drivers/power/reset/axxia-reset.c

   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);