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