[PATCH 1/1] pinctrl: add dt binding support for pinmux mappings

[Dong Aisheng]

Since dt already has the pinmux map information in dts file, it does
not have a pinmux maps table registered in machine code as non-dt
platfrom does. Instead, it will create a pinmux map for each device
dynamically by parsing the device node when calling pinmux_get.

To support this, each device wanting to use a pinmux function should
define a phandle named 'pinmux' pointing to a specific pinmux function
under its device node. And the pinmux function nodes should be defined
under the pinctrl device it belongs to.

The pinmux core will use this phandle to find the pinmux function
name and the pinctrl device this function belongs to to construct
a pinmux map for this device to use.

The constraints are that we still do not support parsing multi groups
for a function via dt, that means only first group will be used.
Usually this does not affect the pinmux to work well via dt since the
board dts file knows which pin group for which function and we do not
need to define more than one useless groups for that function.

Another constraint is that we still do not support hog_on_boot via dt
since dt does not have a pinmux map table and we need to create it
dynamically. We still need to find a good way to cover this issue.

Signed-off-by: Dong Aisheng <b29396@xxxxxxxxxxxxx>
---
 .../devicetree/bindings/pinctrl/pinctrl.txt        |   49 ++++++++++++++
 arch/arm/boot/dts/imx6q-sabreauto.dts              |   24 +++++++
 drivers/pinctrl/core.c                             |   69 ++++++++++++++++++++
 drivers/pinctrl/core.h                             |    2 +
 drivers/pinctrl/pinmux.c                           |   27 +++++++-
 5 files changed, 169 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/pinctrl/pinctrl.txt

diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl.txt
b/Documentation/devicetree/bindings/pinctrl/pinctrl.txt
new file mode 100644
index 0000000..013e733
--- /dev/null
+++ b/Documentation/devicetree/bindings/pinctrl/pinctrl.txt
@@ -0,0 +1,49 @@
+The pin control subsystem
+
+The pin control subsystem supports parsing pinmux map from device tree.
+To support this, each device wanting to use a pinmux function should
+define a phandle named 'pinmux' pointing to a specific pinmux function
+under its device node. And the pinmux function nodes should be defined
+under the pinctrl device it belongs to.
+
+The pinmux core will use this phandle to find the pinmux function
+name and the pinctrl device this function belongs to to construct
+a pinmux map for this device to use.
+
+Examples:
+soc {
+	aips-bus@02000000 { /* AIPS1 */
+		iomuxc@020e0000 {
+			pinctrl_uart4: uart4 {
+				func-name = "uart4";
+				grp-name = "uart4grp";
+				grp-pins = <107 108>;
+				num-pins = <2>;
+				grp-mux = <4 4>;
+				num-mux = <2>;
+			};
+
+			pinctrl_sd4: sd4 {
+				func-name = "sd4";
+				grp-name = "sd4grp";
+				grp-pins = <170 171 180 181 182 183 184 185 186 187>;
+				num-pins = <10>;
+				grp-mux = <0 0 1 1 1 1 1 1 1 1>;
+				num-mux = <10>;
+			};
+		};
+	};
+
+	aips-bus@02100000 { /* AIPS2 */
+		usdhc@0219c000 { /* uSDHC4 */
+			fsl,card-wired;
+			status = "okay";
+			pinmux = <&pinctrl_sd4>;
+		};
+
+		uart3: uart@021f0000 { /* UART4 */
+			status = "okay";
+			pinmux = <&pinctrl_uart4>;
+		};
+	};
+};
diff --git a/arch/arm/boot/dts/imx6q-sabreauto.dts
b/arch/arm/boot/dts/imx6q-sabreauto.dts
index 072974e..0863b1d 100644
--- a/arch/arm/boot/dts/imx6q-sabreauto.dts
+++ b/arch/arm/boot/dts/imx6q-sabreauto.dts
@@ -26,6 +26,28 @@
 	};

 	soc {
+		aips-bus@02000000 { /* AIPS1 */
+			iomuxc@020e0000 {
+				pinctrl_uart4: uart4 {
+					func-name = "uart4";
+					grp-name = "uart4grp";
+					grp-pins = <107 108>;
+					num-pins = <2>;
+					grp-mux = <4 4>;
+					num-mux = <2>;
+				};
+
+				pinctrl_sd4: sd4 {
+					func-name = "sd4";
+					grp-name = "sd4grp";
+					grp-pins = <170 171 180 181 182 183 184 185 186 187>;
+					num-pins = <10>;
+					grp-mux = <0 0 1 1 1 1 1 1 1 1>;
+					num-mux = <10>;
+				};
+			};
+		};
+
 		aips-bus@02100000 { /* AIPS2 */
 			enet@02188000 {
 				phy-mode = "rgmii";
@@ -42,10 +64,12 @@
 			usdhc@0219c000 { /* uSDHC4 */
 				fsl,card-wired;
 				status = "okay";
+				pinmux = <&pinctrl_sd4>;
 			};

 			uart3: uart@021f0000 { /* UART4 */
 				status = "okay";
+				pinmux = <&pinctrl_uart4>;
 			};
 		};
 	};
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 39f393b..09de5fa 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -20,6 +20,7 @@
 #include <linux/err.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/of_device.h>
 #include <linux/spinlock.h>
 #include <linux/sysfs.h>
 #include <linux/debugfs.h>
@@ -48,6 +49,74 @@ void *pinctrl_dev_get_drvdata(struct pinctrl_dev *pctldev)
 EXPORT_SYMBOL_GPL(pinctrl_dev_get_drvdata);

 /**
+ * of_get_pinctrl_dev_from_dev() - look up pin controller device via dt
+ * @dev: a device pointer
+ * @map: the pinmux map returned
+ *
+ * Looks up a pin control device matching a certain device name and return
+ * a pinmux map constructed from dt info.
+ */
+struct pinctrl_dev *of_get_pinctrl_dev_from_dev(struct device *dev,
+						struct pinmux_map **map)
+{
+	struct pinctrl_dev *pctldev = NULL;
+	struct device_node *pinmux_np;
+	struct device_node *pinctrl_np;
+	struct pinmux_map *p;
+	bool found = false;
+	char str[16];
+
+	if (!dev || !dev->of_node)
+		return NULL;
+
+	dev_dbg(dev, "find pinctrl dev and pinmux map from device tree\n");
+
+	pinmux_np = of_parse_phandle(dev->of_node, "pinmux", 0);
+	if (!pinmux_np) {
+		dev_err(dev, "unable to get the phandle pinmux\n");
+		return NULL;
+	}
+
+	/* pinmux function nodes should be subnodes of pinctrl device */
+	pinctrl_np = of_get_parent(pinmux_np);
+	if (!pinctrl_np)
+		return NULL;
+
+	mutex_lock(&pinctrldev_list_mutex);
+	list_for_each_entry(pctldev, &pinctrldev_list, node) {
+		if (pctldev->dev->of_node == pinctrl_np) {
+			found = true;
+			break;
+		}
+	}
+	mutex_unlock(&pinctrldev_list_mutex);
+
+	if (found) {
+		/*
+		 * construct a pinmux map from device tree for this device
+		 * Note: for dt we do not specify the pin group, instead we
+		 * use the first group as default.
+		 */
+		p = devm_kzalloc(dev, sizeof(struct pinmux_map), GFP_KERNEL);
+		if (!p)
+			return NULL;
+		*map = p;
+		snprintf(str, 15, "map_%s", pinmux_np->name);
+		p->name = kstrdup(str, GFP_KERNEL);
+		if (!p->name)
+			return NULL;
+		p->function = pinmux_np->name;
+		p->ctrl_dev = pctldev->dev;
+		p->dev = dev;
+		dev_dbg(dev, "found pinctrl: %s  map: %s function %s dev %s\n",
+			dev_name(p->ctrl_dev), p->name,
+			p->function, dev_name(dev));
+	}
+
+	return found ? pctldev : NULL;
+}
+
+/**
  * get_pinctrl_dev_from_dev() - look up pin controller device
  * @dev: a device pointer, this may be NULL but then devname needs to be
  *	defined instead
diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h
index 5375582..6077508 100644
--- a/drivers/pinctrl/core.h
+++ b/drivers/pinctrl/core.h
@@ -69,6 +69,8 @@ struct pin_desc {

 struct pinctrl_dev *get_pinctrl_dev_from_dev(struct device *dev,
 					     const char *dev_name);
+struct pinctrl_dev *of_get_pinctrl_dev_from_dev(struct device *dev,
+						struct pinmux_map **map);
 struct pin_desc *pin_desc_get(struct pinctrl_dev *pctldev, unsigned int pin);
 int pin_get_from_name(struct pinctrl_dev *pctldev, const char *name);
 int pinctrl_get_device_gpio_range(unsigned gpio,
diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 432feb6..cc1b32a 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -20,6 +20,7 @@
 #include <linux/err.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
+#include <linux/of_device.h>
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/sysfs.h>
@@ -696,7 +697,7 @@ static void pinmux_free_groups(struct pinmux *pmx)
 struct pinmux *pinmux_get(struct device *dev, const char *name)
 {

-	struct pinmux_map const *map = NULL;
+	struct pinmux_map *map = NULL;
 	struct pinctrl_dev *pctldev = NULL;
 	const char *devname = NULL;
 	struct pinmux *pmx;
@@ -727,7 +728,29 @@ struct pinmux *pinmux_get(struct device *dev,
const char *name)
 	pmx->func_selector = UINT_MAX;
 	INIT_LIST_HEAD(&pmx->groups);

-	/* Iterate over the pinmux maps to locate the right ones */
+	/*
+	 * do a dt based lookup first to see if we can find a pinctrl device
+	 * and a pinmux map for a specific device. If not found fallback
+	 * to search the pinmux_maps as before.
+	 */
+	pctldev = of_get_pinctrl_dev_from_dev(dev, &map);
+	if (pctldev) {
+		ret = pinmux_enable_muxmap(pctldev, pmx, dev,
+					   devname, map);
+		if (ret) {
+			pinmux_free_groups(pmx);
+			kfree(pmx);
+			return ERR_PTR(ret);
+		}
+		num_maps++;
+	}
+
+	/*
+	 * Iterate over the pinmux maps to locate the right ones
+	 * Note: if we're using dt binding, we do not have a predefined pinmux
+	 * maps table registered in machine code as non-dt platfrom does.
+	 * Then, pinmux_maps_num is 0 by default.
+	 */
 	for (i = 0; i < pinmux_maps_num; i++) {
 		map = &pinmux_maps[i];
 		found_map = false;
-- 
1.7.0.4


Regards
Dong Aisheng
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