1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * ARM System Control and Management Interface (ARM SCMI) reset driver
  4 *
  5 * Copyright (C) 2019-2021 ARM Ltd.
  6 */
  7
  8#include <linux/module.h>
  9#include <linux/of.h>
 10#include <linux/device.h>
 11#include <linux/reset-controller.h>
 12#include <linux/scmi_protocol.h>
 13
 14static const struct scmi_reset_proto_ops *reset_ops;
 15
 16/**
 17 * struct scmi_reset_data - reset controller information structure
 18 * @rcdev: reset controller entity
 19 * @ph: ARM SCMI protocol handle used for communication with system controller
 20 */
 21struct scmi_reset_data {
 22	struct reset_controller_dev rcdev;
 23	const struct scmi_protocol_handle *ph;
 24};
 25
 26#define to_scmi_reset_data(p)	container_of((p), struct scmi_reset_data, rcdev)
 27#define to_scmi_handle(p)	(to_scmi_reset_data(p)->ph)
 28
 29/**
 30 * scmi_reset_assert() - assert device reset
 31 * @rcdev: reset controller entity
 32 * @id: ID of the reset to be asserted
 33 *
 34 * This function implements the reset driver op to assert a device's reset
 35 * using the ARM SCMI protocol.
 36 *
 37 * Return: 0 for successful request, else a corresponding error value
 38 */
 39static int
 40scmi_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
 41{
 42	const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev);
 43
 44	return reset_ops->assert(ph, id);
 45}
 46
 47/**
 48 * scmi_reset_deassert() - deassert device reset
 49 * @rcdev: reset controller entity
 50 * @id: ID of the reset to be deasserted
 51 *
 52 * This function implements the reset driver op to deassert a device's reset
 53 * using the ARM SCMI protocol.
 54 *
 55 * Return: 0 for successful request, else a corresponding error value
 56 */
 57static int
 58scmi_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
 59{
 60	const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev);
 61
 62	return reset_ops->deassert(ph, id);
 63}
 64
 65/**
 66 * scmi_reset_reset() - reset the device
 67 * @rcdev: reset controller entity
 68 * @id: ID of the reset signal to be reset(assert + deassert)
 69 *
 70 * This function implements the reset driver op to trigger a device's
 71 * reset signal using the ARM SCMI protocol.
 72 *
 73 * Return: 0 for successful request, else a corresponding error value
 74 */
 75static int
 76scmi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
 77{
 78	const struct scmi_protocol_handle *ph = to_scmi_handle(rcdev);
 79
 80	return reset_ops->reset(ph, id);
 81}
 82
 83static const struct reset_control_ops scmi_reset_ops = {
 84	.assert		= scmi_reset_assert,
 85	.deassert	= scmi_reset_deassert,
 86	.reset		= scmi_reset_reset,
 87};
 88
 89static int scmi_reset_probe(struct scmi_device *sdev)
 90{
 91	struct scmi_reset_data *data;
 92	struct device *dev = &sdev->dev;
 93	struct device_node *np = dev->of_node;
 94	const struct scmi_handle *handle = sdev->handle;
 95	struct scmi_protocol_handle *ph;
 96
 97	if (!handle)
 98		return -ENODEV;
 99
100	reset_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_RESET, &ph);
101	if (IS_ERR(reset_ops))
102		return PTR_ERR(reset_ops);
103
104	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
105	if (!data)
106		return -ENOMEM;
107
108	data->rcdev.ops = &scmi_reset_ops;
109	data->rcdev.owner = THIS_MODULE;
110	data->rcdev.of_node = np;
111	data->rcdev.nr_resets = reset_ops->num_domains_get(ph);
112	data->ph = ph;
113
114	return devm_reset_controller_register(dev, &data->rcdev);
115}
116
117static const struct scmi_device_id scmi_id_table[] = {
118	{ SCMI_PROTOCOL_RESET, "reset" },
119	{ },
120};
121MODULE_DEVICE_TABLE(scmi, scmi_id_table);
122
123static struct scmi_driver scmi_reset_driver = {
124	.name = "scmi-reset",
125	.probe = scmi_reset_probe,
126	.id_table = scmi_id_table,
127};
128module_scmi_driver(scmi_reset_driver);
129
130MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
131MODULE_DESCRIPTION("ARM SCMI reset controller driver");
132MODULE_LICENSE("GPL v2");