2 files changed, 96 insertions, 0 deletions

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index a447be128328..aadc1d797449 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -27,6 +27,8 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/device.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
 
 #define MAX_PWMS 1024
 
@@ -338,3 +340,91 @@ void pwm_disable(struct pwm_device *pwm)
                 pwm->chip->ops->disable(pwm->chip, pwm);
 }
 EXPORT_SYMBOL_GPL(pwm_disable);
+
+#ifdef CONFIG_DEBUG_FS
+static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
+{
+        unsigned int i;
+
+        for (i = 0; i < chip->npwm; i++) {
+                struct pwm_device *pwm = &chip->pwms[i];
+
+                seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
+
+                if (test_bit(PWMF_REQUESTED, &pwm->flags))
+                        seq_printf(s, " requested");
+
+                if (test_bit(PWMF_ENABLED, &pwm->flags))
+                        seq_printf(s, " enabled");
+
+                seq_printf(s, "\n");
+        }
+}
+
+static void *pwm_seq_start(struct seq_file *s, loff_t *pos)
+{
+        mutex_lock(&pwm_lock);
+        s->private = "";
+
+        return seq_list_start(&pwm_chips, *pos);
+}
+
+static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+        s->private = "\n";
+
+        return seq_list_next(v, &pwm_chips, pos);
+}
+
+static void pwm_seq_stop(struct seq_file *s, void *v)
+{
+        mutex_unlock(&pwm_lock);
+}
+
+static int pwm_seq_show(struct seq_file *s, void *v)
+{
+        struct pwm_chip *chip = list_entry(v, struct pwm_chip, list);
+
+        seq_printf(s, "%s%s/%s, %d PWM device%s\n", (char *)s->private,
+                   chip->dev->bus ? chip->dev->bus->name : "no-bus",
+                   dev_name(chip->dev), chip->npwm,
+                   (chip->npwm != 1) ? "s" : "");
+
+        if (chip->ops->dbg_show)
+                chip->ops->dbg_show(chip, s);
+        else
+                pwm_dbg_show(chip, s);
+
+        return 0;
+}
+
+static const struct seq_operations pwm_seq_ops = {
+        .start = pwm_seq_start,
+        .next = pwm_seq_next,
+        .stop = pwm_seq_stop,
+        .show = pwm_seq_show,
+};
+
+static int pwm_seq_open(struct inode *inode, struct file *file)
+{
+        return seq_open(file, &pwm_seq_ops);
+}
+
+static const struct file_operations pwm_debugfs_ops = {
+        .owner = THIS_MODULE,
+        .open = pwm_seq_open,
+        .read = seq_read,
+        .llseek = seq_lseek,
+        .release = seq_release,
+};
+
+static int __init pwm_debugfs_init(void)
+{
+        debugfs_create_file("pwm", S_IFREG | S_IRUGO, NULL, NULL,
+                            &pwm_debugfs_ops);
+
+        return 0;
+}
+
+subsys_initcall(pwm_debugfs_init);
+#endif /* CONFIG_DEBUG_FS */
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 57103911f4c7..047cd5351a3b 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -2,6 +2,7 @@
 #define __LINUX_PWM_H
 
 struct pwm_device;
+struct seq_file;
 
 /*
  * pwm_request - request a PWM device
@@ -65,6 +66,7 @@ static inline unsigned int pwm_get_period(struct pwm_device *pwm)
  * @config: configure duty cycles and period length for this PWM
  * @enable: enable PWM output toggling
  * @disable: disable PWM output toggling
+ * @dbg_show: optional routine to show contents in debugfs
  * @owner: helps prevent removal of modules exporting active PWMs
  */
 struct pwm_ops {
@@ -79,6 +81,10 @@ struct pwm_ops {
                                           struct pwm_device *pwm);
         void                    (*disable)(struct pwm_chip *chip,
                                            struct pwm_device *pwm);
+#ifdef CONFIG_DEBUG_FS
+        void                    (*dbg_show)(struct pwm_chip *chip,
+                                            struct seq_file *s);
+#endif
         struct module           *owner;
 };