[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>
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 2ecb86c..3ecedcc 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -38,7 +38,7 @@
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 @@
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 @@
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 @@
/* 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 @@
return proxy;
fail:
- class_device_put(&master->cdev);
+ spi_master_put(master);
kfree(proxy);
return NULL;
}
@@ -324,8 +324,6 @@
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 @@
/**
* 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 @@
* 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 @@
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 @@
*
* 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 @@
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 @@
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 @@
*/
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 @@
* 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 @@
* 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,