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85b03b3033
This reverts commit 923b93e451.
Make sure consumers do not overwrite gpio flags for pins that have
already been claimed.
While adding support for gpio drivers to refuse a request using
unsupported flags, the order of when the requested flag was checked and
the new flags were applied was reversed to that consumers could
overwrite flags for already requested gpios.
This not only affects device-tree setups where two drivers could request
the same gpio using conflicting configurations, but also allowed user
space to clear gpio flags for already claimed pins simply by attempting
to export them through the sysfs interface. By for example clearing the
FLAG_ACTIVE_LOW flag this way, user space could effectively change the
polarity of a signal.
Reverting this change obviously prevents gpio drivers from doing sanity
checks on the flags in their request callbacks. Fortunately only one
recently added driver (gpio-tps65218 in v4.6) appears to do this, and a
follow up patch could restore this functionality through a different
interface.
Cc: stable <stable@vger.kernel.org> # 4.4
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
113 lines
2.4 KiB
C
113 lines
2.4 KiB
C
#include <linux/gpio/consumer.h>
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#include <linux/gpio/driver.h>
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#include <linux/gpio.h>
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#include "gpiolib.h"
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void gpio_free(unsigned gpio)
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{
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gpiod_free(gpio_to_desc(gpio));
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}
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EXPORT_SYMBOL_GPL(gpio_free);
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/**
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* gpio_request_one - request a single GPIO with initial configuration
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* @gpio: the GPIO number
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* @flags: GPIO configuration as specified by GPIOF_*
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* @label: a literal description string of this GPIO
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*/
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int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
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{
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struct gpio_desc *desc;
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int err;
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desc = gpio_to_desc(gpio);
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/* Compatibility: assume unavailable "valid" GPIOs will appear later */
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if (!desc && gpio_is_valid(gpio))
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return -EPROBE_DEFER;
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err = gpiod_request(desc, label);
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if (err)
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return err;
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if (flags & GPIOF_OPEN_DRAIN)
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set_bit(FLAG_OPEN_DRAIN, &desc->flags);
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if (flags & GPIOF_OPEN_SOURCE)
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set_bit(FLAG_OPEN_SOURCE, &desc->flags);
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if (flags & GPIOF_ACTIVE_LOW)
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set_bit(FLAG_ACTIVE_LOW, &desc->flags);
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if (flags & GPIOF_DIR_IN)
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err = gpiod_direction_input(desc);
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else
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err = gpiod_direction_output_raw(desc,
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(flags & GPIOF_INIT_HIGH) ? 1 : 0);
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if (err)
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goto free_gpio;
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if (flags & GPIOF_EXPORT) {
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err = gpiod_export(desc, flags & GPIOF_EXPORT_CHANGEABLE);
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if (err)
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goto free_gpio;
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}
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return 0;
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free_gpio:
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gpiod_free(desc);
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return err;
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}
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EXPORT_SYMBOL_GPL(gpio_request_one);
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int gpio_request(unsigned gpio, const char *label)
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{
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struct gpio_desc *desc = gpio_to_desc(gpio);
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/* Compatibility: assume unavailable "valid" GPIOs will appear later */
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if (!desc && gpio_is_valid(gpio))
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return -EPROBE_DEFER;
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return gpiod_request(desc, label);
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}
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EXPORT_SYMBOL_GPL(gpio_request);
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/**
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* gpio_request_array - request multiple GPIOs in a single call
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* @array: array of the 'struct gpio'
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* @num: how many GPIOs in the array
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*/
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int gpio_request_array(const struct gpio *array, size_t num)
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{
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int i, err;
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for (i = 0; i < num; i++, array++) {
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err = gpio_request_one(array->gpio, array->flags, array->label);
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if (err)
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goto err_free;
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}
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return 0;
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err_free:
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while (i--)
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gpio_free((--array)->gpio);
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return err;
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}
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EXPORT_SYMBOL_GPL(gpio_request_array);
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/**
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* gpio_free_array - release multiple GPIOs in a single call
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* @array: array of the 'struct gpio'
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* @num: how many GPIOs in the array
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*/
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void gpio_free_array(const struct gpio *array, size_t num)
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{
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while (num--)
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gpio_free((array++)->gpio);
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}
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EXPORT_SYMBOL_GPL(gpio_free_array);
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