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 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 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