ANDROID: serial: msm_geni_serial_console : Add Earlycon support

This change enables earlyconsole support as static driver for geni
based UART. Kernel space UART console driver will be generic for
console and other usecases of UART.

Bug: 144074026
Test: Earlyconsole logs are fine and switch kernel console is fine.

Change-Id: I34c9910cc8aa9586f842362fae62bc7127bcee5e
Signed-off-by: Mukesh Kumar Savaliya <msavaliy@codeaurora.org>
(cherry picked from commit ac0ec822779819c8d5cdc1d97d44afdefe1d3ece)
Signed-off-by: Will McVicker <willmcvicker@google.com>

drivers/tty/serial/Kconfig

@@ -989,6 +989,21 @@ config SERIAL_MSM_CONSOLE
 	select SERIAL_CORE_CONSOLE
 	select SERIAL_EARLYCON
 
+config SERIAL_MSM_GENI_HALF_SAMPLING
+	bool "Changes clock divider which impacts sampling rate for QUP HW ver greater than 2.5.0"
+	help
+	  Clock divider value should be doubled for QUP hardware version
+	  greater than 2.5.0.
+	  As earlycon can't have HW version awareness, decision is taken
+	  based on the configuration.
+
+config SERIAL_MSM_GENI_EARLY_CONSOLE
+	bool "MSM on-chip GENI HW based early console support"
+	select SERIAL_MSM_GENI_HALF_SAMPLING
+	help
+	  Serial early console driver for Qualcomm Technologies Inc's GENI
+	  based QUP hardware.
+
 config SERIAL_QCOM_GENI
 	tristate "QCOM on-chip GENI based serial port support"
 	depends on ARCH_QCOM || COMPILE_TEST

drivers/tty/serial/Makefile

@@ -58,6 +58,7 @@ obj-$(CONFIG_SERIAL_SGI_IOC3) += ioc3_serial.o
 obj-$(CONFIG_SERIAL_ATMEL) += atmel_serial.o
 obj-$(CONFIG_SERIAL_UARTLITE) += uartlite.o
 obj-$(CONFIG_SERIAL_MSM) += msm_serial.o
+obj-$(CONFIG_SERIAL_MSM_GENI_EARLY_CONSOLE) += msm_geni_serial_console.o
 obj-$(CONFIG_SERIAL_QCOM_GENI) += qcom_geni_serial.o
 obj-$(CONFIG_SERIAL_NETX) += netx-serial.o
 obj-$(CONFIG_SERIAL_KS8695) += serial_ks8695.o