gpio-keys-polled improvements

gpio-keys-polled improvements

[Enrico Weigelt, metux IT consult]

Hello folks,


here're some improvements for the gpio-keys-polled driver.

The first patch isn't in the driver itself, but adds a little module helper
for conditionally declaring oftree module table if oftree is enabled
(only needed for the last patch)


have fun.

--mtx

[PATCH 1/4] mod_devicetable: helper macro for declaring oftree module device table

[Enrico Weigelt, metux IT consult]

Little helper macro that declares an oftree module device table,
if CONFIG_OF is enabled. Otherwise it's just noop.

This is also helpful if some drivers can be built w/ or w/o
oftree support.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 include/linux/mod_devicetable.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 448621c..853e301 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -245,6 +245,15 @@ struct of_device_id {
 	const void *data;
 };
 
+/*
+ * macro for adding the of module device table only if CONFIG_OF enabled
+ */
+#ifdef CONFIG_OF
+#define MODULE_DEVICE_TABLE_OF(name)	MODULE_DEVICE_TABLE(of,name)
+#else
+#define MODULE_DEVICE_TABLE_OF(name)
+#endif /* CONFIG_OF */
+
 /* VIO */
 struct vio_device_id {
 	char type[32];
-- 
1.9.1

Re: [PATCH 1/4] mod_devicetable: helper macro for declaring oftree module device table

[Dmitry Torokhov]

Hi Enrico,

On Tue, Apr 16, 2019 at 09:57:22PM +0200, Enrico Weigelt, metux IT consult wrote:
> Little helper macro that declares an oftree module device table,
> if CONFIG_OF is enabled. Otherwise it's just noop.
> 
> This is also helpful if some drivers can be built w/ or w/o
> oftree support.

This should go to OF folks, please.

> 
> Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
> ---
>  include/linux/mod_devicetable.h | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index 448621c..853e301 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -245,6 +245,15 @@ struct of_device_id {
>  	const void *data;
>  };
>  
> +/*
> + * macro for adding the of module device table only if CONFIG_OF enabled
> + */
> +#ifdef CONFIG_OF
> +#define MODULE_DEVICE_TABLE_OF(name)	MODULE_DEVICE_TABLE(of,name)
> +#else
> +#define MODULE_DEVICE_TABLE_OF(name)
> +#endif /* CONFIG_OF */
> +
>  /* VIO */
>  struct vio_device_id {
>  	char type[32];
> -- 
> 1.9.1
> 

-- 
Dmitry

Re: [PATCH 1/4] mod_devicetable: helper macro for declaring oftree module device table

[Enrico Weigelt, metux IT consult]

On 19.04.19 09:40, Dmitry Torokhov wrote:
> Hi Enrico,
> 
> On Tue, Apr 16, 2019 at 09:57:22PM +0200, Enrico Weigelt, metux IT consult wrote:
>> Little helper macro that declares an oftree module device table,
>> if CONFIG_OF is enabled. Otherwise it's just noop.
>>
>> This is also helpful if some drivers can be built w/ or w/o
>> oftree support.
> 
> This should go to OF folks, please.

hmm, they should be CCed, if my script works right.
This one is only needed for the 4th patch (skip oftree...).


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@metux.net -- +49-151-27565287

Re: [PATCH 1/4] mod_devicetable: helper macro for declaring oftree module device table

[Frank Rowand]

On 4/24/19 3:48 AM, Enrico Weigelt, metux IT consult wrote:
> On 19.04.19 09:40, Dmitry Torokhov wrote:
>> Hi Enrico,
>>
>> On Tue, Apr 16, 2019 at 09:57:22PM +0200, Enrico Weigelt, metux IT consult wrote:
>>> Little helper macro that declares an oftree module device table,
>>> if CONFIG_OF is enabled. Otherwise it's just noop.
>>>
>>> This is also helpful if some drivers can be built w/ or w/o
>>> oftree support.
>>
>> This should go to OF folks, please.
> 
> hmm, they should be CCed, if my script works right.
> This one is only needed for the 4th patch (skip oftree...).

Your script did not work (BTDT).  I just happened to notice this on lkml.

-Frank

> 
> 
> --mtx
> 

[PATCH 2/4] input: keyboard: gpio-keys-polled: use input name from pdata if available

[Enrico Weigelt, metux IT consult]

Instead of hardcoding the input name to the driver name
('gpio-keys-polled'), allow the passing a name via platform data
('name' field was already present), but default to old behaviour
in case of NULL.

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: linux-input@vger.kernel.org
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 drivers/input/keyboard/gpio_keys_polled.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/gpio_keys_polled.c b/drivers/input/keyboard/gpio_keys_polled.c
index edc7262..3312186 100644
--- a/drivers/input/keyboard/gpio_keys_polled.c
+++ b/drivers/input/keyboard/gpio_keys_polled.c
@@ -272,7 +272,7 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
 
 	input = poll_dev->input;
 
-	input->name = pdev->name;
+	input->name = (pdata->name ? pdata->name : pdev->name);
 	input->phys = DRV_NAME"/input0";
 
 	input->id.bustype = BUS_HOST;
-- 
1.9.1

[PATCH 3/4] input: keyboard: gpio_keys_polled: use gpio lookup table

[Enrico Weigelt, metux IT consult]

Support the recently introduced gpio lookup tables for
attaching to gpio lines. So, harcoded gpio numbers aren't
needed anymore.

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: linux-input@vger.kernel.org
Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 drivers/input/keyboard/gpio_keys_polled.c | 167 +++++++++++++++++++++---------
 1 file changed, 119 insertions(+), 48 deletions(-)

diff --git a/drivers/input/keyboard/gpio_keys_polled.c b/drivers/input/keyboard/gpio_keys_polled.c
index 3312186..3f773b2 100644
--- a/drivers/input/keyboard/gpio_keys_polled.c
+++ b/drivers/input/keyboard/gpio_keys_polled.c
@@ -24,6 +24,7 @@
 #include <linux/platform_device.h>
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
+#include <linux/gpio/machine.h>
 #include <linux/gpio_keys.h>
 #include <linux/property.h>
 
@@ -227,6 +228,119 @@ static void gpio_keys_polled_set_abs_params(struct input_dev *input,
 };
 MODULE_DEVICE_TABLE(of, gpio_keys_polled_of_match);
 
+static struct gpio_desc *gpio_keys_polled_get_gpiod_fwnode(
+	struct device *dev,
+	int idx,
+	const char *desc)
+{
+	struct gpio_desc *gpiod;
+	struct fwnode_handle *child;
+	int x;
+
+	/* get the idx'th child node */
+	child = device_get_next_child_node(dev, NULL);
+	while (child && x) {
+		child = device_get_next_child_node(dev, child);
+		x--;
+	}
+
+	if (!child) {
+		dev_err(dev, "missing oftree child node #%d\n", idx);
+		return ERR_PTR(-EINVAL);
+	}
+
+	gpiod = devm_fwnode_get_gpiod_from_child(dev,
+						 NULL,
+						 child,
+						 GPIOD_IN,
+						 desc);
+	if (IS_ERR(gpiod)) {
+		if (PTR_ERR(gpiod) != -EPROBE_DEFER)
+			dev_err(dev,
+				"failed to get gpio: %ld\n",
+				PTR_ERR(gpiod));
+		fwnode_handle_put(child);
+		return gpiod;
+	}
+
+	return gpiod;
+}
+
+static struct gpio_desc *gpio_keys_polled_get_gpiod_legacy(
+	struct device *dev,
+	int idx,
+	const struct gpio_keys_button *button)
+{
+	/*
+	 * Legacy GPIO number so request the GPIO here and
+	 * convert it to descriptor.
+	 */
+	unsigned int flags = GPIOF_IN;
+	struct gpio_desc *gpiod;
+	int error;
+
+	dev_info(dev, "hardcoded gpio IDs are deprecated.\n");
+
+	if (button->active_low)
+		flags |= GPIOF_ACTIVE_LOW;
+
+	error = devm_gpio_request_one(dev, button->gpio,
+			flags, button->desc ? : DRV_NAME);
+	if (error) {
+		dev_err(dev,
+			"unable to claim gpio %u, err=%d\n",
+			button->gpio, error);
+		return ERR_PTR(error);
+	}
+
+	gpiod = gpio_to_desc(button->gpio);
+	if (!gpiod) {
+		dev_err(dev,
+			"unable to convert gpio %u to descriptor\n",
+			button->gpio);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return gpiod;
+}
+
+static struct gpio_desc *gpio_keys_polled_get_gpiod(
+	struct device *dev,
+	int idx,
+	const struct gpio_keys_button *button)
+{
+	struct gpio_desc *gpiod = NULL;
+	int error;
+
+	/* No legacy static platform data - use oftree */
+	if (!dev_get_platdata(dev)) {
+		return gpio_keys_polled_get_gpiod_fwnode(
+			dev, idx, button->desc);
+	}
+
+	gpiod = devm_gpiod_get_index(dev, NULL, idx, GPIOF_IN);
+
+	if (!IS_ERR(gpiod)) {
+		dev_info(dev, "picked gpiod idx %d from gpio table\n", idx);
+		gpiod_set_consumer_name(gpiod, button->desc ? : DRV_NAME);
+		return gpiod;
+	}
+
+	if (PTR_ERR(gpiod) != -ENOENT) {
+		dev_err(dev, "failed fetching gpiod #%d: %d\n",
+			idx, PTR_ERR(gpiod));
+		return gpiod;
+	}
+
+	/* Use legacy gpio id, if defined */
+	if (gpio_is_valid(button->gpio)) {
+		return gpio_keys_polled_get_gpiod_legacy(
+			dev, idx, button);
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
 static int gpio_keys_polled_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -291,57 +405,14 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
 
 		if (button->wakeup) {
 			dev_err(dev, DRV_NAME " does not support wakeup\n");
-			fwnode_handle_put(child);
 			return -EINVAL;
 		}
 
-		if (!dev_get_platdata(dev)) {
-			/* No legacy static platform data */
-			child = device_get_next_child_node(dev, child);
-			if (!child) {
-				dev_err(dev, "missing child device node\n");
-				return -EINVAL;
-			}
-
-			bdata->gpiod = devm_fwnode_get_gpiod_from_child(dev,
-								NULL, child,
-								GPIOD_IN,
-								button->desc);
-			if (IS_ERR(bdata->gpiod)) {
-				error = PTR_ERR(bdata->gpiod);
-				if (error != -EPROBE_DEFER)
-					dev_err(dev,
-						"failed to get gpio: %d\n",
-						error);
-				fwnode_handle_put(child);
-				return error;
-			}
-		} else if (gpio_is_valid(button->gpio)) {
-			/*
-			 * Legacy GPIO number so request the GPIO here and
-			 * convert it to descriptor.
-			 */
-			unsigned flags = GPIOF_IN;
-
-			if (button->active_low)
-				flags |= GPIOF_ACTIVE_LOW;
-
-			error = devm_gpio_request_one(dev, button->gpio,
-					flags, button->desc ? : DRV_NAME);
-			if (error) {
-				dev_err(dev,
-					"unable to claim gpio %u, err=%d\n",
-					button->gpio, error);
-				return error;
-			}
-
-			bdata->gpiod = gpio_to_desc(button->gpio);
-			if (!bdata->gpiod) {
-				dev_err(dev,
-					"unable to convert gpio %u to descriptor\n",
-					button->gpio);
-				return -EINVAL;
-			}
+		bdata->gpiod = gpio_keys_polled_get_gpiod(dev, i, button);
+
+		if (IS_ERR(bdata->gpiod)) {
+			dev_err(dev, "failed to fetch gpiod #%d\n", i);
+			return PTR_ERR(bdata->gpiod);
 		}
 
 		bdata->last_state = -1;
-- 
1.9.1

Re: [PATCH 3/4] input: keyboard: gpio_keys_polled: use gpio lookup table

[Dmitry Torokhov]

Hi Enrico,

On Tue, Apr 16, 2019 at 09:57:24PM +0200, Enrico Weigelt, metux IT consult wrote:
> Support the recently introduced gpio lookup tables for
> attaching to gpio lines. So, harcoded gpio numbers aren't
> needed anymore.

I would prefer if gpiod API could parse static board data/gpio lookup
tables for child nodes, instead of adding this to gpio-keys. Now that
Heikki Krogerus work on software nodes has landed I need to resurrect
my patch to gpiolib.

Thanks.

-- 
Dmitry

Re: [PATCH 3/4] input: keyboard: gpio_keys_polled: use gpio lookup table

[Enrico Weigelt, metux IT consult]

On 19.04.19 09:48, Dmitry Torokhov wrote:

> I would prefer if gpiod API could parse static board data/gpio lookup
> tables for child nodes, instead of adding this to gpio-keys. Now that
> Heikki Krogerus work on software nodes has landed I need to resurrect
> my patch to gpiolib.

Of course, a more generic approach would be better.

I did it that way I wasn't that aware that a more generic approach is
in the pipeline, and I needed something usable now.

The patch is already used in the field and seems to work quite well,
but if I'm alway open for better solutions.

I figure that the generic solution will still take some time, so can we
take this one for the next merge window and rework it in the next one ?


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@metux.net -- +49-151-27565287

[PATCH 4/4] input: keyboard: gpio-keys-polled: skip oftree code when CONFIG_OF disabled

[Enrico Weigelt, metux IT consult]

we don't need to build in oftree probing stuff when oftree isn't
enabled at all.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 drivers/input/keyboard/gpio_keys_polled.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/gpio_keys_polled.c b/drivers/input/keyboard/gpio_keys_polled.c
index 3f773b2..fbccb89 100644
--- a/drivers/input/keyboard/gpio_keys_polled.c
+++ b/drivers/input/keyboard/gpio_keys_polled.c
@@ -147,6 +147,7 @@ static void gpio_keys_polled_close(struct input_polled_dev *dev)
 static struct gpio_keys_platform_data *
 gpio_keys_polled_get_devtree_pdata(struct device *dev)
 {
+#ifdef CONFIG_OF
 	struct gpio_keys_platform_data *pdata;
 	struct gpio_keys_button *button;
 	struct fwnode_handle *child;
@@ -200,6 +201,9 @@ static void gpio_keys_polled_close(struct input_polled_dev *dev)
 	}
 
 	return pdata;
+#else /* CONFIG_OF */
+	return ERR_PTR(-ENOENT);
+#endif /* CONFIG_OF */
 }
 
 static void gpio_keys_polled_set_abs_params(struct input_dev *input,
@@ -226,7 +230,7 @@ static void gpio_keys_polled_set_abs_params(struct input_dev *input,
 	{ .compatible = "gpio-keys-polled", },
 	{ },
 };
-MODULE_DEVICE_TABLE(of, gpio_keys_polled_of_match);
+MODULE_DEVICE_TABLE_OF(gpio_keys_polled_of_match);
 
 static struct gpio_desc *gpio_keys_polled_get_gpiod_fwnode(
 	struct device *dev,
@@ -452,7 +456,9 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
 	.probe	= gpio_keys_polled_probe,
 	.driver	= {
 		.name	= DRV_NAME,
+#ifdef CONFIG_OF
 		.of_match_table = gpio_keys_polled_of_match,
+#endif /* CONFIG_OF */
 	},
 };
 module_platform_driver(gpio_keys_polled_driver);
-- 
1.9.1

Re: [PATCH 4/4] input: keyboard: gpio-keys-polled: skip oftree code when CONFIG_OF disabled

[Frank Rowand]

On 4/16/19 12:57 PM, Enrico Weigelt, metux IT consult wrote:
> we don't need to build in oftree probing stuff when oftree isn't
> enabled at all.
> 
> Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
> ---
>  drivers/input/keyboard/gpio_keys_polled.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/input/keyboard/gpio_keys_polled.c b/drivers/input/keyboard/gpio_keys_polled.c
> index 3f773b2..fbccb89 100644
> --- a/drivers/input/keyboard/gpio_keys_polled.c
> +++ b/drivers/input/keyboard/gpio_keys_polled.c
> @@ -147,6 +147,7 @@ static void gpio_keys_polled_close(struct input_polled_dev *dev)
>  static struct gpio_keys_platform_data *
>  gpio_keys_polled_get_devtree_pdata(struct device *dev)
>  {
> +#ifdef CONFIG_OF
>  	struct gpio_keys_platform_data *pdata;
>  	struct gpio_keys_button *button;
>  	struct fwnode_handle *child;
> @@ -200,6 +201,9 @@ static void gpio_keys_polled_close(struct input_polled_dev *dev)
>  	}
>  
>  	return pdata;
> +#else /* CONFIG_OF */
> +	return ERR_PTR(-ENOENT);
> +#endif /* CONFIG_OF */
>  }
>  
>  static void gpio_keys_polled_set_abs_params(struct input_dev *input,
> @@ -226,7 +230,7 @@ static void gpio_keys_polled_set_abs_params(struct input_dev *input,
>  	{ .compatible = "gpio-keys-polled", },
>  	{ },
>  };


> -MODULE_DEVICE_TABLE(of, gpio_keys_polled_of_match);
> +MODULE_DEVICE_TABLE_OF(gpio_keys_polled_of_match);

Not needed, when you use of_match_ptr() -- see below.

>  
>  static struct gpio_desc *gpio_keys_polled_get_gpiod_fwnode(
>  	struct device *dev,
> @@ -452,7 +456,9 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
>  	.probe	= gpio_keys_polled_probe,
>  	.driver	= {
>  		.name	= DRV_NAME,

> +#ifdef CONFIG_OF
>  		.of_match_table = gpio_keys_polled_of_match,
> +#endif /* CONFIG_OF */

No need for the #ifdef, use of_match_ptr():

  		.of_match_table = of_match_ptr(gpio_keys_polled_of_match),


>  	},
>  };
>  module_platform_driver(gpio_keys_polled_driver);
> 

Re: [PATCH 4/4] input: keyboard: gpio-keys-polled: skip oftree code when CONFIG_OF disabled

[Enrico Weigelt, metux IT consult]

On 29.04.19 21:44, Frank Rowand wrote:
> On 4/16/19 12:57 PM, Enrico Weigelt, metux IT consult wrote:
>> we don't need to build in oftree probing stuff when oftree isn't
>> enabled at all.
>>
>> Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
>> ---
>>  drivers/input/keyboard/gpio_keys_polled.c | 8 +++++++-
>>  1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/input/keyboard/gpio_keys_polled.c b/drivers/input/keyboard/gpio_keys_polled.c
>> index 3f773b2..fbccb89 100644
>> --- a/drivers/input/keyboard/gpio_keys_polled.c
>> +++ b/drivers/input/keyboard/gpio_keys_polled.c
>> @@ -147,6 +147,7 @@ static void gpio_keys_polled_close(struct input_polled_dev *dev)
>>  static struct gpio_keys_platform_data *
>>  gpio_keys_polled_get_devtree_pdata(struct device *dev)
>>  {
>> +#ifdef CONFIG_OF
>>  	struct gpio_keys_platform_data *pdata;
>>  	struct gpio_keys_button *button;
>>  	struct fwnode_handle *child;
>> @@ -200,6 +201,9 @@ static void gpio_keys_polled_close(struct input_polled_dev *dev)
>>  	}
>>  
>>  	return pdata;
>> +#else /* CONFIG_OF */
>> +	return ERR_PTR(-ENOENT);
>> +#endif /* CONFIG_OF */
>>  }
>>  
>>  static void gpio_keys_polled_set_abs_params(struct input_dev *input,
>> @@ -226,7 +230,7 @@ static void gpio_keys_polled_set_abs_params(struct input_dev *input,
>>  	{ .compatible = "gpio-keys-polled", },
>>  	{ },
>>  };
> 
> 
>> -MODULE_DEVICE_TABLE(of, gpio_keys_polled_of_match);
>> +MODULE_DEVICE_TABLE_OF(gpio_keys_polled_of_match);
> 
> Not needed, when you use of_match_ptr() -- see below.

Shall I remove the MODULE_DEVICE_TABLE... line completely ?

I'd like to have nothing of-related compiled in, when oftree isn't
enabled.

>>  static struct gpio_desc *gpio_keys_polled_get_gpiod_fwnode(
>>  	struct device *dev,
>> @@ -452,7 +456,9 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
>>  	.probe	= gpio_keys_polled_probe,
>>  	.driver	= {
>>  		.name	= DRV_NAME,
> 
>> +#ifdef CONFIG_OF
>>  		.of_match_table = gpio_keys_polled_of_match,
>> +#endif /* CONFIG_OF */
> 
> No need for the #ifdef, use of_match_ptr():
> 
>   		.of_match_table = of_match_ptr(gpio_keys_polled_of_match),

Ok, thanks.


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@metux.net -- +49-151-27565287

RFC: declaring DT match tables (2nd take)

[Enrico Weigelt, metux IT consult]

Hi folks,


few days ago I've posted a RFC for getting rid of many #ifdef CONFIG_OF
cases by using a macro that checks for it on its own.
(see: "RFC: get rid of #ifdef CONFIG_OF's around of match tables")

I've already mentioned I'm working on another approach that not just
cares about adding the table to the module, but the also the declaration
of the table itself. Here it is:

Introducing a macro MODULE_DECLARE_OF_TABLE(foo, entries), which declares
a static struct of_device_id array, fills in the entries (automatically
adds the sentinel) and calls MODULE_DEVICE_TABLE() - if CONFIG_OF is
enabled.

The current version isn't fully noop in absence of CONFIG_OF, but also
declares a static const *pointer* variable, initialized NULL, with the
same name. The idea behind: we don't need to use of_match_ptr() anymore.

I believe, the compiler should be clever enough to find out that this
field is always NULL and can't ever change, so it can be easily optimized
away. (correct me if I'm wrong).


Please have a look at the following example patches and let me know,
whether we can go that way. If you're okay w/ that, I'll continue
w/ converting the whole tree to using this approach. I've already did
most of it, yet needs to be sorted out into easily digestable patches :)
And I'd also do the same w/ the other table types (ACPI, PCI, I2C, ...)

By the way: an interesting question arises: shall that conversion be
done *everywhere*, or just those sites where explicit CONFIG_OF's are
involved ?


have fun,

--mtx

[PATCH 1/4] mod_devicetable: helper macro for declaring oftree module device table

[Enrico Weigelt, metux IT consult]

Little helper macros that declares an oftree module device table,
if CONFIG_OF is enabled. Otherwise it's just noop. Helpful for
reducing the number of #ifdef's.

Instead of:
    MODULE_DEVICE_TABLE(of, foo);
now use:
    MODULE_OF_TABLE(foo);

Or declare the whole table via:
    MODULE_DECLARE_OF_TABLE(foo,
        { .compatible = "foo" },
        { .compatible = "bar" });

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
 include/linux/mod_devicetable.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 448621c..5f4f2dc8 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -245,6 +245,19 @@ struct of_device_id {
 	const void *data;
 };
 
+/*
+ * macro for adding the of module device table only if CONFIG_OF enabled
+ */
+#ifdef CONFIG_OF
+#define MODULE_OF_TABLE(name)	MODULE_DEVICE_TABLE(of,name)
+#define MODULE_DECLARE_OF_TABLE(name,entries...) \
+static const struct of_device_id name[] = { entries, {} };
+#else
+#define MODULE_OF_TABLE(name)
+#define MODULE_DECLARE_OF_TABLE(name,entries...) \
+static const struct of_device_id *name = NULL;
+#endif /* CONFIG_OF */
+
 /* VIO */
 struct vio_device_id {
 	char type[32];
-- 
1.9.1