drivers/power/reset/axxia-reset.c

   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);