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