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 */
19 struct 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 */
37 static int
scmi_reset_assert(struct reset_controller_dev * rcdev,unsigned long id)38 scmi_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 */
55 static int
scmi_reset_deassert(struct reset_controller_dev * rcdev,unsigned long id)56 scmi_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 */
73 static int
scmi_reset_reset(struct reset_controller_dev * rcdev,unsigned long id)74 scmi_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
81 static 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
scmi_reset_probe(struct scmi_device * sdev)87 static 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
110 static const struct scmi_device_id scmi_id_table[] = {
111 { SCMI_PROTOCOL_RESET },
112 { },
113 };
114 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
115
116 static struct scmi_driver scmi_reset_driver = {
117 .name = "scmi-reset",
118 .probe = scmi_reset_probe,
119 .id_table = scmi_id_table,
120 };
121 module_scmi_driver(scmi_reset_driver);
122
123 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
124 MODULE_DESCRIPTION("ARM SCMI reset controller driver");
125 MODULE_LICENSE("GPL v2");
126