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/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/watchdog.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/io.h>
  21 #include <linux/device.h>
  22 #include <linux/clk.h>
  23 #include <linux/err.h>
  24
  25 #define MODULE_NAME "DAVINCI-WDT: "
  26
  27 #define DEFAULT_HEARTBEAT 60
  28 #define MAX_HEARTBEAT     600   /* really the max margin is 264/27MHz*/
  29
  30 /* Timer register set definition */
  31 #define PID12   (0x0)
  32 #define EMUMGT  (0x4)
  33 #define TIM12   (0x10)
  34 #define TIM34   (0x14)
  35 #define PRD12   (0x18)
  36 #define PRD34   (0x1C)
  37 #define TCR     (0x20)
  38 #define TGCR    (0x24)
  39 #define WDTCR   (0x28)
  40
  41 /* TCR bit definitions */
  42 #define ENAMODE12_DISABLED      (0 << 6)
  43 #define ENAMODE12_ONESHOT       (1 << 6)
  44 #define ENAMODE12_PERIODIC      (2 << 6)
  45
  46 /* TGCR bit definitions */
  47 #define TIM12RS_UNRESET         (1 << 0)
  48 #define TIM34RS_UNRESET         (1 << 1)
  49 #define TIMMODE_64BIT_WDOG      (2 << 2)
  50
  51 /* WDTCR bit definitions */
  52 #define WDEN                    (1 << 14)
  53 #define WDFLAG                  (1 << 15)
  54 #define WDKEY_SEQ0              (0xa5c6 << 16)
  55 #define WDKEY_SEQ1              (0xda7e << 16)
  56
  57 static int heartbeat;
  58
  59 /*
  60  * struct to hold data for each WDT device
  61  * @base - base io address of WD device
  62  * @clk - source clock of WDT
  63  * @wdd - hold watchdog device as is in WDT core
  64  */
  65 struct davinci_wdt_device {
  66         void __iomem            *base;
  67         struct clk              *clk;
  68         struct watchdog_device  wdd;
  69 };
  70
  71 static int davinci_wdt_start(struct watchdog_device *wdd)
  72 {
  73         u32 tgcr;
  74         u32 timer_margin;
  75         unsigned long wdt_freq;
  76         struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
  77
  78         wdt_freq = clk_get_rate(davinci_wdt->clk);
  79
  80         /* disable, internal clock source */
  81         iowrite32(0, davinci_wdt->base + TCR);
  82         /* reset timer, set mode to 64-bit watchdog, and unreset */
  83         iowrite32(0, davinci_wdt->base + TGCR);
  84         tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;
  85         iowrite32(tgcr, davinci_wdt->base + TGCR);
  86         /* clear counter regs */
  87         iowrite32(0, davinci_wdt->base + TIM12);
  88         iowrite32(0, davinci_wdt->base + TIM34);
  89         /* set timeout period */
  90         timer_margin = (((u64)wdd->timeout * wdt_freq) & 0xffffffff);
  91         iowrite32(timer_margin, davinci_wdt->base + PRD12);
  92         timer_margin = (((u64)wdd->timeout * wdt_freq) >> 32);
  93         iowrite32(timer_margin, davinci_wdt->base + PRD34);
  94         /* enable run continuously */
  95         iowrite32(ENAMODE12_PERIODIC, davinci_wdt->base + TCR);
  96         /* Once the WDT is in pre-active state write to
  97          * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are
  98          * write protected (except for the WDKEY field)
  99          */
 100         /* put watchdog in pre-active state */
 101         iowrite32(WDKEY_SEQ0 | WDEN, davinci_wdt->base + WDTCR);
 102         /* put watchdog in active state */
 103         iowrite32(WDKEY_SEQ1 | WDEN, davinci_wdt->base + WDTCR);
 104         return 0;
 105 }
 106
 107 static int davinci_wdt_ping(struct watchdog_device *wdd)
 108 {
 109         struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
 110
 111         /* put watchdog in service state */
 112         iowrite32(WDKEY_SEQ0, davinci_wdt->base + WDTCR);
 113         /* put watchdog in active state */
 114         iowrite32(WDKEY_SEQ1, davinci_wdt->base + WDTCR);
 115         return 0;
 116 }
 117
 118 static unsigned int davinci_wdt_get_timeleft(struct watchdog_device *wdd)
 119 {
 120         u64 timer_counter;
 121         unsigned long freq;
 122         u32 val;
 123         struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
 124
 125         /* if timeout has occured then return 0 */
 126         val = ioread32(davinci_wdt->base + WDTCR);
 127         if (val & WDFLAG)
 128                 return 0;
 129
 130         freq = clk_get_rate(davinci_wdt->clk);
 131
 132         if (!freq)
 133                 return 0;
 134
 135         timer_counter = ioread32(davinci_wdt->base + TIM12);
 136         timer_counter |= ((u64)ioread32(davinci_wdt->base + TIM34) << 32);
 137
 138         do_div(timer_counter, freq);
 139
 140         return wdd->timeout - timer_counter;
 141 }
 142
 143 static const struct watchdog_info davinci_wdt_info = {
 144         .options = WDIOF_KEEPALIVEPING,
 145         .identity = "DaVinci/Keystone Watchdog",
 146 };
 147
 148 static const struct watchdog_ops davinci_wdt_ops = {
 149         .owner          = THIS_MODULE,
 150         .start          = davinci_wdt_start,
 151         .stop           = davinci_wdt_ping,
 152         .ping           = davinci_wdt_ping,
 153         .get_timeleft   = davinci_wdt_get_timeleft,
 154 };
 155
 156 static int davinci_wdt_probe(struct platform_device *pdev)
 157 {
 158         int ret = 0;
 159         struct device *dev = &pdev->dev;
 160         struct resource  *wdt_mem;
 161         struct watchdog_device *wdd;
 162         struct davinci_wdt_device *davinci_wdt;
 163
 164         davinci_wdt = devm_kzalloc(dev, sizeof(*davinci_wdt), GFP_KERNEL);
 165         if (!davinci_wdt)
 166                 return -ENOMEM;
 167
 168         davinci_wdt->clk = devm_clk_get(dev, NULL);
 169         if (WARN_ON(IS_ERR(davinci_wdt->clk)))
 170                 return PTR_ERR(davinci_wdt->clk);
 171
 172         clk_prepare_enable(davinci_wdt->clk);
 173
 174         platform_set_drvdata(pdev, davinci_wdt);
 175
 176         wdd                     = &davinci_wdt->wdd;
 177         wdd->info               = &davinci_wdt_info;
 178         wdd->ops                = &davinci_wdt_ops;
 179         wdd->min_timeout        = 1;
 180         wdd->max_timeout        = MAX_HEARTBEAT;
 181         wdd->timeout            = DEFAULT_HEARTBEAT;
 182         wdd->parent             = &pdev->dev;
 183
 184         watchdog_init_timeout(wdd, heartbeat, dev);
 185
 186         dev_info(dev, "heartbeat %d sec\n", wdd->timeout);
 187
 188         watchdog_set_drvdata(wdd, davinci_wdt);
 189         watchdog_set_nowayout(wdd, 1);
 190
 191         wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 192         davinci_wdt->base = devm_ioremap_resource(dev, wdt_mem);
 193         if (IS_ERR(davinci_wdt->base))
 194                 return PTR_ERR(davinci_wdt->base);
 195
 196         ret = watchdog_register_device(wdd);
 197         if (ret < 0)
 198                 dev_err(dev, "cannot register watchdog device\n");
 199
 200         return ret;
 201 }
 202
 203 static int davinci_wdt_remove(struct platform_device *pdev)
 204 {
 205         struct davinci_wdt_device *davinci_wdt = platform_get_drvdata(pdev);
 206
 207         watchdog_unregister_device(&davinci_wdt->wdd);
 208         clk_disable_unprepare(davinci_wdt->clk);
 209
 210         return 0;
 211 }
 212
 213 static const struct of_device_id davinci_wdt_of_match[] = {
 214         { .compatible = "ti,davinci-wdt", },
 215         {},
 216 };
 217 MODULE_DEVICE_TABLE(of, davinci_wdt_of_match);
 218
 219 static struct platform_driver platform_wdt_driver = {
 220         .driver = {
 221                 .name = "davinci-wdt",
 222                 .of_match_table = davinci_wdt_of_match,
 223         },
 224         .probe = davinci_wdt_probe,
 225         .remove = davinci_wdt_remove,
 226 };
 227
 228 module_platform_driver(platform_wdt_driver);
 229
 230 MODULE_AUTHOR("Texas Instruments");
 231 MODULE_DESCRIPTION("DaVinci Watchdog Driver");
 232
 233 module_param(heartbeat, int, 0);
 234 MODULE_PARM_DESC(heartbeat,
 235                  "Watchdog heartbeat period in seconds from 1 to "
 236                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 237                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 238
 239 MODULE_LICENSE("GPL");
 240 MODULE_ALIAS("platform:davinci-wdt");