1/*
  2 * Copyright (c) 2015, National Instruments Corp.
  3 *
  4 * Xilinx Zynq Reset controller driver
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License as published by
  8 * the Free Software Foundation; version 2 of the License.
  9 *
 10 * This program is distributed in the hope that it will be useful,
 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 13 * GNU General Public License for more details.
 14 */
 15
 16#include <linux/err.h>
 17#include <linux/io.h>
 18#include <linux/module.h>
 19#include <linux/mfd/syscon.h>
 20#include <linux/of.h>
 21#include <linux/platform_device.h>
 22#include <linux/reset-controller.h>
 23#include <linux/regmap.h>
 24#include <linux/types.h>
 25
 26struct zynq_reset_data {
 27	struct regmap *slcr;
 28	struct reset_controller_dev rcdev;
 29	u32 offset;
 30};
 31
 32#define to_zynq_reset_data(p)		\
 33	container_of((p), struct zynq_reset_data, rcdev)
 34
 35static int zynq_reset_assert(struct reset_controller_dev *rcdev,
 36			     unsigned long id)
 37{
 38	struct zynq_reset_data *priv = to_zynq_reset_data(rcdev);
 39
 40	int bank = id / BITS_PER_LONG;
 41	int offset = id % BITS_PER_LONG;
 42
 43	pr_debug("%s: %s reset bank %u offset %u\n", KBUILD_MODNAME, __func__,
 44		 bank, offset);
 45
 46	return regmap_update_bits(priv->slcr,
 47				  priv->offset + (bank * 4),
 48				  BIT(offset),
 49				  BIT(offset));
 50}
 51
 52static int zynq_reset_deassert(struct reset_controller_dev *rcdev,
 53			       unsigned long id)
 54{
 55	struct zynq_reset_data *priv = to_zynq_reset_data(rcdev);
 56
 57	int bank = id / BITS_PER_LONG;
 58	int offset = id % BITS_PER_LONG;
 59
 60	pr_debug("%s: %s reset bank %u offset %u\n", KBUILD_MODNAME, __func__,
 61		 bank, offset);
 62
 63	return regmap_update_bits(priv->slcr,
 64				  priv->offset + (bank * 4),
 65				  BIT(offset),
 66				  ~BIT(offset));
 67}
 68
 69static int zynq_reset_status(struct reset_controller_dev *rcdev,
 70			     unsigned long id)
 71{
 72	struct zynq_reset_data *priv = to_zynq_reset_data(rcdev);
 73
 74	int bank = id / BITS_PER_LONG;
 75	int offset = id % BITS_PER_LONG;
 76	int ret;
 77	u32 reg;
 78
 79	pr_debug("%s: %s reset bank %u offset %u\n", KBUILD_MODNAME, __func__,
 80		 bank, offset);
 81
 82	ret = regmap_read(priv->slcr, priv->offset + (bank * 4), &reg);
 83	if (ret)
 84		return ret;
 85
 86	return !!(reg & BIT(offset));
 87}
 88
 89static const struct reset_control_ops zynq_reset_ops = {
 90	.assert		= zynq_reset_assert,
 91	.deassert	= zynq_reset_deassert,
 92	.status		= zynq_reset_status,
 93};
 94
 95static int zynq_reset_probe(struct platform_device *pdev)
 96{
 97	struct resource *res;
 98	struct zynq_reset_data *priv;
 99
100	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
101	if (!priv)
102		return -ENOMEM;
103	platform_set_drvdata(pdev, priv);
104
105	priv->slcr = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
106						     "syscon");
107	if (IS_ERR(priv->slcr)) {
108		dev_err(&pdev->dev, "unable to get zynq-slcr regmap");
109		return PTR_ERR(priv->slcr);
110	}
111
112	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
113	if (!res) {
114		dev_err(&pdev->dev, "missing IO resource\n");
115		return -ENODEV;
116	}
117
118	priv->offset = res->start;
119
120	priv->rcdev.owner = THIS_MODULE;
121	priv->rcdev.nr_resets = resource_size(res) / 4 * BITS_PER_LONG;
122	priv->rcdev.ops = &zynq_reset_ops;
123	priv->rcdev.of_node = pdev->dev.of_node;
124
125	return reset_controller_register(&priv->rcdev);
126}
127
128static int zynq_reset_remove(struct platform_device *pdev)
129{
130	struct zynq_reset_data *priv = platform_get_drvdata(pdev);
131
132	reset_controller_unregister(&priv->rcdev);
133
134	return 0;
135}
136
137static const struct of_device_id zynq_reset_dt_ids[] = {
138	{ .compatible = "xlnx,zynq-reset", },
139	{ /* sentinel */ },
140};
141
142static struct platform_driver zynq_reset_driver = {
143	.probe	= zynq_reset_probe,
144	.remove	= zynq_reset_remove,
145	.driver = {
146		.name		= KBUILD_MODNAME,
147		.of_match_table	= zynq_reset_dt_ids,
148	},
149};
150module_platform_driver(zynq_reset_driver);
151
152MODULE_LICENSE("GPL v2");
153MODULE_AUTHOR("Moritz Fischer <moritz.fischer@ettus.com>");
154MODULE_DESCRIPTION("Zynq Reset Controller Driver");