[PATCH 0/3] Automatically register i2c devices from the device tree

[PATCH 0/3] Automatically register i2c devices from the device tree

[Grant Likely]

The following series adds automatic registration of i2c devices from
OF device tree data.  If the i2c bus has the of_node pointer set, then
it will use that node pointer as the parent for a set of i2c devices and
automatically register the child nodes as new i2c devices.

When CONFIG_OF is not set, the of i2c hooks become empty stubs.

---

Grant Likely (3):
      of/i2c: Generalize OF support
      i2c: Add OF-style registration and binding
      of: refactor of_modalias_node() and remove explicit match table.


 arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c |    6 ++
 drivers/i2c/busses/i2c-cpm.c                   |    6 --
 drivers/i2c/busses/i2c-ibm_iic.c               |    4 --
 drivers/i2c/busses/i2c-mpc.c                   |    2 -
 drivers/i2c/i2c-core.c                         |    9 +++
 drivers/mmc/host/mmc_spi.c                     |    8 +++
 drivers/of/Kconfig                             |    2 -
 drivers/of/base.c                              |   64 +++---------------------
 drivers/of/of_i2c.c                            |   50 +++++++++++--------
 include/linux/of_i2c.h                         |   13 ++++-
 10 files changed, 75 insertions(+), 89 deletions(-)

[PATCH 0/3] Automatically register i2c devices from the device tree

[Grant Likely]

The following series adds automatic registration of i2c devices from
OF device tree data.  If the i2c bus has the of_node pointer set, then
it will use that node pointer as the parent for a set of i2c devices and
automatically register the child nodes as new i2c devices.

When CONFIG_OF is not set, the of i2c hooks become empty stubs.

---

Grant Likely (3):
      of/i2c: Generalize OF support
      i2c: Add OF-style registration and binding
      of: refactor of_modalias_node() and remove explicit match table.


 arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c |    6 ++
 drivers/i2c/busses/i2c-cpm.c                   |    6 --
 drivers/i2c/busses/i2c-ibm_iic.c               |    4 --
 drivers/i2c/busses/i2c-mpc.c                   |    2 -
 drivers/i2c/i2c-core.c                         |    9 +++
 drivers/mmc/host/mmc_spi.c                     |    8 +++
 drivers/of/Kconfig                             |    2 -
 drivers/of/base.c                              |   64 +++---------------------
 drivers/of/of_i2c.c                            |   50 +++++++++++--------
 include/linux/of_i2c.h                         |   13 ++++-
 10 files changed, 75 insertions(+), 89 deletions(-)

[PATCH 1/3] of/i2c: Generalize OF support

[Grant Likely]

This patch cleans up the i2c OF support code to make it selectable by
all architectures and allow for automatic registration of i2c devices.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 drivers/i2c/busses/i2c-cpm.c     |    3 ++
 drivers/i2c/busses/i2c-ibm_iic.c |    3 ++
 drivers/i2c/busses/i2c-mpc.c     |    3 ++
 drivers/of/Kconfig               |    2 +-
 drivers/of/of_i2c.c              |   50 ++++++++++++++++++++++----------------
 include/linux/of_i2c.h           |   13 ++++++++--
 6 files changed, 46 insertions(+), 28 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c
index b02b453..03ae62e 100644
--- a/drivers/i2c/busses/i2c-cpm.c
+++ b/drivers/i2c/busses/i2c-cpm.c
@@ -652,6 +652,7 @@ static int __devinit cpm_i2c_probe(struct of_device *ofdev,
 	cpm->adap = cpm_ops;
 	i2c_set_adapdata(&cpm->adap, cpm);
 	cpm->adap.dev.parent = &ofdev->dev;
+	cpm->adap.dev.of_node = of_node_get(ofdev->dev.of_node);
 
 	result = cpm_i2c_setup(cpm);
 	if (result) {
@@ -679,7 +680,7 @@ static int __devinit cpm_i2c_probe(struct of_device *ofdev,
 	/*
 	 * register OF I2C devices
 	 */
-	of_register_i2c_devices(&cpm->adap, ofdev->dev.of_node);
+	of_i2c_register_devices(&cpm->adap);
 
 	return 0;
 out_shut:
diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index bf34413..d964121 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -745,6 +745,7 @@ static int __devinit iic_probe(struct of_device *ofdev,
 	/* Register it with i2c layer */
 	adap = &dev->adap;
 	adap->dev.parent = &ofdev->dev;
+	adap->dev.of_node = of_node_get(np);
 	strlcpy(adap->name, "IBM IIC", sizeof(adap->name));
 	i2c_set_adapdata(adap, dev);
 	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
@@ -761,7 +762,7 @@ static int __devinit iic_probe(struct of_device *ofdev,
 		 dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)");
 
 	/* Now register all the child nodes */
-	of_register_i2c_devices(adap, np);
+	of_i2c_register_devices(adap);
 
 	return 0;
 
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index df00eb1..d2e26d2 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -600,13 +600,14 @@ static int __devinit fsl_i2c_probe(struct of_device *op,
 	i2c->adap = mpc_ops;
 	i2c_set_adapdata(&i2c->adap, i2c);
 	i2c->adap.dev.parent = &op->dev;
+	i2c->adap.dev.of_node = of_node_get(op->dev.of_node);
 
 	result = i2c_add_adapter(&i2c->adap);
 	if (result < 0) {
 		dev_err(i2c->dev, "failed to add adapter\n");
 		goto fail_add;
 	}
-	of_register_i2c_devices(&i2c->adap, op->dev.of_node);
+	of_i2c_register_devices(&i2c->adap);
 
 	return result;
 
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 097f42a..80dd631 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -26,7 +26,7 @@ config OF_GPIO
 
 config OF_I2C
 	def_tristate I2C
-	depends on (PPC_OF || MICROBLAZE) && I2C
+	depends on OF && !SPARC && I2C
 	help
 	  OpenFirmware I2C accessors
 
diff --git a/drivers/of/of_i2c.c b/drivers/of/of_i2c.c
index ab6522c..0a694de 100644
--- a/drivers/of/of_i2c.c
+++ b/drivers/of/of_i2c.c
@@ -14,57 +14,65 @@
 #include <linux/i2c.h>
 #include <linux/of.h>
 #include <linux/of_i2c.h>
+#include <linux/of_irq.h>
 #include <linux/module.h>
 
-void of_register_i2c_devices(struct i2c_adapter *adap,
-			     struct device_node *adap_node)
+void of_i2c_register_devices(struct i2c_adapter *adap)
 {
 	void *result;
 	struct device_node *node;
 
-	for_each_child_of_node(adap_node, node) {
+	/* Only register child devices if the adapter has a node pointer set */
+	if (!adap->dev.of_node)
+		return;
+
+	dev_dbg(&adap->dev, "of_i2c: walking child nodes\n");
+
+	for_each_child_of_node(adap->dev.of_node, node) {
 		struct i2c_board_info info = {};
 		struct dev_archdata dev_ad = {};
 		const __be32 *addr;
 		int len;
 
-		if (of_modalias_node(node, info.type, sizeof(info.type)) < 0)
+		dev_dbg(&adap->dev, "of_i2c: register %s\n", node->full_name);
+
+		if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
+			dev_err(&adap->dev, "of_i2c: modalias failure on %s\n",
+				node->full_name);
 			continue;
+		}
 
 		addr = of_get_property(node, "reg", &len);
-		if (!addr || len < sizeof(int) || *addr > (1 << 10) - 1) {
-			printk(KERN_ERR
-			       "of-i2c: invalid i2c device entry\n");
+		if (!addr || (len < sizeof(int))) {
+			dev_err(&adap->dev, "of_i2c: invalid reg on %s\n",
+				node->full_name);
 			continue;
 		}
 
-		info.irq = irq_of_parse_and_map(node, 0);
-
 		info.addr = be32_to_cpup(addr);
+		if (info.addr > (1 << 10) - 1) {
+			dev_err(&adap->dev, "of_i2c: invalid addr=%x on %s\n",
+				info.addr, node->full_name);
+			continue;
+		}
 
-		info.of_node = node;
+		info.irq = irq_of_parse_and_map(node, 0);
+		info.of_node = of_node_get(node);
 		info.archdata = &dev_ad;
 
 		request_module("%s", info.type);
 
 		result = i2c_new_device(adap, &info);
 		if (result == NULL) {
-			printk(KERN_ERR
-			       "of-i2c: Failed to load driver for %s\n",
-			       info.type);
+			dev_err(&adap->dev, "of_i2c: Failure registering %s\n",
+			        node->full_name);
+			of_node_put(node);
 			irq_dispose_mapping(info.irq);
 			continue;
 		}
-
-		/*
-		 * Get the node to not lose the dev_archdata->of_node.
-		 * Currently there is no way to put it back, as well as no
-		 * of_unregister_i2c_devices() call.
-		 */
-		of_node_get(node);
 	}
 }
-EXPORT_SYMBOL(of_register_i2c_devices);
+EXPORT_SYMBOL(of_i2c_register_devices);
 
 static int of_dev_node_match(struct device *dev, void *data)
 {
diff --git a/include/linux/of_i2c.h b/include/linux/of_i2c.h
index 34974b5..0efe8d4 100644
--- a/include/linux/of_i2c.h
+++ b/include/linux/of_i2c.h
@@ -12,12 +12,19 @@
 #ifndef __LINUX_OF_I2C_H
 #define __LINUX_OF_I2C_H
 
+#if defined(CONFIG_OF_I2C) || defined(CONFIG_OF_I2C_MODULE)
 #include <linux/i2c.h>
 
-void of_register_i2c_devices(struct i2c_adapter *adap,
-			     struct device_node *adap_node);
+extern void of_i2c_register_devices(struct i2c_adapter *adap);
 
 /* must call put_device() when done with returned i2c_client device */
-struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
+extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
+
+#else
+static inline void of_i2c_register_devices(struct i2c_adapter *adap)
+{
+	return;
+}
+#endif /* CONFIG_OF_I2C */
 
 #endif /* __LINUX_OF_I2C_H */

[PATCH 2/3] i2c: Add OF-style registration and binding

[Grant Likely]

This patch adds OF hooks to the i2c core so that devices can automatically
be registered based on device tree data.

Signed-off-by: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
---
 drivers/i2c/busses/i2c-cpm.c     |    5 -----
 drivers/i2c/busses/i2c-ibm_iic.c |    3 ---
 drivers/i2c/busses/i2c-mpc.c     |    1 -
 drivers/i2c/i2c-core.c           |    9 +++++++++
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c
index 03ae62e..e591de1 100644
--- a/drivers/i2c/busses/i2c-cpm.c
+++ b/drivers/i2c/busses/i2c-cpm.c
@@ -677,11 +677,6 @@ static int __devinit cpm_i2c_probe(struct of_device *ofdev,
 	dev_dbg(&ofdev->dev, "hw routines for %s registered.\n",
 		cpm->adap.name);
 
-	/*
-	 * register OF I2C devices
-	 */
-	of_i2c_register_devices(&cpm->adap);
-
 	return 0;
 out_shut:
 	cpm_i2c_shutdown(cpm);
diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index d964121..1168d61 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -761,9 +761,6 @@ static int __devinit iic_probe(struct of_device *ofdev,
 	dev_info(&ofdev->dev, "using %s mode\n",
 		 dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)");
 
-	/* Now register all the child nodes */
-	of_i2c_register_devices(adap);
-
 	return 0;
 
 error_cleanup:
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index d2e26d2..9f7fef8 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -607,7 +607,6 @@ static int __devinit fsl_i2c_probe(struct of_device *op,
 		dev_err(i2c->dev, "failed to add adapter\n");
 		goto fail_add;
 	}
-	of_i2c_register_devices(&i2c->adap);
 
 	return result;
 
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 1cca263..5588ac1 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -30,6 +30,8 @@
 #include <linux/init.h>
 #include <linux/idr.h>
 #include <linux/mutex.h>
+#include <linux/of_i2c.h>
+#include <linux/of_device.h>
 #include <linux/completion.h>
 #include <linux/hardirq.h>
 #include <linux/irqflags.h>
@@ -70,6 +72,10 @@ static int i2c_device_match(struct device *dev, struct device_driver *drv)
 	if (!client)
 		return 0;
 
+	/* Attempt an OF style match */
+	if (of_driver_match_device(dev, drv))
+		return 1;
+
 	driver = to_i2c_driver(drv);
 	/* match on an id table if there is one */
 	if (driver->id_table)
@@ -790,6 +796,9 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	if (adap->nr < __i2c_first_dynamic_bus_num)
 		i2c_scan_static_board_info(adap);
 
+	/* Register devices from the device tree */
+	of_i2c_register_devices(adap);
+
 	/* Notify drivers */
 	mutex_lock(&core_lock);
 	dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap,

[PATCH 2/3] i2c: Add OF-style registration and binding

[Grant Likely]

This patch adds OF hooks to the i2c core so that devices can automatically
be registered based on device tree data.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 drivers/i2c/busses/i2c-cpm.c     |    5 -----
 drivers/i2c/busses/i2c-ibm_iic.c |    3 ---
 drivers/i2c/busses/i2c-mpc.c     |    1 -
 drivers/i2c/i2c-core.c           |    9 +++++++++
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c
index 03ae62e..e591de1 100644
--- a/drivers/i2c/busses/i2c-cpm.c
+++ b/drivers/i2c/busses/i2c-cpm.c
@@ -677,11 +677,6 @@ static int __devinit cpm_i2c_probe(struct of_device *ofdev,
 	dev_dbg(&ofdev->dev, "hw routines for %s registered.\n",
 		cpm->adap.name);
 
-	/*
-	 * register OF I2C devices
-	 */
-	of_i2c_register_devices(&cpm->adap);
-
 	return 0;
 out_shut:
 	cpm_i2c_shutdown(cpm);
diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index d964121..1168d61 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -761,9 +761,6 @@ static int __devinit iic_probe(struct of_device *ofdev,
 	dev_info(&ofdev->dev, "using %s mode\n",
 		 dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)");
 
-	/* Now register all the child nodes */
-	of_i2c_register_devices(adap);
-
 	return 0;
 
 error_cleanup:
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index d2e26d2..9f7fef8 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -607,7 +607,6 @@ static int __devinit fsl_i2c_probe(struct of_device *op,
 		dev_err(i2c->dev, "failed to add adapter\n");
 		goto fail_add;
 	}
-	of_i2c_register_devices(&i2c->adap);
 
 	return result;
 
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 1cca263..5588ac1 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -30,6 +30,8 @@
 #include <linux/init.h>
 #include <linux/idr.h>
 #include <linux/mutex.h>
+#include <linux/of_i2c.h>
+#include <linux/of_device.h>
 #include <linux/completion.h>
 #include <linux/hardirq.h>
 #include <linux/irqflags.h>
@@ -70,6 +72,10 @@ static int i2c_device_match(struct device *dev, struct device_driver *drv)
 	if (!client)
 		return 0;
 
+	/* Attempt an OF style match */
+	if (of_driver_match_device(dev, drv))
+		return 1;
+
 	driver = to_i2c_driver(drv);
 	/* match on an id table if there is one */
 	if (driver->id_table)
@@ -790,6 +796,9 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
 	if (adap->nr < __i2c_first_dynamic_bus_num)
 		i2c_scan_static_board_info(adap);
 
+	/* Register devices from the device tree */
+	of_i2c_register_devices(adap);
+
 	/* Notify drivers */
 	mutex_lock(&core_lock);
 	dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap,

[PATCH 3/3] of: refactor of_modalias_node() and remove explicit match table.

[Grant Likely]

This patch tightens up the behaviour of of_modalias_node() to be more
predicatable and to eliminate the explicit of_modalias_tablep[] that
is currently used to override the first entry in the compatible list
of a device.  The override table was needed originally because spi
and i2c drivers had no way to do of-style matching.  Now that all
devices can have an of_node pointer, and all drivers can have an
of_match_table, the explicit override table is no longer needed
because each driver can specify its own OF-style match data.

The mpc8349emitx-mcu driver is modified to explicitly specify the
correct device to bind against.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
 arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c |    6 ++
 drivers/mmc/host/mmc_spi.c                     |    8 +++
 drivers/of/base.c                              |   64 +++---------------------
 3 files changed, 23 insertions(+), 55 deletions(-)

diff --git a/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c b/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c
index 59b0ed1..70798ac 100644
--- a/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c
+++ b/arch/powerpc/platforms/83xx/mcu_mpc8349emitx.c
@@ -160,10 +160,16 @@ static const struct i2c_device_id mcu_ids[] = {
 };
 MODULE_DEVICE_TABLE(i2c, mcu_ids);
 
+static struct of_device_id mcu_of_match_table[] __devinitdata = {
+	{ .compatible = "fsl,mcu-mpc8349emitx", },
+	{ },
+};
+
 static struct i2c_driver mcu_driver = {
 	.driver = {
 		.name = "mcu-mpc8349emitx",
 		.owner = THIS_MODULE,
+		.of_match_table = mcu_of_match_table,
 	},
 	.probe = mcu_probe,
 	.remove	= __devexit_p(mcu_remove),
diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c
index ad847a2..7b0f3ef 100644
--- a/drivers/mmc/host/mmc_spi.c
+++ b/drivers/mmc/host/mmc_spi.c
@@ -1533,12 +1533,20 @@ static int __devexit mmc_spi_remove(struct spi_device *spi)
 	return 0;
 }
 
+#if defined(CONFIG_OF)
+static struct of_device_id mmc_spi_of_match_table[] __devinitdata = {
+	{ .compatible = "mmc-spi-slot", },
+};
+#endif
 
 static struct spi_driver mmc_spi_driver = {
 	.driver = {
 		.name =		"mmc_spi",
 		.bus =		&spi_bus_type,
 		.owner =	THIS_MODULE,
+#if defined(CONFIG_OF)
+		.of_match_table = mmc_spi_of_match_table,
+#endif
 	},
 	.probe =	mmc_spi_probe,
 	.remove =	__devexit_p(mmc_spi_remove),
diff --git a/drivers/of/base.c b/drivers/of/base.c
index b5ad974..e3f7af8 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -545,74 +545,28 @@ struct device_node *of_find_matching_node(struct device_node *from,
 EXPORT_SYMBOL(of_find_matching_node);
 
 /**
- * of_modalias_table: Table of explicit compatible ==> modalias mappings
- *
- * This table allows particulare compatible property values to be mapped
- * to modalias strings.  This is useful for busses which do not directly
- * understand the OF device tree but are populated based on data contained
- * within the device tree.  SPI and I2C are the two current users of this
- * table.
- *
- * In most cases, devices do not need to be listed in this table because
- * the modalias value can be derived directly from the compatible table.
- * However, if for any reason a value cannot be derived, then this table
- * provides a method to override the implicit derivation.
- *
- * At the moment, a single table is used for all bus types because it is
- * assumed that the data size is small and that the compatible values
- * should already be distinct enough to differentiate between SPI, I2C
- * and other devices.
- */
-struct of_modalias_table {
-	char *of_device;
-	char *modalias;
-};
-static struct of_modalias_table of_modalias_table[] = {
-	{ "fsl,mcu-mpc8349emitx", "mcu-mpc8349emitx" },
-	{ "mmc-spi-slot", "mmc_spi" },
-};
-
-/**
  * of_modalias_node - Lookup appropriate modalias for a device node
  * @node:	pointer to a device tree node
  * @modalias:	Pointer to buffer that modalias value will be copied into
  * @len:	Length of modalias value
  *
- * Based on the value of the compatible property, this routine will determine
- * an appropriate modalias value for a particular device tree node.  Two
- * separate methods are attempted to derive a modalias value.
+ * Based on the value of the compatible property, this routine will attempt
+ * to choose an appropriate modalias value for a particular device tree node.
+ * It does this by stripping the manufacturer prefix (as delimited by a ',')
+ * from the first entry in the compatible list property.
  *
- * First method is to lookup the compatible value in of_modalias_table.
- * Second is to strip off the manufacturer prefix from the first
- * compatible entry and use the remainder as modalias
- *
- * This routine returns 0 on success
+ * This routine returns 0 on success, <0 on failure.
  */
 int of_modalias_node(struct device_node *node, char *modalias, int len)
 {
-	int i, cplen;
-	const char *compatible;
-	const char *p;
-
-	/* 1. search for exception list entry */
-	for (i = 0; i < ARRAY_SIZE(of_modalias_table); i++) {
-		compatible = of_modalias_table[i].of_device;
-		if (!of_device_is_compatible(node, compatible))
-			continue;
-		strlcpy(modalias, of_modalias_table[i].modalias, len);
-		return 0;
-	}
+	const char *compatible, *p;
+	int cplen;
 
 	compatible = of_get_property(node, "compatible", &cplen);
-	if (!compatible)
+	if (!compatible || strlen(compatible) > cplen)
 		return -ENODEV;
-
-	/* 2. take first compatible entry and strip manufacturer */
 	p = strchr(compatible, ',');
-	if (!p)
-		return -ENODEV;
-	p++;
-	strlcpy(modalias, p, len);
+	strlcpy(modalias, p ? p + 1 : compatible, len);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(of_modalias_node);