gpiolib: Refactor gpio_export
[pandora-kernel.git] / drivers / gpio / gpiolib.c
index de0213c..d5f9742 100644 (file)
@@ -702,8 +702,9 @@ int gpio_export(unsigned gpio, bool direction_may_change)
 {
        unsigned long           flags;
        struct gpio_desc        *desc;
-       int                     status = -EINVAL;
+       int                     status;
        const char              *ioname = NULL;
+       struct device           *dev;
 
        /* can't export until sysfs is available ... */
        if (!gpio_class.p) {
@@ -711,59 +712,65 @@ int gpio_export(unsigned gpio, bool direction_may_change)
                return -ENOENT;
        }
 
-       if (!gpio_is_valid(gpio))
-               goto done;
+       if (!gpio_is_valid(gpio)) {
+               pr_debug("%s: gpio %d is not valid\n", __func__, gpio);
+               return -EINVAL;
+       }
 
        mutex_lock(&sysfs_lock);
 
        spin_lock_irqsave(&gpio_lock, flags);
        desc = &gpio_desc[gpio];
-       if (test_bit(FLAG_REQUESTED, &desc->flags)
-                       && !test_bit(FLAG_EXPORT, &desc->flags)) {
-               status = 0;
-               if (!desc->chip->direction_input
-                               || !desc->chip->direction_output)
-                       direction_may_change = false;
+       if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
+            test_bit(FLAG_EXPORT, &desc->flags)) {
+               spin_unlock_irqrestore(&gpio_lock, flags);
+               pr_debug("%s: gpio %d unavailable (requested=%d, exported=%d)\n",
+                               __func__, gpio,
+                               test_bit(FLAG_REQUESTED, &desc->flags),
+                               test_bit(FLAG_EXPORT, &desc->flags));
+               return -EPERM;
        }
+
+       if (!desc->chip->direction_input || !desc->chip->direction_output)
+               direction_may_change = false;
        spin_unlock_irqrestore(&gpio_lock, flags);
 
        if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
                ioname = desc->chip->names[gpio - desc->chip->base];
 
-       if (status == 0) {
-               struct device   *dev;
-
-               dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
-                               desc, ioname ? ioname : "gpio%u", gpio);
-               if (!IS_ERR(dev)) {
-                       status = sysfs_create_group(&dev->kobj,
-                                               &gpio_attr_group);
-
-                       if (!status && direction_may_change)
-                               status = device_create_file(dev,
-                                               &dev_attr_direction);
-
-                       if (!status && gpio_to_irq(gpio) >= 0
-                                       && (direction_may_change
-                                               || !test_bit(FLAG_IS_OUT,
-                                                       &desc->flags)))
-                               status = device_create_file(dev,
-                                               &dev_attr_edge);
-
-                       if (status != 0)
-                               device_unregister(dev);
-               } else
-                       status = PTR_ERR(dev);
-               if (status == 0)
-                       set_bit(FLAG_EXPORT, &desc->flags);
+       dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
+                           desc, ioname ? ioname : "gpio%u", gpio);
+       if (IS_ERR(dev)) {
+               status = PTR_ERR(dev);
+               goto fail_unlock;
        }
 
-       mutex_unlock(&sysfs_lock);
-
-done:
+       status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
        if (status)
-               pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
+               goto fail_unregister_device;
+
+       if (direction_may_change) {
+               status = device_create_file(dev, &dev_attr_direction);
+               if (status)
+                       goto fail_unregister_device;
+       }
 
+       if (gpio_to_irq(gpio) >= 0 && (direction_may_change ||
+                                      !test_bit(FLAG_IS_OUT, &desc->flags))) {
+               status = device_create_file(dev, &dev_attr_edge);
+               if (status)
+                       goto fail_unregister_device;
+       }
+
+       set_bit(FLAG_EXPORT, &desc->flags);
+       mutex_unlock(&sysfs_lock);
+       return 0;
+
+fail_unregister_device:
+       device_unregister(dev);
+fail_unlock:
+       mutex_unlock(&sysfs_lock);
+       pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
        return status;
 }
 EXPORT_SYMBOL_GPL(gpio_export);
@@ -1773,56 +1780,102 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
        }
 }
 
-static int gpiolib_show(struct seq_file *s, void *unused)
+static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
 {
-       struct gpio_chip        *chip = NULL;
-       unsigned                gpio;
-       int                     started = 0;
+       struct gpio_chip *chip = NULL;
+       unsigned int gpio;
+       void *ret = NULL;
+       loff_t index = 0;
 
        /* REVISIT this isn't locked against gpio_chip removal ... */
 
        for (gpio = 0; gpio_is_valid(gpio); gpio++) {
-               struct device *dev;
-
-               if (chip == gpio_desc[gpio].chip)
+               if (gpio_desc[gpio].chip == chip)
                        continue;
+
                chip = gpio_desc[gpio].chip;
                if (!chip)
                        continue;
 
-               seq_printf(s, "%sGPIOs %d-%d",
-                               started ? "\n" : "",
-                               chip->base, chip->base + chip->ngpio - 1);
-               dev = chip->dev;
-               if (dev)
-                       seq_printf(s, ", %s/%s",
-                               dev->bus ? dev->bus->name : "no-bus",
-                               dev_name(dev));
-               if (chip->label)
-                       seq_printf(s, ", %s", chip->label);
-               if (chip->can_sleep)
-                       seq_printf(s, ", can sleep");
-               seq_printf(s, ":\n");
-
-               started = 1;
-               if (chip->dbg_show)
-                       chip->dbg_show(s, chip);
-               else
-                       gpiolib_dbg_show(s, chip);
+               if (index++ >= *pos) {
+                       ret = chip;
+                       break;
+               }
+       }
+
+       s->private = "";
+
+       return ret;
+}
+
+static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+       struct gpio_chip *chip = v;
+       unsigned int gpio;
+       void *ret = NULL;
+
+       /* skip GPIOs provided by the current chip */
+       for (gpio = chip->base + chip->ngpio; gpio_is_valid(gpio); gpio++) {
+               chip = gpio_desc[gpio].chip;
+               if (chip) {
+                       ret = chip;
+                       break;
+               }
        }
+
+       s->private = "\n";
+       ++*pos;
+
+       return ret;
+}
+
+static void gpiolib_seq_stop(struct seq_file *s, void *v)
+{
+}
+
+static int gpiolib_seq_show(struct seq_file *s, void *v)
+{
+       struct gpio_chip *chip = v;
+       struct device *dev;
+
+       seq_printf(s, "%sGPIOs %d-%d", (char *)s->private,
+                       chip->base, chip->base + chip->ngpio - 1);
+       dev = chip->dev;
+       if (dev)
+               seq_printf(s, ", %s/%s", dev->bus ? dev->bus->name : "no-bus",
+                       dev_name(dev));
+       if (chip->label)
+               seq_printf(s, ", %s", chip->label);
+       if (chip->can_sleep)
+               seq_printf(s, ", can sleep");
+       seq_printf(s, ":\n");
+
+       if (chip->dbg_show)
+               chip->dbg_show(s, chip);
+       else
+               gpiolib_dbg_show(s, chip);
+
        return 0;
 }
 
+static const struct seq_operations gpiolib_seq_ops = {
+       .start = gpiolib_seq_start,
+       .next = gpiolib_seq_next,
+       .stop = gpiolib_seq_stop,
+       .show = gpiolib_seq_show,
+};
+
 static int gpiolib_open(struct inode *inode, struct file *file)
 {
-       return single_open(file, gpiolib_show, NULL);
+       return seq_open(file, &gpiolib_seq_ops);
 }
 
 static const struct file_operations gpiolib_operations = {
+       .owner          = THIS_MODULE,
        .open           = gpiolib_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
-       .release        = single_release,
+       .release        = seq_release,
 };
 
 static int __init gpiolib_debugfs_init(void)