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authorDavid Brownell <david-b@pacbell.net>2006-01-08 13:34:25 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2006-01-13 16:29:55 -0800
commit0c868461fcb8413cb9f691d68e5b99b0fd3c0737 (patch)
treeb43db6239f5d72a279b35b14de85cf34d8f6bc74 /drivers/spi/spi.c
parentb885244eb2628e0b8206e7edaaa6a314da78e9a4 (diff)
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[PATCH] SPI core tweaks, bugfix
This includes various updates to the SPI core: - Fixes a driver model refcount bug in spi_unregister_master() paths. - The spi_master structures now have wrappers which help keep drivers from needing class-level get/put for device data or for refcounts. - Check for a few setup errors that would cause oopsing later. - Docs say more about memory management. Highlights the use of DMA-safe i/o buffers, and zero-initializing spi_message and such metadata. - Provide a simple alloc/free for spi_message and its spi_transfer; this is only one of the possible memory management policies. Nothing to break code that already works. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/spi/spi.c')
-rw-r--r--drivers/spi/spi.c45
1 files changed, 28 insertions, 17 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 2ecb86cb368..3ecedccdb96 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -38,7 +38,7 @@ static void spidev_release(struct device *dev)
if (spi->master->cleanup)
spi->master->cleanup(spi);
- class_device_put(&spi->master->cdev);
+ spi_master_put(spi->master);
kfree(dev);
}
@@ -90,7 +90,7 @@ static int spi_suspend(struct device *dev, pm_message_t message)
int value;
struct spi_driver *drv = to_spi_driver(dev->driver);
- if (!drv || !drv->suspend)
+ if (!drv->suspend)
return 0;
/* suspend will stop irqs and dma; no more i/o */
@@ -105,7 +105,7 @@ static int spi_resume(struct device *dev)
int value;
struct spi_driver *drv = to_spi_driver(dev->driver);
- if (!drv || !drv->resume)
+ if (!drv->resume)
return 0;
/* resume may restart the i/o queue */
@@ -198,7 +198,7 @@ spi_new_device(struct spi_master *master, struct spi_board_info *chip)
/* NOTE: caller did any chip->bus_num checks necessary */
- if (!class_device_get(&master->cdev))
+ if (!spi_master_get(master))
return NULL;
proxy = kzalloc(sizeof *proxy, GFP_KERNEL);
@@ -244,7 +244,7 @@ spi_new_device(struct spi_master *master, struct spi_board_info *chip)
return proxy;
fail:
- class_device_put(&master->cdev);
+ spi_master_put(master);
kfree(proxy);
return NULL;
}
@@ -324,8 +324,6 @@ static void spi_master_release(struct class_device *cdev)
struct spi_master *master;
master = container_of(cdev, struct spi_master, cdev);
- put_device(master->cdev.dev);
- master->cdev.dev = NULL;
kfree(master);
}
@@ -339,8 +337,9 @@ static struct class spi_master_class = {
/**
* spi_alloc_master - allocate SPI master controller
* @dev: the controller, possibly using the platform_bus
- * @size: how much driver-private data to preallocate; a pointer to this
- * memory in the class_data field of the returned class_device
+ * @size: how much driver-private data to preallocate; the pointer to this
+ * memory is in the class_data field of the returned class_device,
+ * accessible with spi_master_get_devdata().
*
* This call is used only by SPI master controller drivers, which are the
* only ones directly touching chip registers. It's how they allocate
@@ -350,14 +349,17 @@ static struct class spi_master_class = {
* master structure on success, else NULL.
*
* The caller is responsible for assigning the bus number and initializing
- * the master's methods before calling spi_add_master(), or else (on error)
- * calling class_device_put() to prevent a memory leak.
+ * the master's methods before calling spi_add_master(); and (after errors
+ * adding the device) calling spi_master_put() to prevent a memory leak.
*/
struct spi_master * __init_or_module
spi_alloc_master(struct device *dev, unsigned size)
{
struct spi_master *master;
+ if (!dev)
+ return NULL;
+
master = kzalloc(size + sizeof *master, SLAB_KERNEL);
if (!master)
return NULL;
@@ -365,7 +367,7 @@ spi_alloc_master(struct device *dev, unsigned size)
class_device_initialize(&master->cdev);
master->cdev.class = &spi_master_class;
master->cdev.dev = get_device(dev);
- class_set_devdata(&master->cdev, &master[1]);
+ spi_master_set_devdata(master, &master[1]);
return master;
}
@@ -387,6 +389,8 @@ EXPORT_SYMBOL_GPL(spi_alloc_master);
*
* This must be called from context that can sleep. It returns zero on
* success, else a negative error code (dropping the master's refcount).
+ * After a successful return, the caller is responsible for calling
+ * spi_unregister_master().
*/
int __init_or_module
spi_register_master(struct spi_master *master)
@@ -396,6 +400,9 @@ spi_register_master(struct spi_master *master)
int status = -ENODEV;
int dynamic = 0;
+ if (!dev)
+ return -ENODEV;
+
/* convention: dynamically assigned bus IDs count down from the max */
if (master->bus_num == 0) {
master->bus_num = atomic_dec_return(&dyn_bus_id);
@@ -425,7 +432,7 @@ EXPORT_SYMBOL_GPL(spi_register_master);
static int __unregister(struct device *dev, void *unused)
{
/* note: before about 2.6.14-rc1 this would corrupt memory: */
- device_unregister(dev);
+ spi_unregister_device(to_spi_device(dev));
return 0;
}
@@ -440,8 +447,9 @@ static int __unregister(struct device *dev, void *unused)
*/
void spi_unregister_master(struct spi_master *master)
{
- class_device_unregister(&master->cdev);
(void) device_for_each_child(master->cdev.dev, NULL, __unregister);
+ class_device_unregister(&master->cdev);
+ master->cdev.dev = NULL;
}
EXPORT_SYMBOL_GPL(spi_unregister_master);
@@ -487,6 +495,9 @@ EXPORT_SYMBOL_GPL(spi_busnum_to_master);
* by leaving it selected in anticipation that the next message will go
* to the same chip. (That may increase power usage.)
*
+ * Also, the caller is guaranteeing that the memory associated with the
+ * message will not be freed before this call returns.
+ *
* The return value is a negative error code if the message could not be
* submitted, else zero. When the value is zero, then message->status is
* also defined: it's the completion code for the transfer, either zero
@@ -524,9 +535,9 @@ static u8 *buf;
* is zero for success, else a negative errno status code.
* This call may only be used from a context that may sleep.
*
- * Parameters to this routine are always copied using a small buffer,
- * large transfers should use use spi_{async,sync}() calls with
- * dma-safe buffers.
+ * Parameters to this routine are always copied using a small buffer;
+ * performance-sensitive or bulk transfer code should instead use
+ * spi_{async,sync}() calls with dma-safe buffers.
*/
int spi_write_then_read(struct spi_device *spi,
const u8 *txbuf, unsigned n_tx,