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(map: syscon, SC_CRIT_WRITE_KEY, val: 0xab);
35 /* Select internal boot from 0xffff0000 */
36 regmap_write(map: syscon, SC_LATCH_ON_RESET, val: 0x00000040);
37 /* Assert ResetReadDone (to avoid hanging in boot ROM) */
38 regmap_write(map: syscon, SC_EFUSE_INT_STATUS, EFUSE_READ_DONE);
39 /* Assert chip reset */
40 regmap_update_bits(map: 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(np: dev->of_node, property: "syscon");
53 if (IS_ERR(ptr: syscon)) {
54 pr_err("%pOFn: syscon lookup failed\n", dev->of_node);
55 return PTR_ERR(ptr: syscon);
56 }
57
58 err = devm_register_sys_off_handler(dev: &pdev->dev, mode: SYS_OFF_MODE_RESTART,
59 priority: 128, callback: axxia_restart_handler, cb_data: 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

source code of linux/drivers/power/reset/axxia-reset.c