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Subject[PATCH v4 4/5] gpiolib: Support 'gpio-reserved-ranges' property
Date
From: Stephen Boyd <sboyd@codeaurora.org>

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>
---
drivers/gpio/gpiolib-of.c | 24 +++++++++++++++++++
drivers/gpio/gpiolib.c | 46 +++++++++++++++++++++++++++++++++++++
include/linux/gpio/driver.h | 16 +++++++++++++
3 files changed, 86 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 84e5a9df2344..ed81d9a6316f 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -511,6 +511,28 @@ void of_mm_gpiochip_remove(struct of_mm_gpio_chip *mm_gc)
}
EXPORT_SYMBOL(of_mm_gpiochip_remove);

+static void of_gpiochip_init_valid_mask(struct gpio_chip *chip)
+{
+ int len, i;
+ u32 start, count;
+ struct device_node *np = chip->of_node;
+
+ len = of_property_count_u32_elems(np, "gpio-reserved-ranges");
+ if (len < 0 || len % 2 != 0)
+ return;
+
+ for (i = 0; i < len; i += 2) {
+ of_property_read_u32_index(np, "gpio-reserved-ranges",
+ i, &start);
+ of_property_read_u32_index(np, "gpio-reserved-ranges",
+ i + 1, &count);
+ if (start >= chip->ngpio || start + count >= chip->ngpio)
+ continue;
+
+ bitmap_clear(chip->valid_mask, start, count);
+ }
+};
+
#ifdef CONFIG_PINCTRL
static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
{
@@ -615,6 +637,8 @@ int of_gpiochip_add(struct gpio_chip *chip)
if (chip->of_gpio_n_cells > MAX_PHANDLE_ARGS)
return -EINVAL;

+ of_gpiochip_init_valid_mask(chip);
+
status = of_gpiochip_add_pin_range(chip);
if (status)
return status;
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 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
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;
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 1ba9a331ec51..5382b5183b7e 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -288,6 +288,21 @@ struct gpio_chip {
struct gpio_irq_chip irq;
#endif

+ /**
+ * @need_valid_mask:
+ *
+ * If set core allocates @valid_mask with all bits set to one.
+ */
+ bool need_valid_mask;
+
+ /**
+ * @valid_mask:
+ *
+ * If not %NULL holds bitmask of GPIOs which are valid to be used
+ * from the chip.
+ */
+ unsigned long *valid_mask;
+
#if defined(CONFIG_OF_GPIO)
/*
* If CONFIG_OF is enabled, then all GPIO controllers described in the
@@ -384,6 +399,7 @@ bool gpiochip_line_is_open_source(struct gpio_chip *chip, unsigned int offset);

/* Sleep persistence inquiry for drivers */
bool gpiochip_line_is_persistent(struct gpio_chip *chip, unsigned int offset);
+bool gpiochip_line_is_valid(const struct gpio_chip *chip, unsigned int offset);

/* get driver data */
void *gpiochip_get_data(struct gpio_chip *chip);
--
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