kernel/drivers/power/reset/keystone-reset.c

   1 /*
   2  * TI keystone reboot driver
   3  *
   4  * Copyright (C) 2014 Texas Instruments Incorporated. http://www.ti.com/
   5  *
   6  * Author: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/io.h>
  14 #include <linux/module.h>
  15 #include <linux/notifier.h>
  16 #include <linux/reboot.h>
  17 #include <linux/regmap.h>
  18 #include <linux/mfd/syscon.h>
  19 #include <linux/of_platform.h>
  20
  21 #define RSTYPE_RG                       0x0
  22 #define RSCTRL_RG                       0x4
  23 #define RSCFG_RG                        0x8
  24 #define RSISO_RG                        0xc
  25
  26 #define RSCTRL_KEY_MASK                 0x0000ffff
  27 #define RSCTRL_RESET_MASK               BIT(16)
  28 #define RSCTRL_KEY                      0x5a69
  29
  30 #define RSMUX_OMODE_MASK                0xe
  31 #define RSMUX_OMODE_RESET_ON            0xa
  32 #define RSMUX_OMODE_RESET_OFF           0x0
  33 #define RSMUX_LOCK_MASK                 0x1
  34 #define RSMUX_LOCK_SET                  0x1
  35
  36 #define RSCFG_RSTYPE_SOFT               0x300f
  37 #define RSCFG_RSTYPE_HARD               0x0
  38
  39 #define WDT_MUX_NUMBER                  0x4
  40
  41 static int rspll_offset;
  42 static struct regmap *pllctrl_regs;
  43
  44 /**
  45  * rsctrl_enable_rspll_write - enable access to RSCTRL, RSCFG
  46  * To be able to access to RSCTRL, RSCFG registers
  47  * we have to write a key before
  48  */
  49 static inline int rsctrl_enable_rspll_write(void)
  50 {
  51         return regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
  52                                   RSCTRL_KEY_MASK, RSCTRL_KEY);
  53 }
  54
  55 static int rsctrl_restart_handler(struct notifier_block *this,
  56                                   unsigned long mode, void *cmd)
  57 {
  58         /* enable write access to RSTCTRL */
  59         rsctrl_enable_rspll_write();
  60
  61         /* reset the SOC */
  62         regmap_update_bits(pllctrl_regs, rspll_offset + RSCTRL_RG,
  63                            RSCTRL_RESET_MASK, 0);
  64
  65         return NOTIFY_DONE;
  66 }
  67
  68 static struct notifier_block rsctrl_restart_nb = {
  69         .notifier_call = rsctrl_restart_handler,
  70         .priority = 128,
  71 };
  72
  73 static const struct of_device_id rsctrl_of_match[] = {
  74         {.compatible = "ti,keystone-reset", },
  75         {},
  76 };
  77
  78 static int rsctrl_probe(struct platform_device *pdev)
  79 {
  80         int i;
  81         int ret;
  82         u32 val;
  83         unsigned int rg;
  84         u32 rsmux_offset;
  85         struct regmap *devctrl_regs;
  86         struct device *dev = &pdev->dev;
  87         struct device_node *np = dev->of_node;
  88
  89         if (!np)
  90                 return -ENODEV;
  91
  92         /* get regmaps */
  93         pllctrl_regs = syscon_regmap_lookup_by_phandle(np, "ti,syscon-pll");
  94         if (IS_ERR(pllctrl_regs))
  95                 return PTR_ERR(pllctrl_regs);
  96
  97         devctrl_regs = syscon_regmap_lookup_by_phandle(np, "ti,syscon-dev");
  98         if (IS_ERR(devctrl_regs))
  99                 return PTR_ERR(devctrl_regs);
 100
 101         ret = of_property_read_u32_index(np, "ti,syscon-pll", 1, &rspll_offset);
 102         if (ret) {
 103                 dev_err(dev, "couldn't read the reset pll offset!\n");
 104                 return -EINVAL;
 105         }
 106
 107         ret = of_property_read_u32_index(np, "ti,syscon-dev", 1, &rsmux_offset);
 108         if (ret) {
 109                 dev_err(dev, "couldn't read the rsmux offset!\n");
 110                 return -EINVAL;
 111         }
 112
 113         /* set soft/hard reset */
 114         val = of_property_read_bool(np, "ti,soft-reset");
 115         val = val ? RSCFG_RSTYPE_SOFT : RSCFG_RSTYPE_HARD;
 116
 117         ret = rsctrl_enable_rspll_write();
 118         if (ret)
 119                 return ret;
 120
 121         ret = regmap_write(pllctrl_regs, rspll_offset + RSCFG_RG, val);
 122         if (ret)
 123                 return ret;
 124
 125         /* disable a reset isolation for all module clocks */
 126         ret = regmap_write(pllctrl_regs, rspll_offset + RSISO_RG, 0);
 127         if (ret)
 128                 return ret;
 129
 130         /* enable a reset for watchdogs from wdt-list */
 131         for (i = 0; i < WDT_MUX_NUMBER; i++) {
 132                 ret = of_property_read_u32_index(np, "ti,wdt-list", i, &val);
 133                 if (ret == -EOVERFLOW && !i) {
 134                         dev_err(dev, "ti,wdt-list property has to contain at"
 135                                 "least one entry\n");
 136                         return -EINVAL;
 137                 } else if (ret) {
 138                         break;
 139                 }
 140
 141                 if (val >= WDT_MUX_NUMBER) {
 142                         dev_err(dev, "ti,wdt-list property can contain"
 143                                 "only numbers < 4\n");
 144                         return -EINVAL;
 145                 }
 146
 147                 rg = rsmux_offset + val * 4;
 148
 149                 ret = regmap_update_bits(devctrl_regs, rg, RSMUX_OMODE_MASK,
 150                                          RSMUX_OMODE_RESET_ON |
 151                                          RSMUX_LOCK_SET);
 152                 if (ret)
 153                         return ret;
 154         }
 155
 156         ret = register_restart_handler(&rsctrl_restart_nb);
 157         if (ret)
 158                 dev_err(dev, "cannot register restart handler (err=%d)\n", ret);
 159
 160         return ret;
 161 }
 162
 163 static struct platform_driver rsctrl_driver = {
 164         .probe = rsctrl_probe,
 165         .driver = {
 166                 .name = KBUILD_MODNAME,
 167                 .of_match_table = rsctrl_of_match,
 168         },
 169 };
 170 module_platform_driver(rsctrl_driver);
 171
 172 MODULE_AUTHOR("Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>");
 173 MODULE_DESCRIPTION("Texas Instruments keystone reset driver");
 174 MODULE_LICENSE("GPL v2");
 175 MODULE_ALIAS("platform:" KBUILD_MODNAME);