Commit 082c8cb4 authored by David Brownell's avatar David Brownell Committed by Linus Torvalds
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spi device setup gets better error checking

This updates some error reporting paths in SPI device setup:

 - Move validation logic for SPI chipselects to spi_new_device(),
   which is where it should always have been.

 - In spi_new_device(), emit error messages if the device can't
   be created.  This is LOTS better than a silent failure; though
   eventually, the calling convention should probably change to
   use the <linux/err.h> conventions.

 - Includes one previously-missing check:  SPI masters must always
   have at least one chipselect, even for dedicated busses which
   always keep it selected!

It also adds a FIXME (IDR for dynamic ID allocation) so the issue doesn't live
purely in my mailbox.
Signed-off-by: default avatarDavid Brownell <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 2604288f
......@@ -200,6 +200,8 @@ static DEFINE_MUTEX(board_lock);
* platforms may not be able to use spi_register_board_info though, and
* this is exported so that for example a USB or parport based adapter
* driver could add devices (which it would learn about out-of-band).
* Returns the new device, or NULL.
struct spi_device *spi_new_device(struct spi_master *master,
struct spi_board_info *chip)
......@@ -208,7 +210,20 @@ struct spi_device *spi_new_device(struct spi_master *master,
struct device *dev = master->;
int status;
/* NOTE: caller did any chip->bus_num checks necessary */
/* NOTE: caller did any chip->bus_num checks necessary.
* Also, unless we change the return value convention to use
* error-or-pointer (not NULL-or-pointer), troubleshootability
* suggests syslogged diagnostics are best here (ugh).
/* Chipselects are numbered 0..max; validate. */
if (chip->chip_select >= master->num_chipselect) {
dev_err(dev, "cs%d > max %d\n",
return NULL;
if (!spi_master_get(master))
return NULL;
......@@ -236,10 +251,10 @@ struct spi_device *spi_new_device(struct spi_master *master,
proxy->controller_state = NULL;
proxy->dev.release = spidev_release;
/* drivers may modify this default i/o setup */
/* drivers may modify this initial i/o setup */
status = master->setup(proxy);
if (status < 0) {
dev_dbg(dev, "can't %s %s, status %d\n",
dev_err(dev, "can't %s %s, status %d\n",
"setup", proxy->dev.bus_id, status);
goto fail;
......@@ -249,7 +264,7 @@ struct spi_device *spi_new_device(struct spi_master *master,
status = device_register(&proxy->dev);
if (status < 0) {
dev_dbg(dev, "can't %s %s, status %d\n",
dev_err(dev, "can't %s %s, status %d\n",
"add", proxy->dev.bus_id, status);
goto fail;
......@@ -306,7 +321,6 @@ spi_register_board_info(struct spi_board_info const *info, unsigned n)
static void scan_boardinfo(struct spi_master *master)
struct boardinfo *bi;
struct device *dev = master->;
list_for_each_entry(bi, &board_list, list) {
......@@ -316,17 +330,9 @@ static void scan_boardinfo(struct spi_master *master)
for (n = bi->n_board_info; n > 0; n--, chip++) {
if (chip->bus_num != master->bus_num)
/* some controllers only have one chip, so they
* might not use chipselects. otherwise, the
* chipselects are numbered 0..max.
/* NOTE: this relies on spi_new_device to
* issue diagnostics when given bogus inputs
if (chip->chip_select >= master->num_chipselect
&& master->num_chipselect) {
dev_dbg(dev, "cs%d > max %d\n",
(void) spi_new_device(master, chip);
......@@ -419,8 +425,17 @@ int spi_register_master(struct spi_master *master)
if (!dev)
return -ENODEV;
/* even if it's just one always-selected device, there must
* be at least one chipselect
if (master->num_chipselect == 0)
return -EINVAL;
/* convention: dynamically assigned bus IDs count down from the max */
if (master->bus_num < 0) {
/* FIXME switch to an IDR based scheme, something like
* I2C now uses, so we can't run out of "dynamic" IDs
master->bus_num = atomic_dec_return(&dyn_bus_id);
dynamic = 1;
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