1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * TI SYSCON regmap reset driver
4 *
5 * Copyright (C) 2015-2016 Texas Instruments Incorporated - https://www.ti.com/
6 * Andrew F. Davis <afd@ti.com>
7 * Suman Anna <afd@ti.com>
8 */
9
10 #include <linux/mfd/syscon.h>
11 #include <linux/module.h>
12 #include <linux/of.h>
13 #include <linux/platform_device.h>
14 #include <linux/regmap.h>
15 #include <linux/reset-controller.h>
16
17 #include <dt-bindings/reset/ti-syscon.h>
18
19 /**
20 * struct ti_syscon_reset_control - reset control structure
21 * @assert_offset: reset assert control register offset from syscon base
22 * @assert_bit: reset assert bit in the reset assert control register
23 * @deassert_offset: reset deassert control register offset from syscon base
24 * @deassert_bit: reset deassert bit in the reset deassert control register
25 * @status_offset: reset status register offset from syscon base
26 * @status_bit: reset status bit in the reset status register
27 * @flags: reset flag indicating how the (de)assert and status are handled
28 */
29 struct ti_syscon_reset_control {
30 unsigned int assert_offset;
31 unsigned int assert_bit;
32 unsigned int deassert_offset;
33 unsigned int deassert_bit;
34 unsigned int status_offset;
35 unsigned int status_bit;
36 u32 flags;
37 };
38
39 /**
40 * struct ti_syscon_reset_data - reset controller information structure
41 * @rcdev: reset controller entity
42 * @regmap: regmap handle containing the memory-mapped reset registers
43 * @controls: array of reset controls
44 * @nr_controls: number of controls in control array
45 */
46 struct ti_syscon_reset_data {
47 struct reset_controller_dev rcdev;
48 struct regmap *regmap;
49 struct ti_syscon_reset_control *controls;
50 unsigned int nr_controls;
51 };
52
53 #define to_ti_syscon_reset_data(_rcdev) \
54 container_of(_rcdev, struct ti_syscon_reset_data, rcdev)
55
56 /**
57 * ti_syscon_reset_assert() - assert device reset
58 * @rcdev: reset controller entity
59 * @id: ID of the reset to be asserted
60 *
61 * This function implements the reset driver op to assert a device's reset.
62 * This asserts the reset in a manner prescribed by the reset flags.
63 *
64 * Return: 0 for successful request, else a corresponding error value
65 */
ti_syscon_reset_assert(struct reset_controller_dev * rcdev,unsigned long id)66 static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
67 unsigned long id)
68 {
69 struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
70 struct ti_syscon_reset_control *control;
71 unsigned int mask, value;
72
73 if (id >= data->nr_controls)
74 return -EINVAL;
75
76 control = &data->controls[id];
77
78 if (control->flags & ASSERT_NONE)
79 return -ENOTSUPP; /* assert not supported for this reset */
80
81 mask = BIT(control->assert_bit);
82 value = (control->flags & ASSERT_SET) ? mask : 0x0;
83
84 return regmap_write_bits(data->regmap, control->assert_offset, mask, value);
85 }
86
87 /**
88 * ti_syscon_reset_deassert() - deassert device reset
89 * @rcdev: reset controller entity
90 * @id: ID of reset to be deasserted
91 *
92 * This function implements the reset driver op to deassert a device's reset.
93 * This deasserts the reset in a manner prescribed by the reset flags.
94 *
95 * Return: 0 for successful request, else a corresponding error value
96 */
ti_syscon_reset_deassert(struct reset_controller_dev * rcdev,unsigned long id)97 static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
98 unsigned long id)
99 {
100 struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
101 struct ti_syscon_reset_control *control;
102 unsigned int mask, value;
103
104 if (id >= data->nr_controls)
105 return -EINVAL;
106
107 control = &data->controls[id];
108
109 if (control->flags & DEASSERT_NONE)
110 return -ENOTSUPP; /* deassert not supported for this reset */
111
112 mask = BIT(control->deassert_bit);
113 value = (control->flags & DEASSERT_SET) ? mask : 0x0;
114
115 return regmap_write_bits(data->regmap, control->deassert_offset, mask, value);
116 }
117
118 /**
119 * ti_syscon_reset_status() - check device reset status
120 * @rcdev: reset controller entity
121 * @id: ID of the reset for which the status is being requested
122 *
123 * This function implements the reset driver op to return the status of a
124 * device's reset.
125 *
126 * Return: 0 if reset is deasserted, true if reset is asserted, else a
127 * corresponding error value
128 */
ti_syscon_reset_status(struct reset_controller_dev * rcdev,unsigned long id)129 static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
130 unsigned long id)
131 {
132 struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
133 struct ti_syscon_reset_control *control;
134 unsigned int reset_state;
135 int ret;
136
137 if (id >= data->nr_controls)
138 return -EINVAL;
139
140 control = &data->controls[id];
141
142 if (control->flags & STATUS_NONE)
143 return -ENOTSUPP; /* status not supported for this reset */
144
145 ret = regmap_read(data->regmap, control->status_offset, &reset_state);
146 if (ret)
147 return ret;
148
149 return !(reset_state & BIT(control->status_bit)) ==
150 !(control->flags & STATUS_SET);
151 }
152
153 static const struct reset_control_ops ti_syscon_reset_ops = {
154 .assert = ti_syscon_reset_assert,
155 .deassert = ti_syscon_reset_deassert,
156 .status = ti_syscon_reset_status,
157 };
158
ti_syscon_reset_probe(struct platform_device * pdev)159 static int ti_syscon_reset_probe(struct platform_device *pdev)
160 {
161 struct device *dev = &pdev->dev;
162 struct device_node *np = dev->of_node;
163 struct ti_syscon_reset_data *data;
164 struct regmap *regmap;
165 const __be32 *list;
166 struct ti_syscon_reset_control *controls;
167 int size, nr_controls, i;
168
169 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
170 if (!data)
171 return -ENOMEM;
172
173 regmap = syscon_node_to_regmap(np->parent);
174 if (IS_ERR(regmap))
175 return PTR_ERR(regmap);
176
177 list = of_get_property(np, "ti,reset-bits", &size);
178 if (!list || (size / sizeof(*list)) % 7 != 0) {
179 dev_err(dev, "invalid DT reset description\n");
180 return -EINVAL;
181 }
182
183 nr_controls = (size / sizeof(*list)) / 7;
184 controls = devm_kcalloc(dev, nr_controls, sizeof(*controls),
185 GFP_KERNEL);
186 if (!controls)
187 return -ENOMEM;
188
189 for (i = 0; i < nr_controls; i++) {
190 controls[i].assert_offset = be32_to_cpup(list++);
191 controls[i].assert_bit = be32_to_cpup(list++);
192 controls[i].deassert_offset = be32_to_cpup(list++);
193 controls[i].deassert_bit = be32_to_cpup(list++);
194 controls[i].status_offset = be32_to_cpup(list++);
195 controls[i].status_bit = be32_to_cpup(list++);
196 controls[i].flags = be32_to_cpup(list++);
197 }
198
199 data->rcdev.ops = &ti_syscon_reset_ops;
200 data->rcdev.owner = THIS_MODULE;
201 data->rcdev.of_node = np;
202 data->rcdev.nr_resets = nr_controls;
203 data->regmap = regmap;
204 data->controls = controls;
205 data->nr_controls = nr_controls;
206
207 platform_set_drvdata(pdev, data);
208
209 return devm_reset_controller_register(dev, &data->rcdev);
210 }
211
212 static const struct of_device_id ti_syscon_reset_of_match[] = {
213 { .compatible = "ti,syscon-reset", },
214 { /* sentinel */ },
215 };
216 MODULE_DEVICE_TABLE(of, ti_syscon_reset_of_match);
217
218 static struct platform_driver ti_syscon_reset_driver = {
219 .probe = ti_syscon_reset_probe,
220 .driver = {
221 .name = "ti-syscon-reset",
222 .of_match_table = ti_syscon_reset_of_match,
223 },
224 };
225 module_platform_driver(ti_syscon_reset_driver);
226
227 MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
228 MODULE_AUTHOR("Suman Anna <s-anna@ti.com>");
229 MODULE_DESCRIPTION("TI SYSCON Regmap Reset Driver");
230 MODULE_LICENSE("GPL v2");
231
