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path: root/recipes/linux/linux-2.6.18/gpio-dev-blocking-read.patch
blob: 9508d9e3aa841e19fb7f8717d633ef6b42800153 (plain)
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---
 arch/avr32/mach-at32ap/pio.c |  113 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)

Index: linux-2.6.18-avr32/arch/avr32/mach-at32ap/pio.c
===================================================================
--- linux-2.6.18-avr32.orig/arch/avr32/mach-at32ap/pio.c	2006-11-30 13:16:43.000000000 +0100
+++ linux-2.6.18-avr32/arch/avr32/mach-at32ap/pio.c	2006-11-30 17:15:24.000000000 +0100
@@ -250,7 +250,11 @@ EXPORT_SYMBOL(gpio_set_value);
 #ifdef CONFIG_PIO_DEV
 #include <linux/configfs.h>
 #include <linux/cdev.h>
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <linux/poll.h>
 #include <linux/uaccess.h>
+#include <linux/wait.h>
 
 #define GPIO_DEV_MAX			8
 
@@ -267,6 +271,13 @@ struct gpio_item {
 	u32 pin_mask;
 	u32 oe_mask;
 
+	/* Pin state last time we read it (for blocking reads) */
+	u32 pin_state;
+	int changed;
+
+	wait_queue_head_t change_wq;
+	struct fasync_struct *async_queue;
+
 	int id;
 	struct class_device *gpio_dev;
 	struct cdev char_dev;
@@ -279,36 +290,135 @@ struct gpio_attribute {
 	ssize_t (*store)(struct gpio_item *, const char *, size_t);
 };
 
+static irqreturn_t gpio_dev_interrupt(int irq, void *dev_id,
+				      struct pt_regs *regs)
+{
+	struct gpio_item *gpio = dev_id;
+	u32 old_state, new_state;
+
+	old_state = gpio->pin_state;
+	new_state = pio_readl(gpio->pio, PDSR);
+	gpio->pin_state = new_state;
+
+	if (new_state != old_state) {
+		gpio->changed = 1;
+		wake_up_interruptible(&gpio->change_wq);
+
+		if (gpio->async_queue)
+			kill_fasync(&gpio->async_queue, SIGIO, POLL_IN);
+	}
+
+	return IRQ_HANDLED;
+}
+
 static int gpio_dev_open(struct inode *inode, struct file *file)
 {
 	struct gpio_item *gpio = container_of(inode->i_cdev,
 					      struct gpio_item,
 					      char_dev);
+	unsigned int irq;
+	unsigned int i;
+	int ret;
 
+	nonseekable_open(inode, file);
 	config_item_get(&gpio->item);
 	file->private_data = gpio;
+
+	gpio->pin_state = pio_readl(gpio->pio, PDSR) & gpio->pin_mask;
+	gpio->changed = 1;
+
+	for (i = 0; i < 32; i++) {
+		if (gpio->pin_mask & (1 << i)) {
+			irq = gpio_to_irq(32 * pio_id(gpio->pio) + i);
+			ret = request_irq(irq, gpio_dev_interrupt, 0,
+					  "gpio-dev", gpio);
+			if (ret)
+				goto err_irq;
+		}
+	}
+
 	return 0;
+
+err_irq:
+	while (i--) {
+		if (gpio->pin_mask & (1 << i)) {
+			irq = gpio_to_irq(32 * pio_id(gpio->pio) + i);
+			free_irq(irq, gpio);
+		}
+	}
+
+	config_item_put(&gpio->item);
+
+	return ret;
+}
+
+static int gpio_dev_fasync(int fd, struct file *file, int mode)
+{
+	struct gpio_item *gpio = file->private_data;
+
+	return fasync_helper(fd, file, mode, &gpio->async_queue);
 }
 
 static int gpio_dev_release(struct inode *inode, struct file *file)
 {
 	struct gpio_item *gpio = file->private_data;
+	unsigned int irq;
+	unsigned int i;
+
+	gpio_dev_fasync(-1, file, 0);
+
+	for (i = 0; i < 32; i++) {
+		if (gpio->pin_mask & (1 << i)) {
+			irq = gpio_to_irq(32 * pio_id(gpio->pio) + i);
+			free_irq(irq, gpio);
+		}
+	}
 
 	config_item_put(&gpio->item);
+
 	return 0;
 }
 
+static unsigned int gpio_dev_poll(struct file *file, poll_table *wait)
+{
+	struct gpio_item *gpio = file->private_data;
+	unsigned int mask = 0;
+
+	poll_wait(file, &gpio->change_wq, wait);
+	if (gpio->changed)
+		mask |= POLLIN | POLLRDNORM;
+
+	return mask;
+}
+
 static ssize_t gpio_dev_read(struct file *file, char __user *buf,
 			     size_t count, loff_t *offset)
 {
 	struct gpio_item *gpio = file->private_data;
 	u32 value;
 
+	spin_lock_irq(&gpio->lock);
+	while (!gpio->changed) {
+		spin_unlock_irq(&gpio->lock);
+
+		if (file->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
+		if (wait_event_interruptible(gpio->change_wq, gpio->changed))
+			return -ERESTARTSYS;
+
+		spin_lock_irq(&gpio->lock);
+	}
+
+	gpio->changed = 0;
 	value = pio_readl(gpio->pio, PDSR) & gpio->pin_mask;
 
+	spin_unlock_irq(&gpio->lock);
+
 	count = min(count, (size_t)4);
 	if (copy_to_user(buf, &value, count))
 		return -EFAULT;
+
 	return count;
 }
 
@@ -338,6 +448,8 @@ static struct file_operations gpio_dev_f
 	.llseek		= no_llseek,
 	.open		= gpio_dev_open,
 	.release	= gpio_dev_release,
+	.fasync		= gpio_dev_fasync,
+	.poll		= gpio_dev_poll,
 	.read		= gpio_dev_read,
 	.write		= gpio_dev_write,
 };
@@ -632,6 +744,7 @@ static struct config_item *gpio_make_ite
 	gpio->id = next_id++;
 	config_item_init_type_name(&gpio->item, name, &gpio_item_type);
 	spin_lock_init(&gpio->lock);
+	init_waitqueue_head(&gpio->change_wq);
 
 	return &gpio->item;
 }