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Commit 69eee8e9 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Greg Kroah-Hartman
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serial: sh-sci: Use a bitmask to indicate supported sampling rates 



Replace the single sampling rate and special handling for HSCIF's
variable sampling rates by a bitmask and a custom iterator.
This prepares for the advent of SCIFA/SCIFB's sparse variable sampling
rates.

Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7b5c0c08

drivers/tty/serial/sh-sci.c

+27 −39
Original line number Diff line number Diff line
@@ -84,6 +84,18 @@ enum SCI_CLKS { 
	SCI_NUM_CLKS

};



/* Bit x set means sampling rate x + 1 is supported */

#define SCI_SR(x)		BIT((x) - 1)

#define SCI_SR_RANGE(x, y)	GENMASK((y) - 1, (x) - 1)



#define min_sr(_port)		ffs((_port)->sampling_rate_mask)

#define max_sr(_port)		fls((_port)->sampling_rate_mask)



/* Iterate over all supported sampling rates, from high to low */

#define for_each_sr(_sr, _port)						\

	for ((_sr) = max_sr(_port); (_sr) >= min_sr(_port); (_sr)--)	\

		if ((_port)->sampling_rate_mask & SCI_SR((_sr)))



struct sci_port {

	struct uart_port	port;
@@ -93,7 +105,7 @@ struct sci_port { 
	unsigned int		overrun_mask;

	unsigned int		error_mask;

	unsigned int		error_clear;

	unsigned int		sampling_rate;

	unsigned int		sampling_rate_mask;

	resource_size_t		reg_size;



	/* Break timer */
@@ -1904,21 +1916,13 @@ static int sci_sck_calc(struct sci_port *s, unsigned int bps, 
			unsigned int *srr)

{

	unsigned long freq = s->clk_rates[SCI_SCK];

	unsigned int min_sr, max_sr, sr;

	int err, min_err = INT_MAX;

	unsigned int sr;



	if (s->port.type != PORT_HSCIF)

		freq *= 2;

	if (s->sampling_rate) {

		/* SCI(F) has a fixed sampling rate */

		min_sr = max_sr = s->sampling_rate;

	} else {

		/* HSCIF has a variable 1/(8..32) sampling rate */

		min_sr = 8;

		max_sr = 32;

	}



	for (sr = max_sr; sr >= min_sr; sr--) {

	for_each_sr(sr, s) {

		err = DIV_ROUND_CLOSEST(freq, sr) - bps;

		if (abs(err) >= abs(min_err))

			continue;
@@ -1939,21 +1943,13 @@ static int sci_brg_calc(struct sci_port *s, unsigned int bps, 
			unsigned long freq, unsigned int *dlr,

			unsigned int *srr)

{

	unsigned int min_sr, max_sr, sr, dl;

	int err, min_err = INT_MAX;

	unsigned int sr, dl;



	if (s->port.type != PORT_HSCIF)

		freq *= 2;

	if (s->sampling_rate) {

		/* SCIF has a fixed sampling rate */

		min_sr = max_sr = s->sampling_rate;

	} else {

		/* HSCIF has a variable 1/(8..32) sampling rate */

		min_sr = 8;

		max_sr = 32;

	}



	for (sr = max_sr; sr >= min_sr; sr--) {

	for_each_sr(sr, s) {

		dl = DIV_ROUND_CLOSEST(freq, sr * bps);

		dl = clamp(dl, 1U, 65535U);
@@ -1979,19 +1975,12 @@ static int sci_scbrr_calc(struct sci_port *s, unsigned int bps, 
			  unsigned int *brr, unsigned int *srr,

			  unsigned int *cks)

{

	unsigned int min_sr, max_sr, sr, br, prediv, scrate, c;

	unsigned long freq = s->clk_rates[SCI_FCK];

	unsigned int sr, br, prediv, scrate, c;

	int err, min_err = INT_MAX;



	if (s->port.type != PORT_HSCIF)

		freq *= 2;

	if (s->sampling_rate) {

		min_sr = max_sr = s->sampling_rate;

	} else {

		/* HSCIF has a variable sample rate */

		min_sr = 8;

		max_sr = 32;

	}



	/*

	 * Find the combination of sample rate and clock select with the
@@ -2008,7 +1997,7 @@ static int sci_scbrr_calc(struct sci_port *s, unsigned int bps, 
	 *      (|D - 0.5| / N * (1 + F))|

	 *  NOTE: Usually, treat D for 0.5, F is 0 by this calculation.

	 */

	for (sr = max_sr; sr >= min_sr; sr--) {

	for_each_sr(sr, s) {

		for (c = 0; c <= 3; c++) {

			/* integerized formulas from HSCIF documentation */

			prediv = sr * (1 << (2 * c + 1));
@@ -2102,8 +2091,7 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios, 
	for (i = 0; i < SCI_NUM_CLKS; i++)

		max_freq = max(max_freq, s->clk_rates[i]);



	baud = uart_get_baud_rate(port, termios, old, 0,

				  max_freq / max(s->sampling_rate, 8U));

	baud = uart_get_baud_rate(port, termios, old, 0, max_freq / min_sr(s));

	if (!baud)

		goto done;
@@ -2535,37 +2523,37 @@ static int sci_init_single(struct platform_device *dev, 
		port->fifosize = 256;

		sci_port->overrun_reg = SCxSR;

		sci_port->overrun_mask = SCIFA_ORER;

		sci_port->sampling_rate = 16;

		sci_port->sampling_rate_mask = SCI_SR(16);

		break;

	case PORT_HSCIF:

		port->fifosize = 128;

		sci_port->overrun_reg = SCLSR;

		sci_port->overrun_mask = SCLSR_ORER;

		sci_port->sampling_rate = 0;

		sci_port->sampling_rate_mask = SCI_SR_RANGE(8, 32);

		break;

	case PORT_SCIFA:

		port->fifosize = 64;

		sci_port->overrun_reg = SCxSR;

		sci_port->overrun_mask = SCIFA_ORER;

		sci_port->sampling_rate = 16;

		sci_port->sampling_rate_mask = SCI_SR(16);

		break;

	case PORT_SCIF:

		port->fifosize = 16;

		if (p->regtype == SCIx_SH7705_SCIF_REGTYPE) {

			sci_port->overrun_reg = SCxSR;

			sci_port->overrun_mask = SCIFA_ORER;

			sci_port->sampling_rate = 16;

			sci_port->sampling_rate_mask = SCI_SR(16);

		} else {

			sci_port->overrun_reg = SCLSR;

			sci_port->overrun_mask = SCLSR_ORER;

			sci_port->sampling_rate = 32;

			sci_port->sampling_rate_mask = SCI_SR(32);

		}

		break;

	default:

		port->fifosize = 1;

		sci_port->overrun_reg = SCxSR;

		sci_port->overrun_mask = SCI_ORER;

		sci_port->sampling_rate = 32;

		sci_port->sampling_rate_mask = SCI_SR(32);

		break;

	}
@@ -2574,7 +2562,7 @@ static int sci_init_single(struct platform_device *dev, 
	 * data override the sampling rate for now.

	 */

	if (p->sampling_rate)

		sci_port->sampling_rate = p->sampling_rate;

		sci_port->sampling_rate_mask = SCI_SR(p->sampling_rate);



	if (!early) {

		ret = sci_init_clocks(sci_port, &dev->dev);