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SPI: spi_txx9: Fix bit rate calculation

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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: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Atsushi Nemoto 2009-09-03 22:59:01 +09:00 committed by Ralf Baechle
parent 56f3f55cf9
commit dbf763a2f1
1 changed files with 6 additions and 7 deletions
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13
drivers/spi/spi_txx9.c
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@ -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)