1 // SPDX-License-Identifier: GPL-2.0-only
2 // Copyright (C) 2016 Broadcom
3
4 #include <linux/io.h>
5 #include <linux/mod_devicetable.h>
6 #include <linux/platform_device.h>
7 #include <linux/reboot.h>
8
9 #define RSTMGR_REG_WR_ACCESS_OFFSET 0
10 #define RSTMGR_REG_CHIP_SOFT_RST_OFFSET 4
11
12 #define RSTMGR_WR_PASSWORD 0xa5a5
13 #define RSTMGR_WR_PASSWORD_SHIFT 8
14 #define RSTMGR_WR_ACCESS_ENABLE 1
15
16 static void __iomem *kona_reset_base;
17
kona_reset_handler(struct notifier_block * this,unsigned long mode,void * cmd)18 static int kona_reset_handler(struct notifier_block *this,
19 unsigned long mode, void *cmd)
20 {
21 /*
22 * A soft reset is triggered by writing a 0 to bit 0 of the soft reset
23 * register. To write to that register we must first write the password
24 * and the enable bit in the write access enable register.
25 */
26 writel((RSTMGR_WR_PASSWORD << RSTMGR_WR_PASSWORD_SHIFT) |
27 RSTMGR_WR_ACCESS_ENABLE,
28 kona_reset_base + RSTMGR_REG_WR_ACCESS_OFFSET);
29 writel(0, kona_reset_base + RSTMGR_REG_CHIP_SOFT_RST_OFFSET);
30
31 return NOTIFY_DONE;
32 }
33
34 static struct notifier_block kona_reset_nb = {
35 .notifier_call = kona_reset_handler,
36 .priority = 128,
37 };
38
kona_reset_probe(struct platform_device * pdev)39 static int kona_reset_probe(struct platform_device *pdev)
40 {
41 kona_reset_base = devm_platform_ioremap_resource(pdev, 0);
42 if (IS_ERR(kona_reset_base))
43 return PTR_ERR(kona_reset_base);
44
45 return register_restart_handler(&kona_reset_nb);
46 }
47
48 static const struct of_device_id of_match[] = {
49 { .compatible = "brcm,bcm21664-resetmgr" },
50 {},
51 };
52
53 static struct platform_driver bcm_kona_reset_driver = {
54 .probe = kona_reset_probe,
55 .driver = {
56 .name = "brcm-kona-reset",
57 .of_match_table = of_match,
58 },
59 };
60
61 builtin_platform_driver(bcm_kona_reset_driver);
62