1 /*
2  * TI SYSCON regmap reset driver
3  *
4  * Copyright (C) 2015-2016 Texas Instruments Incorporated - https://www.ti.com/
5  *	Andrew F. Davis <afd@ti.com>
6  *	Suman Anna <afd@ti.com>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  *
12  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
13  * kind, whether express or implied; without even the implied warranty
14  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  */
17 
18 #include <linux/mfd/syscon.h>
19 #include <linux/module.h>
20 #include <linux/of.h>
21 #include <linux/platform_device.h>
22 #include <linux/regmap.h>
23 #include <linux/reset-controller.h>
24 
25 #include <dt-bindings/reset/ti-syscon.h>
26 
27 /**
28  * struct ti_syscon_reset_control - reset control structure
29  * @assert_offset: reset assert control register offset from syscon base
30  * @assert_bit: reset assert bit in the reset assert control register
31  * @deassert_offset: reset deassert control register offset from syscon base
32  * @deassert_bit: reset deassert bit in the reset deassert control register
33  * @status_offset: reset status register offset from syscon base
34  * @status_bit: reset status bit in the reset status register
35  * @flags: reset flag indicating how the (de)assert and status are handled
36  */
37 struct ti_syscon_reset_control {
38 	unsigned int assert_offset;
39 	unsigned int assert_bit;
40 	unsigned int deassert_offset;
41 	unsigned int deassert_bit;
42 	unsigned int status_offset;
43 	unsigned int status_bit;
44 	u32 flags;
45 };
46 
47 /**
48  * struct ti_syscon_reset_data - reset controller information structure
49  * @rcdev: reset controller entity
50  * @regmap: regmap handle containing the memory-mapped reset registers
51  * @controls: array of reset controls
52  * @nr_controls: number of controls in control array
53  */
54 struct ti_syscon_reset_data {
55 	struct reset_controller_dev rcdev;
56 	struct regmap *regmap;
57 	struct ti_syscon_reset_control *controls;
58 	unsigned int nr_controls;
59 };
60 
61 #define to_ti_syscon_reset_data(rcdev)	\
62 	container_of(rcdev, struct ti_syscon_reset_data, rcdev)
63 
64 /**
65  * ti_syscon_reset_assert() - assert device reset
66  * @rcdev: reset controller entity
67  * @id: ID of the reset to be asserted
68  *
69  * This function implements the reset driver op to assert a device's reset.
70  * This asserts the reset in a manner prescribed by the reset flags.
71  *
72  * Return: 0 for successful request, else a corresponding error value
73  */
74 static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
75 				  unsigned long id)
76 {
77 	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
78 	struct ti_syscon_reset_control *control;
79 	unsigned int mask, value;
80 
81 	if (id >= data->nr_controls)
82 		return -EINVAL;
83 
84 	control = &data->controls[id];
85 
86 	if (control->flags & ASSERT_NONE)
87 		return -ENOTSUPP; /* assert not supported for this reset */
88 
89 	mask = BIT(control->assert_bit);
90 	value = (control->flags & ASSERT_SET) ? mask : 0x0;
91 
92 	return regmap_write_bits(data->regmap, control->assert_offset, mask, value);
93 }
94 
95 /**
96  * ti_syscon_reset_deassert() - deassert device reset
97  * @rcdev: reset controller entity
98  * @id: ID of reset to be deasserted
99  *
100  * This function implements the reset driver op to deassert a device's reset.
101  * This deasserts the reset in a manner prescribed by the reset flags.
102  *
103  * Return: 0 for successful request, else a corresponding error value
104  */
105 static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
106 				    unsigned long id)
107 {
108 	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
109 	struct ti_syscon_reset_control *control;
110 	unsigned int mask, value;
111 
112 	if (id >= data->nr_controls)
113 		return -EINVAL;
114 
115 	control = &data->controls[id];
116 
117 	if (control->flags & DEASSERT_NONE)
118 		return -ENOTSUPP; /* deassert not supported for this reset */
119 
120 	mask = BIT(control->deassert_bit);
121 	value = (control->flags & DEASSERT_SET) ? mask : 0x0;
122 
123 	return regmap_write_bits(data->regmap, control->deassert_offset, mask, value);
124 }
125 
126 /**
127  * ti_syscon_reset_status() - check device reset status
128  * @rcdev: reset controller entity
129  * @id: ID of the reset for which the status is being requested
130  *
131  * This function implements the reset driver op to return the status of a
132  * device's reset.
133  *
134  * Return: 0 if reset is deasserted, true if reset is asserted, else a
135  * corresponding error value
136  */
137 static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
138 				  unsigned long id)
139 {
140 	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
141 	struct ti_syscon_reset_control *control;
142 	unsigned int reset_state;
143 	int ret;
144 
145 	if (id >= data->nr_controls)
146 		return -EINVAL;
147 
148 	control = &data->controls[id];
149 
150 	if (control->flags & STATUS_NONE)
151 		return -ENOTSUPP; /* status not supported for this reset */
152 
153 	ret = regmap_read(data->regmap, control->status_offset, &reset_state);
154 	if (ret)
155 		return ret;
156 
157 	return !(reset_state & BIT(control->status_bit)) ==
158 		!(control->flags & STATUS_SET);
159 }
160 
161 static const struct reset_control_ops ti_syscon_reset_ops = {
162 	.assert		= ti_syscon_reset_assert,
163 	.deassert	= ti_syscon_reset_deassert,
164 	.status		= ti_syscon_reset_status,
165 };
166 
167 static int ti_syscon_reset_probe(struct platform_device *pdev)
168 {
169 	struct device *dev = &pdev->dev;
170 	struct device_node *np = dev->of_node;
171 	struct ti_syscon_reset_data *data;
172 	struct regmap *regmap;
173 	const __be32 *list;
174 	struct ti_syscon_reset_control *controls;
175 	int size, nr_controls, i;
176 
177 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
178 	if (!data)
179 		return -ENOMEM;
180 
181 	regmap = syscon_node_to_regmap(np->parent);
182 	if (IS_ERR(regmap))
183 		return PTR_ERR(regmap);
184 
185 	list = of_get_property(np, "ti,reset-bits", &size);
186 	if (!list || (size / sizeof(*list)) % 7 != 0) {
187 		dev_err(dev, "invalid DT reset description\n");
188 		return -EINVAL;
189 	}
190 
191 	nr_controls = (size / sizeof(*list)) / 7;
192 	controls = devm_kcalloc(dev, nr_controls, sizeof(*controls),
193 				GFP_KERNEL);
194 	if (!controls)
195 		return -ENOMEM;
196 
197 	for (i = 0; i < nr_controls; i++) {
198 		controls[i].assert_offset = be32_to_cpup(list++);
199 		controls[i].assert_bit = be32_to_cpup(list++);
200 		controls[i].deassert_offset = be32_to_cpup(list++);
201 		controls[i].deassert_bit = be32_to_cpup(list++);
202 		controls[i].status_offset = be32_to_cpup(list++);
203 		controls[i].status_bit = be32_to_cpup(list++);
204 		controls[i].flags = be32_to_cpup(list++);
205 	}
206 
207 	data->rcdev.ops = &ti_syscon_reset_ops;
208 	data->rcdev.owner = THIS_MODULE;
209 	data->rcdev.of_node = np;
210 	data->rcdev.nr_resets = nr_controls;
211 	data->regmap = regmap;
212 	data->controls = controls;
213 	data->nr_controls = nr_controls;
214 
215 	platform_set_drvdata(pdev, data);
216 
217 	return devm_reset_controller_register(dev, &data->rcdev);
218 }
219 
220 static const struct of_device_id ti_syscon_reset_of_match[] = {
221 	{ .compatible = "ti,syscon-reset", },
222 	{ /* sentinel */ },
223 };
224 MODULE_DEVICE_TABLE(of, ti_syscon_reset_of_match);
225 
226 static struct platform_driver ti_syscon_reset_driver = {
227 	.probe = ti_syscon_reset_probe,
228 	.driver = {
229 		.name = "ti-syscon-reset",
230 		.of_match_table = ti_syscon_reset_of_match,
231 	},
232 };
233 module_platform_driver(ti_syscon_reset_driver);
234 
235 MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
236 MODULE_AUTHOR("Suman Anna <s-anna@ti.com>");
237 MODULE_DESCRIPTION("TI SYSCON Regmap Reset Driver");
238 MODULE_LICENSE("GPL v2");
239