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
14 static 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 */
21 struct 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 */
39 static int
scmi_reset_assert(struct reset_controller_dev * rcdev,unsigned long id)40 scmi_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 */
57 static int
scmi_reset_deassert(struct reset_controller_dev * rcdev,unsigned long id)58 scmi_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 */
75 static int
scmi_reset_reset(struct reset_controller_dev * rcdev,unsigned long id)76 scmi_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
83 static 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
scmi_reset_probe(struct scmi_device * sdev)89 static 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
117 static const struct scmi_device_id scmi_id_table[] = {
118 { SCMI_PROTOCOL_RESET, "reset" },
119 { },
120 };
121 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
122
123 static struct scmi_driver scmi_reset_driver = {
124 .name = "scmi-reset",
125 .probe = scmi_reset_probe,
126 .id_table = scmi_id_table,
127 };
128 module_scmi_driver(scmi_reset_driver);
129
130 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
131 MODULE_DESCRIPTION("ARM SCMI reset controller driver");
132 MODULE_LICENSE("GPL v2");
133