Support the Kindle PW4 (#4324)

* Fix version checks on FW >= 5.10.x
* Bump base

frontend/device/kindle/device.lua

@@ -263,6 +263,14 @@ local KindleBasic2 = Kindle:new{
     touch_dev = "/dev/input/event0",
 }
 
+local KindlePaperWhite4 = Kindle:new{
+    model = "KindlePaperWhite4",
+    isTouchDevice = yes,
+    hasFrontlight = yes,
+    display_dpi = 300,
+    touch_dev = "/dev/input/event2",
+}
+
 function Kindle2:init()
     self.screen = require("ffi/framebuffer_einkfb"):new{device = self, debug = logger.dbg}
     self.powerd = require("device/kindle/powerd"):new{
@@ -623,6 +631,22 @@ function KindleBasic2:init()
     self.input.open("fake_events")
 end
 
+-- NOTE: FrontLight might be wrong, TBC!
+function KindlePaperWhite4:init()
+    self.screen = require("ffi/framebuffer_mxcfb"):new{device = self, debug = logger.dbg}
+    self.powerd = require("device/kindle/powerd"):new{
+        device = self,
+        fl_intensity_file = "/sys/class/backlight/max77696-bl/brightness",
+        batt_capacity_file = "/sys/class/power_supply/bd71827_bat/capacity",
+        is_charging_file = "/sys/class/power_supply/bd71827_bat/charging",
+    }
+
+    Kindle.init(self)
+
+    self.input.open(self.touch_dev)
+    self.input.open("fake_events")
+end
+
 function KindleTouch:exit()
     Generic.exit(self)
     if self.isSpecialOffers then
@@ -648,6 +672,7 @@ KindlePaperWhite3.exit = KindleTouch.exit
 KindleOasis.exit = KindleTouch.exit
 KindleOasis2.exit = KindleTouch.exit
 KindleBasic2.exit = KindleTouch.exit
+KindlePaperWhite4.exit = KindleTouch.exit
 
 function Kindle3:exit()
     -- send double menu key press events to trigger screen refresh
@@ -695,6 +720,8 @@ local koa_set = Set { "0GC", "0GD", "0GR", "0GS", "0GT", "0GU" }
 local koa2_set = Set { "0LM", "0LN", "0LP", "0LQ", "0P1", "0P2", "0P6",
                   "0P7", "0P8", "0S1", "0S2", "0S3", "0S4", "0S7", "0SA" }
 local kt3_set = Set { "0DU", "0K9", "0KA" }
+local pw4_set = Set { "0PP", "0T1", "0T2", "0T3", "0T4", "0T5", "0T6",
+                  "0T7", "0TJ", "0TK", "0TL", "0TM", "0TN"}
 
 if k2_set[kindle_devcode] then
     return Kindle2
@@ -724,6 +751,8 @@ elseif koa2_set[kindle_devcode_v2] then
     return KindleOasis2
 elseif kt3_set[kindle_devcode_v2] then
     return KindleBasic2
+elseif pw4_set[kindle_devcode_v2] then
+    return KindlePaperWhite4
 end
 
 error("unknown Kindle model "..kindle_devcode.." ("..kindle_devcode_v2..")")

platform/kindle/koreader.sh

@@ -183,6 +183,10 @@ if [ "${STOP_FRAMEWORK}" = "yes" ]; then
     fi
 fi
 
+# Normalize a version string for easy numeric comparisons
+# c.f., https://stackoverflow.com/a/37939589
+version() { echo "$@" | awk -F. '{ printf("%d%03d%03d%03d\n", $1,$2,$3,$4); }'; }
+
 # check if kpvbooklet was launched more than once, if not we will disable pillow
 # there's no pillow if we stopped the framework, and it's only there on systems with upstart anyway
 if [ "${STOP_FRAMEWORK}" = "no" ] && [ "${INIT_TYPE}" = "upstart" ]; then
@@ -190,16 +194,16 @@ if [ "${STOP_FRAMEWORK}" = "no" ] && [ "${INIT_TYPE}" = "upstart" ]; then
     if [ "$count" = "" ] || [ "$count" = "0" ]; then
         # NOTE: Dump the fb so we can restore something useful on exit...
         cat /dev/fb0 >/var/tmp/koreader-fb.dump
+        # We're going to need our current FW version...
+        FW_VERSION="$(grep '^Kindle 5' /etc/prettyversion.txt 2>&1 | sed -n -r 's/^(Kindle)([[:blank:]]*)([[:digit:]\.]*)(.*?)$/\3/p')"
         # NOTE: We want to disable the status bar (at the very least). Unfortunately, the soft hide/unhide method doesn't work properly anymore since FW 5.6.5...
-        # shellcheck disable=SC2046
-        if [ "$(printf "%.3s" $(grep '^Kindle 5' /etc/prettyversion.txt 2>&1 | sed -n -r 's/^(Kindle)([[:blank:]]*)([[:digit:].]*)(.*?)$/\3/p' | tr -d '.'))" -ge "565" ]; then
+        if [ "$(version "${FW_VERSION}")" -ge "$(version "5.6.5")" ]; then
             PILLOW_HARD_DISABLED="yes"
             # FIXME: So we resort to killing pillow completely on FW >= 5.6.5...
             logmsg "Disabling pillow . . ."
             lipc-set-prop com.lab126.pillow disableEnablePillow disable
             # NOTE: And, oh, joy, on FW >= 5.7.2, this is not enough to prevent the clock from refreshing, so, take the bull by the horns, and SIGSTOP the WM while we run...
-            # shellcheck disable=SC2046
-            if [ "$(printf "%.3s" $(grep '^Kindle 5' /etc/prettyversion.txt 2>&1 | sed -n -r 's/^(Kindle)([[:blank:]]*)([[:digit:].]*)(.*?)$/\3/p' | tr -d '.'))" -ge "572" ]; then
+            if [ "$(version "${FW_VERSION}")" -ge "$(version "5.7.2")" ]; then
                 logmsg "Stopping awesome . . ."
                 killall -stop awesome
                 AWESOME_STOPPED="yes"