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authorClaudio Mignanti <c.mignanti@gmail.com>2010-06-13 13:27:06 +0000
committerClaudio Mignanti <c.mignanti@gmail.com>2010-06-13 13:27:06 +0000
commit35ff4c9aa8b3c0d8982512187a8112d51c533e85 (patch)
treef9692d7cf9f65cdcf00877a688e315dce0ba18ee
parentfb941964627b43473fa4dec2645ccc9f2df16f8a (diff)
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Extend the gpio device driver (#5671)
SVN-Revision: 21787
-rw-r--r--target/linux/generic-2.6/files/drivers/char/gpio_dev.c78
-rw-r--r--target/linux/generic-2.6/files/include/linux/gpio_dev.h35
2 files changed, 61 insertions, 52 deletions
diff --git a/target/linux/generic-2.6/files/drivers/char/gpio_dev.c b/target/linux/generic-2.6/files/drivers/char/gpio_dev.c
index 8392fcf2d6..e6d5b1d05e 100644
--- a/target/linux/generic-2.6/files/drivers/char/gpio_dev.c
+++ b/target/linux/generic-2.6/files/drivers/char/gpio_dev.c
@@ -17,6 +17,7 @@
*
* Feedback, Bugs... blogic@openwrt.org
*
+ * dpg 20100106
*/
#include <linux/module.h>
@@ -36,54 +37,57 @@
#define DEVNAME "gpio"
static int dev_major;
-static unsigned int gpio_access_mask;
static struct class *gpiodev_class;
-/* Counter is 1, if the device is not opened and zero (or less) if opened. */
-static atomic_t gpio_open_cnt = ATOMIC_INIT(1);
+/* third argument of user space ioctl ('arg' here) contains the <pin> */
static int
-gpio_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg)
+gpio_ioctl(struct inode * inode, struct file * file, unsigned int cmd,
+ unsigned long arg)
{
int retval = 0;
- if (((1 << arg) & gpio_access_mask) != (1 << arg))
- {
- retval = -EINVAL;
- goto out;
- }
-
switch (cmd)
{
case GPIO_GET:
retval = gpio_get_value(arg);
break;
-
case GPIO_SET:
gpio_set_value(arg, 1);
break;
-
case GPIO_CLEAR:
gpio_set_value(arg, 0);
break;
-
case GPIO_DIR_IN:
- gpio_direction_input(arg);
+ retval = gpio_direction_input(arg);
break;
-
case GPIO_DIR_OUT:
- gpio_direction_output(arg, 0);
+ retval = gpio_direction_output(arg, 0);
+ break;
+ case GPIO_DIR_HIGH:
+ retval = gpio_direction_output(arg, 1);
+ break;
+ case GPIO_REQUEST:
+ /* should be first ioctl operation on <pin> */
+ retval = gpio_request(arg, DRVNAME);
+ break;
+ case GPIO_FREE:
+ /* should be last ioctl operation on <pin> */
+ /* may be needed first if previous user missed this ioctl */
+ gpio_free(arg);
+ break;
+ case GPIO_CAN_SLEEP:
+ retval = gpio_cansleep(arg);
break;
-
default:
retval = -EINVAL;
+ /* = -ENOTTY; // correct return but ... */
break;
}
-
-out:
return retval;
}
+/* Allow co-incident opens */
static int
gpio_open(struct inode *inode, struct file *file)
{
@@ -96,19 +100,6 @@ gpio_open(struct inode *inode, struct file *file)
result = -ENODEV;
goto out;
}
-
- /* FIXME: We should really allow multiple applications to open the device
- * at the same time, as long as the apps access different IO pins.
- * The generic gpio-registration functions can be used for that.
- * Two new IOCTLs have to be introduced for that. Need to check userspace
- * compatibility first. --mb */
- if (!atomic_dec_and_test(&gpio_open_cnt)) {
- atomic_inc(&gpio_open_cnt);
- printk(KERN_ERR DRVNAME ": Device with minor ID %d already in use\n", dev_minor);
- result = -EBUSY;
- goto out;
- }
-
out:
return result;
}
@@ -116,9 +107,9 @@ out:
static int
gpio_close(struct inode * inode, struct file * file)
{
- smp_mb__before_atomic_inc();
- atomic_inc(&gpio_open_cnt);
-
+ /* could track all <pin>s requested by this fd and gpio_free()
+ * them here
+ */
return 0;
}
@@ -140,22 +131,9 @@ gpio_probe(struct platform_device *dev)
result = -ENODEV;
goto out;
}
-
gpiodev_class = class_create(THIS_MODULE, DRVNAME);
device_create(gpiodev_class, NULL, MKDEV(dev_major, 0), dev, DEVNAME);
-
printk(KERN_INFO DRVNAME ": gpio device registered with major %d\n", dev_major);
-
- if (dev->num_resources != 1)
- {
- printk(KERN_ERR DRVNAME ": device may only have 1 resource\n");
- result = -ENODEV;
- goto out;
- }
-
- gpio_access_mask = dev->resource[0].start;
-
- printk(KERN_INFO DRVNAME ": gpio platform device registered with access mask %08X\n", gpio_access_mask);
out:
return result;
}
@@ -182,7 +160,7 @@ gpio_mod_init(void)
{
int ret = platform_driver_register(&gpio_driver);
if (ret)
- printk(KERN_INFO DRVNAME ": Error registering platfom driver!");
+ printk(KERN_INFO DRVNAME ": Error registering platfom driver!\n");
return ret;
}
@@ -197,5 +175,5 @@ module_init (gpio_mod_init);
module_exit (gpio_mod_exit);
MODULE_LICENSE("GPL");
-MODULE_AUTHOR("John Crispin / OpenWrt");
+MODULE_AUTHOR("John Crispin / OpenWrt +");
MODULE_DESCRIPTION("Character device for for generic gpio api");
diff --git a/target/linux/generic-2.6/files/include/linux/gpio_dev.h b/target/linux/generic-2.6/files/include/linux/gpio_dev.h
index 3f3c9c772c..a2a4b51c78 100644
--- a/target/linux/generic-2.6/files/include/linux/gpio_dev.h
+++ b/target/linux/generic-2.6/files/include/linux/gpio_dev.h
@@ -1,11 +1,42 @@
-#ifndef _GPIODEV_H__
-#define _GPIODEV_H__
+#ifndef _GPIO_DEV_H__
+#define _GPIO_DEV_H__
+
+/*********************************************************************
+ *
+ * This Linux kernel header is expanded from the original driver
+ * (gpio_dev) by John Crispin. It provides an ioctl based interface to
+ * GPIO pins via the /dev/gpio char device and gpiolib within the kernel.
+ * The third argument to each ioctl is the GPIO pin number.
+ *
+ * This driver has been tested with lk 2.6.31 and works. The original
+ * driver fails quietly with this version. The protocol is now a bit
+ * different: the ioctl(fd, GPIO_REQUEST, <pin>) should be called
+ * after the open("/dev/gpio", O_RDWR) to determine if the <pin> is
+ * already in use. If the ioctl is successful (i.e. returns 0 for not
+ * in use) then the <pin> is claimed by this driver and
+ * ioctl(fd, GPIO_FREE, <pin>) should be called prior to close(fd) .
+ *
+ * See <kernel_source>/Documentation/gpio.txt
+ * Note that kernel designers prefer the use of the sysfs gpio interface.
+ * This char driver is easier to use from code and faster.
+ ********************************************************************/
+
+/* This header can be included in both the user and kernel spaces */
+/* The _IO macro is defined in sys/ioctl.h */
#define IOC_GPIODEV_MAGIC 'B'
+
#define GPIO_GET _IO(IOC_GPIODEV_MAGIC, 10)
#define GPIO_SET _IO(IOC_GPIODEV_MAGIC, 11)
#define GPIO_CLEAR _IO(IOC_GPIODEV_MAGIC, 12)
#define GPIO_DIR_IN _IO(IOC_GPIODEV_MAGIC, 13)
#define GPIO_DIR_OUT _IO(IOC_GPIODEV_MAGIC, 14)
+ /* Sets the direction out and clears the <pin> (low) */
+
+#define GPIO_DIR_HIGH _IO(IOC_GPIODEV_MAGIC, 15)
+ /* Sets the direction out and sets the <pin> (high) */
+#define GPIO_REQUEST _IO(IOC_GPIODEV_MAGIC, 16)
+#define GPIO_FREE _IO(IOC_GPIODEV_MAGIC, 17)
+#define GPIO_CAN_SLEEP _IO(IOC_GPIODEV_MAGIC, 18)
#endif