[PATCH RFC 1/3] pinctrl: add support for acpi PinGroup resource

[Niyas Sait <niyas.sait@xxxxxxxxxx>]

pinctrl-acpi parses and decode PinGroup resources for
the device and generate list of group descriptor.
Descriptors can be used by the pin controller to identify
the groups and pins provided in the group.

Signed-off-by: Niyas Sait <niyas.sait@xxxxxxxxxx>
---
 drivers/pinctrl/Makefile       |  1 +
 drivers/pinctrl/pinctrl-acpi.c | 59 ++++++++++++++++++++++++++++++++++
 drivers/pinctrl/pinctrl-acpi.h | 22 +++++++++++++
 3 files changed, 82 insertions(+)
 create mode 100644 drivers/pinctrl/pinctrl-acpi.c
 create mode 100644 drivers/pinctrl/pinctrl-acpi.h

diff --git a/drivers/pinctrl/Makefile b/drivers/pinctrl/Makefile
index e76f5cdc64b0..0b0ec4080942 100644
--- a/drivers/pinctrl/Makefile
+++ b/drivers/pinctrl/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_PINMUX)		+= pinmux.o
 obj-$(CONFIG_PINCONF)		+= pinconf.o
 obj-$(CONFIG_GENERIC_PINCONF)	+= pinconf-generic.o
 obj-$(CONFIG_OF)		+= devicetree.o
+obj-$(CONFIG_ACPI)		+= pinctrl-acpi.o
 
 obj-$(CONFIG_PINCTRL_AMD)	+= pinctrl-amd.o
 obj-$(CONFIG_PINCTRL_APPLE_GPIO) += pinctrl-apple-gpio.o
diff --git a/drivers/pinctrl/pinctrl-acpi.c b/drivers/pinctrl/pinctrl-acpi.c
new file mode 100644
index 000000000000..75e59fe22387
--- /dev/null
+++ b/drivers/pinctrl/pinctrl-acpi.c
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 Linaro Ltd.
+ */
+#include <linux/acpi.h>
+#include <linux/errno.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/machine.h>
+#include <linux/list.h>
+
+#include "pinctrl-acpi.h"
+
+static int pinctrl_acpi_populate_group_desc(struct acpi_resource *ares, void *data)
+{
+	struct acpi_resource_pin_group *ares_pin_group;
+	struct pinctrl_acpi_group_desc *desc;
+	struct list_head *group_desc_list = data;
+
+	if (ares->type != ACPI_RESOURCE_TYPE_PIN_GROUP)
+		return 1;
+
+	ares_pin_group = &ares->data.pin_group;
+
+	desc = kzalloc(sizeof(struct pinctrl_acpi_group_desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+
+	desc->name = kstrdup_const(ares_pin_group->resource_label.string_ptr, GFP_KERNEL);
+	desc->pins = ares_pin_group->pin_table;
+	desc->num_pins = ares_pin_group->pin_table_length;
+	desc->vendor_data = ares_pin_group->vendor_data;
+	desc->vendor_length = ares_pin_group->vendor_length;
+
+	INIT_LIST_HEAD(&desc->list);
+	list_add(&desc->list, group_desc_list);
+
+	return 1;
+}
+
+/* Get list of acpi pin groups definitions for the controller */
+int pinctrl_acpi_get_pin_groups(struct acpi_device *adev, struct list_head *group_desc_list)
+{
+	struct list_head res_list;
+	int ret;
+
+	INIT_LIST_HEAD(&res_list);
+	INIT_LIST_HEAD(group_desc_list);
+
+	ret = acpi_dev_get_resources(adev, &res_list,
+								 pinctrl_acpi_populate_group_desc,
+								 group_desc_list);
+	if (ret < 0)
+		return ret;
+
+	acpi_dev_free_resource_list(&res_list);
+
+	return 0;
+}
diff --git a/drivers/pinctrl/pinctrl-acpi.h b/drivers/pinctrl/pinctrl-acpi.h
new file mode 100644
index 000000000000..1a0c751a7594
--- /dev/null
+++ b/drivers/pinctrl/pinctrl-acpi.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 Linaro Ltd.
+ */
+
+struct pinctrl_acpi_group_desc {
+	const char *name;
+	short unsigned int *pins;
+	unsigned num_pins;
+	void *vendor_data;
+	unsigned vendor_length;
+	struct list_head list;
+};
+
+#ifdef CONFIG_ACPI
+int pinctrl_acpi_get_pin_groups(struct acpi_device *adev, struct list_head *group_desc_list);
+#else
+int pinctrl_acpi_get_pin_groups(struct acpi_device *adev, struct list_head *group_desc_list)
+{
+	return -ENODEV;
+}
+#endif
-- 
2.25.1