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 <imr@rtschenk.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 8113929..ff46a1b 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.
@@ -2943,6 +3053,53 @@ 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
* @value: value to assign