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Commit dbf763a2 authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by Ralf Baechle
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SPI: spi_txx9: Fix bit rate calculation 



TXx9 SPI bit rate is calculated by:
        fBR = (spi-baseclk) / (n + 1)
Fix calculation of min_speed_hz, max_speed_hz and n.

Signed-off-by: default avatarAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 56f3f55c

drivers/spi/spi_txx9.c

+6 −7
Original line number Diff line number Diff line
@@ -29,6 +29,8 @@ 




#define SPI_FIFO_SIZE 4

#define SPI_MAX_DIVIDER 0xff	/* Max. value for SPCR1.SER */

#define SPI_MIN_DIVIDER 1	/* Min. value for SPCR1.SER */



#define TXx9_SPMCR		0x00

#define TXx9_SPCR0		0x04
@@ -193,11 +195,8 @@ static void txx9spi_work_one(struct txx9spi *c, struct spi_message *m) 


		if (prev_speed_hz != speed_hz

				|| prev_bits_per_word != bits_per_word) {

			u32 n = (c->baseclk + speed_hz - 1) / speed_hz;

			if (n < 1)

				n = 1;

			else if (n > 0xff)

				n = 0xff;

			int n = DIV_ROUND_UP(c->baseclk, speed_hz) - 1;

			n = clamp(n, SPI_MIN_DIVIDER, SPI_MAX_DIVIDER);

			/* enter config mode */

			txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR,

					TXx9_SPMCR);
@@ -370,8 +369,8 @@ static int __init txx9spi_probe(struct platform_device *dev) 
		goto exit;

	}

	c->baseclk = clk_get_rate(c->clk);

	c->min_speed_hz = (c->baseclk + 0xff - 1) / 0xff;

	c->max_speed_hz = c->baseclk;

	c->min_speed_hz = DIV_ROUND_UP(c->baseclk, SPI_MAX_DIVIDER + 1);

	c->max_speed_hz = c->baseclk / (SPI_MIN_DIVIDER + 1);



	res = platform_get_resource(dev, IORESOURCE_MEM, 0);

	if (!res)