diff options
Diffstat (limited to 'drivers/spi/spi_s3c24xx.c')
| -rw-r--r-- | drivers/spi/spi_s3c24xx.c | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/drivers/spi/spi_s3c24xx.c b/drivers/spi/spi_s3c24xx.c index e0d44af4745a..3f3119d760db 100644 --- a/drivers/spi/spi_s3c24xx.c +++ b/drivers/spi/spi_s3c24xx.c @@ -111,29 +111,32 @@ static int s3c24xx_spi_setupxfer(struct spi_device *spi, unsigned int bpw; unsigned int hz; unsigned int div; + unsigned long clk; bpw = t ? t->bits_per_word : spi->bits_per_word; hz = t ? t->speed_hz : spi->max_speed_hz; + if (!bpw) + bpw = 8; + + if (!hz) + hz = spi->max_speed_hz; + if (bpw != 8) { dev_err(&spi->dev, "invalid bits-per-word (%d)\n", bpw); return -EINVAL; } - div = clk_get_rate(hw->clk) / hz; - - /* is clk = pclk / (2 * (pre+1)), or is it - * clk = (pclk * 2) / ( pre + 1) */ - - div /= 2; - - if (div > 0) - div -= 1; + clk = clk_get_rate(hw->clk); + div = DIV_ROUND_UP(clk, hz * 2) - 1; if (div > 255) div = 255; - dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", div, hz); + dev_dbg(&spi->dev, "setting pre-scaler to %d (wanted %d, got %ld)\n", + div, hz, clk / (2 * (div + 1))); + + writeb(div, hw->regs + S3C2410_SPPRE); spin_lock(&hw->bitbang.lock); |