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[PATCH] SPI core tweaks, bugfix

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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>
This commit is contained in:
David Brownell
2006-01-08 13:34:25 -08:00
committed by Greg Kroah-Hartman
parent b885244eb2
commit 0c868461fc
3 changed files with 113 additions and 23 deletions
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75
include/linux/spi/spi.h
View File

@@ -60,8 +60,8 @@ struct spi_device {
u8 mode;
#define SPI_CPHA 0x01 /* clock phase */
#define SPI_CPOL 0x02 /* clock polarity */
#define SPI_MODE_0 (0|0)
#define SPI_MODE_1 (0|SPI_CPHA) /* (original MicroWire) */
#define SPI_MODE_0 (0|0) /* (original MicroWire) */
#define SPI_MODE_1 (0|SPI_CPHA)
#define SPI_MODE_2 (SPI_CPOL|0)
#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
#define SPI_CS_HIGH 0x04 /* chipselect active high? */
@@ -209,6 +209,30 @@ struct spi_master {
void (*cleanup)(const struct spi_device *spi);
};
static inline void *spi_master_get_devdata(struct spi_master *master)
{
return class_get_devdata(&master->cdev);
}
static inline void spi_master_set_devdata(struct spi_master *master, void *data)
{
class_set_devdata(&master->cdev, data);
}
static inline struct spi_master *spi_master_get(struct spi_master *master)
{
if (!master || !class_device_get(&master->cdev))
return NULL;
return master;
}
static inline void spi_master_put(struct spi_master *master)
{
if (master)
class_device_put(&master->cdev);
}
/* the spi driver core manages memory for the spi_master classdev */
extern struct spi_master *
spi_alloc_master(struct device *host, unsigned size);
@@ -271,11 +295,17 @@ extern struct spi_master *spi_busnum_to_master(u16 busnum);
* stay selected until the next transfer. This is purely a performance
* hint; the controller driver may need to select a different device
* for the next message.
*
* The code that submits an spi_message (and its spi_transfers)
* to the lower layers is responsible for managing its memory.
* Zero-initialize every field you don't set up explicitly, to
* insulate against future API updates.
*/
struct spi_transfer {
/* it's ok if tx_buf == rx_buf (right?)
* for MicroWire, one buffer must be null
* buffers must work with dma_*map_single() calls
* buffers must work with dma_*map_single() calls, unless
* spi_message.is_dma_mapped reports a pre-existing mapping
*/
const void *tx_buf;
void *rx_buf;
@@ -302,6 +332,11 @@ struct spi_transfer {
* @status: zero for success, else negative errno
* @queue: for use by whichever driver currently owns the message
* @state: for use by whichever driver currently owns the message
*
* The code that submits an spi_message (and its spi_transfers)
* to the lower layers is responsible for managing its memory.
* Zero-initialize every field you don't set up explicitly, to
* insulate against future API updates.
*/
struct spi_message {
struct spi_transfer *transfers;
@@ -336,6 +371,29 @@ struct spi_message {
void *state;
};
/* It's fine to embed message and transaction structures in other data
* structures so long as you don't free them while they're in use.
*/
static inline struct spi_message *spi_message_alloc(unsigned ntrans, gfp_t flags)
{
struct spi_message *m;
m = kzalloc(sizeof(struct spi_message)
+ ntrans * sizeof(struct spi_transfer),
flags);
if (m) {
m->transfers = (void *)(m + 1);
m->n_transfer = ntrans;
}
return m;
}
static inline void spi_message_free(struct spi_message *m)
{
kfree(m);
}
/**
* spi_setup -- setup SPI mode and clock rate
* @spi: the device whose settings are being modified
@@ -363,7 +421,10 @@ spi_setup(struct spi_device *spi)
* The completion callback is invoked in a context which can't sleep.
* Before that invocation, the value of message->status is undefined.
* When the callback is issued, message->status holds either zero (to
* indicate complete success) or a negative error code.
* indicate complete success) or a negative error code. After that
* callback returns, the driver which issued the transfer request may
* deallocate the associated memory; it's no longer in use by any SPI
* core or controller driver code.
*
* Note that although all messages to a spi_device are handled in
* FIFO order, messages may go to different devices in other orders.
@@ -445,6 +506,7 @@ spi_read(struct spi_device *spi, u8 *buf, size_t len)
return spi_sync(spi, &m);
}
/* this copies txbuf and rxbuf data; for small transfers only! */
extern int spi_write_then_read(struct spi_device *spi,
const u8 *txbuf, unsigned n_tx,
u8 *rxbuf, unsigned n_rx);
@@ -555,8 +617,9 @@ spi_register_board_info(struct spi_board_info const *info, unsigned n)
/* If you're hotplugging an adapter with devices (parport, usb, etc)
* use spi_new_device() to describe each device. You would then call
* spi_unregister_device() to start making that device vanish.
* use spi_new_device() to describe each device. You can also call
* spi_unregister_device() to start making that device vanish, but
* normally that would be handled by spi_unregister_master().
*/
extern struct spi_device *
spi_new_device(struct spi_master *, struct spi_board_info *);