From eec1d566cdf94b57e8f5ba9fe60eea214929bcfc Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Thu, 12 Oct 2017 12:40:10 +0200 Subject: gpio: Introduce ->get_multiple callback SPI-attached GPIO controllers typically read out all inputs in one go. If callers desire the values of multipe inputs, ideally a single readout should take place to return the desired values. However the current driver API only offers a ->get callback but no ->get_multiple (unlike ->set_multiple, which is present). Thus, to read multiple inputs, a full readout needs to be performed for every single value (barring driver-internal caching), which is inefficient. In fact, the lack of a ->get_multiple callback has been bemoaned repeatedly by the gpio subsystem maintainer: http://www.spinics.net/lists/linux-gpio/msg10571.html http://www.spinics.net/lists/devicetree/msg121734.html Introduce the missing callback. Add corresponding consumer functions such as gpiod_get_array_value(). Amend linehandle_ioctl() to take advantage of the newly added infrastructure. Update the documentation. Cc: Rojhalat Ibrahim Signed-off-by: Lukas Wunner Signed-off-by: Linus Walleij --- drivers/gpio/gpiolib.c | 179 ++++++++++++++++++++++++++++++++++++++++++++++--- drivers/gpio/gpiolib.h | 4 ++ 2 files changed, 172 insertions(+), 11 deletions(-) (limited to 'drivers') diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 8113929eb2bd..ff46a1b6299e 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -365,28 +365,28 @@ static long linehandle_ioctl(struct file *filep, unsigned int cmd, struct linehandle_state *lh = filep->private_data; void __user *ip = (void __user *)arg; struct gpiohandle_data ghd; + int vals[GPIOHANDLES_MAX]; int i; if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) { - int val; + /* TODO: check if descriptors are really input */ + int ret = gpiod_get_array_value_complex(false, + true, + lh->numdescs, + lh->descs, + vals); + if (ret) + return ret; memset(&ghd, 0, sizeof(ghd)); - - /* TODO: check if descriptors are really input */ - for (i = 0; i < lh->numdescs; i++) { - val = gpiod_get_value_cansleep(lh->descs[i]); - if (val < 0) - return val; - ghd.values[i] = val; - } + for (i = 0; i < lh->numdescs; i++) + ghd.values[i] = vals[i]; if (copy_to_user(ip, &ghd, sizeof(ghd))) return -EFAULT; return 0; } else if (cmd == GPIOHANDLE_SET_LINE_VALUES_IOCTL) { - int vals[GPIOHANDLES_MAX]; - /* TODO: check if descriptors are really output */ if (copy_from_user(&ghd, ip, sizeof(ghd))) return -EFAULT; @@ -2466,6 +2466,71 @@ static int gpiod_get_raw_value_commit(const struct gpio_desc *desc) return value; } +static int gpio_chip_get_multiple(struct gpio_chip *chip, + unsigned long *mask, unsigned long *bits) +{ + if (chip->get_multiple) { + return chip->get_multiple(chip, mask, bits); + } else if (chip->get) { + int i, value; + + for_each_set_bit(i, mask, chip->ngpio) { + value = chip->get(chip, i); + if (value < 0) + return value; + __assign_bit(i, bits, value); + } + return 0; + } + return -EIO; +} + +int gpiod_get_array_value_complex(bool raw, bool can_sleep, + unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + int i = 0; + + while (i < array_size) { + struct gpio_chip *chip = desc_array[i]->gdev->chip; + unsigned long mask[BITS_TO_LONGS(chip->ngpio)]; + unsigned long bits[BITS_TO_LONGS(chip->ngpio)]; + int first, j, ret; + + if (!can_sleep) + WARN_ON(chip->can_sleep); + + /* collect all inputs belonging to the same chip */ + first = i; + memset(mask, 0, sizeof(mask)); + do { + const struct gpio_desc *desc = desc_array[i]; + int hwgpio = gpio_chip_hwgpio(desc); + + __set_bit(hwgpio, mask); + i++; + } while ((i < array_size) && + (desc_array[i]->gdev->chip == chip)); + + ret = gpio_chip_get_multiple(chip, mask, bits); + if (ret) + return ret; + + for (j = first; j < i; j++) { + const struct gpio_desc *desc = desc_array[j]; + int hwgpio = gpio_chip_hwgpio(desc); + int value = test_bit(hwgpio, bits); + + if (!raw && test_bit(FLAG_ACTIVE_LOW, &desc->flags)) + value = !value; + value_array[j] = value; + trace_gpio_value(desc_to_gpio(desc), 1, value); + } + } + return 0; +} + /** * gpiod_get_raw_value() - return a gpio's raw value * @desc: gpio whose value will be returned @@ -2514,6 +2579,51 @@ int gpiod_get_value(const struct gpio_desc *desc) } EXPORT_SYMBOL_GPL(gpiod_get_value); +/** + * gpiod_get_raw_array_value() - read raw values from an array of GPIOs + * @array_size: number of elements in the descriptor / value arrays + * @desc_array: array of GPIO descriptors whose values will be read + * @value_array: array to store the read values + * + * Read the raw values of the GPIOs, i.e. the values of the physical lines + * without regard for their ACTIVE_LOW status. Return 0 in case of success, + * else an error code. + * + * This function should be called from contexts where we cannot sleep, + * and it will complain if the GPIO chip functions potentially sleep. + */ +int gpiod_get_raw_array_value(unsigned int array_size, + struct gpio_desc **desc_array, int *value_array) +{ + if (!desc_array) + return -EINVAL; + return gpiod_get_array_value_complex(true, false, array_size, + desc_array, value_array); +} +EXPORT_SYMBOL_GPL(gpiod_get_raw_array_value); + +/** + * gpiod_get_array_value() - read values from an array of GPIOs + * @array_size: number of elements in the descriptor / value arrays + * @desc_array: array of GPIO descriptors whose values will be read + * @value_array: array to store the read values + * + * Read the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status + * into account. Return 0 in case of success, else an error code. + * + * This function should be called from contexts where we cannot sleep, + * and it will complain if the GPIO chip functions potentially sleep. + */ +int gpiod_get_array_value(unsigned int array_size, + struct gpio_desc **desc_array, int *value_array) +{ + if (!desc_array) + return -EINVAL; + return gpiod_get_array_value_complex(false, false, array_size, + desc_array, value_array); +} +EXPORT_SYMBOL_GPL(gpiod_get_array_value); + /* * gpio_set_open_drain_value_commit() - Set the open drain gpio's value. * @desc: gpio descriptor whose state need to be set. @@ -2942,6 +3052,53 @@ int gpiod_get_value_cansleep(const struct gpio_desc *desc) } EXPORT_SYMBOL_GPL(gpiod_get_value_cansleep); +/** + * gpiod_get_raw_array_value_cansleep() - read raw values from an array of GPIOs + * @array_size: number of elements in the descriptor / value arrays + * @desc_array: array of GPIO descriptors whose values will be read + * @value_array: array to store the read values + * + * Read the raw values of the GPIOs, i.e. the values of the physical lines + * without regard for their ACTIVE_LOW status. Return 0 in case of success, + * else an error code. + * + * This function is to be called from contexts that can sleep. + */ +int gpiod_get_raw_array_value_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + might_sleep_if(extra_checks); + if (!desc_array) + return -EINVAL; + return gpiod_get_array_value_complex(true, true, array_size, + desc_array, value_array); +} +EXPORT_SYMBOL_GPL(gpiod_get_raw_array_value_cansleep); + +/** + * gpiod_get_array_value_cansleep() - read values from an array of GPIOs + * @array_size: number of elements in the descriptor / value arrays + * @desc_array: array of GPIO descriptors whose values will be read + * @value_array: array to store the read values + * + * Read the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status + * into account. Return 0 in case of success, else an error code. + * + * This function is to be called from contexts that can sleep. + */ +int gpiod_get_array_value_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + might_sleep_if(extra_checks); + if (!desc_array) + return -EINVAL; + return gpiod_get_array_value_complex(false, true, array_size, + desc_array, value_array); +} +EXPORT_SYMBOL_GPL(gpiod_get_array_value_cansleep); + /** * gpiod_set_raw_value_cansleep() - assign a gpio's raw value * @desc: gpio whose value will be assigned diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index d003ccb12781..10a48caf8477 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -180,6 +180,10 @@ static inline bool acpi_can_fallback_to_crs(struct acpi_device *adev, #endif struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip, u16 hwnum); +int gpiod_get_array_value_complex(bool raw, bool can_sleep, + unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array); void gpiod_set_array_value_complex(bool raw, bool can_sleep, unsigned int array_size, struct gpio_desc **desc_array, -- cgit v1.2.3