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