1 /* 2 * Reset driver for Axxia devices 3 * 4 * Copyright (C) 2014 LSI 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 and 8 * only version 2 as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 */ 16 #include <linux/init.h> 17 #include <linux/err.h> 18 #include <linux/io.h> 19 #include <linux/kernel.h> 20 #include <linux/mfd/syscon.h> 21 #include <linux/module.h> 22 #include <linux/notifier.h> 23 #include <linux/of.h> 24 #include <linux/platform_device.h> 25 #include <linux/reboot.h> 26 #include <linux/regmap.h> 27 28 #define SC_CRIT_WRITE_KEY 0x1000 29 #define SC_LATCH_ON_RESET 0x1004 30 #define SC_RESET_CONTROL 0x1008 31 #define RSTCTL_RST_ZERO (1<<3) 32 #define RSTCTL_RST_FAB (1<<2) 33 #define RSTCTL_RST_CHIP (1<<1) 34 #define RSTCTL_RST_SYS (1<<0) 35 #define SC_EFUSE_INT_STATUS 0x180c 36 #define EFUSE_READ_DONE (1<<31) 37 38 static struct regmap *syscon; 39 40 static int axxia_restart_handler(struct notifier_block *this, 41 unsigned long mode, void *cmd) 42 { 43 /* Access Key (0xab) */ 44 regmap_write(syscon, SC_CRIT_WRITE_KEY, 0xab); 45 /* Select internal boot from 0xffff0000 */ 46 regmap_write(syscon, SC_LATCH_ON_RESET, 0x00000040); 47 /* Assert ResetReadDone (to avoid hanging in boot ROM) */ 48 regmap_write(syscon, SC_EFUSE_INT_STATUS, EFUSE_READ_DONE); 49 /* Assert chip reset */ 50 regmap_update_bits(syscon, SC_RESET_CONTROL, 51 RSTCTL_RST_CHIP, RSTCTL_RST_CHIP); 52 53 return NOTIFY_DONE; 54 } 55 56 static struct notifier_block axxia_restart_nb = { 57 .notifier_call = axxia_restart_handler, 58 .priority = 128, 59 }; 60 61 static int axxia_reset_probe(struct platform_device *pdev) 62 { 63 struct device *dev = &pdev->dev; 64 int err; 65 66 syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon"); 67 if (IS_ERR(syscon)) { 68 pr_err("%s: syscon lookup failed\n", dev->of_node->name); 69 return PTR_ERR(syscon); 70 } 71 72 err = register_restart_handler(&axxia_restart_nb); 73 if (err) 74 dev_err(dev, "cannot register restart handler (err=%d)\n", err); 75 76 return err; 77 } 78 79 static const struct of_device_id of_axxia_reset_match[] = { 80 { .compatible = "lsi,axm55xx-reset", }, 81 {}, 82 }; 83 MODULE_DEVICE_TABLE(of, of_axxia_reset_match); 84 85 static struct platform_driver axxia_reset_driver = { 86 .probe = axxia_reset_probe, 87 .driver = { 88 .name = "axxia-reset", 89 .of_match_table = of_match_ptr(of_axxia_reset_match), 90 }, 91 }; 92 93 static int __init axxia_reset_init(void) 94 { 95 return platform_driver_register(&axxia_reset_driver); 96 } 97 device_initcall(axxia_reset_init); 98