diff options
| author | Chen Gong <g.chen@freescale.com> | 2008-07-23 21:29:52 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-07-24 10:47:30 -0700 |
| commit | a61f5345eba34772a71523227de890a28410f320 (patch) | |
| tree | 28c038919fa2d526dbf6992d88956409d0beffc2 /drivers/spi | |
| parent | 708d8cefd0f6d8dc13027f899e865ccfa5f63871 (diff) | |
| download | linux-a61f5345eba34772a71523227de890a28410f320.tar.bz2 | |
spi: spi_mpc83xx clockrate fixes
This updates the SPI clock rate calculations for the spi_mpc83xx driver.
Some boundary conditions were wrong, and in several cases divide-by-16
wasn't always needed
Signed-off-by: Chen Gong <g.chen@freescale.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi_mpc83xx.c | 29 |
1 files changed, 16 insertions, 13 deletions
diff --git a/drivers/spi/spi_mpc83xx.c b/drivers/spi/spi_mpc83xx.c index 6832da6f7109..070c6219e2d6 100644 --- a/drivers/spi/spi_mpc83xx.c +++ b/drivers/spi/spi_mpc83xx.c @@ -266,21 +266,24 @@ int mpc83xx_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t) cs->hw_mode |= SPMODE_LEN(bits_per_word); - if ((mpc83xx_spi->spibrg / hz) >= 64) { - pm = mpc83xx_spi->spibrg / (hz * 64) - 1; - if (pm > 0x0f) { - dev_err(&spi->dev, "Requested speed is too " - "low: %d Hz. Will use %d Hz instead.\n", - hz, mpc83xx_spi->spibrg / 1024); - pm = 0x0f; + if ((mpc83xx_spi->spibrg / hz) > 64) { + pm = mpc83xx_spi->spibrg / (hz * 64); + if (pm > 16) { + cs->hw_mode |= SPMODE_DIV16; + pm /= 16; + if (pm > 16) { + dev_err(&spi->dev, "Requested speed is too " + "low: %d Hz. Will use %d Hz instead.\n", + hz, mpc83xx_spi->spibrg / 1024); + pm = 16; + } } - cs->hw_mode |= SPMODE_PM(pm) | SPMODE_DIV16; - } else { + } else pm = mpc83xx_spi->spibrg / (hz * 4); - if (pm) - pm--; - cs->hw_mode |= SPMODE_PM(pm); - } + if (pm) + pm--; + + cs->hw_mode |= SPMODE_PM(pm); regval = mpc83xx_spi_read_reg(&mpc83xx_spi->base->mode); if (cs->hw_mode != regval) { unsigned long flags; |