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28df169b AD |
1 | /* |
2 | * Texas Instrument's System Control Interface (TI-SCI) reset driver | |
3 | * | |
a6df49f4 | 4 | * Copyright (C) 2015-2017 Texas Instruments Incorporated - https://www.ti.com/ |
28df169b AD |
5 | * Andrew F. Davis <afd@ti.com> |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | * | |
11 | * This program is distributed "as is" WITHOUT ANY WARRANTY of any | |
12 | * kind, whether express or implied; without even the implied warranty | |
13 | * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | */ | |
16 | ||
17 | #include <linux/idr.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/mutex.h> | |
20 | #include <linux/of.h> | |
21 | #include <linux/platform_device.h> | |
22 | #include <linux/reset-controller.h> | |
23 | #include <linux/soc/ti/ti_sci_protocol.h> | |
24 | ||
25 | /** | |
26 | * struct ti_sci_reset_control - reset control structure | |
27 | * @dev_id: SoC-specific device identifier | |
28 | * @reset_mask: reset mask to use for toggling reset | |
29 | * @lock: synchronize reset_mask read-modify-writes | |
30 | */ | |
31 | struct ti_sci_reset_control { | |
32 | u32 dev_id; | |
33 | u32 reset_mask; | |
34 | struct mutex lock; | |
35 | }; | |
36 | ||
37 | /** | |
38 | * struct ti_sci_reset_data - reset controller information structure | |
39 | * @rcdev: reset controller entity | |
40 | * @dev: reset controller device pointer | |
41 | * @sci: TI SCI handle used for communication with system controller | |
42 | * @idr: idr structure for mapping ids to reset control structures | |
43 | */ | |
44 | struct ti_sci_reset_data { | |
45 | struct reset_controller_dev rcdev; | |
46 | struct device *dev; | |
47 | const struct ti_sci_handle *sci; | |
48 | struct idr idr; | |
49 | }; | |
50 | ||
51 | #define to_ti_sci_reset_data(p) \ | |
52 | container_of((p), struct ti_sci_reset_data, rcdev) | |
53 | ||
54 | /** | |
55 | * ti_sci_reset_set() - program a device's reset | |
56 | * @rcdev: reset controller entity | |
57 | * @id: ID of the reset to toggle | |
58 | * @assert: boolean flag to indicate assert or deassert | |
59 | * | |
60 | * This is a common internal function used to assert or deassert a device's | |
61 | * reset using the TI SCI protocol. The device's reset is asserted if the | |
62 | * @assert argument is true, or deasserted if @assert argument is false. | |
63 | * The mechanism itself is a read-modify-write procedure, the current device | |
64 | * reset register is read using a TI SCI device operation, the new value is | |
65 | * set or un-set using the reset's mask, and the new reset value written by | |
66 | * using another TI SCI device operation. | |
67 | * | |
68 | * Return: 0 for successful request, else a corresponding error value | |
69 | */ | |
70 | static int ti_sci_reset_set(struct reset_controller_dev *rcdev, | |
71 | unsigned long id, bool assert) | |
72 | { | |
73 | struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev); | |
74 | const struct ti_sci_handle *sci = data->sci; | |
75 | const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops; | |
76 | struct ti_sci_reset_control *control; | |
77 | u32 reset_state; | |
78 | int ret; | |
79 | ||
80 | control = idr_find(&data->idr, id); | |
81 | if (!control) | |
82 | return -EINVAL; | |
83 | ||
84 | mutex_lock(&control->lock); | |
85 | ||
86 | ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state); | |
87 | if (ret) | |
88 | goto out; | |
89 | ||
90 | if (assert) | |
91 | reset_state |= control->reset_mask; | |
92 | else | |
93 | reset_state &= ~control->reset_mask; | |
94 | ||
95 | ret = dev_ops->set_device_resets(sci, control->dev_id, reset_state); | |
96 | out: | |
97 | mutex_unlock(&control->lock); | |
98 | ||
99 | return ret; | |
100 | } | |
101 | ||
102 | /** | |
103 | * ti_sci_reset_assert() - assert device reset | |
104 | * @rcdev: reset controller entity | |
105 | * @id: ID of the reset to be asserted | |
106 | * | |
107 | * This function implements the reset driver op to assert a device's reset | |
108 | * using the TI SCI protocol. This invokes the function ti_sci_reset_set() | |
109 | * with the corresponding parameters as passed in, but with the @assert | |
110 | * argument set to true for asserting the reset. | |
111 | * | |
112 | * Return: 0 for successful request, else a corresponding error value | |
113 | */ | |
114 | static int ti_sci_reset_assert(struct reset_controller_dev *rcdev, | |
115 | unsigned long id) | |
116 | { | |
117 | return ti_sci_reset_set(rcdev, id, true); | |
118 | } | |
119 | ||
120 | /** | |
121 | * ti_sci_reset_deassert() - deassert device reset | |
122 | * @rcdev: reset controller entity | |
123 | * @id: ID of the reset to be deasserted | |
124 | * | |
125 | * This function implements the reset driver op to deassert a device's reset | |
126 | * using the TI SCI protocol. This invokes the function ti_sci_reset_set() | |
127 | * with the corresponding parameters as passed in, but with the @assert | |
128 | * argument set to false for deasserting the reset. | |
129 | * | |
130 | * Return: 0 for successful request, else a corresponding error value | |
131 | */ | |
132 | static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev, | |
133 | unsigned long id) | |
134 | { | |
135 | return ti_sci_reset_set(rcdev, id, false); | |
136 | } | |
137 | ||
138 | /** | |
139 | * ti_sci_reset_status() - check device reset status | |
140 | * @rcdev: reset controller entity | |
141 | * @id: ID of reset to be checked | |
142 | * | |
143 | * This function implements the reset driver op to return the status of a | |
144 | * device's reset using the TI SCI protocol. The reset register value is read | |
145 | * by invoking the TI SCI device operation .get_device_resets(), and the | |
146 | * status of the specific reset is extracted and returned using this reset's | |
147 | * reset mask. | |
148 | * | |
149 | * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted | |
150 | */ | |
151 | static int ti_sci_reset_status(struct reset_controller_dev *rcdev, | |
152 | unsigned long id) | |
153 | { | |
154 | struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev); | |
155 | const struct ti_sci_handle *sci = data->sci; | |
156 | const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops; | |
157 | struct ti_sci_reset_control *control; | |
158 | u32 reset_state; | |
159 | int ret; | |
160 | ||
161 | control = idr_find(&data->idr, id); | |
162 | if (!control) | |
163 | return -EINVAL; | |
164 | ||
165 | ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state); | |
166 | if (ret) | |
167 | return ret; | |
168 | ||
169 | return reset_state & control->reset_mask; | |
170 | } | |
171 | ||
172 | static const struct reset_control_ops ti_sci_reset_ops = { | |
173 | .assert = ti_sci_reset_assert, | |
174 | .deassert = ti_sci_reset_deassert, | |
175 | .status = ti_sci_reset_status, | |
176 | }; | |
177 | ||
178 | /** | |
179 | * ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID | |
180 | * @rcdev: reset controller entity | |
181 | * @reset_spec: OF reset argument specifier | |
182 | * | |
183 | * This function performs the translation of the reset argument specifier | |
184 | * values defined in a reset consumer device node. The function allocates a | |
185 | * reset control structure for that device reset, and will be used by the | |
186 | * driver for performing any reset functions on that reset. An idr structure | |
187 | * is allocated and used to map to the reset control structure. This idr | |
188 | * is used by the driver to do reset lookups. | |
189 | * | |
190 | * Return: 0 for successful request, else a corresponding error value | |
191 | */ | |
192 | static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev, | |
193 | const struct of_phandle_args *reset_spec) | |
194 | { | |
195 | struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev); | |
196 | struct ti_sci_reset_control *control; | |
197 | ||
198 | if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells)) | |
199 | return -EINVAL; | |
200 | ||
201 | control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL); | |
202 | if (!control) | |
203 | return -ENOMEM; | |
204 | ||
205 | control->dev_id = reset_spec->args[0]; | |
206 | control->reset_mask = reset_spec->args[1]; | |
207 | mutex_init(&control->lock); | |
208 | ||
209 | return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL); | |
210 | } | |
211 | ||
212 | static const struct of_device_id ti_sci_reset_of_match[] = { | |
213 | { .compatible = "ti,sci-reset", }, | |
214 | { /* sentinel */ }, | |
215 | }; | |
216 | MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match); | |
217 | ||
218 | static int ti_sci_reset_probe(struct platform_device *pdev) | |
219 | { | |
220 | struct ti_sci_reset_data *data; | |
221 | ||
222 | if (!pdev->dev.of_node) | |
223 | return -ENODEV; | |
224 | ||
225 | data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); | |
226 | if (!data) | |
227 | return -ENOMEM; | |
228 | ||
229 | data->sci = devm_ti_sci_get_handle(&pdev->dev); | |
230 | if (IS_ERR(data->sci)) | |
231 | return PTR_ERR(data->sci); | |
232 | ||
233 | data->rcdev.ops = &ti_sci_reset_ops; | |
234 | data->rcdev.owner = THIS_MODULE; | |
235 | data->rcdev.of_node = pdev->dev.of_node; | |
236 | data->rcdev.of_reset_n_cells = 2; | |
237 | data->rcdev.of_xlate = ti_sci_reset_of_xlate; | |
238 | data->dev = &pdev->dev; | |
239 | idr_init(&data->idr); | |
240 | ||
241 | platform_set_drvdata(pdev, data); | |
242 | ||
243 | return reset_controller_register(&data->rcdev); | |
244 | } | |
245 | ||
246 | static int ti_sci_reset_remove(struct platform_device *pdev) | |
247 | { | |
248 | struct ti_sci_reset_data *data = platform_get_drvdata(pdev); | |
249 | ||
250 | reset_controller_unregister(&data->rcdev); | |
251 | ||
252 | idr_destroy(&data->idr); | |
253 | ||
254 | return 0; | |
255 | } | |
256 | ||
257 | static struct platform_driver ti_sci_reset_driver = { | |
258 | .probe = ti_sci_reset_probe, | |
259 | .remove = ti_sci_reset_remove, | |
260 | .driver = { | |
261 | .name = "ti-sci-reset", | |
262 | .of_match_table = ti_sci_reset_of_match, | |
263 | }, | |
264 | }; | |
265 | module_platform_driver(ti_sci_reset_driver); | |
266 | ||
267 | MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>"); | |
268 | MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver"); | |
269 | MODULE_LICENSE("GPL v2"); |