1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Reset driver for Axxia devices
4 *
5 * Copyright (C) 2014 LSI
6 */
7#include <linux/init.h>
8#include <linux/err.h>
9#include <linux/io.h>
10#include <linux/kernel.h>
11#include <linux/mfd/syscon.h>
12#include <linux/module.h>
13#include <linux/notifier.h>
14#include <linux/of.h>
15#include <linux/platform_device.h>
16#include <linux/reboot.h>
17#include <linux/regmap.h>
18
19#define SC_CRIT_WRITE_KEY	0x1000
20#define SC_LATCH_ON_RESET	0x1004
21#define SC_RESET_CONTROL	0x1008
22#define   RSTCTL_RST_ZERO	(1<<3)
23#define   RSTCTL_RST_FAB	(1<<2)
24#define   RSTCTL_RST_CHIP	(1<<1)
25#define   RSTCTL_RST_SYS	(1<<0)
26#define SC_EFUSE_INT_STATUS	0x180c
27#define   EFUSE_READ_DONE	(1<<31)
28
29static int axxia_restart_handler(struct sys_off_data *data)
30{
31	struct regmap *syscon = data->cb_data;
32
33	/* Access Key (0xab) */
34	regmap_write(syscon, SC_CRIT_WRITE_KEY, 0xab);
35	/* Select internal boot from 0xffff0000 */
36	regmap_write(syscon, SC_LATCH_ON_RESET, 0x00000040);
37	/* Assert ResetReadDone (to avoid hanging in boot ROM) */
38	regmap_write(syscon, SC_EFUSE_INT_STATUS, EFUSE_READ_DONE);
39	/* Assert chip reset */
40	regmap_update_bits(syscon, SC_RESET_CONTROL,
41			   RSTCTL_RST_CHIP, RSTCTL_RST_CHIP);
42
43	return NOTIFY_DONE;
44}
45
46static int axxia_reset_probe(struct platform_device *pdev)
47{
48	struct device *dev = &pdev->dev;
49	struct regmap *syscon;
50	int err;
51
52	syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
53	if (IS_ERR(syscon)) {
54		pr_err("%pOFn: syscon lookup failed\n", dev->of_node);
55		return PTR_ERR(syscon);
56	}
57
58	err = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_RESTART,
59					    128, axxia_restart_handler, syscon);
60	if (err)
61		dev_err(dev, "cannot register restart handler (err=%d)\n", err);
62
63	return err;
64}
65
66static const struct of_device_id of_axxia_reset_match[] = {
67	{ .compatible = "lsi,axm55xx-reset", },
68	{},
69};
70MODULE_DEVICE_TABLE(of, of_axxia_reset_match);
71
72static struct platform_driver axxia_reset_driver = {
73	.probe = axxia_reset_probe,
74	.driver = {
75		.name = "axxia-reset",
76		.of_match_table = of_match_ptr(of_axxia_reset_match),
77	},
78};
79builtin_platform_driver(axxia_reset_driver);
80