[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>

1 files changed, 14 insertions, 10 deletions

diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c
index 0f7f5c64391..dd2f950b21a 100644
--- 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);