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 
29 static struct regmap *syscon;
30 
31 static int axxia_restart_handler(struct notifier_block *this,
32 				 unsigned long mode, void *cmd)
33 {
34 	/* Access Key (0xab) */
35 	regmap_write(syscon, SC_CRIT_WRITE_KEY, 0xab);
36 	/* Select internal boot from 0xffff0000 */
37 	regmap_write(syscon, SC_LATCH_ON_RESET, 0x00000040);
38 	/* Assert ResetReadDone (to avoid hanging in boot ROM) */
39 	regmap_write(syscon, SC_EFUSE_INT_STATUS, EFUSE_READ_DONE);
40 	/* Assert chip reset */
41 	regmap_update_bits(syscon, SC_RESET_CONTROL,
42 			   RSTCTL_RST_CHIP, RSTCTL_RST_CHIP);
43 
44 	return NOTIFY_DONE;
45 }
46 
47 static struct notifier_block axxia_restart_nb = {
48 	.notifier_call = axxia_restart_handler,
49 	.priority = 128,
50 };
51 
52 static int axxia_reset_probe(struct platform_device *pdev)
53 {
54 	struct device *dev = &pdev->dev;
55 	int err;
56 
57 	syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
58 	if (IS_ERR(syscon)) {
59 		pr_err("%pOFn: syscon lookup failed\n", dev->of_node);
60 		return PTR_ERR(syscon);
61 	}
62 
63 	err = register_restart_handler(&axxia_restart_nb);
64 	if (err)
65 		dev_err(dev, "cannot register restart handler (err=%d)\n", err);
66 
67 	return err;
68 }
69 
70 static const struct of_device_id of_axxia_reset_match[] = {
71 	{ .compatible = "lsi,axm55xx-reset", },
72 	{},
73 };
74 MODULE_DEVICE_TABLE(of, of_axxia_reset_match);
75 
76 static struct platform_driver axxia_reset_driver = {
77 	.probe = axxia_reset_probe,
78 	.driver = {
79 		.name = "axxia-reset",
80 		.of_match_table = of_match_ptr(of_axxia_reset_match),
81 	},
82 };
83 
84 static int __init axxia_reset_init(void)
85 {
86 	return platform_driver_register(&axxia_reset_driver);
87 }
88 device_initcall(axxia_reset_init);
89