linux/drivers/power/reset/axxia-reset.c
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   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
  38static struct regmap *syscon;
  39
  40static 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
  56static struct notifier_block axxia_restart_nb = {
  57        .notifier_call = axxia_restart_handler,
  58        .priority = 128,
  59};
  60
  61static 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
  79static const struct of_device_id of_axxia_reset_match[] = {
  80        { .compatible = "lsi,axm55xx-reset", },
  81        {},
  82};
  83MODULE_DEVICE_TABLE(of, of_axxia_reset_match);
  84
  85static 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
  93static int __init axxia_reset_init(void)
  94{
  95        return platform_driver_register(&axxia_reset_driver);
  96}
  97device_initcall(axxia_reset_init);
  98
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