWifiStatusQuery = yes,
    hasWifiManager = yes,
    canStandby = no, -- will get updated by checkStandby()
    canReboot = yes,
    canPowerOff = yes,
    canSuspend = yes,
    supportsScreensaver = yes,
    -- most Kobos have X/Y switched for the touch screen
    touch_switch_xy = true,
    -- most Kobos have also mirrored X coordinates
    touch_mirrored_x = true,
    -- enforce portrait mode on Kobos
    --- @note: In practice, the check that is used for in ffi/framebuffer is no longer relevant,
    ---        since, in almost every case, we enforce a hardware Portrait rotation via fbdepth on startup by default ;).
    ---        We still want to keep it in case an unfortunate soul on an older device disables the bitdepth switch...
    isAlwaysPortrait = yes,
    -- we don't need an extra refreshFull on resume, thank you very much.
    needsScreenRefreshAfterResume = no,
    -- currently only the Aura One and Forma have coloured frontlights
    hasNaturalLight = no,
    hasNaturalLightMixer = no,
    -- HW inversion is generally safe on Kobo, except on a few boards/kernels
    canHWInvert = yes,
    home_dir = "/mnt/onboard",
    canToggleMassStorage = yes,
    -- New devices *may* be REAGL-aware, but generally don't expect explicit REAGL requests, default to not.
    isREAGL = no,
    -- Mark 7 devices sport an updated driver.
    isMk7 = no,
    -- MXCFB_WAIT_FOR_UPDATE_COMPLETE ioctls are generally reliable
    hasReliableMxcWaitFor = yes,
    -- Sunxi devices require a completely different fb backend...
    isSunxi = no,
    -- On sunxi, "native" panel layout used to compute the G2D rotation handle (e.g., deviceQuirks.nxtBootRota in FBInk).
    boot_rota = nil,
    -- Standard sysfs path to the battery directory
    battery_sysfs = "/sys/class/power_supply/mc13892_bat",
    -- Stable path to the NTX input device
    ntx_dev = "/dev/input/event0",
    -- Stable path to the Touch input device
    touch_dev = "/dev/input/event1",
    -- Stable path to the Power Button input device
    power_dev = nil,
    -- Event code to use to detect contact pressure
    pressure_event = nil,
    -- Device features multiple CPU cores
    isSMP = no,
    -- Device supports "eclipse" waveform modes (i.e., optimized for nightmode).
    hasEclipseWfm = no,
    -- Device ships with various hardware revisions under the same device code, requirign automatic hardware detection...
    automagic_sysfs = false,

    unexpected_wakeup_count = 0
}

local KoboTrilogyA = Kobo:extend{
    model = "Kobo_trilogy_A",
    -- Unlike its B brethren, this one doesn't do the weird translation dance when ABS_PRESSURE is 0...
    hasKeys = yes,
    hasMultitouch = no,
}
-- Kobo Touch B:
local KoboTrilogyB = Kobo:extend{
    model = "Kobo_trilogy_B",
    touch_kobo_mk3_protocol = true,
    hasKeys = yes,
    hasMultitouch = no,
}
-- Kobo Touch C:
local KoboTrilogyC = Kobo:extend{
    model = "Kobo_trilogy_C",
    hasKeys = yes,
    hasMultitouch = no,
}

-- Kobo Mini:
local KoboPixie = Kobo:extend{
    model = "Kobo_pixie",
    display_dpi = 200,
    hasMultitouch = no,
    -- bezel:
    viewport = Geom:new{x=0, y=2, w=596, h=794},
}

-- Kobo Aura One:
local KoboDaylight = Kobo:extend{
    model = "Kobo_daylight",
    hasFrontlight = yes,
    touch_phoenix_protocol = true,
    display_dpi = 300,
    hasNaturalLight = yes,
    frontlight_settings = {
        frontlight_white = "/sys/class/backlight/lm3630a_led1b",
        frontlight_red = "/sys/class/backlight/lm3630a_led1a",
        frontlight_green = "/sys/class/backlight/lm3630a_ledb",
    },
}

-- Kobo Aura H2O:
local KoboDahlia = Kobo:extend{
    model = "Kobo_dahlia",
    canToggleChargingLED = yes,
    led_uses_channel_3 = true,
    hasFrontlight = yes,
    touch_phoenix_protocol = true,
    -- There's no slot 0, the first finger gets assigned slot 1, and the second slot 2.
    -- NOTE: Could be queried at runtime via EVIOCGABS on C.ABS_MT_TRACKING_ID (minimum field).
    --       Used to be handled via an adjustTouchAlyssum hook that just mangled ABS_MT_TRACKING_ID values.
    main_finger_slot = 1,
    display_dpi = 265,
    -- the bezel covers the top 11 pixels:
    viewport = Geom:new{x=0, y=11, w=1080, h=1429},
}

-- Kobo Aura HD:
local KoboDragon = Kobo:extend{
    model = "Kobo_dragon",
    hasFrontlight = yes,
    hasMultitouch = no,
    display_dpi = 265,
}

-- Kobo Glo:
local KoboKraken = Kobo:extend{
    model = "Kobo_kraken",
    hasFrontlight = yes,
    hasMultitouch = no,
    display_dpi = 212,
}

-- Kobo Aura:
local KoboPhoenix = Kobo:extend{
    model = "Kobo_phoenix",
    hasFrontlight = yes,
    touch_phoenix_protocol = true,
    display_dpi = 212,
    -- The bezel covers 10 pixels at the bottom:
    viewport = Geom:new{x=0, y=0, w=758, h=1014},
    -- NOTE: AFAICT, the Aura was the only one explicitly requiring REAGL requests...
    isREAGL = yes,
    -- NOTE: May have a buggy kernel, according to the nightmode hack...
    canHWInvert = no,
}

-- Kobo Aura H2O2:
local KoboSnow = Kobo:extend{
    model = "Kobo_snow",
    hasFrontlight = yes,
    touch_snow_protocol = true,
    touch_mirrored_x = false,
    display_dpi = 265,
    hasNaturalLight = yes,
    frontlight_settings = {
        frontlight_white = "/sys/class/backlight/lm3630a_ledb",
        frontlight_red = "/sys/class/backlight/lm3630a_led",
        frontlight_green = "/sys/class/backlight/lm3630a_leda",
    },
}

-- Kobo Aura H2O2, Rev2:
--- @fixme Check if the Clara fix actually helps here... (#4015)
local KoboSnowRev2 = Kobo:extend{
    model = "Kobo_snow_r2",
    isMk7 = yes,
    hasFrontlight = yes,
    touch_snow_protocol = true,
    display_dpi = 265,
    hasNaturalLight = yes,
    frontlight_settings = {
        frontlight_white = "/sys/class/backlight/lm3630a_ledb",
        frontlight_red = "/sys/class/backlight/lm3630a_leda",
    },
}

-- Kobo Aura second edition:
local KoboStar = Kobo:extend{
    model = "Kobo_star",
    hasFrontlight = yes,
    touch_phoenix_protocol = true,
    display_dpi = 212,
}

-- Kobo Aura second edition, Rev 2:
local KoboStarRev2 = Kobo:extend{
    model = "Kobo_star_r2",
    isMk7 = yes,
    hasFrontlight = yes,
    touch_phoenix_protocol = true,
    display_dpi = 212,
}

-- Kobo Glo HD:
local KoboAlyssum = Kobo:extend{
    model = "Kobo_alyssum",
    hasFrontlight = yes,
    touch_phoenix_protocol = true,
    main_finger_slot = 1,
    display_dpi = 300,
}

-- Kobo Touch 2.0:
local KoboPika = Kobo:extend{
    model = "Kobo_pika",
    touch_phoenix_protocol = true,
    main_finger_slot = 1,
}

-- Kobo Clara HD:
local KoboNova = Kobo:extend{
    model = "Kobo_nova",
    isMk7 = yes,
    canToggleChargingLED = yes,
    hasFrontlight = yes,
    touch_snow_protocol = true,
    display_dpi = 300,
    hasNaturalLight = yes,
    frontlight_settings = {
        frontlight_white = "/sys/class/backlight/mxc_msp430.0/brightness",
        frontlight_mixer = "/sys/class/backlight/lm3630a_led/color",
        nl_min = 0,
        nl_max = 10,
        nl_inverted = true,
    },
}

-- Kobo Forma:
-- NOTE: Right now, we enforce Portrait orientation on startup to avoid getting touch coordinates wrong,
--       no matter the rotation we were started from (c.f., platform/kobo/koreader.sh).
-- NOTE: For the FL, assume brightness is WO, and actual_brightness is RO!
--       i.e., we could have a real KoboPowerD:frontlightIntensityHW() by reading actual_brightness ;).
-- NOTE: Rotation events *may* not be enabled if Nickel has never been brought up in that power cycle.
--       i.e., this will affect KSM users.
--       c.f., https://github.com/koreader/koreader/pull/4414#issuecomment-449652335
--       There's also a CM_ROTARY_ENABLE command, but which seems to do as much nothing as the STATUS one...
local KoboFrost = Kobo:extend{
    model = "Kobo_frost",
    isMk7 = yes,
    canToggleChargingLED = yes,
    hasFrontlight = yes,
    hasKeys = yes,
    hasGSensor = yes,
    canToggleGSensor = yes,
    touch_snow_protocol = true,
    misc_ntx_gsensor_protocol = true,
    display_dpi = 300,
    hasNaturalLight = yes,
    frontlight_settings = {
        frontlight_white = "/sys/class/backlight/mxc_msp430.0/brightness",
        frontlight_mixer = "/sys/class/backlight/tlc5947_bl/color",
        -- Warmth goes from 0 to 10 on the device's side (our own internal scale is still normalized to [0...100])
        -- NOTE: Those three extra keys are *MANDATORY* if frontlight_mixer is set!
        nl_min = 0,
        nl_max = 10,
        nl_inverted = true,
    },
}

-- Kobo Libra:
-- NOTE: Assume the same quirks as the Forma apply.
local KoboStorm = Kobo:extend{
    model = "Kobo_storm",
    isMk7 = yes,
    canToggleChargingLED = yes,
    hasFrontlight = yes,
    hasKeys = yes,
    hasGSensor = yes,
    canToggleGSensor = yes,
    touch_snow_protocol = true,
    misc_ntx_gsensor_protocol = true,
    display_dpi = 300,
    hasNaturalLight = yes,
    frontlight_settings = {
        frontlight_white = "/sys/class/backlight/mxc_msp430.0/brightness",
        frontlight_mixer = "/sys/class/backlight/lm3630a_led/color",
        -- Warmth goes from 0 to 10 on the device's side (our own internal scale is still normalized to [0...100])
        -- NOTE: Those three extra keys are *MANDATORY* if frontlight_mixer is set!
        nl_min = 0,
        nl_max = 10,
        nl_inverted = true,
    },
    -- NOTE: The Libra apparently suffers from a mysterious issue where completely innocuous WAIT_FOR_UPDATE_COMPLETE ioctls
    --       will mysteriously fail with a timeout (5s)...
    --       This obviously leads to *terrible* user experience, so, until more is understood avout the issue,
    --       bypass this ioctl on this device.
    --       c.f., https://github.com/koreader/koreader/issues/7340
    hasReliableMxcWaitFor = no,
}

-- Kobo Nia:
--- @fixme: Mostly untested, assume it's Clara-ish for now.
local KoboLuna = Kobo:extend{
    model = "Kobo_luna",
    isMk7 = yes,
    canToggleChargingLED = yes,
    hasFrontlight = yes,
    touch_phoenix_protocol = true,
    display_dpi = 212,
    hasReliableMxcWaitFor = no, -- Board is similar to the Libra 2, but it's such an unpopular device that reports are scarce.
}

-- Kobo Elipsa
local KoboEuropa = Kobo:extend{
    model = "Kobo_europa",
    isSunxi = yes,
    hasEclipseWfm = yes,
    canToggleChargingLED = yes,
    led_uses_channel_3 = true,
    hasFrontlight = yes,
    hasGSensor = yes,
    canToggleGSensor = yes,
    pressure_event = C.ABS_MT_PRESSURE,
    misc_ntx_gsensor_protocol = true,
    display_dpi = 227,
    boot_rota = C.FB_ROTATE_CCW,
    battery_sysfs = "/sys/class/power_supply/battery",
    ntx_dev = "/dev/input/by-path/platform-ntx_event0-event",
    touch_dev = "/dev/input/by-path/platform-0-0010-event",
    isSMP = yes,
}

-- Kobo Sage
local KoboCadmus = Kobo:extend{
    model = "Kobo_cadmus",
    isSunxi = yes,
    hasEclipseWfm = yes,
    canToggleChargingLED = yes,
    led_uses_channel_3 = true,
    hasFrontlight = yes,
    hasKeys = yes,
    hasGSensor = yes,
    canToggleGSensor = yes,
    pressure_event = C.ABS_MT_PRESSURE,
    misc_ntx_gsensor_protocol = true,
    display_dpi = 300,
    hasNaturalLight = yes,
    frontlight_settings = {
        frontlight_white = "/sys/class/backlight/mxc_msp430.0/brightness",
        frontlight_mixer = "/sys/class/leds/aw99703-bl_FL1/color",
        -- Warmth goes from 0 to 10 on the device's side (our own internal scale is still normalized to [0...100])
        -- NOTE: Those three extra keys are *MANDATORY* if frontlight_mixer is set!
        nl_min = 0,
        nl_max = 10,
        nl_inverted = false,
    },
    boot_rota = C.FB_ROTATE_CW,
    battery_sysfs = "/sys/class/power_supply/battery",
    hasAuxBattery = yes,
    aux_battery_sysfs = "/sys/class/misc/cilix",
    ntx_dev = "/dev/input/by-path/platform-ntx_event0-event",
    touch_dev = "/dev/input/by-path/platform-0-0010-event",
    isSMP = yes,
}

-- Kobo Libra 2:
local KoboIo = Kobo:extend{
    model = "Kobo_io",
    isMk7 = yes,
    hasEclipseWfm = yes,
    canToggleChargingLED = yes,
    hasFrontlight = yes,
    hasKeys = yes,
    hasGSensor = yes,
    canToggleGSensor = yes,
    pressure_event = C.ABS_MT_PRESSURE,
    touch_mirrored_x = false,
    misc_ntx_gsensor_protocol = true,
    display_dpi = 300,
    hasNaturalLight = yes,
    frontlight_settings = {
        frontlight_white = "/sys/class/backlight/mxc_msp430.0/brightness",
        -- Warmth goes from 0 to 10 on the device's side (our own internal scale is still normalized to [0...100])
        -- NOTE: Those three extra keys are *MANDATORY* if frontlight_mixer is set!
        nl_min = 0,
        nl_max = 10,
        nl_inverted = true,
    },
    -- It would appear that the Libra 2 inherited its ancestor's quirks, and more...
    -- c.f., https://github.com/koreader/koreader/issues/8414 & https://github.com/koreader/koreader/issues/8664
    hasReliableMxcWaitFor = no,
    -- NOTE: There are at least two hardware revisions of this device (*without* a device code change, this time),
    --       with *significant* hardware changes, so we'll handle this by making the sysfs path discovery automagic.
    --       c.f., https://github.com/koreader/koreader/issues/9218
    automagic_sysfs = true,
}

-- Kobo Clara 2E:
local KoboGoldfinch = Kobo:extend{
    model = "Kobo_goldfinch",
    isMk7 = yes,
    hasEclipseWfm = yes,
    canToggleChargingLED = yes,
    led_uses_channel_3 = true,
    hasFrontlight = yes,
    display_dpi = 300,
    hasNaturalLight = yes,
    frontlight_settings = {
        frontlight_white = "/sys/class/backlight/mxc_msp430.0/brightness",
        frontlight_mixer = "/sys/class/leds/aw99703-bl_FL1/color",
        nl_min = 0,
        nl_max = 10,
        nl_inverted = true,
    },
    battery_sysfs = "/sys/class/power_supply/battery",
    power_dev = "/dev/input/by-path/platform-bd71828-pwrkey-event",
    -- Board is eerily similar to the Libra 2, which, unfortunately, means it's also buggy as hell...
    -- c.f., https://github.com/koreader/koreader/issues/9552#issuecomment-1293000313
    hasReliableMxcWaitFor = no,
}

function Kobo:setupChargingLED()
    if G_reader_settings:nilOrTrue("enable_charging_led") then
        if self:hasAuxBattery() and self.powerd:isAuxBatteryConnected() then
            self:toggleChargingLED(self.powerd:isAuxCharging() and not self.powerd:isAuxCharged())
        else
            self:toggleChargingLED(self.powerd:isCharging() and not self.powerd:isCharged())
        end
    end
end

function Kobo:getKeyRepeat()
    -- Sanity check (mostly for the testsuite's benefit...)
    if not self.ntx_fd then
        return false
    end

    self.key_repeat = ffi.new("unsigned int[?]", C.REP_CNT)
    if C.ioctl(self.ntx_fd, C.EVIOCGREP, self.key_repeat) < 0 then
        local err = ffi.errno()
        logger.warn("Device:getKeyRepeat: EVIOCGREP ioctl failed:", ffi.string(C.strerror(err)))
        return false
    else
        logger.dbg("Key repeat is set up to repeat every", self.key_repeat[C.REP_PERIOD], "ms after a delay of", self.key_repeat[C.REP_DELAY], "ms")
        return true
    end
end

function Kobo:disableKeyRepeat()
    -- NOTE: LuaJIT zero inits, and PERIOD == 0 with DELAY == 0 disables repeats ;).
    local key_repeat = ffi.new("unsigned int[?]", C.REP_CNT)
    if C.ioctl(self.ntx_fd, C.EVIOCSREP, key_repeat) < 0 then
        local err = ffi.errno()
        logger.warn("Device:disableKeyRepeat: EVIOCSREP ioctl failed:", ffi.string(C.strerror(err)))
    end
end

function Kobo:restoreKeyRepeat()
    if C.ioctl(self.ntx_fd, C.EVIOCSREP, self.key_repeat) < 0 then
        local err = ffi.errno()
        logger.warn("Device:restoreKeyRepeat: EVIOCSREP ioctl failed:", ffi.string(C.strerror(err)))
    end
end

function Kobo:init()
    -- Check if we need to disable MXCFB_WAIT_FOR_UPDATE_COMPLETE ioctls...
    local mxcfb_bypass_wait_for
    if G_reader_settings:has("mxcfb_bypass_wait_for") then
        mxcfb_bypass_wait_for = G_reader_settings:isTrue("mxcfb_bypass_wait_for")
    else
        mxcfb_bypass_wait_for = not self:hasReliableMxcWaitFor()
    end

    if self:isSunxi() then
        self.screen = require("ffi/framebuffer_sunxi"):new{
            device = self,
            debug = logger.dbg,
            is_always_portrait = self.isAlwaysPortrait(),
            mxcfb_bypass_wait_for = mxcfb_bypass_wait_for,
            boot_rota = self.boot_rota,
        }

        -- Sunxi means no HW inversion :(
        self.canHWInvert = no
    else
        self.screen = require("ffi/framebuffer_mxcfb"):new{
            device = self,
            debug = logger.dbg,
            is_always_portrait = self.isAlwaysPortrait(),
            mxcfb_bypass_wait_for = mxcfb_bypass_wait_for,
        }
        if self.screen.fb_bpp == 32 then
            -- Ensure we decode images properly, as our framebuffer is BGRA...
            logger.info("Enabling Kobo @ 32bpp BGR tweaks")
            self.hasBGRFrameBuffer = yes
        end
    end

    -- Automagic sysfs discovery
    if self.automagic_sysfs then
        -- Battery
        if util.pathExists("/sys/class/power_supply/battery") then
            -- Newer devices (circa sunxi)
            self.battery_sysfs = "/sys/class/power_supply/battery"
        else
            self.battery_sysfs = "/sys/class/power_supply/mc13892_bat"
        end

        -- Frontlight
        if self:hasNaturalLight() then
            if util.fileExists("/sys/class/leds/aw99703-bl_FL1/color") then
                -- HWConfig FL_PWM is AW99703x2
                self.frontlight_settings.frontlight_mixer = "/sys/class/leds/aw99703-bl_FL1/color"
            elseif util.fileExists("/sys/class/backlight/lm3630a_led/color") then
                -- HWConfig FL_PWM is LM3630
                self.frontlight_settings.frontlight_mixer = "/sys/class/backlight/lm3630a_led/color"
            elseif util.fileExists("/sys/class/backlight/tlc5947_bl/color") then
                -- HWConfig FL_PWM is TLC5947
                self.frontlight_settings.frontlight_mixer = "/sys/class/backlight/tlc5947_bl/color"
            end
        end

        -- Input
        if util.fileExists("/dev/input/by-path/platform-1-0010-event") then
            -- Elan (HWConfig TouchCtrl is ekth6) on i2c bus 1
            self.touch_dev = "/dev/input/by-path/platform-1-0010-event"
        elseif util.fileExists("/dev/input/by-path/platform-0-0010-event") then
            -- Elan (HWConfig TouchCtrl is ekth6) on i2c bus 0
            self.touch_dev = "/dev/input/by-path/platform-0-0010-event"
        else
            self.touch_dev = "/dev/input/event1"
        end

        if util.fileExists("/dev/input/by-path/platform-gpio-keys-event") then
            -- Libra 2 w/ a BD71828 PMIC
            self.ntx_dev = "/dev/input/by-path/platform-gpio-keys-event"
        elseif util.fileExists("/dev/input/by-path/platform-ntx_event0-event") then
            -- sunxi & Mk. 7
            self.ntx_dev = "/dev/input/by-path/platform-ntx_event0-event"
        elseif util.fileExists("/dev/input/by-path/platform-mxckpd-event") then
            -- circa Mk. 5 i.MX
            self.ntx_dev = "/dev/input/by-path/platform-mxckpd-event"
        else
            self.ntx_dev = "/dev/input/event0"
        end

        if util.fileExists("/dev/input/by-path/platform-bd71828-pwrkey-event") then
            -- Libra 2 w/ a BD71828 PMIC
            self.power_dev = "/dev/input/by-path/platform-bd71828-pwrkey-event"
        end
    end

    -- NOTE: i.MX5 devices have a wonky RTC that doesn't like alarms set further away that UINT16_MAX seconds from now...
    --       (c.f., WakeupMgr for more details).
    -- NOTE: getRTCName is currently hardcoded to rtc0 (which is also WakeupMgr's default).
    local dodgy_rtc = false
    if getRTCName() == "pmic_rtc" then
        -- This *should* match the 'RTC' (46) NTX HWConfig field being set to 'MSP430' (0).
        dodgy_rtc = true
    end

    -- Detect the various CPU governor sysfs knobs...
    if util.pathExists("/sys/devices/system/cpu/cpufreq/policy0") then
        self.cpu_governor_knob = "/sys/devices/system/cpu/cpufreq/policy0/scaling_governor"
    else
        self.cpu_governor_knob = "/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor"
    end
    self.default_cpu_governor = getCPUGovernor(self.cpu_governor_knob)
    -- NOP unsupported methods
    if not self.default_cpu_governor then
        self.performanceCPUGovernor = NOP
        self.defaultCPUGovernor = NOP
    end

    -- And while we're on CPU-related endeavors...
    self.cpu_count = self:isSMP() and getCPUCount() or 1
    -- NOP unsupported methods
    if self.cpu_count == 1 then
        self.enableCPUCores = NOP
    end

    -- Automagically set this so we never have to remember to do it manually ;p
    if self:hasNaturalLight() and self.frontlight_settings and self.frontlight_settings.frontlight_mixer then
        self.hasNaturalLightMixer = yes
    end
    -- Ditto
    if self:isMk7() then
        self.canHWDither = yes
    end

    self.powerd = require("device/kobo/powerd"):new{
        device = self,
        battery_sysfs = self.battery_sysfs,
        aux_battery_sysfs = self.aux_battery_sysfs,
    }
    -- NOTE: For the Forma, with the buttons on the right, 193 is Top, 194 Bottom.
    self.input = require("device/input"):new{
        device = self,
        event_map = {
            [35] = "SleepCover",  -- KEY_H, Elipsa
            [59] = "SleepCover",
            [90] = "LightButton",
            [102] = "Home",
            [116] = "Power",
            [193] = "RPgBack",
            [194] = "RPgFwd",
            [331] = "Eraser",
            [332] = "Highlighter",
        },
        event_map_adapter = {
            SleepCover = function(ev)
                if self.input:isEvKeyPress(ev) then
                    return "SleepCoverClosed"
                elseif self.input:isEvKeyRelease(ev) then
                    return "SleepCoverOpened"
                end
            end,
            LightButton = function(ev)
                if self.input:isEvKeyRelease(ev) then
                    return "Light"
                end
            end,
        },
        main_finger_slot = self.main_finger_slot or 0,
        pressure_event = self.pressure_event,
    }
    self.wakeup_mgr = WakeupMgr:new{
        dodgy_rtc = dodgy_rtc,
    }

    -- Let generic properly setup the standard stuff
    Generic.init(self)

    -- Various HW Buttons, Switches & Synthetic NTX events
    self.ntx_fd = self.input.open(self.ntx_dev)
    -- Dedicated Power Button input device (if any)
    if self.power_dev then
        self.input.open(self.power_dev)
    end
    -- Touch panel
    self.input.open(self.touch_dev)
    -- NOTE: On devices with a gyro, there may be a dedicated input device outputting the raw accelerometer data
    --       (3-Axis Orientation/Motion Detection).
    --       We skip it because we don't need it (synthetic rotation change events are sent to the main ntx input device),
    --       and it's usually *extremely* verbose, so it'd just be a waste of processing power.
    -- fake_events is only used for usb plug & charge events so far (generated via uevent, c.f., input/iput-kobo.h in base).
    -- NOTE: usb hotplug event is also available in /tmp/nickel-hardware-status (... but only when Nickel is running ;p)
    self.input.open("fake_events")

    -- Input handling on Kobo is a thing of nightmares, start by setting up the actual evdev handler...
    self:setTouchEventHandler()
    -- And then handle the extra shenanigans if necessary.
    self:initEventAdjustHooks()

    -- See if the device supports key repeat
    if not self:getKeyRepeat() then
        -- NOP unsupported methods
        self.disableKeyRepeat = NOP
        self.restoreKeyRepeat = NOP
    end

    -- Detect the NTX charging LED sysfs knob
    if util.pathExists("/sys/devices/platform/ntx_led/lit") then
        self.ntx_lit_sysfs_knob = "/sys/devices/platform/ntx_led/lit"
    elseif util.pathExists("/sys/devices/platform/pmic_light.1/lit") then
        self.ntx_lit_sysfs_knob = "/sys/devices/platform/pmic_light.1/lit"
    else
        self.canToggleChargingLED = no
    end

    -- NOP unsupported methods
    if not self:canToggleChargingLED() then
        self.toggleChargingLED = NOP
        self.setupChargingLED = NOP
    end

    -- We have no way of querying the current state of the charging LED, so, start from scratch.
    -- Much like Nickel, start by turning it off.
    self:toggleChargingLED(false)
    self:setupChargingLED()

    -- Only enable a single core on startup
    self:enableCPUCores(1)

    self.canStandby = checkStandby()
    if self.canStandby() and (self:isMk7() or self:isSunxi())  then
        self.canPowerSaveWhileCharging = yes
    end

    -- Check if the device has a Neonode IR grid (to tone down the chatter on resume ;)).
    if lfs.attributes("/sys/devices/virtual/input/input1/neocmd", "mode") == "file" then
        -- As found on (at least), the Aura H2O
        self.hasIRGridSysfsKnob = "/sys/devices/virtual/input/input1/neocmd"
    elseif lfs.attributes("/sys/devices/platform/imx-i2c.1/i2c-1/1-0050/neocmd", "mode") == "file" then
        -- As found on (at least) the Glo HD (c.f., https://github.com/koreader/koreader/pull/9377#issuecomment-1213544478)
        self.hasIRGridSysfsKnob = "/sys/devices/platform/imx-i2c.1/i2c-1/1-0050/neocmd"
    end
end

function Kobo:setDateTime(year, month, day, hour, min, sec)
    if hour == nil or min == nil then return true end
    local command
    if year and month and day then
        command = string.format("date -s '%d-%d-%d %d:%d:%d'", year, month, day, hour, min, sec)
    else
        command = string.format("date -s '%d:%d'",hour, min)
    end
    if os.execute(command) == 0 then
        os.execute("hwclock -u -w")
        return true
    else
        return false
    end
end

function Kobo:initNetworkManager(NetworkMgr)
    function NetworkMgr:turnOffWifi(complete_callback)
        self:releaseIP()
        koboEnableWifi(false)
        if complete_callback then
            complete_callback()
        end
    end

    function NetworkMgr:turnOnWifi(complete_callback)
        koboEnableWifi(true)
        self:reconnectOrShowNetworkMenu(complete_callback)
    end

    local net_if = os.getenv("INTERFACE")
    if not net_if then
        net_if = "eth0"
    end
    function NetworkMgr:getNetworkInterfaceName()
        return net_if
    end
    NetworkMgr:setWirelessBackend(
        "wpa_supplicant", {ctrl_interface = "/var/run/wpa_supplicant/" .. net_if})

    function NetworkMgr:obtainIP()
        os.execute("./obtain-ip.sh")
    end

    function NetworkMgr:releaseIP()
        os.execute("./release-ip.sh")
    end

    function NetworkMgr:restoreWifiAsync()
        os.execute("./restore-wifi-async.sh")
    end

    NetworkMgr.isWifiOn = koboIsWifiOn
end

function Kobo:setTouchEventHandler()
    if self.touch_snow_protocol then
        self.input.snow_protocol = true
    elseif self.touch_phoenix_protocol then
        self.input.handleTouchEv = self.input.handleTouchEvPhoenix
    elseif not self:hasMultitouch() then
        self.input.handleTouchEv = self.input.handleTouchEvLegacy
        if self.touch_kobo_mk3_protocol then
            self.input.touch_kobo_mk3_protocol = true
        end
    end

    -- Accelerometer
    if self.misc_ntx_gsensor_protocol then
        if G_reader_settings:isTrue("input_ignore_gsensor") then
            self.input.isNTXAccelHooked = false
        else
            self.input.handleMiscEv = self.input.handleMiscEvNTX
            self.input.isNTXAccelHooked = true
        end
    end
end

function Kobo:initEventAdjustHooks()
    -- NOTE: adjustTouchSwitchXY needs to be called before adjustTouchMirrorX
    if self.touch_switch_xy then
        self.input:registerEventAdjustHook(self.input.adjustTouchSwitchXY)
    end

    if self.touch_mirrored_x then
        self.input:registerEventAdjustHook(
            self.input.adjustTouchMirrorX,
            --- NOTE: This is safe, we enforce the canonical portrait rotation on startup.
            (self.screen:getWidth() - 1)
        )
    end
end

local function getCodeName()
    -- Try to get it from the env first
    local codename = os.getenv("PRODUCT")
    -- If that fails, run the script ourselves
    if not codename then
        local std_out = io.popen("/bin/kobo_config.sh 2>/dev/null", "re")
        if std_out then
            codename = std_out:read("*line")
            std_out:close()
        end
    end
    return codename
end

function Kobo:getFirmwareVersion()
    local version_file = io.open("/mnt/onboard/.kobo/version", "re")
    if not version_file then
        self.firmware_rev = "none"
        return
    end
    local version_str = version_file:read("*line")
    version_file:close()

    local i = 1
    for field in version_str:gmatch("([^,]+)") do
        if i == 3 then
            self.firmware_rev = field
            break
        end
        i = i + 1
    end
end

local function getProductId()
    -- Try to get it from the env first (KSM only)
    local product_id = os.getenv("MODEL_NUMBER")
    -- If that fails, devise it ourselves
    if not product_id then
        local version_file = io.open("/mnt/onboard/.kobo/version", "re")
        if not version_file then
            return "000"
        end
        local version_str = version_file:read("*line")
        version_file:close()

        product_id = string.sub(version_str, -3, -1)
    end

    return product_id
end

-- NOTE: We overload this to make sure checkUnexpectedWakeup doesn't trip *before* the newly scheduled suspend
function Kobo:rescheduleSuspend()
    UIManager:unschedule(self.suspend)
    UIManager:unschedule(self.checkUnexpectedWakeup)
    UIManager:scheduleIn(self.suspend_wait_timeout, self.suspend, self)
end

function Kobo:checkUnexpectedWakeup()
    -- Just in case another event like SleepCoverClosed also scheduled a suspend
    UIManager:unschedule(self.suspend)

    -- The proximity window is rather large, because we're scheduled to run 15 seconds after resuming,
    -- so we're already guaranteed to be at least 15s away from the alarm ;).
    if self.wakeup_mgr:isWakeupAlarmScheduled() and self.wakeup_mgr:wakeupAction(30) then
        -- Assume we want to go back to sleep after running the scheduled action
        -- (Kobo:resume will unschedule this on an user-triggered resume).
        logger.info("Kobo suspend: scheduled wakeup; the device will go back to sleep in 30s.")
        -- We need significant leeway for the poweroff action to send out close events to all requisite widgets,
        -- since we don't actually want to suspend behind its back ;).
        UIManager:scheduleIn(30, self.suspend, self)
    else
        -- We've hit an early resume, assume this is unexpected (as we only run if Kobo:resume hasn't already).
        logger.dbg("Kobo suspend: checking unexpected wakeup number", self.unexpected_wakeup_count)
        if self.unexpected_wakeup_count > 20 then
            -- If we've failed to put the device back to sleep over 20 consecutive times, we give up.
            -- Broadcast a specific event, so that AutoSuspend can pick up the baton...
            local Event = require("ui/event")
            UIManager:broadcastEvent(Event:new("UnexpectedWakeupLimit"))
            return
        end

        logger.err("Kobo suspend: putting device back to sleep after", self.unexpected_wakeup_count, "unexpected wakeups.")
        self:suspend()
    end
end

--- The function to put the device into standby, with enabled touchscreen.
-- max_duration ... maximum time for the next standby, can wake earlier (e.g. Tap, Button ...)
function Kobo:standby(max_duration)
    -- NOTE: Switch to the performance CPU governor, in order to speed up the resume process so as to lower its latency cost...
    --       (It won't have any impact on power efficiency *during* suspend, so there's not really any drawback).
    self:performanceCPUGovernor()

    --[[
    -- On most devices, attempting to PM with a Wi-Fi module loaded will horribly crash the kernel, so, don't?
    -- NOTE: Much like suspend, our caller should ensure this never happens, hence this being commented out ;).
    if koboIsWifiOn() then
        -- AutoSuspend relies on NetworkMgr:getWifiState to prevent this, so, if we ever trip this, it's a bug ;).
        logger.err("Kobo standby: cannot standby with Wi-Fi modules loaded! (NetworkMgr is confused: this is a bug)")
        return
    end
    --]]

    -- We don't really have anything to schedule, we just need an alarm out of WakeupMgr ;).
    local function standby_alarm()
    end

    if max_duration then
        self.wakeup_mgr:addTask(max_duration, standby_alarm)
    end

    logger.dbg("Kobo standby: asking to enter standby . . .")
    local standby_time = time.boottime_or_realtime_coarse()

    local ret = writeToSys("standby", "/sys/power/state")

    self.last_standby_time = time.boottime_or_realtime_coarse() - standby_time
    self.total_standby_time = self.total_standby_time + self.last_standby_time

    if ret then
        logger.dbg("Kobo standby: zZz zZz zZz zZz... And woke up!")
        if G_reader_settings:isTrue("pm_debug_entry_failure") then
            -- NOTE: This is a debug option where we coopt the charging LED, hence us not using setupChargingLED here.
            --       (It's called on resume anyway).
            self:toggleChargingLED(false)
        end
    else
        logger.warn("Kobo standby: the kernel refused to enter standby!")
        if G_reader_settings:isTrue("pm_debug_entry_failure") then
            self:toggleChargingLED(true)
        end
    end

    if max_duration then
        -- NOTE: We don't actually care about discriminating exactly *why* we woke up,
        --       and our scheduled wakeup action is a NOP anyway,
        --       so we can just drop the task instead of doing things the right way like suspend ;).
        --       This saves us some pointless RTC shenanigans, so, everybody wins.
        --[[
        -- There's no scheduling shenanigans like in suspend, so the proximity window can be much tighter...
        if self.wakeup_mgr:isWakeupAlarmScheduled() and self.wakeup_mgr:wakeupAction(5) then
            -- We tripped the standby alarm, UIManager will be able to run whatever was actually scheduled,
            -- and AutoSuspend will handle going back to standby if necessary.
            logger.dbg("Kobo standby: tripped rtc wake alarm")
        end
        --]]
        self.wakeup_mgr:removeTasks(nil, standby_alarm)
    end

    -- And restore the standard CPU scheduler once we're done dealing with the wakeup event.
    UIManager:tickAfterNext(self.defaultCPUGovernor, self)
end

function Kobo:suspend()
    logger.info("Kobo suspend: going to sleep . . .")
    UIManager:unschedule(self.checkUnexpectedWakeup)
    -- NOTE: Sleep as little as possible here, sleeping has a tendency to make
    -- everything mysteriously hang...

    -- Depending on device/FW version, some kernels do not support
    -- wakeup_count, account for that
    --
    -- NOTE: ... and of course, it appears to be broken, which probably
    -- explains why nickel doesn't use this facility...
    -- (By broken, I mean that the system wakes up right away).
    -- So, unless that changes, unconditionally disable it.

    --[[
    local f, re, err_msg, err_code
    local has_wakeup_count = false
    f = io.open("/sys/power/wakeup_count", "re")
    if f ~= nil then
        f:close()
        has_wakeup_count = true
    end

    -- Clear the kernel ring buffer... (we're missing a proper -C flag...)
    --dmesg -c >/dev/null

    -- Go to sleep
    local curr_wakeup_count
    if has_wakeup_count then
        curr_wakeup_count = "$(cat /sys/power/wakeup_count)"
        logger.dbg("Kobo suspend: Current WakeUp count:", curr_wakeup_count)
    end
    -]]

    -- NOTE: Sets gSleep_Mode_Suspend to 1. Used as a flag throughout the
    --       kernel to suspend/resume various subsystems
    --       c.f., state_extended_store @ kernel/power/main.c
    local ret = writeToSys("1", "/sys/power/state-extended")
    if ret then
        logger.dbg("Kobo suspend: successfully asked the kernel to put subsystems to sleep")
    else
        logger.warn("Kobo suspend: the kernel refused to flag subsystems for suspend!")
    end

    ffiUtil.sleep(2)
    logger.dbg("Kobo suspend: waited for 2s because of reasons...")

    os.execute("sync")
    logger.dbg("Kobo suspend: synced FS")

    --[[
    if has_wakeup_count then
        f = io.open("/sys/power/wakeup_count", "we")
        if not f then
            logger.err("cannot open /sys/power/wakeup_count")
            return false
        end
        re, err_msg, err_code = f:write(tostring(curr_wakeup_count), "\n")
        logger.dbg("Kobo suspend: wrote WakeUp count:", curr_wakeup_count)
        if not re then
            logger.err("Kobo suspend: failed to write WakeUp count:",
                       err_msg,
                       err_code)
        end
        f:close()
    end
    --]]

    logger.dbg("Kobo suspend: asking for a suspend to RAM . . .")
    local suspend_time = time.boottime_or_realtime_coarse()

    ret = writeToSys("mem", "/sys/power/state")

    -- NOTE: At this point, we *should* be in suspend to RAM, as such,
    --       execution should only resume on wakeup...
    self.last_suspend_time = time.boottime_or_realtime_coarse() - suspend_time
    self.total_suspend_time = self.total_suspend_time + self.last_suspend_time

    if ret then
        logger.info("Kobo suspend: ZzZ ZzZ ZzZ... And woke up!")
        if G_reader_settings:isTrue("pm_debug_entry_failure") then
            self:toggleChargingLED(false)
        end
    else
        logger.warn("Kobo suspend: the kernel refused to enter suspend!")
        -- Reset state-extended back to 0 since we are giving up.
        writeToSys("0", "/sys/power/state-extended")
        if G_reader_settings:isTrue("pm_debug_entry_failure") then
            self:toggleChargingLED(true)
        end
    end

    -- NOTE: Ideally, we'd need a way to warn the user that suspending
    --       gloriously failed at this point...
    --       We can safely assume that just from a non-zero return code, without
    --       looking at the detailed stderr message
    --       (most of the failures we'll see are -EBUSY anyway)
    --       For reference, when that happens to nickel, it appears to keep retrying
    --       to wakeup & sleep ad nauseam,
    --       which is where the non-sensical 1 -> mem -> 0 loop idea comes from...
    --       cf. nickel_suspend_strace.txt for more details.
    -- NOTE: On recent enough kernels, with debugfs enabled and mounted, see also
    --       /sys/kernel/debug/suspend_stats & /sys/kernel/debug/wakeup_sources

    --[[
    if has_wakeup_count then
        logger.dbg("wakeup count: $(cat /sys/power/wakeup_count)")
    end

    -- Print tke kernel log since our attempt to sleep...
    --dmesg -c
    --]]

    -- NOTE: We unflag /sys/power/state-extended in Kobo:resume() to keep
    --       things tidy and easier to follow

    -- Kobo:resume() will reset unexpected_wakeup_count and unschedule the check to signal a sane wakeup.
    self.unexpected_wakeup_count = self.unexpected_wakeup_count + 1
    logger.dbg("Kobo suspend: scheduling unexpected wakeup guard")
    UIManager:scheduleIn(15, self.checkUnexpectedWakeup, self)
end

function Kobo:resume()
    logger.dbg("Kobo resume: clean up after wakeup")
    -- Reset unexpected_wakeup_count ASAP
    self.unexpected_wakeup_count = 0
    -- Unschedule the checkUnexpectedWakeup shenanigans.
    UIManager:unschedule(self.checkUnexpectedWakeup)
    UIManager:unschedule(self.suspend)

    -- Now that we're up, unflag subsystems for suspend...
    -- NOTE: Sets gSleep_Mode_Suspend to 0. Used as a flag throughout the
    --       kernel to suspend/resume various subsystems
    --       cf. kernel/power/main.c @ L#207
    --       Among other things, this sets up the wakeup pins (e.g., resume on input).
    local ret = writeToSys("0", "/sys/power/state-extended")
    if ret then
        logger.dbg("Kobo resume: successfully asked the kernel to resume subsystems")
    else
        logger.warn("Kobo resume: the kernel refused to flag subsystems for resume!")
    end

    -- HACK: wait a bit (0.1 sec) for the kernel to catch up
    ffiUtil.usleep(100000)

    if self.hasIRGridSysfsKnob then
        -- cf. #1862, I can reliably break IR touch input on resume...
        -- cf. also #1943 for the rationale behind applying this workaround in every case...
        -- c.f., neo_ctl @ drivers/input/touchscreen/zforce_i2c.c,
        -- basically, a is wakeup (for activate), d is sleep (for deactivate), and we don't care about s (set res),
        -- and l (led signal level, actually a NOP on NTX kernels).
        writeToSys("a", self.hasIRGridSysfsKnob)
    end

    -- A full suspend may have toggled the LED off.
    self:setupChargingLED()
end

function Kobo:usbPlugOut()
    -- Rewind the unexpected wakeup counter, since we're no longer charging, meaning power savings are now critical again ;).
    -- NOTE: We don't reset it to 0 because, semantically, only resume should ever be allowed to do so.
    if self.unexpected_wakeup_count > 0 then
        self.unexpected_wakeup_count = 1
    end
end

function Kobo:saveSettings()
    -- save frontlight state to G_reader_settings (and NickelConf if needed)
    self.powerd:saveSettings()
end

function Kobo:powerOff()
    -- Much like Nickel itself, disable the RTC alarm before powering down.
    self.wakeup_mgr:unsetWakeupAlarm()

    -- Then shut down without init's help
    os.execute("sleep 1 && poweroff -f &")
end

function Kobo:reboot()
    os.execute("sleep 1 && reboot &")
end

function Kobo:toggleGSensor(toggle)
    if self:canToggleGSensor() and self.input then
        if self.misc_ntx_gsensor_protocol then
            self.input:toggleMiscEvNTX(toggle)
        end
    end
end

function Kobo:toggleChargingLED(toggle)
    -- We have no way of querying the current state from the HW!
    if toggle == nil then
        return
    end
    -- Don't do anything if the state is already correct
    -- NOTE: What happens to the LED when attempting/successfully entering PM is... kind of a mess.
    --       On a H2O, even *attempting* to enter PM will kill the light (and it'll stay off).
    --       On a Forma, a failed attempt will *not* affect the light, but a successful one *will* kill it,
    --       be that standby or suspend, but it'll be restored on wakeup...
    --       On sunxi, PM appears to have zero effect on the LED.
    if self.charging_led_state == toggle then
        return
    end
    self.charging_led_state = toggle
    logger.dbg("Kobo: Turning the charging LED", toggle and "on" or "off")

    -- NOTE: While most/all Kobos actually have a charging LED, and it can usually be fiddled with in a similar fashion,
    --       we've seen *extremely* weird behavior in the past when playing with it on older devices (c.f., #5479).
    --       In fact, Nickel itself doesn't provide this feature on said older devices
    --       (when it does, it's an option in the Energy saving settings),
    --       which is why we also limit ourselves to "true" on devices where this was tested.
    -- c.f., drivers/misc/ntx_misc_light.c
    local fd = C.open(self.ntx_lit_sysfs_knob, bit.bor(C.O_WRONLY, C.O_CLOEXEC)) -- procfs/sysfs, we shouldn't need O_TRUNC
    if fd == -1 then
        logger.err("Cannot open file `" .. self.ntx_lit_sysfs_knob .. "`:", ffi.string(C.strerror(ffi.errno())))
        return false
    end

    -- c.f., strace -fittTvyy -e trace=ioctl,file,signal,ipc,desc -s 256 -o /tmp/nickel.log -p $(pidof -s nickel) &
    -- This was observed on a Forma, so I'm mildly hopeful that it's safe on other Mk. 7 devices ;).
    -- NOTE: ch stands for channel, cur for current, dc for duty cycle. c.f., the driver source.
    if toggle == true then
        -- NOTE: Technically, Nickel forces a toggle off before that, too.
        --       But since we do that on startup, it shouldn't be necessary here...
        for ch = self.led_uses_channel_3 and 3 or 4, 4 do
            C.write(fd, "ch " .. tostring(ch), 4)
            C.write(fd, "cur 1", 5)
            C.write(fd, "dc 63", 5)
        end
    else
        for ch = 3, 5 do
            C.write(fd, "ch " .. tostring(ch), 4)
            C.write(fd, "cur 1", 5)
            C.write(fd, "dc 0", 4)
        end
    end

    C.close(fd)
end

-- Return the highest core number
function Kobo:getCPUCount()
    local fd = io.open("/sys/devices/system/cpu/possible", "re")
    if fd then
        local str = fd:read("*line")
        fd:close()

        -- Format is n-N, where n is the first core, and N the last (e.g., 0-3)
        return tonumber(str:match("%d+$")) or 1
    else
        return 1
    end
end

function Kobo:enableCPUCores(amount)
    -- CPU0 is *always* online ;).
    for n = 1, self.cpu_count do
        local path = "/sys/devices/system/cpu/cpu" .. n .. "/online"
        local up
        if n >= amount then
            up = "0"
        else
            up = "1"
        end

        writeToSys(up, path)
    end
end

function Kobo:performanceCPUGovernor()
    writeToSys("performance", self.cpu_governor_knob)
end

function Kobo:defaultCPUGovernor()
    writeToSys(self.default_cpu_governor, self.cpu_governor_knob)
end

function Kobo:isStartupScriptUpToDate()
    -- Compare the hash of the *active* script (i.e., the one in /tmp) to the *potential* one (i.e., the one in KOREADER_DIR)
    local current_script = "/tmp/koreader.sh"
    local new_script = os.getenv("KOREADER_DIR") .. "/" .. "koreader.sh"

    local md5 = require("ffi/MD5")
    return md5.sumFile(current_script) == md5.sumFile(new_script)
end

function Kobo:setEventHandlers(uimgr)
    -- Update our module-local
    UIManager = uimgr

    -- We do not want auto suspend procedure to waste battery during
    -- suspend. So let's unschedule it when suspending, and restart it after
    -- resume. Done via the plugin's onSuspend/onResume handlers.
    UIManager.event_handlers.Suspend = function()
        self:_beforeSuspend()
        self:onPowerEvent("Suspend")
    end
    UIManager.event_handlers.Resume = function()
        -- MONOTONIC doesn't tick during suspend,
        -- invalidate the last battery capacity pull time so that we get up to date data immediately.
        self:getPowerDevice():invalidateCapacityCache()

        self:onPowerEvent("Resume")
        self:_afterResume()
    end
    UIManager.event_handlers.PowerPress = function()
        -- Always schedule power off.
        -- Press the power button for 2+ seconds to shutdown directly from suspend.
        UIManager:scheduleIn(2, UIManager.poweroff_action)
    end
    UIManager.event_handlers.PowerRelease = function()
        if not UIManager._entered_poweroff_stage then
            UIManager:unschedule(UIManager.poweroff_action)
            -- resume if we were suspended
            if self.screen_saver_mode then
                if self.screen_saver_lock then
                    -- This can only happen when some sort of screensaver_delay is set,
                    -- and the user presses the Power button *after* already having woken up the device.
                    -- In this case, we want to go back to suspend *without* affecting the screensaver,
                    -- so we mimic UIManager.event_handlers.Suspend's behavior when *not* in screen_saver_mode ;).
                    logger.dbg("Pressed power while awake in screen saver mode, going back to suspend...")
                    self:_beforeSuspend()
                    self.powerd:beforeSuspend() -- this won't be run by onPowerEvent because we're in screen_saver_mode
                    self:onPowerEvent("Suspend")
                else
                    UIManager.event_handlers.Resume()
                end
            else
                UIManager.event_handlers.Suspend()
            end
        end
    end
    UIManager.event_handlers.Light = function()
        self:getPowerDevice():toggleFrontlight()
    end
    -- USB plug events with a power-only charger
    UIManager.event_handlers.Charging = function()
        self:_beforeCharging()
        -- NOTE: Plug/unplug events will wake the device up, which is why we put it back to sleep.
        if self.screen_saver_mode then
           UIManager.event_handlers.Suspend()
        end
    end
    UIManager.event_handlers.NotCharging = function()
        -- We need to put the device into suspension, other things need to be done before it.
        self:usbPlugOut()
        self:_afterNotCharging()
        if self.screen_saver_mode then
           UIManager.event_handlers.Suspend()
        end
    end
    -- USB plug events with a data-aware host
    UIManager.event_handlers.UsbPlugIn = function()
        self:_beforeCharging()
        -- NOTE: Plug/unplug events will wake the device up, which is why we put it back to sleep.
        if self.screen_saver_mode then
            UIManager.event_handlers.Suspend()
        else
            -- Potentially start an USBMS session
            local MassStorage = require("ui/elements/mass_storage")
            MassStorage:start()
        end
    end
    UIManager.event_handlers.UsbPlugOut = function()
        -- We need to put the device into suspension, other things need to be done before it.
        self:usbPlugOut()
        self:_afterNotCharging()
        if self.screen_saver_mode then
            UIManager.event_handlers.Suspend()
        else
            -- Potentially dismiss the USBMS ConfirmBox
            local MassStorage = require("ui/elements/mass_storage")
            MassStorage:dismiss()
        end
    end
    -- Sleep Cover handling
    if G_reader_settings:isTrue("ignore_power_sleepcover") then
        -- NOTE: The hardware event itself will wake the kernel up if it's in suspend (:/).
        --       Let the unexpected wakeup guard handle that.
        UIManager.event_handlers.SleepCoverClosed = nil
        UIManager.event_handlers.SleepCoverOpened = nil
    elseif G_reader_settings:isTrue("ignore_open_sleepcover") then
        -- Just ignore wakeup events, and do NOT set is_cover_closed,
        -- so device/generic/device will let us use the power button to wake ;).
        UIManager.event_handlers.SleepCoverClosed = function()
            UIManager.event_handlers.Suspend()
        end
        UIManager.event_handlers.SleepCoverOpened = function()
            self.is_cover_closed = false
        end
    else
        UIManager.event_handlers.SleepCoverClosed = function()
            self.is_cover_closed = true
            UIManager.event_handlers.Suspend()
        end
        UIManager.event_handlers.SleepCoverOpened = function()
            self.is_cover_closed = false
            UIManager.event_handlers.Resume()
        end
    end
end

-------------- device probe ------------

local codename = getCodeName()
local product_id = getProductId()

if codename == "dahlia" then
    return KoboDahlia
elseif codename == "dragon" then
    return KoboDragon
elseif codename == "kraken" then
    return KoboKraken
elseif codename == "phoenix" then
    return KoboPhoenix
elseif codename == "trilogy" and product_id == "310" then
    -- This is where things get interesting...
    -- The early 'A' variant (the actual model name being N905, without any letter suffix, unlike the two other variants)
    -- does *NOT* feature an internal SD card, and is manufactured in China instead of Taiwan... because it is *NOT* an NTX board.
    -- c.f., #9742
    if os.getenv("PLATFORM") == "freescale" then
        return KoboTrilogyA
    else
        return KoboTrilogyB
    end
elseif codename == "trilogy" and product_id == "320" then
    return KoboTrilogyC
elseif codename == "pixie" then
    return KoboPixie
elseif codename == "alyssum" then
    return KoboAlyssum
elseif codename == "pika" then
    return KoboPika
elseif codename == "star" and product_id == "379" then
    return KoboStarRev2
elseif codename == "star" then
    return KoboStar
elseif codename == "daylight" then
    return KoboDaylight
elseif codename == "snow" and product_id == "378" then
    return KoboSnowRev2
elseif codename == "snow" then
    return KoboSnow
elseif codename == "nova" then
    return KoboNova
elseif codename == "frost" then
    return KoboFrost
elseif codename == "storm" then
    return KoboStorm
elseif codename == "luna" then
    return KoboLuna
elseif codename == "europa" then
    return KoboEuropa
elseif codename == "cadmus" then
    return KoboCadmus
elseif codename == "io" then
    return KoboIo
elseif codename == "goldfinch" then
    return KoboGoldfinch
else
    error("unrecognized Kobo model ".. codename .. " with device id " .. product_id)
end