1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Texas Instrument's System Control Interface (TI-SCI) reset driver
4  *
5  * Copyright (C) 2015-2017 Texas Instruments Incorporated - https://www.ti.com/
6  *	Andrew F. Davis <afd@ti.com>
7  */
8 
9 #include <linux/idr.h>
10 #include <linux/module.h>
11 #include <linux/mutex.h>
12 #include <linux/of.h>
13 #include <linux/platform_device.h>
14 #include <linux/reset-controller.h>
15 #include <linux/soc/ti/ti_sci_protocol.h>
16 
17 /**
18  * struct ti_sci_reset_control - reset control structure
19  * @dev_id: SoC-specific device identifier
20  * @reset_mask: reset mask to use for toggling reset
21  * @lock: synchronize reset_mask read-modify-writes
22  */
23 struct ti_sci_reset_control {
24 	u32 dev_id;
25 	u32 reset_mask;
26 	struct mutex lock;
27 };
28 
29 /**
30  * struct ti_sci_reset_data - reset controller information structure
31  * @rcdev: reset controller entity
32  * @dev: reset controller device pointer
33  * @sci: TI SCI handle used for communication with system controller
34  * @idr: idr structure for mapping ids to reset control structures
35  */
36 struct ti_sci_reset_data {
37 	struct reset_controller_dev rcdev;
38 	struct device *dev;
39 	const struct ti_sci_handle *sci;
40 	struct idr idr;
41 };
42 
43 #define to_ti_sci_reset_data(p)	\
44 	container_of((p), struct ti_sci_reset_data, rcdev)
45 
46 /**
47  * ti_sci_reset_set() - program a device's reset
48  * @rcdev: reset controller entity
49  * @id: ID of the reset to toggle
50  * @assert: boolean flag to indicate assert or deassert
51  *
52  * This is a common internal function used to assert or deassert a device's
53  * reset using the TI SCI protocol. The device's reset is asserted if the
54  * @assert argument is true, or deasserted if @assert argument is false.
55  * The mechanism itself is a read-modify-write procedure, the current device
56  * reset register is read using a TI SCI device operation, the new value is
57  * set or un-set using the reset's mask, and the new reset value written by
58  * using another TI SCI device operation.
59  *
60  * Return: 0 for successful request, else a corresponding error value
61  */
ti_sci_reset_set(struct reset_controller_dev * rcdev,unsigned long id,bool assert)62 static int ti_sci_reset_set(struct reset_controller_dev *rcdev,
63 			    unsigned long id, bool assert)
64 {
65 	struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
66 	const struct ti_sci_handle *sci = data->sci;
67 	const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
68 	struct ti_sci_reset_control *control;
69 	u32 reset_state;
70 	int ret;
71 
72 	control = idr_find(&data->idr, id);
73 	if (!control)
74 		return -EINVAL;
75 
76 	mutex_lock(&control->lock);
77 
78 	ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
79 	if (ret)
80 		goto out;
81 
82 	if (assert)
83 		reset_state |= control->reset_mask;
84 	else
85 		reset_state &= ~control->reset_mask;
86 
87 	ret = dev_ops->set_device_resets(sci, control->dev_id, reset_state);
88 out:
89 	mutex_unlock(&control->lock);
90 
91 	return ret;
92 }
93 
94 /**
95  * ti_sci_reset_assert() - assert device reset
96  * @rcdev: reset controller entity
97  * @id: ID of the reset to be asserted
98  *
99  * This function implements the reset driver op to assert a device's reset
100  * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
101  * with the corresponding parameters as passed in, but with the @assert
102  * argument set to true for asserting the reset.
103  *
104  * Return: 0 for successful request, else a corresponding error value
105  */
ti_sci_reset_assert(struct reset_controller_dev * rcdev,unsigned long id)106 static int ti_sci_reset_assert(struct reset_controller_dev *rcdev,
107 			       unsigned long id)
108 {
109 	return ti_sci_reset_set(rcdev, id, true);
110 }
111 
112 /**
113  * ti_sci_reset_deassert() - deassert device reset
114  * @rcdev: reset controller entity
115  * @id: ID of the reset to be deasserted
116  *
117  * This function implements the reset driver op to deassert a device's reset
118  * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
119  * with the corresponding parameters as passed in, but with the @assert
120  * argument set to false for deasserting the reset.
121  *
122  * Return: 0 for successful request, else a corresponding error value
123  */
ti_sci_reset_deassert(struct reset_controller_dev * rcdev,unsigned long id)124 static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev,
125 				 unsigned long id)
126 {
127 	return ti_sci_reset_set(rcdev, id, false);
128 }
129 
130 /**
131  * ti_sci_reset_status() - check device reset status
132  * @rcdev: reset controller entity
133  * @id: ID of reset to be checked
134  *
135  * This function implements the reset driver op to return the status of a
136  * device's reset using the TI SCI protocol. The reset register value is read
137  * by invoking the TI SCI device operation .get_device_resets(), and the
138  * status of the specific reset is extracted and returned using this reset's
139  * reset mask.
140  *
141  * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted
142  */
ti_sci_reset_status(struct reset_controller_dev * rcdev,unsigned long id)143 static int ti_sci_reset_status(struct reset_controller_dev *rcdev,
144 			       unsigned long id)
145 {
146 	struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
147 	const struct ti_sci_handle *sci = data->sci;
148 	const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
149 	struct ti_sci_reset_control *control;
150 	u32 reset_state;
151 	int ret;
152 
153 	control = idr_find(&data->idr, id);
154 	if (!control)
155 		return -EINVAL;
156 
157 	ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
158 	if (ret)
159 		return ret;
160 
161 	return reset_state & control->reset_mask;
162 }
163 
164 static const struct reset_control_ops ti_sci_reset_ops = {
165 	.assert		= ti_sci_reset_assert,
166 	.deassert	= ti_sci_reset_deassert,
167 	.status		= ti_sci_reset_status,
168 };
169 
170 /**
171  * ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID
172  * @rcdev: reset controller entity
173  * @reset_spec: OF reset argument specifier
174  *
175  * This function performs the translation of the reset argument specifier
176  * values defined in a reset consumer device node. The function allocates a
177  * reset control structure for that device reset, and will be used by the
178  * driver for performing any reset functions on that reset. An idr structure
179  * is allocated and used to map to the reset control structure. This idr
180  * is used by the driver to do reset lookups.
181  *
182  * Return: 0 for successful request, else a corresponding error value
183  */
ti_sci_reset_of_xlate(struct reset_controller_dev * rcdev,const struct of_phandle_args * reset_spec)184 static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev,
185 				 const struct of_phandle_args *reset_spec)
186 {
187 	struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
188 	struct ti_sci_reset_control *control;
189 
190 	if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
191 		return -EINVAL;
192 
193 	control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL);
194 	if (!control)
195 		return -ENOMEM;
196 
197 	control->dev_id = reset_spec->args[0];
198 	control->reset_mask = reset_spec->args[1];
199 	mutex_init(&control->lock);
200 
201 	return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL);
202 }
203 
204 static const struct of_device_id ti_sci_reset_of_match[] = {
205 	{ .compatible = "ti,sci-reset", },
206 	{ /* sentinel */ },
207 };
208 MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match);
209 
ti_sci_reset_probe(struct platform_device * pdev)210 static int ti_sci_reset_probe(struct platform_device *pdev)
211 {
212 	struct ti_sci_reset_data *data;
213 
214 	if (!pdev->dev.of_node)
215 		return -ENODEV;
216 
217 	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
218 	if (!data)
219 		return -ENOMEM;
220 
221 	data->sci = devm_ti_sci_get_handle(&pdev->dev);
222 	if (IS_ERR(data->sci))
223 		return PTR_ERR(data->sci);
224 
225 	data->rcdev.ops = &ti_sci_reset_ops;
226 	data->rcdev.owner = THIS_MODULE;
227 	data->rcdev.of_node = pdev->dev.of_node;
228 	data->rcdev.of_reset_n_cells = 2;
229 	data->rcdev.of_xlate = ti_sci_reset_of_xlate;
230 	data->dev = &pdev->dev;
231 	idr_init(&data->idr);
232 
233 	platform_set_drvdata(pdev, data);
234 
235 	return reset_controller_register(&data->rcdev);
236 }
237 
ti_sci_reset_remove(struct platform_device * pdev)238 static int ti_sci_reset_remove(struct platform_device *pdev)
239 {
240 	struct ti_sci_reset_data *data = platform_get_drvdata(pdev);
241 
242 	reset_controller_unregister(&data->rcdev);
243 
244 	idr_destroy(&data->idr);
245 
246 	return 0;
247 }
248 
249 static struct platform_driver ti_sci_reset_driver = {
250 	.probe = ti_sci_reset_probe,
251 	.remove = ti_sci_reset_remove,
252 	.driver = {
253 		.name = "ti-sci-reset",
254 		.of_match_table = ti_sci_reset_of_match,
255 	},
256 };
257 module_platform_driver(ti_sci_reset_driver);
258 
259 MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
260 MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver");
261 MODULE_LICENSE("GPL v2");
262