drivers/watchdog/ie6xx_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *      Intel Atom E6xx Watchdog driver
   4  *
   5  *      Copyright (C) 2011 Alexander Stein
   6  *                <alexander.stein@systec-electronic.com>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/moduleparam.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/io.h>
  13 #include <linux/kernel.h>
  14 #include <linux/types.h>
  15 #include <linux/watchdog.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/debugfs.h>
  18 #include <linux/uaccess.h>
  19 #include <linux/spinlock.h>
  20
  21 #define DRIVER_NAME "ie6xx_wdt"
  22
  23 #define PV1     0x00
  24 #define PV2     0x04
  25
  26 #define RR0     0x0c
  27 #define RR1     0x0d
  28 #define WDT_RELOAD      0x01
  29 #define WDT_TOUT        0x02
  30
  31 #define WDTCR   0x10
  32 #define WDT_PRE_SEL     0x04
  33 #define WDT_RESET_SEL   0x08
  34 #define WDT_RESET_EN    0x10
  35 #define WDT_TOUT_EN     0x20
  36
  37 #define DCR     0x14
  38
  39 #define WDTLR   0x18
  40 #define WDT_LOCK        0x01
  41 #define WDT_ENABLE      0x02
  42 #define WDT_TOUT_CNF    0x03
  43
  44 #define MIN_TIME        1
  45 #define MAX_TIME        (10 * 60) /* 10 minutes */
  46 #define DEFAULT_TIME    60
  47
  48 static unsigned int timeout = DEFAULT_TIME;
  49 module_param(timeout, uint, 0);
  50 MODULE_PARM_DESC(timeout,
  51                 "Default Watchdog timer setting ("
  52                 __MODULE_STRING(DEFAULT_TIME) "s)."
  53                 "The range is from 1 to 600");
  54
  55 static bool nowayout = WATCHDOG_NOWAYOUT;
  56 module_param(nowayout, bool, 0);
  57 MODULE_PARM_DESC(nowayout,
  58         "Watchdog cannot be stopped once started (default="
  59                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  60
  61 static u8 resetmode = 0x10;
  62 module_param(resetmode, byte, 0);
  63 MODULE_PARM_DESC(resetmode,
  64         "Resetmode bits: 0x08 warm reset (cold reset otherwise), "
  65         "0x10 reset enable, 0x20 disable toggle GPIO[4] (default=0x10)");
  66
  67 static struct {
  68         unsigned short sch_wdtba;
  69         spinlock_t unlock_sequence;
  70 #ifdef CONFIG_DEBUG_FS
  71         struct dentry *debugfs;
  72 #endif
  73 } ie6xx_wdt_data;
  74
  75 /*
  76  * This is needed to write to preload and reload registers
  77  * struct ie6xx_wdt_data.unlock_sequence must be used
  78  * to prevent sequence interrupts
  79  */
  80 static void ie6xx_wdt_unlock_registers(void)
  81 {
  82         outb(0x80, ie6xx_wdt_data.sch_wdtba + RR0);
  83         outb(0x86, ie6xx_wdt_data.sch_wdtba + RR0);
  84 }
  85
  86 static int ie6xx_wdt_ping(struct watchdog_device *wdd)
  87 {
  88         spin_lock(&ie6xx_wdt_data.unlock_sequence);
  89         ie6xx_wdt_unlock_registers();
  90         outb(WDT_RELOAD, ie6xx_wdt_data.sch_wdtba + RR1);
  91         spin_unlock(&ie6xx_wdt_data.unlock_sequence);
  92         return 0;
  93 }
  94
  95 static int ie6xx_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
  96 {
  97         u32 preload;
  98         u64 clock;
  99         u8 wdtcr;
 100
 101         /* Watchdog clock is PCI Clock (33MHz) */
 102         clock = 33000000;
 103         /* and the preload value is loaded into [34:15] of the down counter */
 104         preload = (t * clock) >> 15;
 105         /*
 106          * Manual states preload must be one less.
 107          * Does not wrap as t is at least 1
 108          */
 109         preload -= 1;
 110
 111         spin_lock(&ie6xx_wdt_data.unlock_sequence);
 112
 113         /* Set ResetMode & Enable prescaler for range 10ms to 10 min */
 114         wdtcr = resetmode & 0x38;
 115         outb(wdtcr, ie6xx_wdt_data.sch_wdtba + WDTCR);
 116
 117         ie6xx_wdt_unlock_registers();
 118         outl(0, ie6xx_wdt_data.sch_wdtba + PV1);
 119
 120         ie6xx_wdt_unlock_registers();
 121         outl(preload, ie6xx_wdt_data.sch_wdtba + PV2);
 122
 123         ie6xx_wdt_unlock_registers();
 124         outb(WDT_RELOAD | WDT_TOUT, ie6xx_wdt_data.sch_wdtba + RR1);
 125
 126         spin_unlock(&ie6xx_wdt_data.unlock_sequence);
 127
 128         wdd->timeout = t;
 129         return 0;
 130 }
 131
 132 static int ie6xx_wdt_start(struct watchdog_device *wdd)
 133 {
 134         ie6xx_wdt_set_timeout(wdd, wdd->timeout);
 135
 136         /* Enable the watchdog timer */
 137         spin_lock(&ie6xx_wdt_data.unlock_sequence);
 138         outb(WDT_ENABLE, ie6xx_wdt_data.sch_wdtba + WDTLR);
 139         spin_unlock(&ie6xx_wdt_data.unlock_sequence);
 140
 141         return 0;
 142 }
 143
 144 static int ie6xx_wdt_stop(struct watchdog_device *wdd)
 145 {
 146         if (inb(ie6xx_wdt_data.sch_wdtba + WDTLR) & WDT_LOCK)
 147                 return -1;
 148
 149         /* Disable the watchdog timer */
 150         spin_lock(&ie6xx_wdt_data.unlock_sequence);
 151         outb(0, ie6xx_wdt_data.sch_wdtba + WDTLR);
 152         spin_unlock(&ie6xx_wdt_data.unlock_sequence);
 153
 154         return 0;
 155 }
 156
 157 static const struct watchdog_info ie6xx_wdt_info = {
 158         .identity =     "Intel Atom E6xx Watchdog",
 159         .options =      WDIOF_SETTIMEOUT |
 160                         WDIOF_MAGICCLOSE |
 161                         WDIOF_KEEPALIVEPING,
 162 };
 163
 164 static const struct watchdog_ops ie6xx_wdt_ops = {
 165         .owner =        THIS_MODULE,
 166         .start =        ie6xx_wdt_start,
 167         .stop =         ie6xx_wdt_stop,
 168         .ping =         ie6xx_wdt_ping,
 169         .set_timeout =  ie6xx_wdt_set_timeout,
 170 };
 171
 172 static struct watchdog_device ie6xx_wdt_dev = {
 173         .info =         &ie6xx_wdt_info,
 174         .ops =          &ie6xx_wdt_ops,
 175         .min_timeout =  MIN_TIME,
 176         .max_timeout =  MAX_TIME,
 177 };
 178
 179 #ifdef CONFIG_DEBUG_FS
 180
 181 static int ie6xx_wdt_show(struct seq_file *s, void *unused)
 182 {
 183         seq_printf(s, "PV1   = 0x%08x\n",
 184                 inl(ie6xx_wdt_data.sch_wdtba + PV1));
 185         seq_printf(s, "PV2   = 0x%08x\n",
 186                 inl(ie6xx_wdt_data.sch_wdtba + PV2));
 187         seq_printf(s, "RR    = 0x%08x\n",
 188                 inw(ie6xx_wdt_data.sch_wdtba + RR0));
 189         seq_printf(s, "WDTCR = 0x%08x\n",
 190                 inw(ie6xx_wdt_data.sch_wdtba + WDTCR));
 191         seq_printf(s, "DCR   = 0x%08x\n",
 192                 inl(ie6xx_wdt_data.sch_wdtba + DCR));
 193         seq_printf(s, "WDTLR = 0x%08x\n",
 194                 inw(ie6xx_wdt_data.sch_wdtba + WDTLR));
 195
 196         seq_printf(s, "\n");
 197         return 0;
 198 }
 199
 200 DEFINE_SHOW_ATTRIBUTE(ie6xx_wdt);
 201
 202 static void ie6xx_wdt_debugfs_init(void)
 203 {
 204         /* /sys/kernel/debug/ie6xx_wdt */
 205         ie6xx_wdt_data.debugfs = debugfs_create_file("ie6xx_wdt",
 206                 S_IFREG | S_IRUGO, NULL, NULL, &ie6xx_wdt_fops);
 207 }
 208
 209 static void ie6xx_wdt_debugfs_exit(void)
 210 {
 211         debugfs_remove(ie6xx_wdt_data.debugfs);
 212 }
 213
 214 #else
 215 static void ie6xx_wdt_debugfs_init(void)
 216 {
 217 }
 218
 219 static void ie6xx_wdt_debugfs_exit(void)
 220 {
 221 }
 222 #endif
 223
 224 static int ie6xx_wdt_probe(struct platform_device *pdev)
 225 {
 226         struct resource *res;
 227         u8 wdtlr;
 228         int ret;
 229
 230         res = platform_get_resource(pdev, IORESOURCE_IO, 0);
 231         if (!res)
 232                 return -ENODEV;
 233
 234         if (!request_region(res->start, resource_size(res), pdev->name)) {
 235                 dev_err(&pdev->dev, "Watchdog region 0x%llx already in use!\n",
 236                         (u64)res->start);
 237                 return -EBUSY;
 238         }
 239
 240         ie6xx_wdt_data.sch_wdtba = res->start;
 241         dev_dbg(&pdev->dev, "WDT = 0x%X\n", ie6xx_wdt_data.sch_wdtba);
 242
 243         ie6xx_wdt_dev.timeout = timeout;
 244         watchdog_set_nowayout(&ie6xx_wdt_dev, nowayout);
 245         ie6xx_wdt_dev.parent = &pdev->dev;
 246
 247         spin_lock_init(&ie6xx_wdt_data.unlock_sequence);
 248
 249         wdtlr = inb(ie6xx_wdt_data.sch_wdtba + WDTLR);
 250         if (wdtlr & WDT_LOCK)
 251                 dev_warn(&pdev->dev,
 252                         "Watchdog Timer is Locked (Reg=0x%x)\n", wdtlr);
 253
 254         ie6xx_wdt_debugfs_init();
 255
 256         ret = watchdog_register_device(&ie6xx_wdt_dev);
 257         if (ret)
 258                 goto misc_register_error;
 259
 260         return 0;
 261
 262 misc_register_error:
 263         ie6xx_wdt_debugfs_exit();
 264         release_region(res->start, resource_size(res));
 265         ie6xx_wdt_data.sch_wdtba = 0;
 266         return ret;
 267 }
 268
 269 static int ie6xx_wdt_remove(struct platform_device *pdev)
 270 {
 271         struct resource *res;
 272
 273         res = platform_get_resource(pdev, IORESOURCE_IO, 0);
 274         ie6xx_wdt_stop(NULL);
 275         watchdog_unregister_device(&ie6xx_wdt_dev);
 276         ie6xx_wdt_debugfs_exit();
 277         release_region(res->start, resource_size(res));
 278         ie6xx_wdt_data.sch_wdtba = 0;
 279
 280         return 0;
 281 }
 282
 283 static struct platform_driver ie6xx_wdt_driver = {
 284         .probe          = ie6xx_wdt_probe,
 285         .remove         = ie6xx_wdt_remove,
 286         .driver         = {
 287                 .name   = DRIVER_NAME,
 288         },
 289 };
 290
 291 static int __init ie6xx_wdt_init(void)
 292 {
 293         /* Check boot parameters to verify that their initial values */
 294         /* are in range. */
 295         if ((timeout < MIN_TIME) ||
 296             (timeout > MAX_TIME)) {
 297                 pr_err("Watchdog timer: value of timeout %d (dec) "
 298                   "is out of range from %d to %d (dec)\n",
 299                   timeout, MIN_TIME, MAX_TIME);
 300                 return -EINVAL;
 301         }
 302
 303         return platform_driver_register(&ie6xx_wdt_driver);
 304 }
 305
 306 static void __exit ie6xx_wdt_exit(void)
 307 {
 308         platform_driver_unregister(&ie6xx_wdt_driver);
 309 }
 310
 311 late_initcall(ie6xx_wdt_init);
 312 module_exit(ie6xx_wdt_exit);
 313
 314 MODULE_AUTHOR("Alexander Stein <alexander.stein@systec-electronic.com>");
 315 MODULE_DESCRIPTION("Intel Atom E6xx Watchdog Device Driver");
 316 MODULE_LICENSE("GPL");
 317 MODULE_ALIAS("platform:" DRIVER_NAME);