[PATCH RFC v2 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 | 99 ++++++++++++++++++++++++++++++++++
 drivers/pinctrl/pinctrl-acpi.h | 34 ++++++++++++
 3 files changed, 134 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 89bfa01b5231..b5423465131f 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..cd0d4b2d8868
--- /dev/null
+++ b/drivers/pinctrl/pinctrl-acpi.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACPI helpers for PinCtrl API
+ *
+ * Copyright (C) 2022 Linaro Ltd.
+ * Author: Niyas Sait <niyas.sait@xxxxxxxxxx>
+ */
+#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;
+	int i;
+
+	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->num_pins = ares_pin_group->pin_table_length;
+	desc->pins = kmalloc_array(desc->num_pins, sizeof(*desc->pins), GFP_KERNEL);
+	if (!desc->pins)
+		return -ENOMEM;
+
+	for (i = 0; i < desc->num_pins; i++)
+		desc->pins[i] = ares_pin_group->pin_table[i];
+
+	desc->vendor_length = ares_pin_group->vendor_length;
+	desc->vendor_data = kmalloc_array(desc->vendor_length,
+				sizeof(*desc->vendor_data),
+				GFP_KERNEL);
+	if (!desc->vendor_data)
+		return -ENOMEM;
+
+	for (i = 0; i < desc->vendor_length; i++)
+		desc->vendor_data[i] = ares_pin_group->vendor_data[i];
+
+	INIT_LIST_HEAD(&desc->list);
+	list_add(&desc->list, group_desc_list);
+
+	return 1;
+}
+
+/**
+ * pinctrl_acpi_get_pin_groups() - Get ACPI PinGroup Descriptors for the device
+ * @adev: ACPI device node for retrieving PinGroup descriptors
+ * @group_desc_list: list head to add PinGroup descriptors
+ *
+ * This will parse ACPI PinGroup resources for the given ACPI device
+ * and will add descriptors to the provided @group_desc_list list
+ */
+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;
+}
+
+/**
+ * pinctrl_acpi_free_group_desc() - free allocated group descriptor
+ * @group_desc_list: list head for group descriptor to free
+ *
+ * Call this function to free the allocated group descriptors
+ */
+void pinctrl_acpi_free_group_desc(struct list_head *group_desc_list)
+{
+	struct pinctrl_acpi_group_desc *grp, *tmp;
+
+	list_for_each_entry_safe(grp, tmp, group_desc_list, list) {
+		list_del(&grp->list);
+		kfree_const(grp->name);
+		kfree(grp->pins);
+		kfree(grp->vendor_data);
+		kfree(grp);
+	}
+}
diff --git a/drivers/pinctrl/pinctrl-acpi.h b/drivers/pinctrl/pinctrl-acpi.h
new file mode 100644
index 000000000000..e3a6b61bea90
--- /dev/null
+++ b/drivers/pinctrl/pinctrl-acpi.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * ACPI helpers for PinCtrl API
+ *
+ * Copyright (C) 2022 Linaro Ltd.
+ */
+
+/**
+ * struct pinctrl_acpi_group_desc - Descriptor to hold PinGroup resource from ACPI
+ * @name: name of the pin group
+ * @pins: array of pins that belong to the group
+ * @num_pins: number of pins in the group
+ * @vendor_data: vendor data from parsed ACPI resources
+ * @vendor_length: length of vendor data
+ * @list: list head for the descriptor
+ */
+struct pinctrl_acpi_group_desc {
+	const char *name;
+	u16 *pins;
+	unsigned int num_pins;
+	u8 *vendor_data;
+	unsigned int 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
+static inline int pinctrl_acpi_get_pin_groups(struct acpi_device *adev,
+			struct list_head *group_desc_list)
+{
+	return -ENXIO;
+}
+#endif
-- 
2.25.1