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>

1 files changed, 198 insertions, 0 deletions

diff --git a/drivers/mfd/ab8500-debugfs.c b/drivers/mfd/ab8500-debugfs.c
index 5a8e707bc038..2e40e12fc687 100644
--- 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: