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at24: support write-protect GPIO 

Signed-off-by: Jan Luebbe <jluebbe@debian.org>
This commit is contained in:
Jan Luebbe 2015-07-02 16:29:48 +02:00
parent 9f78d1b7a7
commit d7c8571e2e
1 changed files with 37 additions and 0 deletions
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37
drivers/eeprom/at24.c
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@ -21,6 +21,8 @@
#include <linux/log2.h>
#include <i2c/i2c.h>
#include <i2c/at24.h>
#include <gpio.h>
#include <of_gpio.h>
/*
* I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
@ -55,6 +57,8 @@ struct at24_data {
u8 *writebuf;
unsigned write_max;
unsigned num_addresses;
int wp_gpio;
int wp_active_low;
/*
* Some chips tie up multiple I2C addresses; dummy devices reserve
@ -345,6 +349,25 @@ static ssize_t at24_cdev_write(struct cdev *cdev, const void *buf, size_t count,
return at24_write(at24, buf, off, count);
}
static ssize_t at24_cdev_protect(struct cdev *cdev, size_t count, loff_t offset,
int prot)
{
struct at24_data *at24 = cdev->priv;
if (!gpio_is_valid(at24->wp_gpio))
return -EOPNOTSUPP;
prot = !!prot;
if (at24->wp_active_low)
prot = !prot;
gpio_set_value(at24->wp_gpio, prot);
udelay(50);
return 0;
}
static int at24_probe(struct device_d *dev)
{
struct i2c_client *client = to_i2c_client(dev);
@ -403,6 +426,7 @@ static int at24_probe(struct device_d *dev)
at24->cdev.ops = &at24->fops;
at24->fops.lseek = dev_lseek_default;
at24->fops.read = at24_cdev_read,
at24->fops.protect = at24_cdev_protect,
at24->cdev.size = chip.byte_len;
writable = !(chip.flags & AT24_FLAG_READONLY);
@ -419,6 +443,18 @@ static int at24_probe(struct device_d *dev)
at24->writebuf = xmalloc(write_max + 2);
}
at24->wp_gpio = -1;
if (dev->device_node) {
enum of_gpio_flags flags;
at24->wp_gpio = of_get_named_gpio_flags(dev->device_node,
"wp-gpios", 0, &flags);
if (gpio_is_valid(at24->wp_gpio)) {
at24->wp_active_low = flags & OF_GPIO_ACTIVE_LOW;
gpio_request(at24->wp_gpio, "eeprom-wp");
gpio_direction_output(at24->wp_gpio, !at24->wp_active_low);
}
}
at24->client[0] = client;
/* use dummy devices for multiple-address chips */
@ -440,6 +476,7 @@ static int at24_probe(struct device_d *dev)
return 0;
err_clients:
gpio_free(at24->wp_gpio);
kfree(at24->writebuf);
kfree(at24);
err_out: