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