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");
126