xref: /openbmc/linux/drivers/reset/sti/reset-syscfg.c (revision 2db4da59)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2013 STMicroelectronics Limited
4  * Author: Stephen Gallimore <stephen.gallimore@st.com>
5  *
6  * Inspired by mach-imx/src.c
7  */
8 #include <linux/kernel.h>
9 #include <linux/platform_device.h>
10 #include <linux/module.h>
11 #include <linux/err.h>
12 #include <linux/types.h>
13 #include <linux/of_device.h>
14 #include <linux/regmap.h>
15 #include <linux/mfd/syscon.h>
16 
17 #include "reset-syscfg.h"
18 
19 /**
20  * struct syscfg_reset_channel - Reset channel regmap configuration
21  *
22  * @reset: regmap field for the channel's reset bit.
23  * @ack: regmap field for the channel's ack bit (optional).
24  */
25 struct syscfg_reset_channel {
26 	struct regmap_field *reset;
27 	struct regmap_field *ack;
28 };
29 
30 /**
31  * struct syscfg_reset_controller - A reset controller which groups together
32  * a set of related reset bits, which may be located in different system
33  * configuration registers.
34  *
35  * @rst: base reset controller structure.
36  * @active_low: are the resets in this controller active low, i.e. clearing
37  *              the reset bit puts the hardware into reset.
38  * @channels: An array of reset channels for this controller.
39  */
40 struct syscfg_reset_controller {
41 	struct reset_controller_dev rst;
42 	bool active_low;
43 	struct syscfg_reset_channel *channels;
44 };
45 
46 #define to_syscfg_reset_controller(_rst) \
47 	container_of(_rst, struct syscfg_reset_controller, rst)
48 
syscfg_reset_program_hw(struct reset_controller_dev * rcdev,unsigned long idx,int assert)49 static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
50 				   unsigned long idx, int assert)
51 {
52 	struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
53 	const struct syscfg_reset_channel *ch;
54 	u32 ctrl_val = rst->active_low ? !assert : !!assert;
55 	int err;
56 
57 	if (idx >= rcdev->nr_resets)
58 		return -EINVAL;
59 
60 	ch = &rst->channels[idx];
61 
62 	err = regmap_field_write(ch->reset, ctrl_val);
63 	if (err)
64 		return err;
65 
66 	if (ch->ack) {
67 		u32 ack_val;
68 
69 		err = regmap_field_read_poll_timeout(ch->ack, ack_val, (ack_val == ctrl_val),
70 						     100, USEC_PER_SEC);
71 		if (err)
72 			return err;
73 	}
74 
75 	return 0;
76 }
77 
syscfg_reset_assert(struct reset_controller_dev * rcdev,unsigned long idx)78 static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
79 			       unsigned long idx)
80 {
81 	return syscfg_reset_program_hw(rcdev, idx, true);
82 }
83 
syscfg_reset_deassert(struct reset_controller_dev * rcdev,unsigned long idx)84 static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
85 				 unsigned long idx)
86 {
87 	return syscfg_reset_program_hw(rcdev, idx, false);
88 }
89 
syscfg_reset_dev(struct reset_controller_dev * rcdev,unsigned long idx)90 static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
91 			    unsigned long idx)
92 {
93 	int err;
94 
95 	err = syscfg_reset_assert(rcdev, idx);
96 	if (err)
97 		return err;
98 
99 	return syscfg_reset_deassert(rcdev, idx);
100 }
101 
syscfg_reset_status(struct reset_controller_dev * rcdev,unsigned long idx)102 static int syscfg_reset_status(struct reset_controller_dev *rcdev,
103 			       unsigned long idx)
104 {
105 	struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
106 	const struct syscfg_reset_channel *ch;
107 	u32 ret_val = 0;
108 	int err;
109 
110 	if (idx >= rcdev->nr_resets)
111 		return -EINVAL;
112 
113 	ch = &rst->channels[idx];
114 	if (ch->ack)
115 		err = regmap_field_read(ch->ack, &ret_val);
116 	else
117 		err = regmap_field_read(ch->reset, &ret_val);
118 	if (err)
119 		return err;
120 
121 	return rst->active_low ? !ret_val : !!ret_val;
122 }
123 
124 static const struct reset_control_ops syscfg_reset_ops = {
125 	.reset    = syscfg_reset_dev,
126 	.assert   = syscfg_reset_assert,
127 	.deassert = syscfg_reset_deassert,
128 	.status   = syscfg_reset_status,
129 };
130 
syscfg_reset_controller_register(struct device * dev,const struct syscfg_reset_controller_data * data)131 static int syscfg_reset_controller_register(struct device *dev,
132 				const struct syscfg_reset_controller_data *data)
133 {
134 	struct syscfg_reset_controller *rc;
135 	int i, err;
136 
137 	rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
138 	if (!rc)
139 		return -ENOMEM;
140 
141 	rc->channels = devm_kcalloc(dev, data->nr_channels,
142 				    sizeof(*rc->channels), GFP_KERNEL);
143 	if (!rc->channels)
144 		return -ENOMEM;
145 
146 	rc->rst.ops = &syscfg_reset_ops;
147 	rc->rst.of_node = dev->of_node;
148 	rc->rst.nr_resets = data->nr_channels;
149 	rc->active_low = data->active_low;
150 
151 	for (i = 0; i < data->nr_channels; i++) {
152 		struct regmap *map;
153 		struct regmap_field *f;
154 		const char *compatible = data->channels[i].compatible;
155 
156 		map = syscon_regmap_lookup_by_compatible(compatible);
157 		if (IS_ERR(map))
158 			return PTR_ERR(map);
159 
160 		f = devm_regmap_field_alloc(dev, map, data->channels[i].reset);
161 		if (IS_ERR(f))
162 			return PTR_ERR(f);
163 
164 		rc->channels[i].reset = f;
165 
166 		if (!data->wait_for_ack)
167 			continue;
168 
169 		f = devm_regmap_field_alloc(dev, map, data->channels[i].ack);
170 		if (IS_ERR(f))
171 			return PTR_ERR(f);
172 
173 		rc->channels[i].ack = f;
174 	}
175 
176 	err = reset_controller_register(&rc->rst);
177 	if (!err)
178 		dev_info(dev, "registered\n");
179 
180 	return err;
181 }
182 
syscfg_reset_probe(struct platform_device * pdev)183 int syscfg_reset_probe(struct platform_device *pdev)
184 {
185 	struct device *dev = pdev ? &pdev->dev : NULL;
186 	const struct of_device_id *match;
187 
188 	if (!dev || !dev->driver)
189 		return -ENODEV;
190 
191 	match = of_match_device(dev->driver->of_match_table, dev);
192 	if (!match || !match->data)
193 		return -EINVAL;
194 
195 	return syscfg_reset_controller_register(dev, match->data);
196 }
197