[PATCH 3/6 v7] gpio: Add userland device interface to block GPIO
Roland Stigge
stigge at antcom.de
Sat Nov 17 04:59:50 EST 2012
This patch adds a character device interface to the block GPIO system.
Signed-off-by: Roland Stigge <stigge at antcom.de>
---
Documentation/ABI/testing/dev-gpioblock | 25 ++++++
drivers/gpio/gpiolib.c | 117 +++++++++++++++++++++++++++++++-
include/linux/gpio.h | 5 +
3 files changed, 144 insertions(+), 3 deletions(-)
--- /dev/null
+++ linux-2.6/Documentation/ABI/testing/dev-gpioblock
@@ -0,0 +1,25 @@
+What: /dev/<gpioblock>
+Date: Nov 2012
+KernelVersion: 3.7
+Contact: Roland Stigge <stigge at antcom.de>
+Description: The /dev/<gpioblock> character device node provides userspace
+ access to GPIO blocks, named exactly as the block, e.g.
+ /dev/block0.
+
+ Reading:
+ When reading sizeof(unsigned long) bytes from the device, the
+ current state of the block, masked by the current mask (see
+ below) can be obtained as a word.
+
+ Writing:
+ By writing sizeof(unsigned long) bytes to the device, the
+ current state of the block can be set. This operation is
+ masked by the current mask (see below).
+
+ Setting the mask (default: all bits set):
+ By doing an ioctl(fd, 0, &mask) with an unsigned long mask, the
+ current mask for read and write operations on this gpio block
+ can be set.
+
+ See also Documentation/gpio.txt for an explanation of block
+ GPIO.
--- linux-2.6.orig/drivers/gpio/gpiolib.c
+++ linux-2.6/drivers/gpio/gpiolib.c
@@ -11,6 +11,7 @@
#include <linux/of_gpio.h>
#include <linux/idr.h>
#include <linux/slab.h>
+#include <linux/uaccess.h>
#define CREATE_TRACE_POINTS
#include <trace/events/gpio.h>
@@ -991,12 +992,13 @@ static ssize_t gpio_block_value_show(str
"0x%016lx\n", gpio_block_get(block, ~0));
}
-static bool gpio_block_is_output(struct gpio_block *block)
+static bool gpio_block_is_output(struct gpio_block *block, unsigned long mask)
{
int i;
for (i = 0; i < block->ngpio; i++)
- if (!test_bit(FLAG_IS_OUT, &gpio_desc[block->gpio[i]].flags))
+ if ((mask & BIT(i)) &&
+ !test_bit(FLAG_IS_OUT, &gpio_desc[block->gpio[i]].flags))
return false;
return true;
}
@@ -1012,7 +1014,7 @@ static ssize_t gpio_block_value_store(st
status = kstrtoul(buf, 0, &value);
if (status == 0) {
mutex_lock(&sysfs_lock);
- if (gpio_block_is_output(block)) {
+ if (gpio_block_is_output(block, ~0)) {
gpio_block_set(block, ~0, value);
status = size;
} else {
@@ -2086,6 +2088,106 @@ struct gpio_block *gpio_block_find_by_na
}
EXPORT_SYMBOL_GPL(gpio_block_find_by_name);
+static struct gpio_block *gpio_block_find_by_minor(int minor)
+{
+ struct gpio_block *i;
+
+ list_for_each_entry(i, &gpio_block_list, list)
+ if (i->miscdev.minor == minor)
+ return i;
+ return NULL;
+}
+
+static int gpio_block_fop_open(struct inode *in, struct file *f)
+{
+ int i;
+ struct gpio_block *block = gpio_block_find_by_minor(MINOR(in->i_rdev));
+
+ if (!block)
+ return -ENOENT;
+
+ for (i = 0; i < block->ngpio; i++) {
+ int status = gpio_request(block->gpio[i], "gpioblock dev");
+
+ if (status)
+ return -EBUSY;
+ }
+
+ block->cur_mask = ~0;
+ f->private_data = block;
+
+ return 0;
+}
+
+static int gpio_block_fop_release(struct inode *in, struct file *f)
+{
+ int i;
+ struct gpio_block *block = (struct gpio_block *)f->private_data;
+
+ for (i = 0; i < block->ngpio; i++)
+ gpio_free(block->gpio[i]);
+
+ return 0;
+}
+
+static ssize_t gpio_block_fop_read(struct file *f, char __user *buf, size_t n,
+ loff_t *offset)
+{
+ struct gpio_block *block = (struct gpio_block *)f->private_data;
+ int err;
+
+ if (n >= sizeof(unsigned long)) {
+ unsigned long values = gpio_block_get(block, block->cur_mask);
+
+ err = put_user(values, buf);
+ if (err)
+ return err;
+
+ return sizeof(unsigned long);
+ }
+ return 0;
+}
+static ssize_t gpio_block_fop_write(struct file *f, const char __user *buf,
+ size_t n, loff_t *offset)
+{
+ struct gpio_block *block = (struct gpio_block *)f->private_data;
+ int err;
+
+ if (n >= sizeof(unsigned long)) {
+ unsigned long values;
+
+ err = get_user(values, buf);
+ if (err)
+ return err;
+ if (gpio_block_is_output(block, block->cur_mask))
+ gpio_block_set(block, block->cur_mask, values);
+ else
+ return -EPERM;
+ return sizeof(unsigned long);
+ }
+ return 0;
+}
+
+static long gpio_block_fop_ioctl(struct file *f, unsigned int cmd,
+ unsigned long arg)
+{
+ struct gpio_block *block = (struct gpio_block *)f->private_data;
+ unsigned long __user *x = (unsigned long __user *)arg;
+
+ if (cmd == 0)
+ return get_user(block->cur_mask, x);
+
+ return -EINVAL;
+}
+
+static const struct file_operations gpio_block_fops = {
+ .open = gpio_block_fop_open,
+ .release = gpio_block_fop_release,
+ .read = gpio_block_fop_read,
+ .write = gpio_block_fop_write,
+ .unlocked_ioctl = gpio_block_fop_ioctl,
+};
+
int gpio_block_register(struct gpio_block *block)
{
if (gpio_block_find_by_name(block->name))
@@ -2094,6 +2196,14 @@ int gpio_block_register(struct gpio_bloc
list_add(&block->list, &gpio_block_list);
gpio_block_export(block);
+ block->miscdev.name = block->name;
+ block->miscdev.nodename = block->name;
+ block->miscdev.minor = MISC_DYNAMIC_MINOR;
+ block->miscdev.fops = &gpio_block_fops;
+ block->miscdev.mode = S_IWUSR | S_IRUGO;
+
+ misc_register(&block->miscdev);
+
return 0;
}
EXPORT_SYMBOL_GPL(gpio_block_register);
@@ -2106,6 +2216,7 @@ void gpio_block_unregister(struct gpio_b
if (i == block) {
list_del(&i->list);
gpio_block_unexport(block);
+ misc_deregister(&block->miscdev);
break;
}
}
--- linux-2.6.orig/include/linux/gpio.h
+++ linux-2.6/include/linux/gpio.h
@@ -4,6 +4,7 @@
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/list.h>
+#include <linux/miscdevice.h>
/* see Documentation/gpio.txt */
@@ -88,6 +89,8 @@ struct gpio_block_chip {
* @ngpio: number of gpios in this block
* @gpio: list of gpios in this block
* @list: global list of blocks, maintained by gpiolib
+ * @miscdev: userspace API / device
+ * @cur_mask: currently used gpio mask used by userspace API
*/
struct gpio_block {
struct list_head gbc_list;
@@ -97,6 +100,8 @@ struct gpio_block {
unsigned *gpio;
struct list_head list;
+ struct miscdevice miscdev;
+ unsigned long cur_mask;
};
#ifdef CONFIG_GENERIC_GPIO
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