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[PATCH] SPI: spi_bitbang: clocking fixes

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This fixes two problems triggered by the MMC stack updating clocks:

 - SPI masters driver should accept a max clock speed of zero; that's one
   convention for marking idle devices.  (Presumably that helps controllers
   that don't autogate clocks to "off" when not in use.)

 - There are more than 1000 nanoseconds per millisecond; setting the clock
   down to 125 KHz now works properly.

Showing once again that Zero (http://en.wikipedia.org/wiki/Zero) is still
an inexhaustible number of bugs.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
David Brownell 2006-04-06 22:25:56 -07:00 committed by Greg Kroah-Hartman
parent 9708c121c3
commit 1e316d7566
1 changed files with 14 additions and 10 deletions
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24
drivers/spi/spi_bitbang.c
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@ -167,9 +167,11 @@ int spi_bitbang_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
/* nsecs = (clock period)/2 */ /* nsecs = (clock period)/2 */
if (!hz) if (!hz)
hz = spi->max_speed_hz; hz = spi->max_speed_hz;
cs->nsecs = (1000000000/2) / hz; if (hz) {
if (cs->nsecs > MAX_UDELAY_MS * 1000) cs->nsecs = (1000000000/2) / hz;
return -EINVAL; if (cs->nsecs > (MAX_UDELAY_MS * 1000 * 1000))
return -EINVAL;
}
return 0; return 0;
} }
@ -184,9 +186,6 @@ int spi_bitbang_setup(struct spi_device *spi)
struct spi_bitbang *bitbang; struct spi_bitbang *bitbang;
int retval; int retval;
if (!spi->max_speed_hz)
return -EINVAL;
bitbang = spi_master_get_devdata(spi->master); bitbang = spi_master_get_devdata(spi->master);
/* REVISIT: some systems will want to support devices using lsb-first /* REVISIT: some systems will want to support devices using lsb-first
@ -216,7 +215,7 @@ int spi_bitbang_setup(struct spi_device *spi)
if (retval < 0) if (retval < 0)
return retval; return retval;
dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec\n", dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec/bit\n",
__FUNCTION__, spi->mode & (SPI_CPOL | SPI_CPHA), __FUNCTION__, spi->mode & (SPI_CPOL | SPI_CPHA),
spi->bits_per_word, 2 * cs->nsecs); spi->bits_per_word, 2 * cs->nsecs);
@ -405,6 +404,7 @@ int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m)
{ {
struct spi_bitbang *bitbang; struct spi_bitbang *bitbang;
unsigned long flags; unsigned long flags;
int status = 0;
m->actual_length = 0; m->actual_length = 0;
m->status = -EINPROGRESS; m->status = -EINPROGRESS;
@ -414,11 +414,15 @@ int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m)
return -ESHUTDOWN; return -ESHUTDOWN;
spin_lock_irqsave(&bitbang->lock, flags); spin_lock_irqsave(&bitbang->lock, flags);
list_add_tail(&m->queue, &bitbang->queue); if (!spi->max_speed_hz)
queue_work(bitbang->workqueue, &bitbang->work); status = -ENETDOWN;
else {
list_add_tail(&m->queue, &bitbang->queue);
queue_work(bitbang->workqueue, &bitbang->work);
}
spin_unlock_irqrestore(&bitbang->lock, flags); spin_unlock_irqrestore(&bitbang->lock, flags);
return 0; return status;
} }
EXPORT_SYMBOL_GPL(spi_bitbang_transfer); EXPORT_SYMBOL_GPL(spi_bitbang_transfer);