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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: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
authored by Atsushi Nemoto and committed by Ralf Baechle dbf763a2 56f3f55c
+6
-7
drivers/spi/spi_txx9.c
+6
-7
drivers/spi/spi_txx9.c
···
29
30
31
#define SPI_FIFO_SIZE 4
32
33
#define TXx9_SPMCR 0x00
34
#define TXx9_SPCR0 0x04
···
195
196
if (prev_speed_hz != speed_hz
197
|| prev_bits_per_word != bits_per_word) {
198
-
u32 n = (c->baseclk + speed_hz - 1) / speed_hz;
199
-
if (n < 1)
200
-
n = 1;
201
-
else if (n > 0xff)
202
-
n = 0xff;
203
/* enter config mode */
204
txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR,
205
TXx9_SPMCR);
···
369
goto exit;
370
}
371
c->baseclk = clk_get_rate(c->clk);
372
-
c->min_speed_hz = (c->baseclk + 0xff - 1) / 0xff;
373
-
c->max_speed_hz = c->baseclk;
374
375
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
376
if (!res)
···
29
30
31
#define SPI_FIFO_SIZE 4
32
+
#define SPI_MAX_DIVIDER 0xff /* Max. value for SPCR1.SER */
33
+
#define SPI_MIN_DIVIDER 1 /* Min. value for SPCR1.SER */
34
35
#define TXx9_SPMCR 0x00
36
#define TXx9_SPCR0 0x04
···
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194
if (prev_speed_hz != speed_hz
195
|| prev_bits_per_word != bits_per_word) {
196
+
int n = DIV_ROUND_UP(c->baseclk, speed_hz) - 1;
197
+
n = clamp(n, SPI_MIN_DIVIDER, SPI_MAX_DIVIDER);
198
/* enter config mode */
199
txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR,
200
TXx9_SPMCR);
···
370
goto exit;
371
}
372
c->baseclk = clk_get_rate(c->clk);
373
+
c->min_speed_hz = DIV_ROUND_UP(c->baseclk, SPI_MAX_DIVIDER + 1);
374
+
c->max_speed_hz = c->baseclk / (SPI_MIN_DIVIDER + 1);
375
376
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
377
if (!res)