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>

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 84e5a9d..ed81d9a 100644 (file)
--- 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 db3788d..fecbb55 100644 (file)
--- 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;

diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 1ba9a33..5382b51 100644 (file)
--- 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);