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>
diff --git a/drivers/spi/spi_mpc83xx.c b/drivers/spi/spi_mpc83xx.c
index 6832da6..070c621 100644
--- a/drivers/spi/spi_mpc83xx.c
+++ b/drivers/spi/spi_mpc83xx.c
@@ -266,21 +266,24 @@
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;