1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Texas Instruments System Control Interface (TI SCI) reset driver
4 *
5 * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
6 * Andreas Dannenberg <dannenberg@ti.com>
7 *
8 * Loosely based on Linux kernel reset-ti-sci.c...
9 */
10
11 #include <common.h>
12 #include <dm.h>
13 #include <errno.h>
14 #include <log.h>
15 #include <malloc.h>
16 #include <reset-uclass.h>
17 #include <dm/device_compat.h>
18 #include <linux/err.h>
19 #include <linux/soc/ti/ti_sci_protocol.h>
20
21 /**
22 * struct ti_sci_reset_data - reset controller information structure
23 * @sci: TI SCI handle used for communication with system controller
24 */
25 struct ti_sci_reset_data {
26 const struct ti_sci_handle *sci;
27 };
28
ti_sci_reset_probe(struct udevice * dev)29 static int ti_sci_reset_probe(struct udevice *dev)
30 {
31 struct ti_sci_reset_data *data = dev_get_priv(dev);
32
33 debug("%s(dev=%p)\n", __func__, dev);
34
35 if (!data)
36 return -ENOMEM;
37
38 /* Store handle for communication with the system controller */
39 data->sci = ti_sci_get_handle(dev);
40 if (IS_ERR(data->sci))
41 return PTR_ERR(data->sci);
42
43 return 0;
44 }
45
ti_sci_reset_of_xlate(struct reset_ctl * rst,struct ofnode_phandle_args * args)46 static int ti_sci_reset_of_xlate(struct reset_ctl *rst,
47 struct ofnode_phandle_args *args)
48 {
49 debug("%s(rst=%p, args_count=%d)\n", __func__, rst, args->args_count);
50
51 if (args->args_count != 2) {
52 debug("Invalid args_count: %d\n", args->args_count);
53 return -EINVAL;
54 }
55
56 /*
57 * On TI SCI-based devices, the reset provider id field is used as a
58 * device ID, and the data field is used as the associated reset mask.
59 */
60 rst->id = args->args[0];
61 rst->data = args->args[1];
62
63 return 0;
64 }
65
ti_sci_reset_request(struct reset_ctl * rst)66 static int ti_sci_reset_request(struct reset_ctl *rst)
67 {
68 debug("%s(rst=%p)\n", __func__, rst);
69 return 0;
70 }
71
ti_sci_reset_free(struct reset_ctl * rst)72 static int ti_sci_reset_free(struct reset_ctl *rst)
73 {
74 debug("%s(rst=%p)\n", __func__, rst);
75 return 0;
76 }
77
78 /**
79 * ti_sci_reset_set() - program a device's reset
80 * @rst: Handle to a single reset signal
81 * @assert: boolean flag to indicate assert or deassert
82 *
83 * This is a common internal function used to assert or deassert a device's
84 * reset using the TI SCI protocol. The device's reset is asserted if the
85 * @assert argument is true, or deasserted if @assert argument is false.
86 * The mechanism itself is a read-modify-write procedure, the current device
87 * reset register is read using a TI SCI device operation, the new value is
88 * set or un-set using the reset's mask, and the new reset value written by
89 * using another TI SCI device operation.
90 *
91 * Return: 0 for successful request, else a corresponding error value
92 */
ti_sci_reset_set(struct reset_ctl * rst,bool assert)93 static int ti_sci_reset_set(struct reset_ctl *rst, bool assert)
94 {
95 struct ti_sci_reset_data *data = dev_get_priv(rst->dev);
96 const struct ti_sci_handle *sci = data->sci;
97 const struct ti_sci_dev_ops *dops = &sci->ops.dev_ops;
98 u32 reset_state;
99 int ret;
100
101 ret = dops->get_device_resets(sci, rst->id, &reset_state);
102 if (ret) {
103 dev_err(rst->dev, "%s: get_device_resets failed (%d)\n",
104 __func__, ret);
105 return ret;
106 }
107
108 if (assert)
109 reset_state |= rst->data;
110 else
111 reset_state &= ~rst->data;
112
113 ret = dops->set_device_resets(sci, rst->id, reset_state);
114 if (ret) {
115 dev_err(rst->dev, "%s: set_device_resets failed (%d)\n",
116 __func__, ret);
117 return ret;
118 }
119
120 return 0;
121 }
122
123 /**
124 * ti_sci_reset_assert() - assert device reset
125 * @rst: Handle to a single reset signal
126 *
127 * This function implements the reset driver op to assert a device's reset
128 * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
129 * with the corresponding parameters as passed in, but with the @assert
130 * argument set to true for asserting the reset.
131 *
132 * Return: 0 for successful request, else a corresponding error value
133 */
ti_sci_reset_assert(struct reset_ctl * rst)134 static int ti_sci_reset_assert(struct reset_ctl *rst)
135 {
136 debug("%s(rst=%p)\n", __func__, rst);
137 return ti_sci_reset_set(rst, true);
138 }
139
140 /**
141 * ti_sci_reset_deassert() - deassert device reset
142 * @rst: Handle to a single reset signal
143 *
144 * This function implements the reset driver op to deassert a device's reset
145 * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
146 * with the corresponding parameters as passed in, but with the @assert
147 * argument set to false for deasserting the reset.
148 *
149 * Return: 0 for successful request, else a corresponding error value
150 */
ti_sci_reset_deassert(struct reset_ctl * rst)151 static int ti_sci_reset_deassert(struct reset_ctl *rst)
152 {
153 debug("%s(rst=%p)\n", __func__, rst);
154 return ti_sci_reset_set(rst, false);
155 }
156
157 /**
158 * ti_sci_reset_status() - check device reset status
159 * @rst: Handle to a single reset signal
160 *
161 * This function implements the reset driver op to return the status of a
162 * device's reset using the TI SCI protocol. The reset register value is read
163 * by invoking the TI SCI device operation .get_device_resets(), and the
164 * status of the specific reset is extracted and returned using this reset's
165 * reset mask.
166 *
167 * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted
168 */
ti_sci_reset_status(struct reset_ctl * rst)169 static int ti_sci_reset_status(struct reset_ctl *rst)
170 {
171 struct ti_sci_reset_data *data = dev_get_priv(rst->dev);
172 const struct ti_sci_handle *sci = data->sci;
173 const struct ti_sci_dev_ops *dops = &sci->ops.dev_ops;
174 u32 reset_state;
175 int ret;
176
177 debug("%s(rst=%p)\n", __func__, rst);
178
179 ret = dops->get_device_resets(sci, rst->id, &reset_state);
180 if (ret) {
181 dev_err(rst->dev, "%s: get_device_resets failed (%d)\n",
182 __func__, ret);
183 return ret;
184 }
185
186 return reset_state & rst->data;
187 }
188
189 static const struct udevice_id ti_sci_reset_of_match[] = {
190 { .compatible = "ti,sci-reset", },
191 { /* sentinel */ },
192 };
193
194 static struct reset_ops ti_sci_reset_ops = {
195 .of_xlate = ti_sci_reset_of_xlate,
196 .request = ti_sci_reset_request,
197 .rfree = ti_sci_reset_free,
198 .rst_assert = ti_sci_reset_assert,
199 .rst_deassert = ti_sci_reset_deassert,
200 .rst_status = ti_sci_reset_status,
201 };
202
203 U_BOOT_DRIVER(ti_sci_reset) = {
204 .name = "ti-sci-reset",
205 .id = UCLASS_RESET,
206 .of_match = ti_sci_reset_of_match,
207 .probe = ti_sci_reset_probe,
208 .priv_auto = sizeof(struct ti_sci_reset_data),
209 .ops = &ti_sci_reset_ops,
210 };
211