drivers/watchdog/davinci_wdt.c

   1 /*
   2  * drivers/char/watchdog/davinci_wdt.c
   3  *
   4  * Watchdog driver for DaVinci DM644x/DM646x processors
   5  *
   6  * Copyright (C) 2006-2013 Texas Instruments.
   7  *
   8  * 2007 (c) MontaVista Software, Inc. This file is licensed under
   9  * the terms of the GNU General Public License version 2. This program
  10  * is licensed "as is" without any warranty of any kind, whether express
  11  * or implied.
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/mod_devicetable.h>
  17 #include <linux/types.h>
  18 #include <linux/kernel.h>
  19 #include <linux/watchdog.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/io.h>
  22 #include <linux/device.h>
  23 #include <linux/clk.h>
  24 #include <linux/err.h>
  25
  26 #define MODULE_NAME "DAVINCI-WDT: "
  27
  28 #define DEFAULT_HEARTBEAT 60
  29 #define MAX_HEARTBEAT     600   /* really the max margin is 264/27MHz*/
  30
  31 /* Timer register set definition */
  32 #define PID12   (0x0)
  33 #define EMUMGT  (0x4)
  34 #define TIM12   (0x10)
  35 #define TIM34   (0x14)
  36 #define PRD12   (0x18)
  37 #define PRD34   (0x1C)
  38 #define TCR     (0x20)
  39 #define TGCR    (0x24)
  40 #define WDTCR   (0x28)
  41
  42 /* TCR bit definitions */
  43 #define ENAMODE12_DISABLED      (0 << 6)
  44 #define ENAMODE12_ONESHOT       (1 << 6)
  45 #define ENAMODE12_PERIODIC      (2 << 6)
  46
  47 /* TGCR bit definitions */
  48 #define TIM12RS_UNRESET         (1 << 0)
  49 #define TIM34RS_UNRESET         (1 << 1)
  50 #define TIMMODE_64BIT_WDOG      (2 << 2)
  51
  52 /* WDTCR bit definitions */
  53 #define WDEN                    (1 << 14)
  54 #define WDFLAG                  (1 << 15)
  55 #define WDKEY_SEQ0              (0xa5c6 << 16)
  56 #define WDKEY_SEQ1              (0xda7e << 16)
  57
  58 static int heartbeat;
  59
  60 /*
  61  * struct to hold data for each WDT device
  62  * @base - base io address of WD device
  63  * @clk - source clock of WDT
  64  * @wdd - hold watchdog device as is in WDT core
  65  */
  66 struct davinci_wdt_device {
  67         void __iomem            *base;
  68         struct clk              *clk;
  69         struct watchdog_device  wdd;
  70 };
  71
  72 static int davinci_wdt_start(struct watchdog_device *wdd)
  73 {
  74         u32 tgcr;
  75         u32 timer_margin;
  76         unsigned long wdt_freq;
  77         struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
  78
  79         wdt_freq = clk_get_rate(davinci_wdt->clk);
  80
  81         /* disable, internal clock source */
  82         iowrite32(0, davinci_wdt->base + TCR);
  83         /* reset timer, set mode to 64-bit watchdog, and unreset */
  84         iowrite32(0, davinci_wdt->base + TGCR);
  85         tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;
  86         iowrite32(tgcr, davinci_wdt->base + TGCR);
  87         /* clear counter regs */
  88         iowrite32(0, davinci_wdt->base + TIM12);
  89         iowrite32(0, davinci_wdt->base + TIM34);
  90         /* set timeout period */
  91         timer_margin = (((u64)wdd->timeout * wdt_freq) & 0xffffffff);
  92         iowrite32(timer_margin, davinci_wdt->base + PRD12);
  93         timer_margin = (((u64)wdd->timeout * wdt_freq) >> 32);
  94         iowrite32(timer_margin, davinci_wdt->base + PRD34);
  95         /* enable run continuously */
  96         iowrite32(ENAMODE12_PERIODIC, davinci_wdt->base + TCR);
  97         /* Once the WDT is in pre-active state write to
  98          * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are
  99          * write protected (except for the WDKEY field)
 100          */
 101         /* put watchdog in pre-active state */
 102         iowrite32(WDKEY_SEQ0 | WDEN, davinci_wdt->base + WDTCR);
 103         /* put watchdog in active state */
 104         iowrite32(WDKEY_SEQ1 | WDEN, davinci_wdt->base + WDTCR);
 105         return 0;
 106 }
 107
 108 static int davinci_wdt_ping(struct watchdog_device *wdd)
 109 {
 110         struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
 111
 112         /* put watchdog in service state */
 113         iowrite32(WDKEY_SEQ0, davinci_wdt->base + WDTCR);
 114         /* put watchdog in active state */
 115         iowrite32(WDKEY_SEQ1, davinci_wdt->base + WDTCR);
 116         return 0;
 117 }
 118
 119 static unsigned int davinci_wdt_get_timeleft(struct watchdog_device *wdd)
 120 {
 121         u64 timer_counter;
 122         unsigned long freq;
 123         u32 val;
 124         struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
 125
 126         /* if timeout has occured then return 0 */
 127         val = ioread32(davinci_wdt->base + WDTCR);
 128         if (val & WDFLAG)
 129                 return 0;
 130
 131         freq = clk_get_rate(davinci_wdt->clk);
 132
 133         if (!freq)
 134                 return 0;
 135
 136         timer_counter = ioread32(davinci_wdt->base + TIM12);
 137         timer_counter |= ((u64)ioread32(davinci_wdt->base + TIM34) << 32);
 138
 139         do_div(timer_counter, freq);
 140
 141         return wdd->timeout - timer_counter;
 142 }
 143
 144 static int davinci_wdt_restart(struct watchdog_device *wdd,
 145                                unsigned long action, void *data)
 146 {
 147         struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
 148         u32 tgcr, wdtcr;
 149
 150         /* disable, internal clock source */
 151         iowrite32(0, davinci_wdt->base + TCR);
 152
 153         /* reset timer, set mode to 64-bit watchdog, and unreset */
 154         tgcr = 0;
 155         iowrite32(tgcr, davinci_wdt->base + TGCR);
 156         tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;
 157         iowrite32(tgcr, davinci_wdt->base + TGCR);
 158
 159         /* clear counter and period regs */
 160         iowrite32(0, davinci_wdt->base + TIM12);
 161         iowrite32(0, davinci_wdt->base + TIM34);
 162         iowrite32(0, davinci_wdt->base + PRD12);
 163         iowrite32(0, davinci_wdt->base + PRD34);
 164
 165         /* put watchdog in pre-active state */
 166         wdtcr = WDKEY_SEQ0 | WDEN;
 167         iowrite32(wdtcr, davinci_wdt->base + WDTCR);
 168
 169         /* put watchdog in active state */
 170         wdtcr = WDKEY_SEQ1 | WDEN;
 171         iowrite32(wdtcr, davinci_wdt->base + WDTCR);
 172
 173         /* write an invalid value to the WDKEY field to trigger a restart */
 174         wdtcr = 0x00004000;
 175         iowrite32(wdtcr, davinci_wdt->base + WDTCR);
 176
 177         return 0;
 178 }
 179
 180 static const struct watchdog_info davinci_wdt_info = {
 181         .options = WDIOF_KEEPALIVEPING,
 182         .identity = "DaVinci/Keystone Watchdog",
 183 };
 184
 185 static const struct watchdog_ops davinci_wdt_ops = {
 186         .owner          = THIS_MODULE,
 187         .start          = davinci_wdt_start,
 188         .stop           = davinci_wdt_ping,
 189         .ping           = davinci_wdt_ping,
 190         .get_timeleft   = davinci_wdt_get_timeleft,
 191         .restart        = davinci_wdt_restart,
 192 };
 193
 194 static void davinci_clk_disable_unprepare(void *data)
 195 {
 196         clk_disable_unprepare(data);
 197 }
 198
 199 static int davinci_wdt_probe(struct platform_device *pdev)
 200 {
 201         int ret = 0;
 202         struct device *dev = &pdev->dev;
 203         struct watchdog_device *wdd;
 204         struct davinci_wdt_device *davinci_wdt;
 205
 206         davinci_wdt = devm_kzalloc(dev, sizeof(*davinci_wdt), GFP_KERNEL);
 207         if (!davinci_wdt)
 208                 return -ENOMEM;
 209
 210         davinci_wdt->clk = devm_clk_get(dev, NULL);
 211
 212         if (IS_ERR(davinci_wdt->clk)) {
 213                 if (PTR_ERR(davinci_wdt->clk) != -EPROBE_DEFER)
 214                         dev_err(dev, "failed to get clock node\n");
 215                 return PTR_ERR(davinci_wdt->clk);
 216         }
 217
 218         ret = clk_prepare_enable(davinci_wdt->clk);
 219         if (ret) {
 220                 dev_err(dev, "failed to prepare clock\n");
 221                 return ret;
 222         }
 223         ret = devm_add_action_or_reset(dev, davinci_clk_disable_unprepare,
 224                                        davinci_wdt->clk);
 225         if (ret)
 226                 return ret;
 227
 228         platform_set_drvdata(pdev, davinci_wdt);
 229
 230         wdd                     = &davinci_wdt->wdd;
 231         wdd->info               = &davinci_wdt_info;
 232         wdd->ops                = &davinci_wdt_ops;
 233         wdd->min_timeout        = 1;
 234         wdd->max_timeout        = MAX_HEARTBEAT;
 235         wdd->timeout            = DEFAULT_HEARTBEAT;
 236         wdd->parent             = dev;
 237
 238         watchdog_init_timeout(wdd, heartbeat, dev);
 239
 240         dev_info(dev, "heartbeat %d sec\n", wdd->timeout);
 241
 242         watchdog_set_drvdata(wdd, davinci_wdt);
 243         watchdog_set_nowayout(wdd, 1);
 244         watchdog_set_restart_priority(wdd, 128);
 245
 246         davinci_wdt->base = devm_platform_ioremap_resource(pdev, 0);
 247         if (IS_ERR(davinci_wdt->base))
 248                 return PTR_ERR(davinci_wdt->base);
 249
 250         ret = devm_watchdog_register_device(dev, wdd);
 251         if (ret) {
 252                 dev_err(dev, "cannot register watchdog device\n");
 253                 return ret;
 254         }
 255
 256         return 0;
 257 }
 258
 259 static const struct of_device_id davinci_wdt_of_match[] = {
 260         { .compatible = "ti,davinci-wdt", },
 261         {},
 262 };
 263 MODULE_DEVICE_TABLE(of, davinci_wdt_of_match);
 264
 265 static struct platform_driver platform_wdt_driver = {
 266         .driver = {
 267                 .name = "davinci-wdt",
 268                 .of_match_table = davinci_wdt_of_match,
 269         },
 270         .probe = davinci_wdt_probe,
 271 };
 272
 273 module_platform_driver(platform_wdt_driver);
 274
 275 MODULE_AUTHOR("Texas Instruments");
 276 MODULE_DESCRIPTION("DaVinci Watchdog Driver");
 277
 278 module_param(heartbeat, int, 0);
 279 MODULE_PARM_DESC(heartbeat,
 280                  "Watchdog heartbeat period in seconds from 1 to "
 281                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 282                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 283
 284 MODULE_LICENSE("GPL");
 285 MODULE_ALIAS("platform:davinci-wdt");