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Commit 4a6ef8e3 authored by Nikolaus Voss's avatar Nikolaus Voss Committed by Thierry Reding
Browse files

pwm: Add support referencing PWMs from ACPI 



In analogy to referencing a GPIO using the "gpios" property from ACPI,
support referencing a PWM using the "pwms" property.

ACPI entries must look like
 Package () {"pwms", Package ()
     { <PWM device reference>, <PWM index>, <PWM period> [, <PWM flags>]}}

In contrast to the DT implementation, only _one_ PWM entry in the "pwms"
property is supported. As a consequence "pwm-names"-property and
con_id lookup aren't supported.

Support for ACPI is added via the firmware-node framework which is an
abstraction layer on top of ACPI/DT. To keep this patch clean, DT and
ACPI paths are kept separate. The firmware-node framework could be used
to unify both paths in a future patch.

To support leds-pwm driver, an additional method devm_fwnode_pwm_get()
which supports both ACPI and DT configuration is exported.

Signed-off-by: default avatarNikolaus Voss <nikolaus.voss@loewensteinmedical.de>
[thierry.reding@gmail.com: fix build failures for !ACPI]
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent 4a5fa56c

drivers/pwm/core.c

+122 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

 */



#include <linux/acpi.h>

#include <linux/module.h>

#include <linux/pwm.h>

#include <linux/radix-tree.h>
@@ -750,6 +751,85 @@ struct pwm_device *of_pwm_get(struct device *dev, struct device_node *np, 
}

EXPORT_SYMBOL_GPL(of_pwm_get);



#if IS_ENABLED(CONFIG_ACPI)

static struct pwm_chip *device_to_pwmchip(struct device *dev)

{

	struct pwm_chip *chip;



	mutex_lock(&pwm_lock);



	list_for_each_entry(chip, &pwm_chips, list) {

		struct acpi_device *adev = ACPI_COMPANION(chip->dev);



		if ((chip->dev == dev) || (adev && &adev->dev == dev)) {

			mutex_unlock(&pwm_lock);

			return chip;

		}

	}



	mutex_unlock(&pwm_lock);



	return ERR_PTR(-EPROBE_DEFER);

}

#endif



/**

 * acpi_pwm_get() - request a PWM via parsing "pwms" property in ACPI

 * @fwnode: firmware node to get the "pwm" property from

 *

 * Returns the PWM device parsed from the fwnode and index specified in the

 * "pwms" property or a negative error-code on failure.

 * Values parsed from the device tree are stored in the returned PWM device

 * object.

 *

 * This is analogous to of_pwm_get() except con_id is not yet supported.

 * ACPI entries must look like

 * Package () {"pwms", Package ()

 *     { <PWM device reference>, <PWM index>, <PWM period> [, <PWM flags>]}}

 *

 * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded

 * error code on failure.

 */

static struct pwm_device *acpi_pwm_get(struct fwnode_handle *fwnode)

{

	struct pwm_device *pwm = ERR_PTR(-ENODEV);

#if IS_ENABLED(CONFIG_ACPI)

	struct fwnode_reference_args args;

	struct acpi_device *acpi;

	struct pwm_chip *chip;

	int ret;



	memset(&args, 0, sizeof(args));



	ret = __acpi_node_get_property_reference(fwnode, "pwms", 0, 3, &args);

	if (ret < 0)

		return ERR_PTR(ret);



	acpi = to_acpi_device_node(args.fwnode);

	if (!acpi)

		return ERR_PTR(-EINVAL);



	if (args.nargs < 2)

		return ERR_PTR(-EPROTO);



	chip = device_to_pwmchip(&acpi->dev);

	if (IS_ERR(chip))

		return ERR_CAST(chip);



	pwm = pwm_request_from_chip(chip, args.args[0], NULL);

	if (IS_ERR(pwm))

		return pwm;



	pwm->args.period = args.args[1];

	pwm->args.polarity = PWM_POLARITY_NORMAL;



	if (args.nargs > 2 && args.args[2] & PWM_POLARITY_INVERTED)

		pwm->args.polarity = PWM_POLARITY_INVERSED;

#endif



	return pwm;

}



/**

 * pwm_add_table() - register PWM device consumers

 * @table: array of consumers to register
@@ -814,6 +894,10 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) 
	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)

		return of_pwm_get(dev, dev->of_node, con_id);



	/* then lookup via ACPI */

	if (dev && is_acpi_node(dev->fwnode))

		return acpi_pwm_get(dev->fwnode);



	/*

	 * We look up the provider in the static table typically provided by

	 * board setup code. We first try to lookup the consumer device by
@@ -999,6 +1083,44 @@ struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np, 
}

EXPORT_SYMBOL_GPL(devm_of_pwm_get);



/**

 * devm_fwnode_pwm_get() - request a resource managed PWM from firmware node

 * @dev: device for PWM consumer

 * @fwnode: firmware node to get the PWM from

 * @con_id: consumer name

 *

 * Returns the PWM device parsed from the firmware node. See of_pwm_get() and

 * acpi_pwm_get() for a detailed description.

 *

 * Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded

 * error code on failure.

 */

struct pwm_device *devm_fwnode_pwm_get(struct device *dev,

				       struct fwnode_handle *fwnode,

				       const char *con_id)

{

	struct pwm_device **ptr, *pwm = ERR_PTR(-ENODEV);



	ptr = devres_alloc(devm_pwm_release, sizeof(*ptr), GFP_KERNEL);

	if (!ptr)

		return ERR_PTR(-ENOMEM);



	if (is_of_node(fwnode))

		pwm = of_pwm_get(dev, to_of_node(fwnode), con_id);

	else if (is_acpi_node(fwnode))

		pwm = acpi_pwm_get(fwnode);



	if (!IS_ERR(pwm)) {

		*ptr = pwm;

		devres_add(dev, ptr);

	} else {

		devres_free(ptr);

	}



	return pwm;

}

EXPORT_SYMBOL_GPL(devm_fwnode_pwm_get);



static int devm_pwm_match(struct device *dev, void *res, void *data)

{

	struct pwm_device **p = res;

include/linux/pwm.h

+10 −0
Original line number Diff line number Diff line
@@ -412,6 +412,9 @@ void pwm_put(struct pwm_device *pwm); 
struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);

struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,

				   const char *con_id);

struct pwm_device *devm_fwnode_pwm_get(struct device *dev,

				       struct fwnode_handle *fwnode,

				       const char *con_id);

void devm_pwm_put(struct device *dev, struct pwm_device *pwm);

#else

static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
@@ -518,6 +521,13 @@ static inline struct pwm_device *devm_of_pwm_get(struct device *dev, 
	return ERR_PTR(-ENODEV);

}



static inline struct pwm_device *

devm_fwnode_pwm_get(struct device *dev, struct fwnode_handle *fwnode,

		    const char *con_id)

{

	return ERR_PTR(-ENODEV);

}



static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)

{

}