Add support for specifying that some GPIOs within a range are unavailable.
Some systems have a sparse list of GPIOs, where a range of GPIOs is
specified (usually 0 to n-1), but some subset within that range is
absent or unavailable for whatever reason.
To support this, allow drivers to specify a bitmask of GPIOs that
are present or absent. Gpiolib will then block access to those that
are absent.
Signed-off-by: Timur Tabi <timur@xxxxxxxxxxxxxx>
---
drivers/gpio/gpiolib.c | 47 ++++++++++++++++++++++++++++++++++++++++++++-
include/linux/gpio/driver.h | 3 +++
2 files changed, 49 insertions(+), 1 deletion(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 168dd831551d..2c71e8db95a3 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -191,6 +191,28 @@ static int gpiochip_find_base(int ngpio)
}
}
+static int gpiochip_init_valid_mask(struct gpio_chip *chip)
+{
+ if (!chip->need_valid_mask)
+ return 0;
+
+ chip->valid_mask = kmalloc_array(BITS_TO_LONGS(chip->ngpio),
+ sizeof(long), GFP_KERNEL);
+ if (!chip->valid_mask)
+ return -ENOMEM;
+
+ /* Assume by default all GPIOs are valid */
+ bitmap_fill(chip->valid_mask, chip->ngpio);
+
+ return 0;
+}
+
+static void gpiochip_remove_valid_mask(struct gpio_chip *chip)
+{
+ kfree(chip->valid_mask);
+ chip->valid_mask = NULL;
+}
+
/**
* gpiod_get_direction - return the current direction of a GPIO
* @desc: GPIO to get the direction of
@@ -1225,10 +1247,14 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
if (status)
goto err_remove_from_list;
- status = gpiochip_irqchip_init_valid_mask(chip);
+ status = gpiochip_init_valid_mask(chip);
if (status)
goto err_remove_from_list;
+ status = gpiochip_irqchip_init_valid_mask(chip);
+ if (status)
+ goto err_remove_valid_mask;
+
status = gpiochip_add_irqchip(chip, key);
if (status)
goto err_remove_chip;
@@ -1259,6 +1285,8 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
gpiochip_free_hogs(chip);
of_gpiochip_remove(chip);
gpiochip_irqchip_free_valid_mask(chip);
+err_remove_valid_mask:
+ gpiochip_remove_valid_mask(chip);
err_remove_from_list:
spin_lock_irqsave(&gpio_lock, flags);
list_del(&gdev->list);
@@ -1311,6 +1339,7 @@ void gpiochip_remove(struct gpio_chip *chip)
/* Numb the device, cancelling all outstanding operations */
gdev->chip = NULL;
gpiochip_irqchip_remove(chip);
+ gpiochip_remove_valid_mask(chip);
acpi_gpiochip_remove(chip);
gpiochip_remove_pin_ranges(chip);
of_gpiochip_remove(chip);
@@ -1500,6 +1529,18 @@ static bool gpiochip_irqchip_irq_valid(const struct gpio_chip *gpiochip,
return test_bit(offset, gpiochip->irq.valid_mask);
}
+static bool gpiochip_available(const struct gpio_chip *gpiochip,
+ unsigned int offset)
+{
+ pr_info("%s:%u offset=%u\n", __func__, __LINE__, offset);
+
+ /* No mask means all valid */
+ if (likely(!gpiochip->valid_mask))
+ return true;
+
+ return test_bit(offset, gpiochip->valid_mask);
+}
+
/**
* gpiochip_set_cascaded_irqchip() - connects a cascaded irqchip to a gpiochip
* @gpiochip: the gpiochip to set the irqchip chain to
@@ -3597,6 +3638,10 @@ struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
return desc;
}
+ /* Check if the GPIO line itself is valid */
+ if (!gpiochip_available(desc->gdev->chip, idx))
+ return ERR_PTR(-EACCES);
+
status = gpiod_request(desc, con_id);
if (status < 0)
return ERR_PTR(status);
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 55e672592fa9..b68450caf554 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -316,6 +316,9 @@ struct gpio_chip {
int (*of_xlate)(struct gpio_chip *gc,
const struct of_phandle_args *gpiospec, u32 *flags);
#endif
+
+ bool need_valid_mask;
+ unsigned long *valid_mask;
};
extern const char *gpiochip_is_requested(struct gpio_chip *chip,
--
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc. Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
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