Eric Lee / linux-smarc-t335x-v3.2

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Commit dbf763a2f1c117cfe45bbbd2c874a150f0e0900b

Authored by Atsushi Nemoto
Committed by Ralf Baechle
1 parent 56f3f55cf9
Exists in master and in 4 other branches v3.2_AM335xPSP_04.06.00.11, v3.2_NEWT335xPSP_04.06.00.11, v3.2_SBC_SMARTMEN, v3.2_SMARCT335xPSP_04.06.00.11

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>

Showing 1 changed file with 6 additions and 7 deletions Side-by-side Diff

drivers/spi/spi_txx9.c
Diff comments   View file @ dbf763a
... ... @@ -29,6 +29,8 @@
29 29  
30 30  
31 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 */
32 34  
33 35 #define TXx9_SPMCR 0x00
34 36 #define TXx9_SPCR0 0x04
... ... @@ -193,11 +195,8 @@
193 195  
194 196 if (prev_speed_hz != speed_hz
195 197 || prev_bits_per_word != bits_per_word) {
196   - u32 n = (c->baseclk + speed_hz - 1) / speed_hz;
197   - if (n < 1)
198   - n = 1;
199   - else if (n > 0xff)
200   - n = 0xff;
  198 + int n = DIV_ROUND_UP(c->baseclk, speed_hz) - 1;
  199 + n = clamp(n, SPI_MIN_DIVIDER, SPI_MAX_DIVIDER);
201 200 /* enter config mode */
202 201 txx9spi_wr(c, mcr | TXx9_SPMCR_CONFIG | TXx9_SPMCR_BCLR,
203 202 TXx9_SPMCR);
... ... @@ -370,8 +369,8 @@
370 369 goto exit;
371 370 }
372 371 c->baseclk = clk_get_rate(c->clk);
373   - c->min_speed_hz = (c->baseclk + 0xff - 1) / 0xff;
374   - c->max_speed_hz = c->baseclk;
  372 + c->min_speed_hz = DIV_ROUND_UP(c->baseclk, SPI_MAX_DIVIDER + 1);
  373 + c->max_speed_hz = c->baseclk / (SPI_MIN_DIVIDER + 1);
375 374  
376 375 res = platform_get_resource(dev, IORESOURCE_MEM, 0);
377 376 if (!res)