1/*
  2 * Copyright (C) 2014 Marvell Technology Group Ltd.
  3 *
  4 * Marvell Berlin reset driver
  5 *
  6 * Antoine Tenart <antoine.tenart@free-electrons.com>
  7 * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
  8 *
  9 * This file is licensed under the terms of the GNU General Public
 10 * License version 2. This program is licensed "as is" without any
 11 * warranty of any kind, whether express or implied.
 12 */
 13
 14#include <linux/delay.h>
 15#include <linux/io.h>
 16#include <linux/mfd/syscon.h>
 17#include <linux/init.h>
 18#include <linux/of.h>
 19#include <linux/of_address.h>
 20#include <linux/platform_device.h>
 21#include <linux/regmap.h>
 22#include <linux/reset-controller.h>
 23#include <linux/slab.h>
 24#include <linux/types.h>
 25
 26#define BERLIN_MAX_RESETS	32
 27
 28#define to_berlin_reset_priv(p)		\
 29	container_of((p), struct berlin_reset_priv, rcdev)
 30
 31struct berlin_reset_priv {
 32	struct regmap			*regmap;
 33	struct reset_controller_dev	rcdev;
 34};
 35
 36static int berlin_reset_reset(struct reset_controller_dev *rcdev,
 37			      unsigned long id)
 38{
 39	struct berlin_reset_priv *priv = to_berlin_reset_priv(rcdev);
 40	int offset = id >> 8;
 41	int mask = BIT(id & 0x1f);
 42
 43	regmap_write(priv->regmap, offset, mask);
 44
 45	/* let the reset be effective */
 46	udelay(10);
 47
 48	return 0;
 49}
 50
 51static const struct reset_control_ops berlin_reset_ops = {
 52	.reset	= berlin_reset_reset,
 53};
 54
 55static int berlin_reset_xlate(struct reset_controller_dev *rcdev,
 56			      const struct of_phandle_args *reset_spec)
 57{
 58	unsigned offset, bit;
 59
 60	offset = reset_spec->args[0];
 61	bit = reset_spec->args[1];
 62
 63	if (bit >= BERLIN_MAX_RESETS)
 64		return -EINVAL;
 65
 66	return (offset << 8) | bit;
 67}
 68
 69static int berlin2_reset_probe(struct platform_device *pdev)
 70{
 71	struct device_node *parent_np = of_get_parent(pdev->dev.of_node);
 72	struct berlin_reset_priv *priv;
 73
 74	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 75	if (!priv)
 76		return -ENOMEM;
 77
 78	priv->regmap = syscon_node_to_regmap(parent_np);
 79	of_node_put(parent_np);
 80	if (IS_ERR(priv->regmap))
 81		return PTR_ERR(priv->regmap);
 82
 83	priv->rcdev.owner = THIS_MODULE;
 84	priv->rcdev.ops = &berlin_reset_ops;
 85	priv->rcdev.of_node = pdev->dev.of_node;
 86	priv->rcdev.of_reset_n_cells = 2;
 87	priv->rcdev.of_xlate = berlin_reset_xlate;
 88
 89	return reset_controller_register(&priv->rcdev);
 90}
 91
 92static const struct of_device_id berlin_reset_dt_match[] = {
 93	{ .compatible = "marvell,berlin2-reset" },
 94	{ },
 95};
 96
 97static struct platform_driver berlin_reset_driver = {
 98	.probe	= berlin2_reset_probe,
 99	.driver	= {
100		.name = "berlin2-reset",
101		.of_match_table = berlin_reset_dt_match,
102	},
103};
104builtin_platform_driver(berlin_reset_driver);