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 int axxia_restart_handler(struct sys_off_data *data)
  30 {
  31         struct regmap *syscon = data->cb_data;
  32
  33         /* Access Key (0xab) */
  34         regmap_write(syscon, SC_CRIT_WRITE_KEY, 0xab);
  35         /* Select internal boot from 0xffff0000 */
  36         regmap_write(syscon, SC_LATCH_ON_RESET, 0x00000040);
  37         /* Assert ResetReadDone (to avoid hanging in boot ROM) */
  38         regmap_write(syscon, SC_EFUSE_INT_STATUS, EFUSE_READ_DONE);
  39         /* Assert chip reset */
  40         regmap_update_bits(syscon, SC_RESET_CONTROL,
  41                            RSTCTL_RST_CHIP, RSTCTL_RST_CHIP);
  42
  43         return NOTIFY_DONE;
  44 }
  45
  46 static int axxia_reset_probe(struct platform_device *pdev)
  47 {
  48         struct device *dev = &pdev->dev;
  49         struct regmap *syscon;
  50         int err;
  51
  52         syscon = syscon_regmap_lookup_by_phandle(dev->of_node, "syscon");
  53         if (IS_ERR(syscon)) {
  54                 pr_err("%pOFn: syscon lookup failed\n", dev->of_node);
  55                 return PTR_ERR(syscon);
  56         }
  57
  58         err = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_RESTART,
  59                                             128, axxia_restart_handler, syscon);
  60         if (err)
  61                 dev_err(dev, "cannot register restart handler (err=%d)\n", err);
  62
  63         return err;
  64 }
  65
  66 static const struct of_device_id of_axxia_reset_match[] = {
  67         { .compatible = "lsi,axm55xx-reset", },
  68         {},
  69 };
  70 MODULE_DEVICE_TABLE(of, of_axxia_reset_match);
  71
  72 static struct platform_driver axxia_reset_driver = {
  73         .probe = axxia_reset_probe,
  74         .driver = {
  75                 .name = "axxia-reset",
  76                 .of_match_table = of_match_ptr(of_axxia_reset_match),
  77         },
  78 };
  79 builtin_platform_driver(axxia_reset_driver);