1/*
2 * Reset driver for Axxia devices
3 *
4 * Copyright (C) 2014 LSI
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 version 2 and
8 * only version 2 as published by the Free Software Foundation.
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/init.h>
17#include <linux/err.h>
18#include <linux/io.h>
19#include <linux/kernel.h>
20#include <linux/mfd/syscon.h>
21#include <linux/module.h>
22#include <linux/notifier.h>
23#include <linux/of.h>
24#include <linux/platform_device.h>
25#include <linux/reboot.h>
26#include <linux/regmap.h>
27
28#define SC_CRIT_WRITE_KEY	0x1000
29#define SC_LATCH_ON_RESET	0x1004
30#define SC_RESET_CONTROL	0x1008
31#define   RSTCTL_RST_ZERO	(1<<3)
32#define   RSTCTL_RST_FAB	(1<<2)
33#define   RSTCTL_RST_CHIP	(1<<1)
34#define   RSTCTL_RST_SYS	(1<<0)
35#define SC_EFUSE_INT_STATUS	0x180c
36#define   EFUSE_READ_DONE	(1<<31)
37
38static struct regmap *syscon;
39
40static int axxia_restart_handler(struct notifier_block *this,
41				 unsigned long mode, void *cmd)
42{
43	/* Access Key (0xab) */
44	regmap_write(syscon, SC_CRIT_WRITE_KEY, 0xab);
45	/* Select internal boot from 0xffff0000 */
46	regmap_write(syscon, SC_LATCH_ON_RESET, 0x00000040);
47	/* Assert ResetReadDone (to avoid hanging in boot ROM) */
48	regmap_write(syscon, SC_EFUSE_INT_STATUS, EFUSE_READ_DONE);
49	/* Assert chip reset */
50	regmap_update_bits(syscon, SC_RESET_CONTROL,
51			   RSTCTL_RST_CHIP, RSTCTL_RST_CHIP);
52
53	return NOTIFY_DONE;
54}
55
56static struct notifier_block axxia_restart_nb = {
57	.notifier_call = axxia_restart_handler,
58	.priority = 128,
59};
60
61static int axxia_reset_probe(struct platform_device *pdev)
62{
63	struct device *dev = &pdev->dev;
64	int err;
65
66	syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
67	if (IS_ERR(syscon)) {
68		pr_err("%s: syscon lookup failed\n", dev->of_node->name);
69		return PTR_ERR(syscon);
70	}
71
72	err = register_restart_handler(&axxia_restart_nb);
73	if (err)
74		dev_err(dev, "cannot register restart handler (err=%d)\n", err);
75
76	return err;
77}
78
79static const struct of_device_id of_axxia_reset_match[] = {
80	{ .compatible = "lsi,axm55xx-reset", },
81	{},
82};
83MODULE_DEVICE_TABLE(of, of_axxia_reset_match);
84
85static struct platform_driver axxia_reset_driver = {
86	.probe = axxia_reset_probe,
87	.driver = {
88		.name = "axxia-reset",
89		.of_match_table = of_match_ptr(of_axxia_reset_match),
90	},
91};
92
93static int __init axxia_reset_init(void)
94{
95	return platform_driver_register(&axxia_reset_driver);
96}
97device_initcall(axxia_reset_init);
98