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gpio: Introduce ->get_multiple callback

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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>
This commit is contained in:
Lukas Wunner
2017-10-12 12:40:10 +02:00
committed by Linus Walleij
parent 5307e2ad69
commit eec1d566cd
5 changed files with 250 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

179
drivers/gpio/gpiolib.c
View File

@@ -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

4
drivers/gpio/gpiolib.h
View File

@@ -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,