gpiolib: provide provision to register pin ranges

pinctrl subsystem needs gpio chip base to prepare set of gpio
pin ranges, which a given pinctrl driver can handle. This is
important to handle pinctrl gpio request calls in order to
program a given pin properly for gpio operation.

As gpio base is allocated dynamically during gpiochip
registration, presently there exists no clean way to pass this
information to the pinctrl subsystem.

After few discussions from [1], it was concluded that may be
gpio controller reporting the pin range it supports, is a
better way than pinctrl subsystem directly registering it.

[1] http://comments.gmane.org/gmane.linux.ports.arm.kernel/184816

Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Shiraz Hashim <shiraz.hashim@st.com>
[Edited documentation a bit]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

2 files changed, 99 insertions, 0 deletions

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index f1a4599..a5b90c8 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -19,6 +19,7 @@
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_gpio.h>
+#include <linux/pinctrl/pinctrl.h>
 #include <linux/slab.h>
 
 /* Private data structure for of_gpiochip_find_and_xlate */
@@ -216,6 +217,58 @@ err0:
 }
 EXPORT_SYMBOL(of_mm_gpiochip_add);
 
+#ifdef CONFIG_PINCTRL
+void of_gpiochip_add_pin_range(struct gpio_chip *chip)
+{
+	struct device_node *np = chip->of_node;
+	struct gpio_pin_range *pin_range;
+	struct of_phandle_args pinspec;
+	int index = 0, ret;
+
+	if (!np)
+		return;
+
+	do {
+		ret = of_parse_phandle_with_args(np, "gpio-ranges",
+				"#gpio-range-cells", index, &pinspec);
+		if (ret)
+			break;
+
+		pin_range = devm_kzalloc(chip->dev, sizeof(*pin_range),
+				GFP_KERNEL);
+		if (!pin_range) {
+			pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
+					chip->label);
+			break;
+		}
+
+		pin_range->range.name = chip->label;
+		pin_range->range.base = chip->base;
+		pin_range->range.pin_base = pinspec.args[0];
+		pin_range->range.npins = pinspec.args[1];
+		pin_range->pctldev = of_pinctrl_add_gpio_range(pinspec.np,
+				&pin_range->range);
+
+		list_add_tail(&pin_range->node, &chip->pin_ranges);
+
+	} while (index++);
+}
+
+void of_gpiochip_remove_pin_range(struct gpio_chip *chip)
+{
+	struct gpio_pin_range *pin_range, *tmp;
+
+	list_for_each_entry_safe(pin_range, tmp, &chip->pin_ranges, node) {
+		list_del(&pin_range->node);
+		pinctrl_remove_gpio_range(pin_range->pctldev,
+				&pin_range->range);
+	}
+}
+#else
+void of_gpiochip_add_pin_range(struct gpio_chip *chip) {}
+void of_gpiochip_remove_pin_range(struct gpio_chip *chip) {}
+#endif
+
 void of_gpiochip_add(struct gpio_chip *chip)
 {
 	if ((!chip->of_node) && (chip->dev))
@@ -229,11 +282,14 @@ void of_gpiochip_add(struct gpio_chip *chip)
 		chip->of_xlate = of_gpio_simple_xlate;
 	}
 
+	of_gpiochip_add_pin_range(chip);
 	of_node_get(chip->of_node);
 }
 
 void of_gpiochip_remove(struct gpio_chip *chip)
 {
+	of_gpiochip_remove_pin_range(chip);
+
 	if (chip->of_node)
 		of_node_put(chip->of_node);
 }
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 1c8d9e3..f0b07bb 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1083,6 +1083,10 @@ int gpiochip_add(struct gpio_chip *chip)
 		}
 	}
 
+#ifdef CONFIG_PINCTRL
+	INIT_LIST_HEAD(&chip->pin_ranges);
+#endif
+
 	of_gpiochip_add(chip);
 
 unlock:
@@ -1180,6 +1184,45 @@ struct gpio_chip *gpiochip_find(void *data,
 }
 EXPORT_SYMBOL_GPL(gpiochip_find);
 
+#ifdef CONFIG_PINCTRL
+void gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
+		unsigned int pin_base, unsigned int npins)
+{
+	struct gpio_pin_range *pin_range;
+
+	pin_range = devm_kzalloc(chip->dev, sizeof(*pin_range), GFP_KERNEL);
+	if (!pin_range) {
+		pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
+				chip->label);
+		return;
+	}
+
+	pin_range->range.name = chip->label;
+	pin_range->range.base = chip->base;
+	pin_range->range.pin_base = pin_base;
+	pin_range->range.npins = npins;
+	pin_range->pctldev = find_pinctrl_and_add_gpio_range(pinctl_name,
+			&pin_range->range);
+
+	list_add_tail(&pin_range->node, &chip->pin_ranges);
+}
+
+void gpiochip_remove_pin_ranges(struct gpio_chip *chip)
+{
+	struct gpio_pin_range *pin_range, *tmp;
+
+	list_for_each_entry_safe(pin_range, tmp, &chip->pin_ranges, node) {
+		list_del(&pin_range->node);
+		pinctrl_remove_gpio_range(pin_range->pctldev,
+				&pin_range->range);
+	}
+}
+#else
+void gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
+		unsigned int pin_base, unsigned int npins) {}
+void gpiochip_remove_pin_ranges(struct gpio_chip *chip) {}
+#endif
+
 /* These "optional" allocation calls help prevent drivers from stomping
  * on each other, and help provide better diagnostics in debugfs.
  * They're called even less than the "set direction" calls.