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