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Commit efa0f494 authored by Alexander Shiyan's avatar Alexander Shiyan Committed by Greg Kroah-Hartman
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serial: sccnxp: Allow to use non-standard baud rates 



This patch adds support for the use of non-standard baud rates.
For these purposes, we use the built-in timer/counter.

Signed-off-by: default avatarAlexander Shiyan <shc_work@mail.ru>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4ce193fd

drivers/tty/serial/sccnxp.c

+19 −3
Original line number Diff line number Diff line
@@ -48,7 +48,6 @@ 
#	define MR2_STOP1		(7 << 0)

#	define MR2_STOP2		(0xf << 0)

#define SCCNXP_SR_REG			(0x01)

#define SCCNXP_CSR_REG			SCCNXP_SR_REG

#	define SR_RXRDY			(1 << 0)

#	define SR_FULL			(1 << 1)

#	define SR_TXRDY			(1 << 2)
@@ -57,6 +56,8 @@ 
#	define SR_PE			(1 << 5)

#	define SR_FE			(1 << 6)

#	define SR_BRK			(1 << 7)

#define SCCNXP_CSR_REG			(SCCNXP_SR_REG)

#	define CSR_TIMER_MODE		(0x0d)

#define SCCNXP_CR_REG			(0x02)

#	define CR_RX_ENABLE		(1 << 0)

#	define CR_RX_DISABLE		(1 << 1)
@@ -83,9 +84,12 @@ 
#	define IMR_RXRDY		(1 << 1)

#	define ISR_TXRDY(x)		(1 << ((x * 4) + 0))

#	define ISR_RXRDY(x)		(1 << ((x * 4) + 1))

#define SCCNXP_CTPU_REG			(0x06)

#define SCCNXP_CTPL_REG			(0x07)

#define SCCNXP_IPR_REG			(0x0d)

#define SCCNXP_OPCR_REG			SCCNXP_IPR_REG

#define SCCNXP_SOP_REG			(0x0e)

#define SCCNXP_START_COUNTER_REG	SCCNXP_SOP_REG

#define SCCNXP_ROP_REG			(0x0f)



/* Route helpers */
@@ -255,7 +259,7 @@ static int sccnxp_update_best_err(int a, int b, int *besterr) 
{

	int err = abs(a - b);



	if ((*besterr < 0) || (*besterr > err)) {

	if (*besterr > err) {

		*besterr = err;

		return 0;

	}
@@ -303,10 +307,22 @@ static const struct { 
static int sccnxp_set_baud(struct uart_port *port, int baud)

{

	struct sccnxp_port *s = dev_get_drvdata(port->dev);

	int div_std, tmp_baud, bestbaud = baud, besterr = -1;

	int div_std, tmp_baud, bestbaud = INT_MAX, besterr = INT_MAX;

	struct sccnxp_chip *chip = s->chip;

	u8 i, acr = 0, csr = 0, mr0 = 0;



	/* Find divisor to load to the timer preset registers */

	div_std = DIV_ROUND_CLOSEST(port->uartclk, 2 * 16 * baud);

	if ((div_std >= 2) && (div_std <= 0xffff)) {

		bestbaud = DIV_ROUND_CLOSEST(port->uartclk, 2 * 16 * div_std);

		sccnxp_update_best_err(baud, bestbaud, &besterr);

		csr = CSR_TIMER_MODE;

		sccnxp_port_write(port, SCCNXP_CTPU_REG, div_std >> 8);

		sccnxp_port_write(port, SCCNXP_CTPL_REG, div_std);

		/* Issue start timer/counter command */

		sccnxp_port_read(port, SCCNXP_START_COUNTER_REG);

	}



	/* Find best baud from table */

	for (i = 0; baud_std[i].baud && besterr; i++) {

		if (baud_std[i].mr0 && !(chip->flags & SCCNXP_HAVE_MR0))