drivers/power/reset/keystone-reset.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * TI keystone reboot driver
   4  *
   5  * Copyright (C) 2014 Texas Instruments Incorporated. https://www.ti.com/
   6  *
   7  * Author: Ivan Khoronzhuk <[email protected]>
   8  */
   9
  10 #include <linux/io.h>
  11 #include <linux/module.h>
  12 #include <linux/notifier.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/reboot.h>
  15 #include <linux/regmap.h>
  16 #include <linux/mfd/syscon.h>
  17 #include <linux/of.h>
  18
  19 #define RSTYPE_RG                       0x0
  20 #define RSCTRL_RG                       0x4
  21 #define RSCFG_RG                        0x8
  22 #define RSISO_RG                        0xc
  23
  24 #define RSCTRL_KEY_MASK                 0x0000ffff
  25 #define RSCTRL_RESET_MASK               BIT(16)
  26 #define RSCTRL_KEY                      0x5a69
  27
  28 #define RSMUX_OMODE_MASK                0xe
  29 #define RSMUX_OMODE_RESET_ON            0xa
  30 #define RSMUX_OMODE_RESET_OFF           0x0
  31 #define RSMUX_LOCK_MASK                 0x1
  32 #define RSMUX_LOCK_SET                  0x1
  33
  34 #define RSCFG_RSTYPE_SOFT               0x300f
  35 #define RSCFG_RSTYPE_HARD               0x0
  36
  37 #define WDT_MUX_NUMBER                  0x4
  38
  39 static int rspll_offset;
  40 static struct regmap *pllctrl_regs;
  41
  42 /**
  43  * rsctrl_enable_rspll_write - enable access to RSCTRL, RSCFG
  44  * To be able to access to RSCTRL, RSCFG registers
  45  * we have to write a key before
  46  */
  47 static inline int rsctrl_enable_rspll_write(void)
  48 {
  49         return regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
  50                                   RSCTRL_KEY_MASK, RSCTRL_KEY);
  51 }
  52
  53 static int rsctrl_restart_handler(struct notifier_block *this,
  54                                   unsigned long mode, void *cmd)
  55 {
  56         /* enable write access to RSTCTRL */
  57         rsctrl_enable_rspll_write();
  58
  59         /* reset the SOC */
  60         regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
  61                            RSCTRL_RESET_MASK, 0);
  62
  63         return NOTIFY_DONE;
  64 }
  65
  66 static struct notifier_block rsctrl_restart_nb = {
  67         .notifier_call = rsctrl_restart_handler,
  68         .priority = 128,
  69 };
  70
  71 static const struct of_device_id rsctrl_of_match[] = {
  72         {.compatible = "ti,keystone-reset", },
  73         {},
  74 };
  75 MODULE_DEVICE_TABLE(of, rsctrl_of_match);
  76
  77 static int rsctrl_probe(struct platform_device *pdev)
  78 {
  79         int i;
  80         int ret;
  81         u32 val;
  82         unsigned int rg;
  83         u32 rsmux_offset;
  84         struct regmap *devctrl_regs;
  85         struct device *dev = &pdev->dev;
  86         struct device_node *np = dev->of_node;
  87
  88         if (!np)
  89                 return -ENODEV;
  90
  91         /* get regmaps */
  92         pllctrl_regs = syscon_regmap_lookup_by_phandle(np, "ti,syscon-pll");
  93         if (IS_ERR(pllctrl_regs))
  94                 return PTR_ERR(pllctrl_regs);
  95
  96         devctrl_regs = syscon_regmap_lookup_by_phandle(np, "ti,syscon-dev");
  97         if (IS_ERR(devctrl_regs))
  98                 return PTR_ERR(devctrl_regs);
  99
 100         ret = of_property_read_u32_index(np, "ti,syscon-pll", 1, &rspll_offset);
 101         if (ret) {
 102                 dev_err(dev, "couldn't read the reset pll offset!\n");
 103                 return -EINVAL;
 104         }
 105
 106         ret = of_property_read_u32_index(np, "ti,syscon-dev", 1, &rsmux_offset);
 107         if (ret) {
 108                 dev_err(dev, "couldn't read the rsmux offset!\n");
 109                 return -EINVAL;
 110         }
 111
 112         /* set soft/hard reset */
 113         val = of_property_read_bool(np, "ti,soft-reset");
 114         val = val ? RSCFG_RSTYPE_SOFT : RSCFG_RSTYPE_HARD;
 115
 116         ret = rsctrl_enable_rspll_write();
 117         if (ret)
 118                 return ret;
 119
 120         ret = regmap_write(pllctrl_regs, rspll_offset + RSCFG_RG, val);
 121         if (ret)
 122                 return ret;
 123
 124         /* disable a reset isolation for all module clocks */
 125         ret = regmap_write(pllctrl_regs, rspll_offset + RSISO_RG, 0);
 126         if (ret)
 127                 return ret;
 128
 129         /* enable a reset for watchdogs from wdt-list */
 130         for (i = 0; i < WDT_MUX_NUMBER; i++) {
 131                 ret = of_property_read_u32_index(np, "ti,wdt-list", i, &val);
 132                 if (ret == -EOVERFLOW && !i) {
 133                         dev_err(dev, "ti,wdt-list property has to contain at"
 134                                 "least one entry\n");
 135                         return -EINVAL;
 136                 } else if (ret) {
 137                         break;
 138                 }
 139
 140                 if (val >= WDT_MUX_NUMBER) {
 141                         dev_err(dev, "ti,wdt-list property can contain "
 142                                 "only numbers < 4\n");
 143                         return -EINVAL;
 144                 }
 145
 146                 rg = rsmux_offset + val * 4;
 147
 148                 ret = regmap_update_bits(devctrl_regs, rg, RSMUX_OMODE_MASK,
 149                                          RSMUX_OMODE_RESET_ON |
 150                                          RSMUX_LOCK_SET);
 151                 if (ret)
 152                         return ret;
 153         }
 154
 155         ret = register_restart_handler(&rsctrl_restart_nb);
 156         if (ret)
 157                 dev_err(dev, "cannot register restart handler (err=%d)\n", ret);
 158
 159         return ret;
 160 }
 161
 162 static struct platform_driver rsctrl_driver = {
 163         .probe = rsctrl_probe,
 164         .driver = {
 165                 .name = KBUILD_MODNAME,
 166                 .of_match_table = rsctrl_of_match,
 167         },
 168 };
 169 module_platform_driver(rsctrl_driver);
 170
 171 MODULE_AUTHOR("Ivan Khoronzhuk <[email protected]>");
 172 MODULE_DESCRIPTION("Texas Instruments keystone reset driver");
 173 MODULE_ALIAS("platform:" KBUILD_MODNAME);