[v2,2/3] gpiolib-of: Support 'reserved-gpio-ranges' property

Message ID 20180126011400.2191-3-sboyd@codeaurora.org
State New
Headers show
Series
  • Support qcom pinctrl protected pins
Related show

Commit Message

Stephen Boyd Jan. 26, 2018, 1:13 a.m.
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.

For now, we plumb this into the gpiochip irq APIs so that
GPIO/pinctrl drivers can use the gpiochip_irqchip_irq_valid() to
test validity of GPIOs.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---

Or this can move into a dedicated API and not be tied to the irq code.
Something like of_gpiochip_init_valid_mask?

 drivers/gpio/gpiolib-of.c | 28 ++++++++++++++++++++++++++++
 drivers/gpio/gpiolib.c    |  9 +++++++++
 2 files changed, 37 insertions(+)

Comments

Andy Shevchenko Jan. 26, 2018, 9:35 a.m. | #1
On Thu, 2018-01-25 at 17:13 -0800, Stephen Boyd wrote:
> 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.
> 
> For now, we plumb this into the gpiochip irq APIs so that
> GPIO/pinctrl drivers can use the gpiochip_irqchip_irq_valid() to
> test validity of GPIOs.


> +static void of_gpiochip_init_irq_valid_mask(struct gpio_chip *chip)
> +{

> +	int len, i;
> +	u32 start, count;
> +	struct device_node *np = chip->of_node;

Perhaps reversed tree style? (In the following function as well)

> +	len = of_property_count_u32_elems(np,  "reserved-gpio-
> ranges");
> 

> +	for (i = 0; i < len; i += 2) {
> +		of_property_read_u32_index(np, "reserved-gpio-
> ranges",
> +					   i, &start);
> +		of_property_read_u32_index(np, "reserved-gpio-
> ranges",
> +					   i + 1, &count);

of_find_property() + of_prop_next_u32() ?

> +	if (size > 0 && size % 2 == 0)
> +		gpiochip->irq.need_valid_mask = true;

 ffs(size) >= 2 ?
Linus Walleij Feb. 7, 2018, 1:34 p.m. | #2
Hi Stephen,

nice work!

On Fri, Jan 26, 2018 at 2:13 AM, Stephen Boyd <sboyd@codeaurora.org> wrote:

> For now, we plumb this into the gpiochip irq APIs so that
> GPIO/pinctrl drivers can use the gpiochip_irqchip_irq_valid() to
> test validity of GPIOs.

But is that the right thing to do, given that we just took the
trouble to define a DT binding that is explicitly about
any GPIO, not just IRQ capable ones?

I am worries that the *irq* infix etc on these functions
will be a bit confusing.

Is it a lot of work to make it just generic and maybe bake it
into the gpio_chip so as to refuse already in
gpiod_request_commit() in gpiolib already?

Yours,
Linus Walleij
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Patch

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 564bb7a31da4..194b3306ef74 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -498,6 +498,32 @@  void of_mm_gpiochip_remove(struct of_mm_gpio_chip *mm_gc)
 }
 EXPORT_SYMBOL(of_mm_gpiochip_remove);
 
+#ifdef CONFIG_GPIOLIB_IRQCHIP
+static void of_gpiochip_init_irq_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,  "reserved-gpio-ranges");
+	if (len < 0 || len % 2 != 0)
+		return;
+
+	for (i = 0; i < len; i += 2) {
+		of_property_read_u32_index(np, "reserved-gpio-ranges",
+					   i, &start);
+		of_property_read_u32_index(np, "reserved-gpio-ranges",
+					   i + 1, &count);
+		if (start >= chip->ngpio || start + count >= chip->ngpio)
+			continue;
+
+		bitmap_clear(chip->irq.valid_mask, start, count);
+	}
+};
+#else
+static void of_gpiochip_init_irq_valid_mask(struct gpio_chip *chip) { }
+#endif
+
 #ifdef CONFIG_PINCTRL
 static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
 {
@@ -602,6 +628,8 @@  int of_gpiochip_add(struct gpio_chip *chip)
 	if (chip->of_gpio_n_cells > MAX_PHANDLE_ARGS)
 		return -EINVAL;
 
+	of_gpiochip_init_irq_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 930676ec9847..8483850463e6 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1483,6 +1483,15 @@  static struct gpio_chip *find_chip_by_name(const char *name)
 
 static int gpiochip_irqchip_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,  "reserved-gpio-ranges");
+	if (size > 0 && size % 2 == 0)
+		gpiochip->irq.need_valid_mask = true;
+#endif
+
 	if (!gpiochip->irq.need_valid_mask)
 		return 0;