pwm: Allow chips to support multiple PWMs
Many PWM controllers provide access to more than a single PWM output and
may even share some resource among them. Allowing a PWM chip to provide
multiple PWM devices enables better sharing of those resources. As a
side-effect this change allows easy integration with the device tree
where a given PWM can be looked up based on the PWM chip's phandle and a
corresponding index.
This commit modifies the PWM core to support multiple PWMs per struct
pwm_chip. It achieves this in a similar way to how gpiolib works, by
allowing PWM ranges to be requested dynamically (pwm_chip.base == -1) or
starting at a given offset (pwm_chip.base >= 0). A chip specifies how
many PWMs it controls using the npwm member. Each of the functions in
the pwm_ops structure gets an additional argument that specified the PWM
number (it can be converted to a per-chip index by subtracting the
chip's base).
The total maximum number of PWM devices is currently fixed to 1024 while
the data is actually stored in a radix tree, thus saving resources if
not all of them are used.
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
[eric@eukrea.com: fix error handling in pwmchip_add]
Signed-off-by: Eric Bénard <eric@eukrea.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 0b8a38e..a447be1 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -2,6 +2,7 @@
* Generic pwmlib implementation
*
* Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
+ * 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
@@ -20,66 +21,161 @@
#include <linux/module.h>
#include <linux/pwm.h>
+#include <linux/radix-tree.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/device.h>
-struct pwm_device {
- struct pwm_chip *chip;
- const char *label;
- unsigned long flags;
-#define FLAG_REQUESTED 0
-#define FLAG_ENABLED 1
- struct list_head node;
-};
-
-static LIST_HEAD(pwm_list);
+#define MAX_PWMS 1024
static DEFINE_MUTEX(pwm_lock);
+static LIST_HEAD(pwm_chips);
+static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
+static RADIX_TREE(pwm_tree, GFP_KERNEL);
-static struct pwm_device *_find_pwm(int pwm_id)
+static struct pwm_device *pwm_to_device(unsigned int pwm)
{
- struct pwm_device *pwm;
+ return radix_tree_lookup(&pwm_tree, pwm);
+}
- list_for_each_entry(pwm, &pwm_list, node) {
- if (pwm->chip->pwm_id == pwm_id)
- return pwm;
+static int alloc_pwms(int pwm, unsigned int count)
+{
+ unsigned int from = 0;
+ unsigned int start;
+
+ if (pwm >= MAX_PWMS)
+ return -EINVAL;
+
+ if (pwm >= 0)
+ from = pwm;
+
+ start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, from,
+ count, 0);
+
+ if (pwm >= 0 && start != pwm)
+ return -EEXIST;
+
+ if (start + count > MAX_PWMS)
+ return -ENOSPC;
+
+ return start;
+}
+
+static void free_pwms(struct pwm_chip *chip)
+{
+ unsigned int i;
+
+ for (i = 0; i < chip->npwm; i++) {
+ struct pwm_device *pwm = &chip->pwms[i];
+ radix_tree_delete(&pwm_tree, pwm->pwm);
}
- return NULL;
+ bitmap_clear(allocated_pwms, chip->base, chip->npwm);
+
+ kfree(chip->pwms);
+ chip->pwms = NULL;
+}
+
+static int pwm_device_request(struct pwm_device *pwm, const char *label)
+{
+ int err;
+
+ if (test_bit(PWMF_REQUESTED, &pwm->flags))
+ return -EBUSY;
+
+ if (!try_module_get(pwm->chip->ops->owner))
+ return -ENODEV;
+
+ if (pwm->chip->ops->request) {
+ err = pwm->chip->ops->request(pwm->chip, pwm);
+ if (err) {
+ module_put(pwm->chip->ops->owner);
+ return err;
+ }
+ }
+
+ set_bit(PWMF_REQUESTED, &pwm->flags);
+ pwm->label = label;
+
+ return 0;
+}
+
+/**
+ * pwm_set_chip_data() - set private chip data for a PWM
+ * @pwm: PWM device
+ * @data: pointer to chip-specific data
+ */
+int pwm_set_chip_data(struct pwm_device *pwm, void *data)
+{
+ if (!pwm)
+ return -EINVAL;
+
+ pwm->chip_data = data;
+
+ return 0;
+}
+
+/**
+ * pwm_get_chip_data() - get private chip data for a PWM
+ * @pwm: PWM device
+ */
+void *pwm_get_chip_data(struct pwm_device *pwm)
+{
+ return pwm ? pwm->chip_data : NULL;
}
/**
* pwmchip_add() - register a new PWM chip
* @chip: the PWM chip to add
+ *
+ * Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
+ * will be used.
*/
int pwmchip_add(struct pwm_chip *chip)
{
struct pwm_device *pwm;
- int ret = 0;
+ unsigned int i;
+ int ret;
- pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
- if (!pwm)
- return -ENOMEM;
-
- pwm->chip = chip;
+ if (!chip || !chip->dev || !chip->ops || !chip->ops->config ||
+ !chip->ops->enable || !chip->ops->disable)
+ return -EINVAL;
mutex_lock(&pwm_lock);
- if (chip->pwm_id >= 0 && _find_pwm(chip->pwm_id)) {
- ret = -EBUSY;
+ ret = alloc_pwms(chip->base, chip->npwm);
+ if (ret < 0)
+ goto out;
+
+ chip->pwms = kzalloc(chip->npwm * sizeof(*pwm), GFP_KERNEL);
+ if (!chip->pwms) {
+ ret = -ENOMEM;
goto out;
}
- list_add_tail(&pwm->node, &pwm_list);
+ chip->base = ret;
+
+ for (i = 0; i < chip->npwm; i++) {
+ pwm = &chip->pwms[i];
+
+ pwm->chip = chip;
+ pwm->pwm = chip->base + i;
+ pwm->hwpwm = i;
+
+ radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
+ }
+
+ bitmap_set(allocated_pwms, chip->base, chip->npwm);
+
+ INIT_LIST_HEAD(&chip->list);
+ list_add(&chip->list, &pwm_chips);
+
+ ret = 0;
+
out:
mutex_unlock(&pwm_lock);
-
- if (ret)
- kfree(pwm);
-
return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_add);
@@ -93,28 +189,25 @@
*/
int pwmchip_remove(struct pwm_chip *chip)
{
- struct pwm_device *pwm;
+ unsigned int i;
int ret = 0;
mutex_lock(&pwm_lock);
- pwm = _find_pwm(chip->pwm_id);
- if (!pwm) {
- ret = -ENOENT;
- goto out;
+ for (i = 0; i < chip->npwm; i++) {
+ struct pwm_device *pwm = &chip->pwms[i];
+
+ if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
+ ret = -EBUSY;
+ goto out;
+ }
}
- if (test_bit(FLAG_REQUESTED, &pwm->flags)) {
- ret = -EBUSY;
- goto out;
- }
+ list_del_init(&chip->list);
+ free_pwms(chip);
- list_del(&pwm->node);
-
- kfree(pwm);
out:
mutex_unlock(&pwm_lock);
-
return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_remove);
@@ -124,52 +217,66 @@
* @pwm_id: global PWM device index
* @label: PWM device label
*/
-struct pwm_device *pwm_request(int pwm_id, const char *label)
+struct pwm_device *pwm_request(int pwm, const char *label)
{
- struct pwm_device *pwm;
- int ret;
+ struct pwm_device *dev;
+ int err;
+
+ if (pwm < 0 || pwm >= MAX_PWMS)
+ return ERR_PTR(-EINVAL);
mutex_lock(&pwm_lock);
- pwm = _find_pwm(pwm_id);
- if (!pwm) {
- pwm = ERR_PTR(-ENOENT);
+ dev = pwm_to_device(pwm);
+ if (!dev) {
+ dev = ERR_PTR(-EPROBE_DEFER);
goto out;
}
- if (test_bit(FLAG_REQUESTED, &pwm->flags)) {
- pwm = ERR_PTR(-EBUSY);
- goto out;
- }
+ err = pwm_device_request(dev, label);
+ if (err < 0)
+ dev = ERR_PTR(err);
- if (!try_module_get(pwm->chip->ops->owner)) {
- pwm = ERR_PTR(-ENODEV);
- goto out;
- }
-
- if (pwm->chip->ops->request) {
- ret = pwm->chip->ops->request(pwm->chip);
- if (ret) {
- pwm = ERR_PTR(ret);
- goto out_put;
- }
- }
-
- pwm->label = label;
- set_bit(FLAG_REQUESTED, &pwm->flags);
-
- goto out;
-
-out_put:
- module_put(pwm->chip->ops->owner);
out:
mutex_unlock(&pwm_lock);
- return pwm;
+ return dev;
}
EXPORT_SYMBOL_GPL(pwm_request);
/**
+ * pwm_request_from_chip() - request a PWM device relative to a PWM chip
+ * @chip: PWM chip
+ * @index: per-chip index of the PWM to request
+ * @label: a literal description string of this PWM
+ *
+ * Returns the PWM at the given index of the given PWM chip. A negative error
+ * code is returned if the index is not valid for the specified PWM chip or
+ * if the PWM device cannot be requested.
+ */
+struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
+ unsigned int index,
+ const char *label)
+{
+ struct pwm_device *pwm;
+ int err;
+
+ if (!chip || index >= chip->npwm)
+ return ERR_PTR(-EINVAL);
+
+ mutex_lock(&pwm_lock);
+ pwm = &chip->pwms[index];
+
+ err = pwm_device_request(pwm, label);
+ if (err < 0)
+ pwm = ERR_PTR(err);
+
+ mutex_unlock(&pwm_lock);
+ return pwm;
+}
+EXPORT_SYMBOL_GPL(pwm_request_from_chip);
+
+/**
* pwm_free() - free a PWM device
* @pwm: PWM device
*/
@@ -177,11 +284,14 @@
{
mutex_lock(&pwm_lock);
- if (!test_and_clear_bit(FLAG_REQUESTED, &pwm->flags)) {
+ if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {
pr_warning("PWM device already freed\n");
goto out;
}
+ if (pwm->chip->ops->free)
+ pwm->chip->ops->free(pwm->chip, pwm);
+
pwm->label = NULL;
module_put(pwm->chip->ops->owner);
@@ -198,7 +308,10 @@
*/
int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
{
- return pwm->chip->ops->config(pwm->chip, duty_ns, period_ns);
+ if (!pwm || period_ns == 0 || duty_ns > period_ns)
+ return -EINVAL;
+
+ return pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns);
}
EXPORT_SYMBOL_GPL(pwm_config);
@@ -208,10 +321,10 @@
*/
int pwm_enable(struct pwm_device *pwm)
{
- if (!test_and_set_bit(FLAG_ENABLED, &pwm->flags))
- return pwm->chip->ops->enable(pwm->chip);
+ if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags))
+ return pwm->chip->ops->enable(pwm->chip, pwm);
- return 0;
+ return pwm ? 0 : -EINVAL;
}
EXPORT_SYMBOL_GPL(pwm_enable);
@@ -221,7 +334,7 @@
*/
void pwm_disable(struct pwm_device *pwm)
{
- if (test_and_clear_bit(FLAG_ENABLED, &pwm->flags))
- pwm->chip->ops->disable(pwm->chip);
+ if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags))
+ pwm->chip->ops->disable(pwm->chip, pwm);
}
EXPORT_SYMBOL_GPL(pwm_disable);