1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 *
4 * Copyright (C) 2010 John Crispin <blogic@phrozen.org>
5 * Copyright (C) 2013-2015 Lantiq Beteiligungs-GmbH & Co.KG
6 * Copyright (C) 2016 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
7 * Copyright (C) 2017 Hauke Mehrtens <hauke@hauke-m.de>
8 */
9
10 #include <linux/mfd/syscon.h>
11 #include <linux/module.h>
12 #include <linux/regmap.h>
13 #include <linux/reset-controller.h>
14 #include <linux/of_address.h>
15 #include <linux/of_platform.h>
16 #include <linux/platform_device.h>
17 #include <linux/property.h>
18
19 #define LANTIQ_RCU_RESET_TIMEOUT 10000
20
21 struct lantiq_rcu_reset_priv {
22 struct reset_controller_dev rcdev;
23 struct device *dev;
24 struct regmap *regmap;
25 u32 reset_offset;
26 u32 status_offset;
27 };
28
to_lantiq_rcu_reset_priv(struct reset_controller_dev * rcdev)29 static struct lantiq_rcu_reset_priv *to_lantiq_rcu_reset_priv(
30 struct reset_controller_dev *rcdev)
31 {
32 return container_of(rcdev, struct lantiq_rcu_reset_priv, rcdev);
33 }
34
lantiq_rcu_reset_status(struct reset_controller_dev * rcdev,unsigned long id)35 static int lantiq_rcu_reset_status(struct reset_controller_dev *rcdev,
36 unsigned long id)
37 {
38 struct lantiq_rcu_reset_priv *priv = to_lantiq_rcu_reset_priv(rcdev);
39 unsigned int status = (id >> 8) & 0x1f;
40 u32 val;
41 int ret;
42
43 ret = regmap_read(priv->regmap, priv->status_offset, &val);
44 if (ret)
45 return ret;
46
47 return !!(val & BIT(status));
48 }
49
lantiq_rcu_reset_status_timeout(struct reset_controller_dev * rcdev,unsigned long id,bool assert)50 static int lantiq_rcu_reset_status_timeout(struct reset_controller_dev *rcdev,
51 unsigned long id, bool assert)
52 {
53 int ret;
54 int retry = LANTIQ_RCU_RESET_TIMEOUT;
55
56 do {
57 ret = lantiq_rcu_reset_status(rcdev, id);
58 if (ret < 0)
59 return ret;
60 if (ret == assert)
61 return 0;
62 usleep_range(20, 40);
63 } while (--retry);
64
65 return -ETIMEDOUT;
66 }
67
lantiq_rcu_reset_update(struct reset_controller_dev * rcdev,unsigned long id,bool assert)68 static int lantiq_rcu_reset_update(struct reset_controller_dev *rcdev,
69 unsigned long id, bool assert)
70 {
71 struct lantiq_rcu_reset_priv *priv = to_lantiq_rcu_reset_priv(rcdev);
72 unsigned int set = id & 0x1f;
73 u32 val = assert ? BIT(set) : 0;
74 int ret;
75
76 ret = regmap_update_bits(priv->regmap, priv->reset_offset, BIT(set),
77 val);
78 if (ret) {
79 dev_err(priv->dev, "Failed to set reset bit %u\n", set);
80 return ret;
81 }
82
83
84 ret = lantiq_rcu_reset_status_timeout(rcdev, id, assert);
85 if (ret)
86 dev_err(priv->dev, "Failed to %s bit %u\n",
87 assert ? "assert" : "deassert", set);
88
89 return ret;
90 }
91
lantiq_rcu_reset_assert(struct reset_controller_dev * rcdev,unsigned long id)92 static int lantiq_rcu_reset_assert(struct reset_controller_dev *rcdev,
93 unsigned long id)
94 {
95 return lantiq_rcu_reset_update(rcdev, id, true);
96 }
97
lantiq_rcu_reset_deassert(struct reset_controller_dev * rcdev,unsigned long id)98 static int lantiq_rcu_reset_deassert(struct reset_controller_dev *rcdev,
99 unsigned long id)
100 {
101 return lantiq_rcu_reset_update(rcdev, id, false);
102 }
103
lantiq_rcu_reset_reset(struct reset_controller_dev * rcdev,unsigned long id)104 static int lantiq_rcu_reset_reset(struct reset_controller_dev *rcdev,
105 unsigned long id)
106 {
107 int ret;
108
109 ret = lantiq_rcu_reset_assert(rcdev, id);
110 if (ret)
111 return ret;
112
113 return lantiq_rcu_reset_deassert(rcdev, id);
114 }
115
116 static const struct reset_control_ops lantiq_rcu_reset_ops = {
117 .assert = lantiq_rcu_reset_assert,
118 .deassert = lantiq_rcu_reset_deassert,
119 .status = lantiq_rcu_reset_status,
120 .reset = lantiq_rcu_reset_reset,
121 };
122
lantiq_rcu_reset_of_parse(struct platform_device * pdev,struct lantiq_rcu_reset_priv * priv)123 static int lantiq_rcu_reset_of_parse(struct platform_device *pdev,
124 struct lantiq_rcu_reset_priv *priv)
125 {
126 struct device *dev = &pdev->dev;
127 const __be32 *offset;
128
129 priv->regmap = syscon_node_to_regmap(dev->of_node->parent);
130 if (IS_ERR(priv->regmap)) {
131 dev_err(&pdev->dev, "Failed to lookup RCU regmap\n");
132 return PTR_ERR(priv->regmap);
133 }
134
135 offset = of_get_address(dev->of_node, 0, NULL, NULL);
136 if (!offset) {
137 dev_err(&pdev->dev, "Failed to get RCU reset offset\n");
138 return -ENOENT;
139 }
140 priv->reset_offset = __be32_to_cpu(*offset);
141
142 offset = of_get_address(dev->of_node, 1, NULL, NULL);
143 if (!offset) {
144 dev_err(&pdev->dev, "Failed to get RCU status offset\n");
145 return -ENOENT;
146 }
147 priv->status_offset = __be32_to_cpu(*offset);
148
149 return 0;
150 }
151
lantiq_rcu_reset_xlate(struct reset_controller_dev * rcdev,const struct of_phandle_args * reset_spec)152 static int lantiq_rcu_reset_xlate(struct reset_controller_dev *rcdev,
153 const struct of_phandle_args *reset_spec)
154 {
155 unsigned int status, set;
156
157 set = reset_spec->args[0];
158 status = reset_spec->args[1];
159
160 if (set >= rcdev->nr_resets || status >= rcdev->nr_resets)
161 return -EINVAL;
162
163 return (status << 8) | set;
164 }
165
lantiq_rcu_reset_probe(struct platform_device * pdev)166 static int lantiq_rcu_reset_probe(struct platform_device *pdev)
167 {
168 struct lantiq_rcu_reset_priv *priv;
169 int err;
170
171 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
172 if (!priv)
173 return -ENOMEM;
174
175 priv->dev = &pdev->dev;
176
177 err = lantiq_rcu_reset_of_parse(pdev, priv);
178 if (err)
179 return err;
180
181 priv->rcdev.ops = &lantiq_rcu_reset_ops;
182 priv->rcdev.owner = THIS_MODULE;
183 priv->rcdev.of_node = pdev->dev.of_node;
184 priv->rcdev.nr_resets = 32;
185 priv->rcdev.of_xlate = lantiq_rcu_reset_xlate;
186 priv->rcdev.of_reset_n_cells = 2;
187
188 return devm_reset_controller_register(&pdev->dev, &priv->rcdev);
189 }
190
191 static const struct of_device_id lantiq_rcu_reset_dt_ids[] = {
192 { .compatible = "lantiq,danube-reset", },
193 { .compatible = "lantiq,xrx200-reset", },
194 { },
195 };
196 MODULE_DEVICE_TABLE(of, lantiq_rcu_reset_dt_ids);
197
198 static struct platform_driver lantiq_rcu_reset_driver = {
199 .probe = lantiq_rcu_reset_probe,
200 .driver = {
201 .name = "lantiq-reset",
202 .of_match_table = lantiq_rcu_reset_dt_ids,
203 },
204 };
205 module_platform_driver(lantiq_rcu_reset_driver);
206
207 MODULE_AUTHOR("Martin Blumenstingl <martin.blumenstingl@googlemail.com>");
208 MODULE_DESCRIPTION("Lantiq XWAY RCU Reset Controller Driver");
209