at24: support write-protect GPIO
Signed-off-by: Jan Luebbe <jluebbe@debian.org> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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1 changed files with 38 additions and 0 deletions
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@ -21,6 +21,8 @@
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#include <linux/log2.h>
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#include <i2c/i2c.h>
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#include <i2c/at24.h>
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#include <gpio.h>
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#include <of_gpio.h>
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/*
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* I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
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@ -55,6 +57,8 @@ struct at24_data {
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u8 *writebuf;
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unsigned write_max;
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unsigned num_addresses;
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int wp_gpio;
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int wp_active_low;
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/*
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* Some chips tie up multiple I2C addresses; dummy devices reserve
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@ -345,6 +349,25 @@ static ssize_t at24_cdev_write(struct cdev *cdev, const void *buf, size_t count,
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return at24_write(at24, buf, off, count);
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}
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static ssize_t at24_cdev_protect(struct cdev *cdev, size_t count, loff_t offset,
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int prot)
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{
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struct at24_data *at24 = cdev->priv;
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if (!gpio_is_valid(at24->wp_gpio))
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return -EOPNOTSUPP;
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prot = !!prot;
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if (at24->wp_active_low)
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prot = !prot;
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gpio_set_value(at24->wp_gpio, prot);
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udelay(50);
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return 0;
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}
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static int at24_probe(struct device_d *dev)
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{
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struct i2c_client *client = to_i2c_client(dev);
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@ -403,6 +426,7 @@ static int at24_probe(struct device_d *dev)
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at24->cdev.ops = &at24->fops;
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at24->fops.lseek = dev_lseek_default;
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at24->fops.read = at24_cdev_read,
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at24->fops.protect = at24_cdev_protect,
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at24->cdev.size = chip.byte_len;
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writable = !(chip.flags & AT24_FLAG_READONLY);
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@ -419,6 +443,19 @@ static int at24_probe(struct device_d *dev)
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at24->writebuf = xmalloc(write_max + 2);
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}
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at24->wp_gpio = -1;
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if (dev->device_node) {
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enum of_gpio_flags flags;
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at24->wp_gpio = of_get_named_gpio_flags(dev->device_node,
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"wp-gpios", 0, &flags);
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if (gpio_is_valid(at24->wp_gpio)) {
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at24->wp_active_low = flags & OF_GPIO_ACTIVE_LOW;
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gpio_request(at24->wp_gpio, "eeprom-wp");
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gpio_direction_output(at24->wp_gpio,
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!at24->wp_active_low);
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}
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}
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at24->client[0] = client;
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/* use dummy devices for multiple-address chips */
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@ -440,6 +477,7 @@ static int at24_probe(struct device_d *dev)
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return 0;
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err_clients:
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gpio_free(at24->wp_gpio);
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kfree(at24->writebuf);
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kfree(at24);
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err_out:
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