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