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/of.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/reboot.h>
  25 #include <linux/regmap.h>
  26
  27 #include <asm/system_misc.h>
  28
  29
  30 #define SC_CRIT_WRITE_KEY       0x1000
  31 #define SC_LATCH_ON_RESET       0x1004
  32 #define SC_RESET_CONTROL        0x1008
  33 #define   RSTCTL_RST_ZERO       (1<<3)
  34 #define   RSTCTL_RST_FAB        (1<<2)
  35 #define   RSTCTL_RST_CHIP       (1<<1)
  36 #define   RSTCTL_RST_SYS        (1<<0)
  37 #define SC_EFUSE_INT_STATUS     0x180c
  38 #define   EFUSE_READ_DONE       (1<<31)
  39
  40 static struct regmap *syscon;
  41
  42 static void do_axxia_restart(enum reboot_mode reboot_mode, const char *cmd)
  43 {
  44         /* Access Key (0xab) */
  45         regmap_write(syscon, SC_CRIT_WRITE_KEY, 0xab);
  46         /* Select internal boot from 0xffff0000 */
  47         regmap_write(syscon, SC_LATCH_ON_RESET, 0x00000040);
  48         /* Assert ResetReadDone (to avoid hanging in boot ROM) */
  49         regmap_write(syscon, SC_EFUSE_INT_STATUS, EFUSE_READ_DONE);
  50         /* Assert chip reset */
  51         regmap_update_bits(syscon, SC_RESET_CONTROL,
  52                            RSTCTL_RST_CHIP, RSTCTL_RST_CHIP);
  53 }
  54
  55 static int axxia_reset_probe(struct platform_device *pdev)
  56 {
  57         struct device *dev = &pdev->dev;
  58
  59         syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
  60         if (IS_ERR(syscon)) {
  61                 pr_err("%s: syscon lookup failed\n", dev->of_node->name);
  62                 return PTR_ERR(syscon);
  63         }
  64
  65         arm_pm_restart = do_axxia_restart;
  66
  67         return 0;
  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);