gpiolib: Support 'gpio-reserved-ranges' property

Some qcom platforms make some GPIOs or pins unavailable for use by
non-secure operating systems, and thus reading or writing the registers
for those pins will cause access control issues. Add support for a DT
property to describe the set of GPIOs that are available for use so that
higher level OSes are able to know what pins to avoid reading/writing.
Non-DT platforms can add support by directly updating the
chip->valid_mask.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Tested-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index db3788d17ba0..fecbb553e8a4 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -351,6 +351,43 @@ static unsigned long *gpiochip_allocate_mask(struct gpio_chip *chip)
 	return p;
 }
 
+static int gpiochip_init_valid_mask(struct gpio_chip *gpiochip)
+{
+#ifdef CONFIG_OF_GPIO
+	int size;
+	struct device_node *np = gpiochip->of_node;
+
+	size = of_property_count_u32_elems(np,  "gpio-reserved-ranges");
+	if (size > 0 && size % 2 == 0)
+		gpiochip->need_valid_mask = true;
+#endif
+
+	if (!gpiochip->need_valid_mask)
+		return 0;
+
+	gpiochip->valid_mask = gpiochip_allocate_mask(gpiochip);
+	if (!gpiochip->valid_mask)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void gpiochip_free_valid_mask(struct gpio_chip *gpiochip)
+{
+	kfree(gpiochip->valid_mask);
+	gpiochip->valid_mask = NULL;
+}
+
+bool gpiochip_line_is_valid(const struct gpio_chip *gpiochip,
+				unsigned int offset)
+{
+	/* No mask means all valid */
+	if (likely(!gpiochip->valid_mask))
+		return true;
+	return test_bit(offset, gpiochip->valid_mask);
+}
+EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
+
 /*
  * GPIO line handle management
  */
@@ -1275,6 +1312,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
 	if (status)
 		goto err_remove_from_list;
 
+	status = gpiochip_init_valid_mask(chip);
+	if (status)
+		goto err_remove_irqchip_mask;
+
 	status = gpiochip_add_irqchip(chip, lock_key, request_key);
 	if (status)
 		goto err_remove_chip;
@@ -1304,6 +1345,8 @@ err_remove_chip:
 	acpi_gpiochip_remove(chip);
 	gpiochip_free_hogs(chip);
 	of_gpiochip_remove(chip);
+	gpiochip_free_valid_mask(chip);
+err_remove_irqchip_mask:
 	gpiochip_irqchip_free_valid_mask(chip);
 err_remove_from_list:
 	spin_lock_irqsave(&gpio_lock, flags);
@@ -1360,6 +1403,7 @@ void gpiochip_remove(struct gpio_chip *chip)
 	acpi_gpiochip_remove(chip);
 	gpiochip_remove_pin_ranges(chip);
 	of_gpiochip_remove(chip);
+	gpiochip_free_valid_mask(chip);
 	/*
 	 * We accept no more calls into the driver from this point, so
 	 * NULL the driver data pointer
@@ -1536,6 +1580,8 @@ static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gpiochip)
 bool gpiochip_irqchip_irq_valid(const struct gpio_chip *gpiochip,
 				unsigned int offset)
 {
+	if (!gpiochip_line_is_valid(gpiochip, offset))
+		return false;
 	/* No mask means all valid */
 	if (likely(!gpiochip->irq.valid_mask))
 		return true;