ep93xx-restart.c

 1// SPDX-License-Identifier: GPL-2.0+
 2/*
 3 * Cirrus EP93xx SoC reset driver
 4 *
 5 * Copyright (C) 2021 Nikita Shubin <nikita.shubin@maquefel.me>
 6 */
 7
 8#include <linux/bits.h>
 9#include <linux/container_of.h>
10#include <linux/delay.h>
11#include <linux/errno.h>
12#include <linux/mfd/syscon.h>
13#include <linux/module.h>
14#include <linux/mod_devicetable.h>
15#include <linux/notifier.h>
16#include <linux/reboot.h>
17#include <linux/slab.h>
18
19#include <linux/soc/cirrus/ep93xx.h>
20
21#define EP93XX_SYSCON_DEVCFG		0x80
22#define EP93XX_SYSCON_DEVCFG_SWRST	BIT(31)
23
24struct ep93xx_restart {
25	struct ep93xx_regmap_adev *aux_dev;
26	struct notifier_block restart_handler;
27};
28
29static int ep93xx_restart_handle(struct notifier_block *this,
30				 unsigned long mode, void *cmd)
31{
32	struct ep93xx_restart *priv =
33		container_of(this, struct ep93xx_restart, restart_handler);
34	struct ep93xx_regmap_adev *aux = priv->aux_dev;
35
36	/* Issue the reboot */
37	aux->update_bits(aux->map, aux->lock, EP93XX_SYSCON_DEVCFG,
38			 EP93XX_SYSCON_DEVCFG_SWRST, EP93XX_SYSCON_DEVCFG_SWRST);
39	aux->update_bits(aux->map, aux->lock, EP93XX_SYSCON_DEVCFG,
40			 EP93XX_SYSCON_DEVCFG_SWRST, 0);
41
42	return NOTIFY_DONE;
43}
44
45static int ep93xx_reboot_probe(struct auxiliary_device *adev,
46			       const struct auxiliary_device_id *id)
47{
48	struct ep93xx_regmap_adev *rdev = to_ep93xx_regmap_adev(adev);
49	struct device *dev = &adev->dev;
50	struct ep93xx_restart *priv;
51	int err;
52
53	if (!rdev->update_bits)
54		return -ENODEV;
55
56	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
57	if (!priv)
58		return -ENOMEM;
59
60	priv->aux_dev = rdev;
61
62	priv->restart_handler.notifier_call = ep93xx_restart_handle;
63	priv->restart_handler.priority = 128;
64
65	err = register_restart_handler(&priv->restart_handler);
66	if (err)
67		return dev_err_probe(dev, err, "can't register restart notifier\n");
68
69	return 0;
70}
71
72static const struct auxiliary_device_id ep93xx_reboot_ids[] = {
73	{
74		.name = "soc_ep93xx.reset-ep93xx",
75	},
76	{ /* sentinel */ }
77};
78MODULE_DEVICE_TABLE(auxiliary, ep93xx_reboot_ids);
79
80static struct auxiliary_driver ep93xx_reboot_driver = {
81	.probe		= ep93xx_reboot_probe,
82	.id_table	= ep93xx_reboot_ids,
83};
84module_auxiliary_driver(ep93xx_reboot_driver);