1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2015, National Instruments Corp.
4  *
5  * Xilinx Zynq Reset controller driver
6  *
7  * Author: Moritz Fischer <moritz.fischer@ettus.com>
8  */
9 
10 #include <linux/err.h>
11 #include <linux/io.h>
12 #include <linux/init.h>
13 #include <linux/mfd/syscon.h>
14 #include <linux/of.h>
15 #include <linux/platform_device.h>
16 #include <linux/reset-controller.h>
17 #include <linux/regmap.h>
18 #include <linux/types.h>
19 
20 struct zynq_reset_data {
21 	struct regmap *slcr;
22 	struct reset_controller_dev rcdev;
23 	u32 offset;
24 };
25 
26 #define to_zynq_reset_data(p)		\
27 	container_of((p), struct zynq_reset_data, rcdev)
28 
zynq_reset_assert(struct reset_controller_dev * rcdev,unsigned long id)29 static int zynq_reset_assert(struct reset_controller_dev *rcdev,
30 			     unsigned long id)
31 {
32 	struct zynq_reset_data *priv = to_zynq_reset_data(rcdev);
33 
34 	int bank = id / BITS_PER_LONG;
35 	int offset = id % BITS_PER_LONG;
36 
37 	pr_debug("%s: %s reset bank %u offset %u\n", KBUILD_MODNAME, __func__,
38 		 bank, offset);
39 
40 	return regmap_update_bits(priv->slcr,
41 				  priv->offset + (bank * 4),
42 				  BIT(offset),
43 				  BIT(offset));
44 }
45 
zynq_reset_deassert(struct reset_controller_dev * rcdev,unsigned long id)46 static int zynq_reset_deassert(struct reset_controller_dev *rcdev,
47 			       unsigned long id)
48 {
49 	struct zynq_reset_data *priv = to_zynq_reset_data(rcdev);
50 
51 	int bank = id / BITS_PER_LONG;
52 	int offset = id % BITS_PER_LONG;
53 
54 	pr_debug("%s: %s reset bank %u offset %u\n", KBUILD_MODNAME, __func__,
55 		 bank, offset);
56 
57 	return regmap_update_bits(priv->slcr,
58 				  priv->offset + (bank * 4),
59 				  BIT(offset),
60 				  ~BIT(offset));
61 }
62 
zynq_reset_status(struct reset_controller_dev * rcdev,unsigned long id)63 static int zynq_reset_status(struct reset_controller_dev *rcdev,
64 			     unsigned long id)
65 {
66 	struct zynq_reset_data *priv = to_zynq_reset_data(rcdev);
67 
68 	int bank = id / BITS_PER_LONG;
69 	int offset = id % BITS_PER_LONG;
70 	int ret;
71 	u32 reg;
72 
73 	pr_debug("%s: %s reset bank %u offset %u\n", KBUILD_MODNAME, __func__,
74 		 bank, offset);
75 
76 	ret = regmap_read(priv->slcr, priv->offset + (bank * 4), &reg);
77 	if (ret)
78 		return ret;
79 
80 	return !!(reg & BIT(offset));
81 }
82 
83 static const struct reset_control_ops zynq_reset_ops = {
84 	.assert		= zynq_reset_assert,
85 	.deassert	= zynq_reset_deassert,
86 	.status		= zynq_reset_status,
87 };
88 
zynq_reset_probe(struct platform_device * pdev)89 static int zynq_reset_probe(struct platform_device *pdev)
90 {
91 	struct resource *res;
92 	struct zynq_reset_data *priv;
93 
94 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
95 	if (!priv)
96 		return -ENOMEM;
97 	platform_set_drvdata(pdev, priv);
98 
99 	priv->slcr = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
100 						     "syscon");
101 	if (IS_ERR(priv->slcr)) {
102 		dev_err(&pdev->dev, "unable to get zynq-slcr regmap");
103 		return PTR_ERR(priv->slcr);
104 	}
105 
106 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
107 	if (!res) {
108 		dev_err(&pdev->dev, "missing IO resource\n");
109 		return -ENODEV;
110 	}
111 
112 	priv->offset = res->start;
113 
114 	priv->rcdev.owner = THIS_MODULE;
115 	priv->rcdev.nr_resets = resource_size(res) / 4 * BITS_PER_LONG;
116 	priv->rcdev.ops = &zynq_reset_ops;
117 	priv->rcdev.of_node = pdev->dev.of_node;
118 
119 	return devm_reset_controller_register(&pdev->dev, &priv->rcdev);
120 }
121 
122 static const struct of_device_id zynq_reset_dt_ids[] = {
123 	{ .compatible = "xlnx,zynq-reset", },
124 	{ /* sentinel */ },
125 };
126 
127 static struct platform_driver zynq_reset_driver = {
128 	.probe	= zynq_reset_probe,
129 	.driver = {
130 		.name		= KBUILD_MODNAME,
131 		.of_match_table	= zynq_reset_dt_ids,
132 	},
133 };
134 builtin_platform_driver(zynq_reset_driver);
135