[PATCH] SPI: spi_bitbang: clocking fixes

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>

diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c
index 0f7f5c6..dd2f950 100644 (file)
--- a/drivers/spi/spi_bitbang.c
+++ b/drivers/spi/spi_bitbang.c
@@ -167,9 +167,11 @@ int spi_bitbang_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
        /* nsecs = (clock period)/2 */
        if (!hz)
                hz = spi->max_speed_hz;
-       cs->nsecs = (1000000000/2) / hz;
-       if (cs->nsecs > MAX_UDELAY_MS * 1000)
-               return -EINVAL;
+       if (hz) {
+               cs->nsecs = (1000000000/2) / hz;
+               if (cs->nsecs > (MAX_UDELAY_MS * 1000 * 1000))
+                       return -EINVAL;
+       }
 
        return 0;
 }
@@ -184,9 +186,6 @@ int spi_bitbang_setup(struct spi_device *spi)
        struct spi_bitbang      *bitbang;
        int                     retval;
 
-       if (!spi->max_speed_hz)
-               return -EINVAL;
-
        bitbang = spi_master_get_devdata(spi->master);
 
        /* 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)
                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),
                        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;
        unsigned long           flags;
+       int                     status = 0;
 
        m->actual_length = 0;
        m->status = -EINPROGRESS;
@@ -414,11 +414,15 @@ int spi_bitbang_transfer(struct spi_device *spi, struct spi_message *m)
                return -ESHUTDOWN;
 
        spin_lock_irqsave(&bitbang->lock, flags);
-       list_add_tail(&m->queue, &bitbang->queue);
-       queue_work(bitbang->workqueue, &bitbang->work);
+       if (!spi->max_speed_hz)
+               status = -ENETDOWN;
+       else {
+               list_add_tail(&m->queue, &bitbang->queue);
+               queue_work(bitbang->workqueue, &bitbang->work);
+       }
        spin_unlock_irqrestore(&bitbang->lock, flags);
 
-       return 0;
+       return status;
 }
 EXPORT_SYMBOL_GPL(spi_bitbang_transfer);