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>

4 files changed, 125 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.
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index b1086dc..71db586 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -345,6 +345,19 @@ void pinctrl_add_gpio_ranges(struct pinctrl_dev *pctldev,
 }
 EXPORT_SYMBOL_GPL(pinctrl_add_gpio_ranges);
 
+struct pinctrl_dev *find_pinctrl_and_add_gpio_range(const char *devname,
+		struct pinctrl_gpio_range *range)
+{
+	struct pinctrl_dev *pctldev = get_pinctrl_dev_from_devname(devname);
+
+	if (!pctldev)
+		return NULL;
+
+	pinctrl_add_gpio_range(pctldev, range);
+	return pctldev;
+}
+EXPORT_SYMBOL_GPL(find_pinctrl_and_add_gpio_range);
+
 /**
  * pinctrl_remove_gpio_range() - remove a range of GPIOs fro a pin controller
  * @pctldev: pin controller device to remove the range from
diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c
index fcb1de4..6728ec7 100644
--- a/drivers/pinctrl/devicetree.c
+++ b/drivers/pinctrl/devicetree.c
@@ -106,6 +106,19 @@ static struct pinctrl_dev *find_pinctrl_by_of_node(struct device_node *np)
 	return NULL;
 }
 
+struct pinctrl_dev *of_pinctrl_add_gpio_range(struct device_node *np,
+		struct pinctrl_gpio_range *range)
+{
+	struct pinctrl_dev *pctldev;
+
+	pctldev = find_pinctrl_by_of_node(np);
+	if (!pctldev)
+		return NULL;
+
+	pinctrl_add_gpio_range(pctldev, range);
+	return pctldev;
+}
+
 static int dt_to_map_one_config(struct pinctrl *p, const char *statename,
 				struct device_node *np_config)
 {