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
axxia_restart_handler(struct notifier_block * this,unsigned long mode,void * cmd)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
axxia_reset_probe(struct platform_device * pdev)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
axxia_reset_init(void)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