1/*
  2 * Allwinner SoCs Reset Controller driver
  3 *
  4 * Copyright 2013 Maxime Ripard
  5 *
  6 * Maxime Ripard <maxime.ripard@free-electrons.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; either version 2 of the License, or
 11 * (at your option) any later version.
 12 */
 13
 14#include <linux/err.h>
 15#include <linux/io.h>
 16#include <linux/module.h>
 17#include <linux/of.h>
 18#include <linux/of_address.h>
 19#include <linux/platform_device.h>
 20#include <linux/reset-controller.h>
 21#include <linux/slab.h>
 22#include <linux/spinlock.h>
 23#include <linux/types.h>
 24
 25struct sunxi_reset_data {
 26	spinlock_t			lock;
 27	void __iomem			*membase;
 28	struct reset_controller_dev	rcdev;
 29};
 30
 31static int sunxi_reset_assert(struct reset_controller_dev *rcdev,
 32			      unsigned long id)
 33{
 34	struct sunxi_reset_data *data = container_of(rcdev,
 35						     struct sunxi_reset_data,
 36						     rcdev);
 37	int bank = id / BITS_PER_LONG;
 38	int offset = id % BITS_PER_LONG;
 39	unsigned long flags;
 40	u32 reg;
 41
 42	spin_lock_irqsave(&data->lock, flags);
 43
 44	reg = readl(data->membase + (bank * 4));
 45	writel(reg & ~BIT(offset), data->membase + (bank * 4));
 46
 47	spin_unlock_irqrestore(&data->lock, flags);
 48
 49	return 0;
 50}
 51
 52static int sunxi_reset_deassert(struct reset_controller_dev *rcdev,
 53				unsigned long id)
 54{
 55	struct sunxi_reset_data *data = container_of(rcdev,
 56						     struct sunxi_reset_data,
 57						     rcdev);
 58	int bank = id / BITS_PER_LONG;
 59	int offset = id % BITS_PER_LONG;
 60	unsigned long flags;
 61	u32 reg;
 62
 63	spin_lock_irqsave(&data->lock, flags);
 64
 65	reg = readl(data->membase + (bank * 4));
 66	writel(reg | BIT(offset), data->membase + (bank * 4));
 67
 68	spin_unlock_irqrestore(&data->lock, flags);
 69
 70	return 0;
 71}
 72
 73static struct reset_control_ops sunxi_reset_ops = {
 74	.assert		= sunxi_reset_assert,
 75	.deassert	= sunxi_reset_deassert,
 76};
 77
 78static int sunxi_reset_init(struct device_node *np)
 79{
 80	struct sunxi_reset_data *data;
 81	struct resource res;
 82	resource_size_t size;
 83	int ret;
 84
 85	data = kzalloc(sizeof(*data), GFP_KERNEL);
 86	if (!data)
 87		return -ENOMEM;
 88
 89	ret = of_address_to_resource(np, 0, &res);
 90	if (ret)
 91		goto err_alloc;
 92
 93	size = resource_size(&res);
 94	if (!request_mem_region(res.start, size, np->name)) {
 95		ret = -EBUSY;
 96		goto err_alloc;
 97	}
 98
 99	data->membase = ioremap(res.start, size);
100	if (!data->membase) {
101		ret = -ENOMEM;
102		goto err_alloc;
103	}
104
105	data->rcdev.owner = THIS_MODULE;
106	data->rcdev.nr_resets = size * 32;
107	data->rcdev.ops = &sunxi_reset_ops;
108	data->rcdev.of_node = np;
109	reset_controller_register(&data->rcdev);
110
111	return 0;
112
113err_alloc:
114	kfree(data);
115	return ret;
116};
117
118/*
119 * These are the reset controller we need to initialize early on in
120 * our system, before we can even think of using a regular device
121 * driver for it.
122 */
123static const struct of_device_id sunxi_early_reset_dt_ids[] __initdata = {
124	{ .compatible = "allwinner,sun6i-a31-ahb1-reset", },
125	{ /* sentinel */ },
126};
127
128void __init sun6i_reset_init(void)
129{
130	struct device_node *np;
131
132	for_each_matching_node(np, sunxi_early_reset_dt_ids)
133		sunxi_reset_init(np);
134}
135
136/*
137 * And these are the controllers we can register through the regular
138 * device model.
139 */
140static const struct of_device_id sunxi_reset_dt_ids[] = {
141	 { .compatible = "allwinner,sun6i-a31-clock-reset", },
142	 { /* sentinel */ },
143};
144MODULE_DEVICE_TABLE(of, sunxi_reset_dt_ids);
145
146static int sunxi_reset_probe(struct platform_device *pdev)
147{
148	return sunxi_reset_init(pdev->dev.of_node);
149}
150
151static int sunxi_reset_remove(struct platform_device *pdev)
152{
153	struct sunxi_reset_data *data = platform_get_drvdata(pdev);
154
155	reset_controller_unregister(&data->rcdev);
156	iounmap(data->membase);
157	kfree(data);
158
159	return 0;
160}
161
162static struct platform_driver sunxi_reset_driver = {
163	.probe	= sunxi_reset_probe,
164	.remove	= sunxi_reset_remove,
165	.driver = {
166		.name		= "sunxi-reset",
167		.owner		= THIS_MODULE,
168		.of_match_table	= sunxi_reset_dt_ids,
169	},
170};
171module_platform_driver(sunxi_reset_driver);
172
173MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
174MODULE_DESCRIPTION("Allwinner SoCs Reset Controller Driver");
175MODULE_LICENSE("GPL");