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
66 /**
67 * ti_sci_reset_set() - program a device's reset
68 * @rst: Handle to a single reset signal
69 * @assert: boolean flag to indicate assert or deassert
70 *
71 * This is a common internal function used to assert or deassert a device's
72 * reset using the TI SCI protocol. The device's reset is asserted if the
73 * @assert argument is true, or deasserted if @assert argument is false.
74 * The mechanism itself is a read-modify-write procedure, the current device
75 * reset register is read using a TI SCI device operation, the new value is
76 * set or un-set using the reset's mask, and the new reset value written by
77 * using another TI SCI device operation.
78 *
79 * Return: 0 for successful request, else a corresponding error value
80 */
ti_sci_reset_set(struct reset_ctl * rst,bool assert)81 static int ti_sci_reset_set(struct reset_ctl *rst, bool assert)
82 {
83 struct ti_sci_reset_data *data = dev_get_priv(rst->dev);
84 const struct ti_sci_handle *sci = data->sci;
85 const struct ti_sci_dev_ops *dops = &sci->ops.dev_ops;
86 u32 reset_state;
87 int ret;
88
89 ret = dops->get_device_resets(sci, rst->id, &reset_state);
90 if (ret) {
91 dev_err(rst->dev, "%s: get_device_resets failed (%d)\n",
92 __func__, ret);
93 return ret;
94 }
95
96 if (assert)
97 reset_state |= rst->data;
98 else
99 reset_state &= ~rst->data;
100
101 ret = dops->set_device_resets(sci, rst->id, reset_state);
102 if (ret) {
103 dev_err(rst->dev, "%s: set_device_resets failed (%d)\n",
104 __func__, ret);
105 return ret;
106 }
107
108 return 0;
109 }
110
111 /**
112 * ti_sci_reset_assert() - assert device reset
113 * @rst: Handle to a single reset signal
114 *
115 * This function implements the reset driver op to assert a device's reset
116 * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
117 * with the corresponding parameters as passed in, but with the @assert
118 * argument set to true for asserting the reset.
119 *
120 * Return: 0 for successful request, else a corresponding error value
121 */
ti_sci_reset_assert(struct reset_ctl * rst)122 static int ti_sci_reset_assert(struct reset_ctl *rst)
123 {
124 debug("%s(rst=%p)\n", __func__, rst);
125 return ti_sci_reset_set(rst, true);
126 }
127
128 /**
129 * ti_sci_reset_deassert() - deassert device reset
130 * @rst: Handle to a single reset signal
131 *
132 * This function implements the reset driver op to deassert a device's reset
133 * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
134 * with the corresponding parameters as passed in, but with the @assert
135 * argument set to false for deasserting the reset.
136 *
137 * Return: 0 for successful request, else a corresponding error value
138 */
ti_sci_reset_deassert(struct reset_ctl * rst)139 static int ti_sci_reset_deassert(struct reset_ctl *rst)
140 {
141 debug("%s(rst=%p)\n", __func__, rst);
142 return ti_sci_reset_set(rst, false);
143 }
144
145 /**
146 * ti_sci_reset_status() - check device reset status
147 * @rst: Handle to a single reset signal
148 *
149 * This function implements the reset driver op to return the status of a
150 * device's reset using the TI SCI protocol. The reset register value is read
151 * by invoking the TI SCI device operation .get_device_resets(), and the
152 * status of the specific reset is extracted and returned using this reset's
153 * reset mask.
154 *
155 * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted
156 */
ti_sci_reset_status(struct reset_ctl * rst)157 static int ti_sci_reset_status(struct reset_ctl *rst)
158 {
159 struct ti_sci_reset_data *data = dev_get_priv(rst->dev);
160 const struct ti_sci_handle *sci = data->sci;
161 const struct ti_sci_dev_ops *dops = &sci->ops.dev_ops;
162 u32 reset_state;
163 int ret;
164
165 debug("%s(rst=%p)\n", __func__, rst);
166
167 ret = dops->get_device_resets(sci, rst->id, &reset_state);
168 if (ret) {
169 dev_err(rst->dev, "%s: get_device_resets failed (%d)\n",
170 __func__, ret);
171 return ret;
172 }
173
174 return reset_state & rst->data;
175 }
176
177 static const struct udevice_id ti_sci_reset_of_match[] = {
178 { .compatible = "ti,sci-reset", },
179 { /* sentinel */ },
180 };
181
182 static struct reset_ops ti_sci_reset_ops = {
183 .of_xlate = ti_sci_reset_of_xlate,
184 .rst_assert = ti_sci_reset_assert,
185 .rst_deassert = ti_sci_reset_deassert,
186 .rst_status = ti_sci_reset_status,
187 };
188
189 U_BOOT_DRIVER(ti_sci_reset) = {
190 .name = "ti-sci-reset",
191 .id = UCLASS_RESET,
192 .of_match = ti_sci_reset_of_match,
193 .probe = ti_sci_reset_probe,
194 .priv_auto = sizeof(struct ti_sci_reset_data),
195 .ops = &ti_sci_reset_ops,
196 };
197