[PATCH v4 03/10] pwm: Add device tree support

@@ -0,0 +1,48 @@
+Specifying PWM information for devices
+======================================
+
+1) PWM user nodes
+-----------------
+
+PWM users should specify a list of PWM devices that they want to use
+with a property containing a 'pwm-list':
+
+	pwm-list ::= <single-pwm> [pwm-list]
+	single-pwm ::= <pwm-phandle> <pwm-specifier>
+	pwm-phandle : phandle to PWM controller node
+	pwm-specifier : array of #pwm-cells specifying the given PWM
+			(controller specific)
+
+PWM properties should be named "[<name>-]pwms". Exact meaning of each
+pwms property must be documented in the device tree binding for each
+device.
+
+The following example could be used to describe a PWM-based backlight
+device:
+
+	pwm: pwm {
+		#pwm-cells = <2>;
+	};
+
+	[...]
+
+	bl: backlight {
+		pwms = <&pwm 0 5000000>;
+	};
+
+pwm-specifier typically encodes the chip-relative PWM number and the PWM
+period in nanoseconds.
+
+2) PWM controller nodes
+-----------------------
+
+PWM controller nodes must specify the number of cells used for the
+specifier using the '#pwm-cells' property.
+
+An example PWM controller might look like this:
+
+	pwm: pwm@7000a000 {
+		compatible = "nvidia,tegra20-pwm";
+		reg = <0x7000a000 0x100>;
+		#pwm-cells = <2>;
+	};

@@ -57,6 +57,12 @@ config OF_GPIO
 	help
 	  OpenFirmware GPIO accessors
 
+config OF_PWM
+	def_bool y
+	depends on PWM
+	help
+	  OpenFirmware PWM accessors
+
 config OF_I2C
 	def_tristate I2C
 	depends on I2C && !SPARC

@@ -20,6 +20,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/of_pwm.h>
 #include <linux/pwm.h>
 #include <linux/radix-tree.h>
 #include <linux/list.h>

@@ -121,6 +122,75 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label)
 	return 0;
 }
 
+#ifdef CONFIG_OF_PWM
+static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
+{
+	struct pwm_chip *chip;
+
+	mutex_lock(&pwm_lock);
+
+	list_for_each_entry(chip, &pwm_chips, list)
+		if (chip->dev && chip->dev->of_node == np) {
+			mutex_unlock(&pwm_lock);
+			return chip;
+		}
+
+	mutex_unlock(&pwm_lock);
+
+	return ERR_PTR(-EPROBE_DEFER);
+}
+
+static struct pwm_device *of_pwm_simple_xlate(struct pwm_chip *pc,
+					      const struct of_phandle_args *args)
+{
+	struct pwm_device *pwm;
+
+	if (pc->of_pwm_n_cells < 2)
+		return ERR_PTR(-EINVAL);
+
+	if (args->args_count < pc->of_pwm_n_cells)
+		return ERR_PTR(-EINVAL);
+
+	if (args->args[0] >= pc->npwm)
+		return ERR_PTR(-EINVAL);
+
+	pwm = pwm_request_from_device(pc->dev, args->args[0], NULL);
+	if (IS_ERR(pwm))
+		return ERR_PTR(-ENODEV);
+
+	pwm_set_period(pwm, args->args[1]);
+
+	return pwm;
+}
+
+void of_pwmchip_add(struct pwm_chip *chip)
+{
+	if (!chip->dev || !chip->dev->of_node)
+		return;
+
+	if (!chip->of_xlate) {
+		chip->of_xlate = of_pwm_simple_xlate;
+		chip->of_pwm_n_cells = 2;
+	}
+
+	of_node_get(chip->dev->of_node);
+}
+
+void of_pwmchip_remove(struct pwm_chip *chip)
+{
+	if (chip->dev && chip->dev->of_node)
+		of_node_put(chip->dev->of_node);
+}
+#else
+static inline void of_pwmchip_add(struct pwm_chip *pc)
+{
+}
+
+static inline void of_pwmchip_remove(struct pwm_chip *pc)
+{
+}
+#endif /* CONFIG_OF_PWM */
+
 /**
  * pwm_set_chip_data - set private chip data for a PWM
  * @pwm: PWM device

@@ -184,6 +254,7 @@ int pwmchip_add(struct pwm_chip *chip)
 
 	INIT_LIST_HEAD(&chip->list);
 	list_add(&chip->list, &pwm_chips);
+	of_pwmchip_add(chip);
 
 out:
 	mutex_unlock(&pwm_lock);

@@ -215,6 +286,7 @@ int pwmchip_remove(struct pwm_chip *chip)
 	}
 
 	list_del_init(&chip->list);
+	of_pwmchip_remove(chip);
 	free_pwms(chip);
 
 out:

@@ -364,6 +436,61 @@ void pwm_disable(struct pwm_device *pwm)
 }
 EXPORT_SYMBOL_GPL(pwm_disable);
 
+#ifdef CONFIG_OF
+/**
+ * of_pwm_request() - request a PWM via the PWM framework
+ * @np: device node to get the PWM from
+ * @propname: property name containing PWM specifier(s)
+ * @index: index of the PWM
+ *
+ * Returns the PWM device parsed from the phandle specified in the given
+ * property of a device tree node or NULL on failure. Values parsed from
+ * the device tree are stored in the returned PWM device object.
+ */
+struct pwm_device *of_pwm_request(struct device_node *np,
+				  const char *propname, int index)
+{
+	struct pwm_device *pwm = NULL;
+	struct of_phandle_args args;
+	struct pwm_chip *pc;
+	int err;
+
+	err = of_parse_phandle_with_args(np, propname, "#pwm-cells", index,
+					 &args);
+	if (err) {
+		pr_debug("%s(): can't parse property \"%s\"\n", __func__,
+			 propname);
+		return ERR_PTR(err);
+	}
+
+	pc = of_node_to_pwmchip(args.np);
+	if (IS_ERR(pc)) {
+		pr_debug("%s(): PWM chip not found\n", __func__);
+		pwm = ERR_CAST(pc);
+		goto put;
+	}
+
+	if (args.args_count != pc->of_pwm_n_cells) {
+		pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name,
+			 args.np->full_name);
+		pwm = ERR_PTR(-EINVAL);
+		goto put;
+	}
+
+	pwm = pc->of_xlate(pc, &args);
+	if (IS_ERR(pwm))
+		goto put;
+
+	pwm->label = np->name;
+
+put:
+	of_node_put(args.np);
+
+	return pwm;
+}
+EXPORT_SYMBOL(of_pwm_request);
+#endif
+
 #ifdef CONFIG_DEBUG_FS
 static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
 {

@@ -0,0 +1,36 @@
+/*
+ * OF helpers for the PWM API
+ *
+ * Copyright (c) 2011-2012 Avionic Design GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef __LINUX_OF_PWM_H
+#define __LINUX_OF_PWM_H
+
+#include <linux/err.h>
+#include <linux/pwm.h>
+
+struct device_node;
+
+#ifdef CONFIG_OF_PWM
+
+struct pwm_device *of_pwm_request(struct device_node *np,
+				  const char *propname, int index);
+
+#else
+
+static inline struct pwm_device *of_pwm_request(struct device_node *np,
+						const char *propname,
+						int index);
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+#endif /* CONFIG_OF_PWM */
+
+#endif /* __LINUX_OF_PWM_H */

@@ -1,6 +1,8 @@
 #ifndef __LINUX_PWM_H
 #define __LINUX_PWM_H
 
+#include <linux/of.h>
+
 struct pwm_device;
 
 /*

@@ -102,6 +104,12 @@ struct pwm_chip {
 	unsigned int		npwm;
 
 	struct pwm_device	*pwms;
+
+#ifdef CONFIG_OF_PWM
+	struct pwm_device *	(*of_xlate)(struct pwm_chip *pc,
+					    const struct of_phandle_args *args);
+	unsigned int		of_pwm_n_cells;
+#endif
 };
 
 int pwm_set_chip_data(struct pwm_device *pwm, void *data);