mfd: ab8500-debugfs: Provide a means for a user subscribe to IRQs

Allow users to subscribe to and view IRQ events live from debugfs.

Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/drivers/mfd/ab8500-debugfs.c b/drivers/mfd/ab8500-debugfs.c
index 5a8e707..2e40e12 100644 (file)
--- a/drivers/mfd/ab8500-debugfs.c
+++ b/drivers/mfd/ab8500-debugfs.c
@@ -11,6 +11,9 @@
 #include <linux/module.h>
 #include <linux/debugfs.h>
 #include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/kobject.h>
+#include <linux/slab.h>
 
 #include <linux/mfd/abx500.h>
 #include <linux/mfd/abx500/ab8500.h>
@@ -18,6 +21,9 @@
 static u32 debug_bank;
 static u32 debug_address;
 
+static int irq_first;
+static int irq_last;
+
 /**
  * struct ab8500_reg_range
  * @first: the first address of the range
@@ -354,6 +360,21 @@ static struct ab8500_prcmu_ranges debug_ranges[AB8500_NUM_BANKS] = {
        },
 };
 
+static irqreturn_t ab8500_debug_handler(int irq, void *data)
+{
+       char buf[16];
+       struct kobject *kobj = (struct kobject *)data;
+
+       /*
+        * This makes it possible to use poll for events (POLLPRI | POLLERR)
+        * from userspace on sysfs file named irq-<nr>
+        */
+       sprintf(buf, "irq-%d", irq);
+       sysfs_notify(kobj, NULL, buf);
+
+       return IRQ_HANDLED;
+}
+
 static int ab8500_registers_print(struct seq_file *s, void *p)
 {
        struct device *dev = s->private;
@@ -519,6 +540,131 @@ static ssize_t ab8500_val_write(struct file *file,
        return count;
 }
 
+static int ab8500_subscribe_unsubscribe_print(struct seq_file *s, void *p)
+{
+       seq_printf(s, "%d\n", irq_first);
+
+       return 0;
+}
+
+static int ab8500_subscribe_unsubscribe_open(struct inode *inode,
+                                            struct file *file)
+{
+       return single_open(file, ab8500_subscribe_unsubscribe_print,
+                          inode->i_private);
+}
+
+/*
+ * This function is used for all interrupts and will always print
+ * the same string. It is however this file sysfs_notify called on.
+ * Userspace should read this file and then poll. When an event occur
+ * the blocking poll will be released.
+ */
+static ssize_t show_irq(struct device *dev,
+                       struct device_attribute *attr, char *buf)
+{
+       return sprintf(buf, "irq\n");
+}
+
+static struct device_attribute *dev_attr[AB8500_NR_IRQS];
+static char *event_name[AB8500_NR_IRQS];
+
+static ssize_t ab8500_subscribe_write(struct file *file,
+                                     const char __user *user_buf,
+                                     size_t count, loff_t *ppos)
+{
+       struct device *dev = ((struct seq_file *)(file->private_data))->private;
+       char buf[32];
+       int buf_size;
+       unsigned long user_val;
+       int err;
+
+       /* Get userspace string and assure termination */
+       buf_size = min(count, (sizeof(buf)-1));
+       if (copy_from_user(buf, user_buf, buf_size))
+               return -EFAULT;
+       buf[buf_size] = 0;
+
+       err = strict_strtoul(buf, 0, &user_val);
+       if (err)
+               return -EINVAL;
+       if (user_val < irq_first) {
+               dev_err(dev, "debugfs error input < %d\n", irq_first);
+               return -EINVAL;
+       }
+       if (user_val > irq_last) {
+               dev_err(dev, "debugfs error input > %d\n", irq_last);
+               return -EINVAL;
+       }
+
+       /*
+        * This will create a sysfs file named irq-<nr> which userspace can
+        * use to select or poll and get the AB8500 events
+        */
+       dev_attr[user_val] = kmalloc(sizeof(struct device_attribute),
+                                    GFP_KERNEL);
+       event_name[user_val] = kmalloc(buf_size, GFP_KERNEL);
+       sprintf(event_name[user_val], "irq-%lu", user_val);
+       dev_attr[user_val]->show = show_irq;
+       dev_attr[user_val]->store = NULL;
+       dev_attr[user_val]->attr.name = event_name[user_val];
+       dev_attr[user_val]->attr.mode = S_IRUGO;
+       err = sysfs_create_file(&dev->kobj, &dev_attr[user_val]->attr);
+       if (err < 0) {
+               printk(KERN_ERR "sysfs_create_file failed %d\n", err);
+               return err;
+       }
+
+       err = request_threaded_irq(user_val, NULL, ab8500_debug_handler,
+                                  IRQF_SHARED | IRQF_NO_SUSPEND,
+                                  "ab8500-debug", &dev->kobj);
+       if (err < 0) {
+               printk(KERN_ERR "request_threaded_irq failed %d, %lu\n",
+                       err, user_val);
+               return err;
+       }
+
+       return buf_size;
+}
+
+static ssize_t ab8500_unsubscribe_write(struct file *file,
+                                       const char __user *user_buf,
+                                       size_t count, loff_t *ppos)
+{
+       struct device *dev = ((struct seq_file *)(file->private_data))->private;
+       char buf[32];
+       int buf_size;
+       unsigned long user_val;
+       int err;
+
+       /* Get userspace string and assure termination */
+       buf_size = min(count, (sizeof(buf)-1));
+       if (copy_from_user(buf, user_buf, buf_size))
+               return -EFAULT;
+       buf[buf_size] = 0;
+
+       err = strict_strtoul(buf, 0, &user_val);
+       if (err)
+               return -EINVAL;
+       if (user_val < irq_first) {
+               dev_err(dev, "debugfs error input < %d\n", irq_first);
+               return -EINVAL;
+       }
+       if (user_val > irq_last) {
+               dev_err(dev, "debugfs error input > %d\n", irq_last);
+               return -EINVAL;
+       }
+
+       free_irq(user_val, &dev->kobj);
+       kfree(event_name[user_val]);
+       kfree(dev_attr[user_val]);
+
+       if (dev_attr[user_val])
+               sysfs_remove_file(&dev->kobj, &dev_attr[user_val]->attr);
+
+       return buf_size;
+}
+
 static const struct file_operations ab8500_bank_fops = {
        .open = ab8500_bank_open,
        .write = ab8500_bank_write,
@@ -546,17 +692,51 @@ static const struct file_operations ab8500_val_fops = {
        .owner = THIS_MODULE,
 };
 
+static const struct file_operations ab8500_subscribe_fops = {
+       .open = ab8500_subscribe_unsubscribe_open,
+       .write = ab8500_subscribe_write,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = single_release,
+       .owner = THIS_MODULE,
+};
+
+static const struct file_operations ab8500_unsubscribe_fops = {
+       .open = ab8500_subscribe_unsubscribe_open,
+       .write = ab8500_unsubscribe_write,
+       .read = seq_read,
+       .llseek = seq_lseek,
+       .release = single_release,
+       .owner = THIS_MODULE,
+};
+
 static struct dentry *ab8500_dir;
 static struct dentry *ab8500_reg_file;
 static struct dentry *ab8500_bank_file;
 static struct dentry *ab8500_address_file;
 static struct dentry *ab8500_val_file;
+static struct dentry *ab8500_subscribe_file;
+static struct dentry *ab8500_unsubscribe_file;
 
 static int ab8500_debug_probe(struct platform_device *plf)
 {
        debug_bank = AB8500_MISC;
        debug_address = AB8500_REV_REG & 0x00FF;
 
+       irq_first = platform_get_irq_byname(plf, "IRQ_FIRST");
+       if (irq_first < 0) {
+               dev_err(&plf->dev, "First irq not found, err %d\n",
+                       irq_first);
+               return irq_first;
+       }
+
+       irq_last = platform_get_irq_byname(plf, "IRQ_LAST");
+       if (irq_last < 0) {
+               dev_err(&plf->dev, "Last irq not found, err %d\n",
+                       irq_last);
+               return irq_last;
+       }
+
        ab8500_dir = debugfs_create_dir(AB8500_NAME_STRING, NULL);
        if (!ab8500_dir)
                goto exit_no_debugfs;
@@ -582,8 +762,26 @@ static int ab8500_debug_probe(struct platform_device *plf)
        if (!ab8500_val_file)
                goto exit_destroy_address;
 
+       ab8500_subscribe_file =
+               debugfs_create_file("irq-subscribe",
+                                   (S_IRUGO | S_IWUGO), ab8500_dir, &plf->dev,
+                                   &ab8500_subscribe_fops);
+       if (!ab8500_subscribe_file)
+               goto exit_destroy_val;
+
+       ab8500_unsubscribe_file =
+               debugfs_create_file("irq-unsubscribe",
+                                   (S_IRUGO | S_IWUGO), ab8500_dir, &plf->dev,
+                                   &ab8500_unsubscribe_fops);
+       if (!ab8500_unsubscribe_file)
+               goto exit_destroy_subscribe;
+
        return 0;
 
+exit_destroy_subscribe:
+       debugfs_remove(ab8500_subscribe_file);
+exit_destroy_val:
+       debugfs_remove(ab8500_val_file);
 exit_destroy_address:
        debugfs_remove(ab8500_address_file);
 exit_destroy_bank: