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Commit 6909dadd authored by Stephen Boyd's avatar Stephen Boyd Committed by Greg Kroah-Hartman
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msm_serial: Make baud_code detection more dynamic 



Currently msm_set_baud_rate() assumes the uart clock rate is
1.8432 MHz. This is not always true, and limits our options to
program the baud rate. Instead of assuming the rate and
hard-coding the baud_code based on it, calculate the divider that
we want and try to find the closest baud_code that matches. This
allows us to support uarts with faster clock speeds.

Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Acked-by: default avatarDavid Brown <davidb@codeaurora.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f8fb952f

drivers/tty/serial/msm_serial.c

+44 −54
Original line number Original line Diff line number Diff line
@@ -322,70 +322,60 @@ static void msm_break_ctl(struct uart_port *port, int break_ctl) 
		msm_write(port, UART_CR_CMD_STOP_BREAK, UART_CR);

		msm_write(port, UART_CR_CMD_STOP_BREAK, UART_CR);

}

}





struct msm_baud_map {

	u16	divisor;

	u8	code;

	u8	rxstale;

};



static const struct msm_baud_map *

msm_find_best_baud(struct uart_port *port, unsigned int baud)

{

	unsigned int i, divisor;

	const struct msm_baud_map *entry;

	static const struct msm_baud_map table[] = {

		{ 1536, 0x00,  1 },

		{  768, 0x11,  1 },

		{  384, 0x22,  1 },

		{  192, 0x33,  1 },

		{   96, 0x44,  1 },

		{   48, 0x55,  1 },

		{   32, 0x66,  1 },

		{   24, 0x77,  1 },

		{   16, 0x88,  1 },

		{   12, 0x99,  6 },

		{    8, 0xaa,  6 },

		{    6, 0xbb,  6 },

		{    4, 0xcc,  6 },

		{    3, 0xdd,  8 },

		{    2, 0xee, 16 },

		{    1, 0xff, 31 },

	};



	divisor = uart_get_divisor(port, baud);



	for (i = 0, entry = table; i < ARRAY_SIZE(table); i++, entry++)

		if (entry->divisor <= divisor)

			break;



	return entry; /* Default to smallest divider */

}



static int msm_set_baud_rate(struct uart_port *port, unsigned int baud)

static int msm_set_baud_rate(struct uart_port *port, unsigned int baud)

{

{

	unsigned int baud_code, rxstale, watermark;

	unsigned int rxstale, watermark;

	struct msm_port *msm_port = UART_TO_MSM(port);

	struct msm_port *msm_port = UART_TO_MSM(port);

	const struct msm_baud_map *entry;





	switch (baud) {

	entry = msm_find_best_baud(port, baud);

	case 300:

		baud_code = UART_CSR_300;

		rxstale = 1;

		break;

	case 600:

		baud_code = UART_CSR_600;

		rxstale = 1;

		break;

	case 1200:

		baud_code = UART_CSR_1200;

		rxstale = 1;

		break;

	case 2400:

		baud_code = UART_CSR_2400;

		rxstale = 1;

		break;

	case 4800:

		baud_code = UART_CSR_4800;

		rxstale = 1;

		break;

	case 9600:

		baud_code = UART_CSR_9600;

		rxstale = 2;

		break;

	case 14400:

		baud_code = UART_CSR_14400;

		rxstale = 3;

		break;

	case 19200:

		baud_code = UART_CSR_19200;

		rxstale = 4;

		break;

	case 28800:

		baud_code = UART_CSR_28800;

		rxstale = 6;

		break;

	case 38400:

		baud_code = UART_CSR_38400;

		rxstale = 8;

		break;

	case 57600:

		baud_code = UART_CSR_57600;

		rxstale = 16;

		break;

	case 115200:

	default:

		baud_code = UART_CSR_115200;

		baud = 115200;

		rxstale = 31;

		break;

	}





	if (msm_port->is_uartdm)

	if (msm_port->is_uartdm)

		msm_write(port, UART_CR_CMD_RESET_RX, UART_CR);

		msm_write(port, UART_CR_CMD_RESET_RX, UART_CR);





	msm_write(port, baud_code, UART_CSR);

	msm_write(port, entry->code, UART_CSR);





	/* RX stale watermark */

	/* RX stale watermark */

	rxstale = entry->rxstale;

	watermark = UART_IPR_STALE_LSB & rxstale;

	watermark = UART_IPR_STALE_LSB & rxstale;

	watermark |= UART_IPR_RXSTALE_LAST;

	watermark |= UART_IPR_RXSTALE_LAST;

	watermark |= UART_IPR_STALE_TIMEOUT_MSB & (rxstale << 2);

	watermark |= UART_IPR_STALE_TIMEOUT_MSB & (rxstale << 2);

drivers/tty/serial/msm_serial.h

+4 −14
Original line number Original line Diff line number Diff line
@@ -39,18 +39,6 @@ 
#define UART_MR2_PARITY_MODE		0x3

#define UART_MR2_PARITY_MODE		0x3





#define UART_CSR			0x0008

#define UART_CSR			0x0008

#define UART_CSR_115200	0xFF

#define UART_CSR_57600	0xEE

#define UART_CSR_38400	0xDD

#define UART_CSR_28800	0xCC

#define UART_CSR_19200	0xBB

#define UART_CSR_14400	0xAA

#define UART_CSR_9600	0x99

#define UART_CSR_4800	0x77

#define UART_CSR_2400	0x55

#define UART_CSR_1200	0x44

#define UART_CSR_600	0x33

#define UART_CSR_300	0x22





#define UART_TF		0x000C

#define UART_TF		0x000C

#define UARTDM_TF	0x0070

#define UARTDM_TF	0x0070
@@ -152,6 +140,7 @@ static inline void msm_serial_set_mnd_regs_tcxo(struct uart_port *port) 
	msm_write(port, 0xF1, UART_NREG);

	msm_write(port, 0xF1, UART_NREG);

	msm_write(port, 0x0F, UART_DREG);

	msm_write(port, 0x0F, UART_DREG);

	msm_write(port, 0x1A, UART_MNDREG);

	msm_write(port, 0x1A, UART_MNDREG);

	port->uartclk = 1843200;

}

}





/*

/*
@@ -163,6 +152,7 @@ static inline void msm_serial_set_mnd_regs_tcxoby4(struct uart_port *port) 
	msm_write(port, 0xF6, UART_NREG);

	msm_write(port, 0xF6, UART_NREG);

	msm_write(port, 0x0F, UART_DREG);

	msm_write(port, 0x0F, UART_DREG);

	msm_write(port, 0x0A, UART_MNDREG);

	msm_write(port, 0x0A, UART_MNDREG);

	port->uartclk = 1843200;

}

}





static inline

static inline
@@ -170,7 +160,7 @@ void msm_serial_set_mnd_regs_from_uartclk(struct uart_port *port) 
{

{

	if (port->uartclk == 19200000)

	if (port->uartclk == 19200000)

		msm_serial_set_mnd_regs_tcxo(port);

		msm_serial_set_mnd_regs_tcxo(port);

	else

	else if (port->uartclk == 4800000)

		msm_serial_set_mnd_regs_tcxoby4(port);

		msm_serial_set_mnd_regs_tcxoby4(port);

}

}