spi: core: Add devm_spi_register_master()

Help simplify the cleanup code for SPI master drivers by providing a
managed master registration function, ensuring that the master is
automatically unregistered whenever the device is unbound.

Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Huang Shijie <b32955@freescale.com>

3 files changed, 40 insertions, 0 deletions

diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index b4671459857f..d4b64589cc41 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -293,3 +293,6 @@ PWM
 PHY
   devm_usb_get_phy()
   devm_usb_put_phy()
+
+SPI
+  devm_spi_register_master()
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index bb1f86fb2c3d..600be70ec92d 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1247,6 +1247,41 @@ done:
 }
 EXPORT_SYMBOL_GPL(spi_register_master);
 
+static void devm_spi_unregister(struct device *dev, void *res)
+{
+        spi_unregister_master(*(struct spi_master **)res);
+}
+
+/**
+ * dev_spi_register_master - register managed SPI master controller
+ * @dev:    device managing SPI master
+ * @master: initialized master, originally from spi_alloc_master()
+ * Context: can sleep
+ *
+ * Register a SPI device as with spi_register_master() which will
+ * automatically be unregister
+ */
+int devm_spi_register_master(struct device *dev, struct spi_master *master)
+{
+        struct spi_master **ptr;
+        int ret;
+
+        ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
+        if (!ptr)
+                return -ENOMEM;
+
+        ret = spi_register_master(master);
+        if (ret != 0) {
+                *ptr = master;
+                devres_add(dev, ptr);
+        } else {
+                devres_free(ptr);
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(devm_spi_register_master);
+
 static int __unregister(struct device *dev, void *null)
 {
         spi_unregister_device(to_spi_device(dev));
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 887116dbce2c..4d634d66ba0b 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -434,6 +434,8 @@ extern struct spi_master *
 spi_alloc_master(struct device *host, unsigned size);
 
 extern int spi_register_master(struct spi_master *master);
+extern int devm_spi_register_master(struct device *dev,
+                                    struct spi_master *master);
 extern void spi_unregister_master(struct spi_master *master);
 
 extern struct spi_master *spi_busnum_to_master(u16 busnum);