[ota]: deprecation check & notice (#10639)

frontend/device/android/device.lua

@@ -450,6 +450,10 @@ function Device:info()
     return common_text..platform_text..eink_text..wakelocks_text
 end
 
+function Device:isDeprecated()
+    return self.firmware_rev < 18
+end
+
 function Device:test()
     android.runTest()
 end

frontend/device/generic/device.lua

@@ -48,6 +48,7 @@ local Device = {
     hasWifiManager = no,
     isDefaultFullscreen = yes,
     isHapticFeedbackEnabled = no,
+    isDeprecated = no, -- device no longer receive OTA updates
     isTouchDevice = no,
     hasFrontlight = no,
     hasNaturalLight = no, -- FL warmth implementation specific to NTX boards (Kobo, Cervantes)

frontend/ui/otamanager.lua

@@ -153,6 +153,8 @@ function OTAManager:getZsyncFilename()
 end
 
 function OTAManager:checkUpdate()
+    if Device:isDeprecated() then return -1 end
+
     local http = require("socket.http")
     local ltn12 = require("ltn12")
     local socket = require("socket")
@@ -227,6 +229,10 @@ function OTAManager:fetchAndProcessUpdate()
         UIManager:show(InfoMessage:new{
             text = _("KOReader is up to date."),
         })
+    elseif ota_version == -1 then
+        UIManager:show(InfoMessage:new{
+            text = T(_("Device no longer supported.\n\nPlease check %1"), "https://github.com/koreader/koreader/wiki/deprecated-devices")
+        })
     elseif ota_version == nil then
         local channel = ota_channels[OTAManager:getOTAChannel()]
         UIManager:show(InfoMessage:new{