[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>

[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>
David Brownell · Greg Kroah-Hartman
1 parent 9708c121c3
Showing 1 changed file with 14 additions and 10 deletions Side-by-side Diff
drivers/spi/spi_bitbang.c
@@ -167,9 +167,11 @@
 	/* 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 @@
 	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 @@
 	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 @@
 {
 	struct spi_bitbang	*bitbang;
 	unsigned long		flags;
+	int			status = 0;
  
 	m->actual_length = 0;
 	m->status = -EINPROGRESS;
  
@@ -414,11 +414,15 @@
 		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);
...	...	@@ -167,9 +167,11 @@
167	167	/* nsecs = (clock period)/2 */
168	168	if (!hz)
169	169	hz = spi->max_speed_hz;
170		- cs->nsecs = (1000000000/2) / hz;
171		- if (cs->nsecs > MAX_UDELAY_MS * 1000)
172		- return -EINVAL;
	170	+ if (hz) {
	171	+ cs->nsecs = (1000000000/2) / hz;
	172	+ if (cs->nsecs > (MAX_UDELAY_MS * 1000 * 1000))
	173	+ return -EINVAL;
	174	+ }
173	175
174	176	return 0;
175	177	}
...	...	@@ -184,9 +186,6 @@
184	186	struct spi_bitbang *bitbang;
185	187	int retval;
186	188
187		- if (!spi->max_speed_hz)
188		- return -EINVAL;
189		-
190	189	bitbang = spi_master_get_devdata(spi->master);
191	190
192	191	/* REVISIT: some systems will want to support devices using lsb-first
...	...	@@ -216,7 +215,7 @@
216	215	if (retval < 0)
217	216	return retval;
218	217
219		- dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec\n",
	218	+ dev_dbg(&spi->dev, "%s, mode %d, %u bits/w, %u nsec/bit\n",
220	219	__FUNCTION__, spi->mode & (SPI_CPOL \| SPI_CPHA),
221	220	spi->bits_per_word, 2 * cs->nsecs);
222	221
...	...	@@ -405,6 +404,7 @@
405	404	{
406	405	struct spi_bitbang *bitbang;
407	406	unsigned long flags;
	407	+ int status = 0;
408	408
409	409	m->actual_length = 0;
410	410	m->status = -EINPROGRESS;
411	411
...	...	@@ -414,11 +414,15 @@
414	414	return -ESHUTDOWN;
415	415
416	416	spin_lock_irqsave(&bitbang->lock, flags);
417		- list_add_tail(&m->queue, &bitbang->queue);
418		- queue_work(bitbang->workqueue, &bitbang->work);
	417	+ if (!spi->max_speed_hz)
	418	+ status = -ENETDOWN;
	419	+ else {
	420	+ list_add_tail(&m->queue, &bitbang->queue);
	421	+ queue_work(bitbang->workqueue, &bitbang->work);
	422	+ }
419	423	spin_unlock_irqrestore(&bitbang->lock, flags);
420	424
421		- return 0;
	425	+ return status;
422	426	}
423	427	EXPORT_SYMBOL_GPL(spi_bitbang_transfer);
424	428