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Commit da5784d1 authored by Stepan Moskovchenko's avatar Stepan Moskovchenko
Browse files

arm64: add support for MSM HSL earlyprintk 



Add support for arm64 earlyprintk using the MSM UARTDM
hardware block. Such support can be enabled by passing
something like "earlyprintk=msm_hsl_uart,0xf991e000" (or
the appropriate equivalent) on the kernel command line.

Change-Id: Ia43ad430e8bdcb0fd724c60949b82b256e2611a8
Signed-off-by: default avatarStepan Moskovchenko <stepanm@codeaurora.org>
parent f9e5104e

arch/arm64/kernel/early_printk.c

+23 −0
Original line number Diff line number Diff line
@@ -72,6 +72,28 @@ static void uart8250_32bit_printch(char ch) 
	writel_relaxed(ch, early_base + (UART_TX << 2));

}



#define MSM_HSL_UART_SR			0xa4

#define MSM_HSL_UART_ISR		0xb4

#define MSM_HSL_UART_TF			0x100

#define MSM_HSL_UART_CR			0xa8

#define MSM_HSL_UART_NCF_TX		0x40

#define MSM_HSL_UART_SR_TXEMT		BIT(3)

#define MSM_HSL_UART_ISR_TXREADY	BIT(7)



void msm_hsl_uart_printch(char ch)

{

	while (!(readl_relaxed(early_base + MSM_HSL_UART_SR) &

						       MSM_HSL_UART_SR_TXEMT) &&

	       !(readl_relaxed(early_base + MSM_HSL_UART_ISR) &

						     MSM_HSL_UART_ISR_TXREADY))

		;



	writel_relaxed(0x300, early_base + MSM_HSL_UART_CR);

	writel_relaxed(1, early_base + MSM_HSL_UART_NCF_TX);

	readl_relaxed(early_base + MSM_HSL_UART_NCF_TX);

	writel_relaxed(ch, early_base + MSM_HSL_UART_TF);

}



struct earlycon_match {

	const char *name;

	void (*printch)(char ch);
@@ -82,6 +104,7 @@ static const struct earlycon_match earlycon_match[] __initconst = { 
	{ .name = "smh", .printch = smh_printch, },

	{ .name = "uart8250-8bit", .printch = uart8250_8bit_printch, },

	{ .name = "uart8250-32bit", .printch = uart8250_32bit_printch, },

	{ .name = "msm_hsl_uart", .printch = msm_hsl_uart_printch, },

	{}

};