[PATCH v3 2/2] pinctrl: add support for ACPI pin groups

[Niyas Sait <niyas.sait@xxxxxxxxxx>]

Add support for following ACPI pin resources

- PinGroups
- PinGroupFunction
- PinGroupConfig

PinGroupFunction and PinGroupConfig resources are processed by
pinctrl-acpi and maps the group to pins using PinGroups resources
before invoking the acpi_node_to_map callback to map the resources
to struct pinctrl_map.

Signed-off-by: Niyas Sait <niyas.sait@xxxxxxxxxx>
---
 Documentation/driver-api/pin-control-acpi.rst |  97 ++++++++++++
 drivers/pinctrl/pinctrl-acpi.c                | 147 ++++++++++++++++++
 2 files changed, 244 insertions(+)

diff --git a/Documentation/driver-api/pin-control-acpi.rst b/Documentation/driver-api/pin-control-acpi.rst
index 5d179ba90e8f..9a427d76a581 100644
--- a/Documentation/driver-api/pin-control-acpi.rst
+++ b/Documentation/driver-api/pin-control-acpi.rst
@@ -109,6 +109,99 @@ Example 1 : I2C controller SDA/SCL muxed with display controller GPIO pin
 		}
 	}
 
+
+Example 2 : Pin muxing and configuration described with pin groups
+==================================================================
+
+The configuration is similar to example 1 but described using pin group resources
+
+.. code-block:: text
+
+	//
+	// Description: GPIO
+	//
+	Device (GPI0)
+	{
+		Name (_HID, "PNPFFFE")
+		Name (_UID, 0x0)
+		Method (_STA)
+		{
+			Return(0xf)
+		}
+		Method (_CRS, 0x0, NotSerialized)
+		{
+			Name (RBUF, ResourceTemplate()
+			{
+				Memory32Fixed(ReadWrite, 0x4FE00000, 0x20)
+				Interrupt(ResourceConsumer, Level, ActiveHigh, Shared) {0x54}
+				PinGroup("group1", ResourceProducer) {2, 3}
+
+			})
+			Return(RBUF)
+		}
+	}
+
+	//
+	// Description: I2C controller 1
+	//
+	Device (I2C1)
+	{
+		Name (_HID, "PNPFFFF")
+		Name (_UID, 0x0)
+		Method (_STA)
+		{
+			Return(0xf)
+		}
+		Method (_CRS, 0x0, NotSerialized)
+		{
+			Name (RBUF, ResourceTemplate()
+			{
+				Memory32Fixed(ReadWrite, 0x4F800000, 0x20)
+				Interrupt(ResourceConsumer, Level, ActiveHigh, Shared) {0x55}
+				// Set function I2C1 for SDA/SCL pins
+				PinGroupFunction(Exclusive, 0x5, "\\_SB.GPI0, 0, "group1", ResourceConsumer, )
+				// Configure 10k Pull up for SDA/SCL pins
+				PinGroupConfig(Exclusive, 0x01, 10000, "\\_SB.GPI0 ", 0, "group1", ResourceConsumer, )
+			})
+			Return(RBUF)
+		}
+	}
+
+	//
+	// Description: Physical display panel
+	//
+	Device (DISP)
+	{
+		Name (_HID, "PNPFFFD")
+		Name (_UID, 0x0)
+		Method (_STA)
+		{
+			Return(0xf)
+		}
+		Method (_CRS, 0x0, NotSerialized)
+		{
+			Name (RBUF, ResourceTemplate()
+			{
+				Memory32Fixed(ReadWrite, 0x4F900000, 0x20)
+				Interrupt(ResourceConsumer, Level, ActiveHigh, Shared) {0x57}
+				// Set function GPIO for pin group group1
+				PinGroupFunction(Exclusive, 0x1, "\\_SB.GPI0 ", 0, "group1",
+				˓ResourceConsumer, )
+				// Configure 20k Pull down
+				PinGroupConfig (Exclusive, 0x02, 20000, "\\_SB.GPI0 ", 0, "group1",
+				˓ResourceConsumer, )
+				//Enable Schmitt-trigger
+				PinGroupConfig (Exclusive, 0x0D, 1, "\\_SB.GPI0 ", 0, "group1",
+				˓ResourceConsumer, )
+				//Set slew rate to custom value 3
+				PinGroupConfig (Exclusive, 0x0B, 3, "\\_SB.GPI0 ", 0, "group1",
+				˓ResourceConsumer, )
+			})
+			Return(RBUF)
+			}
+		}
+	}
+
 Notes for pin controller device driver developers
 =================================================
 
@@ -191,6 +284,10 @@ acpi_node_to_map to map them to struct pinctrl_map. The above ACPI resources wou
 generate two struct pinctrl_acpi_resource descriptors, one for each pin, with list
 of configs to apply for each pin.
 
+ACPI pin resources can be described at group level as described in example 2 above.
+There is no change to the internal pinctrl ACPI interface due to this. ACPI pinctrl
+subsystem will resolve all of the groups defined in AML to pins using PinGroup resources.
+
 References
 ==========
 
diff --git a/drivers/pinctrl/pinctrl-acpi.c b/drivers/pinctrl/pinctrl-acpi.c
index a510ff38c60d..bb1f05c96a65 100644
--- a/drivers/pinctrl/pinctrl-acpi.c
+++ b/drivers/pinctrl/pinctrl-acpi.c
@@ -55,6 +55,18 @@ struct pinctrl_acpi_map {
 	size_t num_maps;
 };
 
+/**
+ * struct pin_groups_lookup_info - context to use for pin group look up
+ * @group: group to use for look up
+ * @pins: populated pin array for the group
+ * @npins: number of pins found for the group
+ */
+struct pin_groups_lookup_info {
+	const char *group;
+	unsigned int *pins;
+	size_t npins;
+};
+
 static void acpi_free_map(struct pinctrl_dev *pctldev, struct pinctrl_map *map,
 			  unsigned int num_maps)
 {
@@ -395,6 +407,129 @@ static int process_pin_config(struct list_head *config_maps,
 	return 0;
 }
 
+static int find_pin_group_cb(struct acpi_resource *ares, void *data)
+{
+	struct acpi_resource_pin_group *ares_pin_group;
+	struct pin_groups_lookup_info *info = data;
+	int i;
+
+	ares_pin_group = &ares->data.pin_group;
+
+	if (ares->type != ACPI_RESOURCE_TYPE_PIN_GROUP)
+		return 1;
+
+	if (strcmp(ares_pin_group->resource_label.string_ptr, info->group))
+		return 1;
+
+	info->npins = ares_pin_group->pin_table_length;
+	info->pins = kcalloc(info->npins, sizeof(*info->pins), GFP_KERNEL);
+	if (!info->pins)
+		return -ENOMEM;
+
+	for (i = 0; i < ares_pin_group->pin_table_length; i++)
+		info->pins[i] = ares_pin_group->pin_table[i];
+
+	return 1;
+}
+
+static int get_pins_in_acpi_pin_group(struct acpi_device *adev,
+				      char *group_name, unsigned int **pins,
+				      size_t *npins)
+{
+	struct pin_groups_lookup_info info = { .group = group_name };
+	struct list_head res_list;
+	int ret;
+
+	INIT_LIST_HEAD(&res_list);
+	ret = acpi_dev_get_resources(adev, &res_list, find_pin_group_cb, &info);
+	if (ret < 0)
+		return ret;
+
+	acpi_dev_free_resource_list(&res_list);
+
+	*pins = info.pins;
+	*npins = info.npins;
+
+	return 0;
+}
+
+static int process_pin_group_config(struct pinctrl *p,
+				    struct list_head *config_maps,
+				    struct acpi_resource_pin_group_config *ares)
+{
+	struct acpi_device *adev;
+	struct pinctrl_dev *pctl_dev;
+	unsigned int config;
+	int ret;
+	size_t npins;
+	unsigned int *pins;
+	char *pinctrl_acpi;
+	char *group;
+
+	ret = acpi_to_generic_pin_config(ares->pin_config_type,
+					 ares->pin_config_value, &config);
+	if (ret < 0)
+		return ret;
+
+	pinctrl_acpi = ares->resource_source.string_ptr;
+	pctl_dev = get_pinctrl_dev_from_acpi_name(pinctrl_acpi);
+	if (!pctl_dev) {
+		dev_err(p->dev, "pctldev with ACPI name '%s' not found\n",
+			pinctrl_acpi);
+		return -ENXIO;
+	}
+
+	adev = ACPI_COMPANION(pctl_dev->dev);
+	group = ares->resource_source_label.string_ptr;
+	ret = get_pins_in_acpi_pin_group(adev, group, &pins, &npins);
+	if (ret < 0)
+		return ret;
+
+	for (int i = 0; i < npins; i++) {
+		ret = add_to_config_map(config_maps, pinctrl_acpi, pins[i],
+					config);
+		if (ret < 0)
+			break;
+	}
+
+	kfree(pins);
+
+	return ret;
+}
+
+static int
+process_pin_group_function(struct pinctrl *p,
+			   struct acpi_resource_pin_group_function *ares)
+{
+	struct pinctrl_dev *pctl_dev;
+	struct acpi_device *adev;
+	unsigned int *pins;
+	char *pinctrl_acpi;
+	char *group;
+	size_t npins;
+	int ret;
+
+	pinctrl_acpi = ares->resource_source.string_ptr;
+	pctl_dev = get_pinctrl_dev_from_acpi_name(pinctrl_acpi);
+	if (!pctl_dev) {
+		dev_err(p->dev, "pctldev with ACPI name '%s' not found\n",
+			pinctrl_acpi);
+		return -ENXIO;
+	}
+
+	adev = ACPI_COMPANION(pctl_dev->dev);
+	group = ares->resource_source_label.string_ptr;
+	ret = get_pins_in_acpi_pin_group(adev, group, &pins, &npins);
+	if (ret < 0)
+		return ret;
+
+	ret = acpi_pin_function_to_pinctrl_map(p, pinctrl_acpi, pins, npins,
+					       ares->function_number);
+
+	kfree(pins);
+
+	return ret;
+}
 
 static int parse_acpi_pin_function_resources(struct acpi_resource *ares,
 					     void *data)
@@ -408,6 +543,12 @@ static int parse_acpi_pin_function_resources(struct acpi_resource *ares,
 		if (ret < 0)
 			return ret;
 		break;
+	case ACPI_RESOURCE_TYPE_PIN_GROUP_FUNCTION:
+		ret = process_pin_group_function(
+			p, &ares->data.pin_group_function);
+		if (ret < 0)
+			return ret;
+		break;
 	}
 
 	return 1;
@@ -426,6 +567,12 @@ static int parse_acpi_pin_config_resources(struct acpi_resource *ares,
 		if (ret < 0)
 			return ret;
 		break;
+	case ACPI_RESOURCE_TYPE_PIN_GROUP_CONFIG:
+		ret = process_pin_group_config(info->pctrl, &info->config_maps,
+					       &ares->data.pin_group_config);
+		if (ret < 0)
+			return ret;
+		break;
 	}
 
 	return 1;
-- 
2.25.1