[PATCH v2 02/10] pwm: Allow chips to support multiple PWMs.
Thierry Reding
thierry.reding at avionic-design.de
Mon Feb 6 10:19:37 EST 2012
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 64, but
can easily be made configurable via Kconfig.
The patch is incomplete in that it doesn't convert any existing drivers
that are now broken.
Signed-off-by: Thierry Reding <thierry.reding at avionic-design.de>
---
Changes in v2:
- add 'struct device *dev' field to pwm_chip, drop label field
- use radix tree for PWM descriptors
- add pwm_set_chip_data() and pwm_get_chip_data() functions to allow
storing and retrieving chip-specific per-PWM data
TODO:
- pass chip-indexed PWM number (PWM descriptor?) to drivers
- merge with Sascha's patch
drivers/pwm/core.c | 287 ++++++++++++++++++++++++++++++++++++++-------------
include/linux/pwm.h | 37 +++++--
2 files changed, 242 insertions(+), 82 deletions(-)
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 71de479..a223bd6 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -17,154 +17,292 @@
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
+
#include <linux/module.h>
+#include <linux/of_pwm.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>
+#define MAX_PWMS 1024
+
struct pwm_device {
- struct pwm_chip *chip;
- const char *label;
+ const char *label;
+ unsigned int pwm;
+};
+
+struct pwm_desc {
+ struct pwm_chip *chip;
+ void *chip_data;
unsigned long flags;
#define FLAG_REQUESTED 0
#define FLAG_ENABLED 1
- struct list_head node;
+ struct pwm_device pwm;
};
-static LIST_HEAD(pwm_list);
-
static DEFINE_MUTEX(pwm_lock);
+static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
+static RADIX_TREE(pwm_desc_tree, GFP_KERNEL);
+
+static struct pwm_desc *pwm_to_desc(unsigned int pwm)
+{
+ return radix_tree_lookup(&pwm_desc_tree, pwm);
+}
+
+static struct pwm_desc *alloc_desc(unsigned int pwm)
+{
+ struct pwm_desc *desc;
+
+ desc = kzalloc(sizeof(*desc), GFP_KERNEL);
+ if (!desc)
+ return NULL;
-static struct pwm_device *_find_pwm(int pwm_id)
+ return desc;
+}
+
+static void free_desc(unsigned int pwm)
+{
+ struct pwm_desc *desc = pwm_to_desc(pwm);
+
+ radix_tree_delete(&pwm_desc_tree, pwm);
+ kfree(desc);
+}
+
+static int alloc_descs(int pwm, unsigned int from, unsigned int count)
{
- struct pwm_device *pwm;
+ unsigned int start;
+ unsigned int i;
+ int ret = 0;
+
+ if (pwm >= 0) {
+ if (from > pwm)
+ return -EINVAL;
+
+ from = pwm;
+ }
+
+ start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, from,
+ count, 0);
- list_for_each_entry(pwm, &pwm_list, node) {
- if (pwm->chip->pwm_id == pwm_id)
- return pwm;
+ if ((pwm >= 0) && (start != pwm))
+ return -EEXIST;
+
+ if (start + count > MAX_PWMS)
+ return -ENOSPC;
+
+ for (i = start; i < start + count; i++) {
+ struct pwm_desc *desc = alloc_desc(i);
+ if (!desc) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ radix_tree_insert(&pwm_desc_tree, i, desc);
}
- return NULL;
+ bitmap_set(allocated_pwms, start, count);
+
+ return start;
+
+err:
+ for (i--; i >= 0; i--)
+ free_desc(i);
+
+ return ret;
+}
+
+static void free_descs(unsigned int from, unsigned int count)
+{
+ unsigned int i;
+
+ for (i = from; i < from + count; i++)
+ free_desc(i);
+
+ bitmap_clear(allocated_pwms, from, count);
}
/**
- * pwmchip_add() - register a new pwm
- * @chip: the pwm
- *
- * register a new pwm. pwm->pwm_id must be initialized. if pwm_id < 0 then
- * a dynamically assigned id will be used, otherwise the id specified,
+ * pwm_set_chip_data - set private chip data for a PWM
+ * @pwm: PWM number
+ * @data: pointer to chip-specific data
*/
-int pwmchip_add(struct pwm_chip *chip)
+int pwm_set_chip_data(unsigned int pwm, void *data)
{
- struct pwm_device *pwm;
- int ret = 0;
+ struct pwm_desc *desc = pwm_to_desc(pwm);
- pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
- if (!pwm)
- return -ENOMEM;
+ if (!desc)
+ return -EINVAL;
- pwm->chip = chip;
+ desc->chip_data = data;
+ return 0;
+}
+
+/**
+ * pwm_get_chip_data - get private chip data for a PWM
+ * @pwm: PWM number
+ */
+void *pwm_get_chip_data(unsigned int pwm)
+{
+ struct pwm_desc *desc = pwm_to_desc(pwm);
+
+ return desc ? desc->chip_data : NULL;
+}
+
+/**
+ * pwmchip_add() - register a new PWM chip
+ * @chip: the PWM chip to add
+ *
+ * Register a new PWM chip. If pwm->base < 0 then a dynamically assigned base
+ * will be used.
+ */
+int pwmchip_add(struct pwm_chip *chip)
+{
+ unsigned int i;
+ int ret;
mutex_lock(&pwm_lock);
- if (chip->pwm_id >= 0 && _find_pwm(chip->pwm_id)) {
- ret = -EBUSY;
+ ret = alloc_descs(chip->base, 0, chip->npwm);
+ if (ret < 0)
goto out;
+
+ chip->base = ret;
+ ret = 0;
+
+ /* initialize descriptors */
+ for (i = chip->base; i < chip->base + chip->npwm; i++) {
+ struct pwm_desc *desc = pwm_to_desc(i);
+
+ if (!desc) {
+ pr_debug("pwm: descriptor %u not initialized\n", i);
+ continue;
+ }
+
+ desc->chip = chip;
}
- list_add_tail(&pwm->node, &pwm_list);
+ of_pwmchip_add(chip);
+
out:
mutex_unlock(&pwm_lock);
-
- if (ret)
- kfree(pwm);
-
return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_add);
/**
- * pwmchip_remove() - remove a pwm
- * @chip: the pwm
+ * pwmchip_remove() - remove a PWM chip
+ * @chip: the PWM chip to remove
*
- * remove a pwm. This function may return busy if the pwm is still requested.
+ * Removes a PWM chip. This function may return busy if the PWM chip provides
+ * a PWM device that is still requested.
*/
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 = chip->base; i < chip->base + chip->npwm; i++) {
+ struct pwm_desc *desc = pwm_to_desc(i);
- if (test_bit(FLAG_REQUESTED, &pwm->flags)) {
- ret = -EBUSY;
- goto out;
+ if (test_bit(FLAG_REQUESTED, &desc->flags)) {
+ ret = -EBUSY;
+ goto out;
+ }
}
- list_del(&pwm->node);
+ free_descs(chip->base, chip->npwm);
+ of_pwmchip_remove(chip);
- kfree(pwm);
out:
mutex_unlock(&pwm_lock);
-
return ret;
}
EXPORT_SYMBOL_GPL(pwmchip_remove);
+/**
+ * pwmchip_find() - iterator for locating a specific pwm_chip
+ * @data: data to pass to match function
+ * @match: callback function to check pwm_chip
+ */
+struct pwm_chip *pwmchip_find(void *data, int (*match)(struct pwm_chip *chip,
+ void *data))
+{
+ struct pwm_chip *chip = NULL;
+ unsigned long i;
+
+ mutex_lock(&pwm_lock);
+
+ for_each_set_bit(i, allocated_pwms, MAX_PWMS) {
+ struct pwm_desc *desc = pwm_to_desc(i);
+
+ if (!desc || !desc->chip)
+ continue;
+
+ if (match(desc->chip, data)) {
+ chip = desc->chip;
+ break;
+ }
+ }
+
+ mutex_unlock(&pwm_lock);
+
+ return chip;
+}
+EXPORT_SYMBOL_GPL(pwmchip_find);
+
/*
* pwm_request - request a PWM device
*/
-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;
+ struct pwm_device *dev;
+ struct pwm_desc *desc;
int ret;
+ if ((pwm < 0) || (pwm >= MAX_PWMS))
+ return ERR_PTR(-ENOENT);
+
mutex_lock(&pwm_lock);
- pwm = _find_pwm(pwm_id);
- if (!pwm) {
- pwm = ERR_PTR(-ENOENT);
- goto out;
- }
+ desc = pwm_to_desc(pwm);
+ dev = &desc->pwm;
- if (test_bit(FLAG_REQUESTED, &pwm->flags)) {
- pwm = ERR_PTR(-EBUSY);
+ if (test_bit(FLAG_REQUESTED, &desc->flags)) {
+ dev = ERR_PTR(-EBUSY);
goto out;
}
- if (!try_module_get(pwm->chip->ops->owner)) {
- pwm = ERR_PTR(-ENODEV);
+ if (!try_module_get(desc->chip->ops->owner)) {
+ dev = ERR_PTR(-ENODEV);
goto out;
}
- if (pwm->chip->ops->request) {
- ret = pwm->chip->ops->request(pwm->chip);
+ if (desc->chip->ops->request) {
+ ret = desc->chip->ops->request(desc->chip, pwm);
if (ret) {
- pwm = ERR_PTR(ret);
+ dev = ERR_PTR(ret);
goto out_put;
}
}
- pwm->label = label;
- set_bit(FLAG_REQUESTED, &pwm->flags);
+ dev->label = label;
+ dev->pwm = pwm;
+ set_bit(FLAG_REQUESTED, &desc->flags);
goto out;
out_put:
- module_put(pwm->chip->ops->owner);
+ module_put(desc->chip->ops->owner);
out:
mutex_unlock(&pwm_lock);
- return pwm;
+ return dev;
}
EXPORT_SYMBOL_GPL(pwm_request);
@@ -173,16 +311,19 @@ EXPORT_SYMBOL_GPL(pwm_request);
*/
void pwm_free(struct pwm_device *pwm)
{
+ struct pwm_desc *desc = container_of(pwm, struct pwm_desc, pwm);
+
mutex_lock(&pwm_lock);
- if (!test_and_clear_bit(FLAG_REQUESTED, &pwm->flags)) {
+ if (!test_and_clear_bit(FLAG_REQUESTED, &desc->flags)) {
pr_warning("PWM device already freed\n");
goto out;
}
pwm->label = NULL;
+ pwm->pwm = 0;
- module_put(pwm->chip->ops->owner);
+ module_put(desc->chip->ops->owner);
out:
mutex_unlock(&pwm_lock);
}
@@ -193,7 +334,9 @@ EXPORT_SYMBOL_GPL(pwm_free);
*/
int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
{
- return pwm->chip->ops->config(pwm->chip, duty_ns, period_ns);
+ struct pwm_desc *desc = container_of(pwm, struct pwm_desc, pwm);
+ return desc->chip->ops->config(desc->chip, pwm->pwm, duty_ns,
+ period_ns);
}
EXPORT_SYMBOL_GPL(pwm_config);
@@ -202,8 +345,10 @@ EXPORT_SYMBOL_GPL(pwm_config);
*/
int pwm_enable(struct pwm_device *pwm)
{
- if (!test_and_set_bit(FLAG_ENABLED, &pwm->flags))
- return pwm->chip->ops->enable(pwm->chip);
+ struct pwm_desc *desc = container_of(pwm, struct pwm_desc, pwm);
+
+ if (!test_and_set_bit(FLAG_ENABLED, &desc->flags))
+ return desc->chip->ops->enable(desc->chip, pwm->pwm);
return 0;
}
@@ -214,7 +359,9 @@ EXPORT_SYMBOL_GPL(pwm_enable);
*/
void pwm_disable(struct pwm_device *pwm)
{
- if (test_and_clear_bit(FLAG_ENABLED, &pwm->flags))
- pwm->chip->ops->disable(pwm->chip);
+ struct pwm_desc *desc = container_of(pwm, struct pwm_desc, pwm);
+
+ if (test_and_clear_bit(FLAG_ENABLED, &desc->flags))
+ desc->chip->ops->disable(desc->chip, pwm->pwm);
}
EXPORT_SYMBOL_GPL(pwm_disable);
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index df9681b..0f8d105 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -32,37 +32,50 @@ void pwm_disable(struct pwm_device *pwm);
struct pwm_chip;
/**
- * struct pwm_ops - PWM operations
+ * struct pwm_ops - PWM controller operations
* @request: optional hook for requesting a PWM
* @free: optional hook for freeing a PWM
* @config: configure duty cycles and period length for this PWM
* @enable: enable PWM output toggling
* @disable: disable PWM output toggling
+ * @owner: helps prevent removal of modules exporting active PWMs
*/
struct pwm_ops {
- int (*request)(struct pwm_chip *chip);
- void (*free)(struct pwm_chip *chip);
- int (*config)(struct pwm_chip *chip, int duty_ns,
+ int (*request)(struct pwm_chip *chip,
+ unsigned int pwm);
+ void (*free)(struct pwm_chip *chip,
+ unsigned int pwm);
+ int (*config)(struct pwm_chip *chip,
+ unsigned int pwm, int duty_ns,
int period_ns);
- int (*enable)(struct pwm_chip *chip);
- void (*disable)(struct pwm_chip *chip);
+ int (*enable)(struct pwm_chip *chip,
+ unsigned int pwm);
+ void (*disable)(struct pwm_chip *chip,
+ unsigned int pwm);
struct module *owner;
};
/**
- * struct pwm_chip - abstract a PWM
- * @label: for diagnostics
- * @owner: helps prevent removal of modules exporting active PWMs
- * @ops: The callbacks for this PWM
+ * struct pwm_chip - abstract a PWM controller
+ * @dev: device providing the PWMs
+ * @ops: callbacks for this PWM controller
+ * @base: number of first PWM controlled by this chip
+ * @npwm: number of PWMs controlled by this chip
*/
struct pwm_chip {
- int pwm_id;
- const char *label;
+ struct device *dev;
struct pwm_ops *ops;
+ int base;
+ unsigned int npwm;
};
+int pwm_set_chip_data(unsigned int pwm, void *data);
+void *pwm_get_chip_data(unsigned int pwm);
+
int pwmchip_add(struct pwm_chip *chip);
int pwmchip_remove(struct pwm_chip *chip);
+struct pwm_chip *pwmchip_find(void *data, int (*match)(struct pwm_chip *chip,
+ void *data));
#endif
#endif /* __LINUX_PWM_H */
--
1.7.9
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