1// SPDX-License-Identifier: GPL-2.0
2
3#include <linux/gpio/consumer.h>
4#include <linux/mod_devicetable.h>
5#include <linux/module.h>
6#include <linux/of.h>
7#include <linux/platform_device.h>
8#include <linux/reset-controller.h>
9
10struct reset_gpio_priv {
11	struct reset_controller_dev rc;
12	struct gpio_desc *reset;
13};
14
15static inline struct reset_gpio_priv
16*rc_to_reset_gpio(struct reset_controller_dev *rc)
17{
18	return container_of(rc, struct reset_gpio_priv, rc);
19}
20
21static int reset_gpio_assert(struct reset_controller_dev *rc, unsigned long id)
22{
23	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
24
25	gpiod_set_value_cansleep(priv->reset, 1);
26
27	return 0;
28}
29
30static int reset_gpio_deassert(struct reset_controller_dev *rc,
31			       unsigned long id)
32{
33	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
34
35	gpiod_set_value_cansleep(priv->reset, 0);
36
37	return 0;
38}
39
40static int reset_gpio_status(struct reset_controller_dev *rc, unsigned long id)
41{
42	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
43
44	return gpiod_get_value_cansleep(priv->reset);
45}
46
47static const struct reset_control_ops reset_gpio_ops = {
48	.assert = reset_gpio_assert,
49	.deassert = reset_gpio_deassert,
50	.status = reset_gpio_status,
51};
52
53static int reset_gpio_of_xlate(struct reset_controller_dev *rcdev,
54			       const struct of_phandle_args *reset_spec)
55{
56	return reset_spec->args[0];
57}
58
59static void reset_gpio_of_node_put(void *data)
60{
61	of_node_put(data);
62}
63
64static int reset_gpio_probe(struct platform_device *pdev)
65{
66	struct device *dev = &pdev->dev;
67	struct of_phandle_args *platdata = dev_get_platdata(dev);
68	struct reset_gpio_priv *priv;
69	int ret;
70
71	if (!platdata)
72		return -EINVAL;
73
74	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
75	if (!priv)
76		return -ENOMEM;
77
78	platform_set_drvdata(pdev, &priv->rc);
79
80	priv->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
81	if (IS_ERR(priv->reset))
82		return dev_err_probe(dev, PTR_ERR(priv->reset),
83				     "Could not get reset gpios\n");
84
85	priv->rc.ops = &reset_gpio_ops;
86	priv->rc.owner = THIS_MODULE;
87	priv->rc.dev = dev;
88	priv->rc.of_args = platdata;
89	ret = devm_add_action_or_reset(dev, reset_gpio_of_node_put,
90				       priv->rc.of_node);
91	if (ret)
92		return ret;
93
94	/* Cells to match GPIO specifier, but it's not really used */
95	priv->rc.of_reset_n_cells = 2;
96	priv->rc.of_xlate = reset_gpio_of_xlate;
97	priv->rc.nr_resets = 1;
98
99	return devm_reset_controller_register(dev, &priv->rc);
100}
101
102static const struct platform_device_id reset_gpio_ids[] = {
103	{ .name = "reset-gpio", },
104	{}
105};
106MODULE_DEVICE_TABLE(platform, reset_gpio_ids);
107
108static struct platform_driver reset_gpio_driver = {
109	.probe		= reset_gpio_probe,
110	.id_table	= reset_gpio_ids,
111	.driver	= {
112		.name = "reset-gpio",
113	},
114};
115module_platform_driver(reset_gpio_driver);
116
117MODULE_AUTHOR("Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>");
118MODULE_DESCRIPTION("Generic GPIO reset driver");
119MODULE_LICENSE("GPL");
120