* Companion function to spi_alloc_device. Devices allocated with
* spi_alloc_device can be added onto the spi bus with this function.
*
- * Returns 0 on success; non-zero on failure
+ * Returns 0 on success; negative errno on failure
*/
int spi_add_device(struct spi_device *spi)
{
+ static DEFINE_MUTEX(spi_add_lock);
struct device *dev = spi->master->dev.parent;
int status;
"%s.%u", spi->master->dev.bus_id,
spi->chip_select);
- /* drivers may modify this initial i/o setup */
+
+ /* We need to make sure there's no other device with this
+ * chipselect **BEFORE** we call setup(), else we'll trash
+ * its configuration. Lock against concurrent add() calls.
+ */
+ mutex_lock(&spi_add_lock);
+
+ if (bus_find_device_by_name(&spi_bus_type, NULL, spi->dev.bus_id)
+ != NULL) {
+ dev_err(dev, "chipselect %d already in use\n",
+ spi->chip_select);
+ status = -EBUSY;
+ goto done;
+ }
+
+ /* Drivers may modify this initial i/o setup, but will
+ * normally rely on the device being setup. Devices
+ * using SPI_CS_HIGH can't coexist well otherwise...
+ */
status = spi->master->setup(spi);
if (status < 0) {
dev_err(dev, "can't %s %s, status %d\n",
"setup", spi->dev.bus_id, status);
- return status;
+ goto done;
}
- /* driver core catches callers that misbehave by defining
- * devices that already exist.
- */
+ /* Device may be bound to an active driver when this returns */
status = device_add(&spi->dev);
- if (status < 0) {
+ if (status < 0)
dev_err(dev, "can't %s %s, status %d\n",
"add", spi->dev.bus_id, status);
- return status;
- }
+ else
+ dev_dbg(dev, "registered child %s\n", spi->dev.bus_id);
- dev_dbg(dev, "registered child %s\n", spi->dev.bus_id);
- return 0;
+done:
+ mutex_unlock(&spi_add_lock);
+ return status;
}
EXPORT_SYMBOL_GPL(spi_add_device);
int status;
struct spi_message message;
- struct spi_transfer x[2];
+ struct spi_transfer x;
u8 *local_buf;
/* Use preallocated DMA-safe buffer. We can't avoid copying here,
return -EINVAL;
spi_message_init(&message);
- memset(x, 0, sizeof x);
- if (n_tx) {
- x[0].len = n_tx;
- spi_message_add_tail(&x[0], &message);
- }
- if (n_rx) {
- x[1].len = n_rx;
- spi_message_add_tail(&x[1], &message);
- }
+ memset(&x, 0, sizeof x);
+ x.len = n_tx + n_rx;
+ spi_message_add_tail(&x, &message);
/* ... unless someone else is using the pre-allocated buffer */
if (!mutex_trylock(&lock)) {
local_buf = buf;
memcpy(local_buf, txbuf, n_tx);
- x[0].tx_buf = local_buf;
- x[1].rx_buf = local_buf + n_tx;
+ x.tx_buf = local_buf;
+ x.rx_buf = local_buf;
/* do the i/o */
status = spi_sync(spi, &message);
if (status == 0)
- memcpy(rxbuf, x[1].rx_buf, n_rx);
+ memcpy(rxbuf, x.rx_buf + n_tx, n_rx);
- if (x[0].tx_buf == buf)
+ if (x.tx_buf == buf)
mutex_unlock(&lock);
else
kfree(local_buf);
* driver registration) _could_ be dynamically linked (modular) ... costs
* include needing to have boardinfo data structures be much more public.
*/
-subsys_initcall(spi_init);
+postcore_initcall(spi_init);