1 /*
2 * Copyright (C) 2014 Marvell Technology Group Ltd.
3 *
4 * Marvell Berlin reset driver
5 *
6 * Antoine Tenart <antoine.tenart@free-electrons.com>
7 * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
8 *
9 * This file is licensed under the terms of the GNU General Public
10 * License version 2. This program is licensed "as is" without any
11 * warranty of any kind, whether express or implied.
12 */
13
14 #include <linux/delay.h>
15 #include <linux/io.h>
16 #include <linux/mfd/syscon.h>
17 #include <linux/init.h>
18 #include <linux/of.h>
19 #include <linux/of_address.h>
20 #include <linux/platform_device.h>
21 #include <linux/regmap.h>
22 #include <linux/reset-controller.h>
23 #include <linux/slab.h>
24 #include <linux/types.h>
25
26 #define BERLIN_MAX_RESETS 32
27
28 #define to_berlin_reset_priv(p) \
29 container_of((p), struct berlin_reset_priv, rcdev)
30
31 struct berlin_reset_priv {
32 struct regmap *regmap;
33 struct reset_controller_dev rcdev;
34 };
35
berlin_reset_reset(struct reset_controller_dev * rcdev,unsigned long id)36 static int berlin_reset_reset(struct reset_controller_dev *rcdev,
37 unsigned long id)
38 {
39 struct berlin_reset_priv *priv = to_berlin_reset_priv(rcdev);
40 int offset = id >> 8;
41 int mask = BIT(id & 0x1f);
42
43 regmap_write(priv->regmap, offset, mask);
44
45 /* let the reset be effective */
46 udelay(10);
47
48 return 0;
49 }
50
51 static const struct reset_control_ops berlin_reset_ops = {
52 .reset = berlin_reset_reset,
53 };
54
berlin_reset_xlate(struct reset_controller_dev * rcdev,const struct of_phandle_args * reset_spec)55 static int berlin_reset_xlate(struct reset_controller_dev *rcdev,
56 const struct of_phandle_args *reset_spec)
57 {
58 unsigned offset, bit;
59
60 offset = reset_spec->args[0];
61 bit = reset_spec->args[1];
62
63 if (bit >= BERLIN_MAX_RESETS)
64 return -EINVAL;
65
66 return (offset << 8) | bit;
67 }
68
berlin2_reset_probe(struct platform_device * pdev)69 static int berlin2_reset_probe(struct platform_device *pdev)
70 {
71 struct device_node *parent_np = of_get_parent(pdev->dev.of_node);
72 struct berlin_reset_priv *priv;
73
74 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
75 if (!priv)
76 return -ENOMEM;
77
78 priv->regmap = syscon_node_to_regmap(parent_np);
79 of_node_put(parent_np);
80 if (IS_ERR(priv->regmap))
81 return PTR_ERR(priv->regmap);
82
83 priv->rcdev.owner = THIS_MODULE;
84 priv->rcdev.ops = &berlin_reset_ops;
85 priv->rcdev.of_node = pdev->dev.of_node;
86 priv->rcdev.of_reset_n_cells = 2;
87 priv->rcdev.of_xlate = berlin_reset_xlate;
88
89 return reset_controller_register(&priv->rcdev);
90 }
91
92 static const struct of_device_id berlin_reset_dt_match[] = {
93 { .compatible = "marvell,berlin2-reset" },
94 { },
95 };
96
97 static struct platform_driver berlin_reset_driver = {
98 .probe = berlin2_reset_probe,
99 .driver = {
100 .name = "berlin2-reset",
101 .of_match_table = berlin_reset_dt_match,
102 },
103 };
104 builtin_platform_driver(berlin_reset_driver);
105