drivers/watchdog/pnx4008_wdt.c

   1 /*
   2  * drivers/char/watchdog/pnx4008_wdt.c
   3  *
   4  * Watchdog driver for PNX4008 board
   5  *
   6  * Authors: Dmitry Chigirev <source@mvista.com>,
   7  *          Vitaly Wool <vitalywool@gmail.com>
   8  * Based on sa1100 driver,
   9  * Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  10  *
  11  * 2005-2006 (c) MontaVista Software, Inc.
  12  *
  13  * (C) 2012 Wolfram Sang, Pengutronix
  14  *
  15  * This file is licensed under the terms of the GNU General Public License
  16  * version 2. This program is licensed "as is" without any warranty of any
  17  * kind, whether express or implied.
  18  */
  19
  20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/types.h>
  25 #include <linux/kernel.h>
  26 #include <linux/watchdog.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/clk.h>
  29 #include <linux/spinlock.h>
  30 #include <linux/io.h>
  31 #include <linux/slab.h>
  32 #include <linux/err.h>
  33 #include <linux/of.h>
  34 #include <linux/delay.h>
  35 #include <linux/reboot.h>
  36 #include <mach/hardware.h>
  37
  38 /* WatchDog Timer - Chapter 23 Page 207 */
  39
  40 #define DEFAULT_HEARTBEAT 19
  41 #define MAX_HEARTBEAT     60
  42
  43 /* Watchdog timer register set definition */
  44 #define WDTIM_INT(p)     ((p) + 0x0)
  45 #define WDTIM_CTRL(p)    ((p) + 0x4)
  46 #define WDTIM_COUNTER(p) ((p) + 0x8)
  47 #define WDTIM_MCTRL(p)   ((p) + 0xC)
  48 #define WDTIM_MATCH0(p)  ((p) + 0x10)
  49 #define WDTIM_EMR(p)     ((p) + 0x14)
  50 #define WDTIM_PULSE(p)   ((p) + 0x18)
  51 #define WDTIM_RES(p)     ((p) + 0x1C)
  52
  53 /* WDTIM_INT bit definitions */
  54 #define MATCH_INT      1
  55
  56 /* WDTIM_CTRL bit definitions */
  57 #define COUNT_ENAB     1
  58 #define RESET_COUNT    (1 << 1)
  59 #define DEBUG_EN       (1 << 2)
  60
  61 /* WDTIM_MCTRL bit definitions */
  62 #define MR0_INT        1
  63 #undef  RESET_COUNT0
  64 #define RESET_COUNT0   (1 << 2)
  65 #define STOP_COUNT0    (1 << 2)
  66 #define M_RES1         (1 << 3)
  67 #define M_RES2         (1 << 4)
  68 #define RESFRC1        (1 << 5)
  69 #define RESFRC2        (1 << 6)
  70
  71 /* WDTIM_EMR bit definitions */
  72 #define EXT_MATCH0      1
  73 #define MATCH_OUTPUT_HIGH (2 << 4)      /*a MATCH_CTRL setting */
  74
  75 /* WDTIM_RES bit definitions */
  76 #define WDOG_RESET      1       /* read only */
  77
  78 #define WDOG_COUNTER_RATE 13000000      /*the counter clock is 13 MHz fixed */
  79
  80 static bool nowayout = WATCHDOG_NOWAYOUT;
  81 static unsigned int heartbeat;
  82
  83 static DEFINE_SPINLOCK(io_lock);
  84 static void __iomem     *wdt_base;
  85 static struct clk       *wdt_clk;
  86
  87 static int pnx4008_wdt_start(struct watchdog_device *wdd)
  88 {
  89         spin_lock(&io_lock);
  90
  91         /* stop counter, initiate counter reset */
  92         writel(RESET_COUNT, WDTIM_CTRL(wdt_base));
  93         /*wait for reset to complete. 100% guarantee event */
  94         while (readl(WDTIM_COUNTER(wdt_base)))
  95                 cpu_relax();
  96         /* internal and external reset, stop after that */
  97         writel(M_RES2 | STOP_COUNT0 | RESET_COUNT0, WDTIM_MCTRL(wdt_base));
  98         /* configure match output */
  99         writel(MATCH_OUTPUT_HIGH, WDTIM_EMR(wdt_base));
 100         /* clear interrupt, just in case */
 101         writel(MATCH_INT, WDTIM_INT(wdt_base));
 102         /* the longest pulse period 65541/(13*10^6) seconds ~ 5 ms. */
 103         writel(0xFFFF, WDTIM_PULSE(wdt_base));
 104         writel(wdd->timeout * WDOG_COUNTER_RATE, WDTIM_MATCH0(wdt_base));
 105         /*enable counter, stop when debugger active */
 106         writel(COUNT_ENAB | DEBUG_EN, WDTIM_CTRL(wdt_base));
 107
 108         spin_unlock(&io_lock);
 109         return 0;
 110 }
 111
 112 static int pnx4008_wdt_stop(struct watchdog_device *wdd)
 113 {
 114         spin_lock(&io_lock);
 115
 116         writel(0, WDTIM_CTRL(wdt_base));        /*stop counter */
 117
 118         spin_unlock(&io_lock);
 119         return 0;
 120 }
 121
 122 static int pnx4008_wdt_set_timeout(struct watchdog_device *wdd,
 123                                     unsigned int new_timeout)
 124 {
 125         wdd->timeout = new_timeout;
 126         return 0;
 127 }
 128
 129 static int pnx4008_restart_handler(struct watchdog_device *wdd,
 130                                    unsigned long mode, void *cmd)
 131 {
 132         const char *boot_cmd = cmd;
 133
 134         /*
 135          * Verify if a "cmd" passed from the userspace program rebooting
 136          * the system; if available, handle it.
 137          * - For details, see the 'reboot' syscall in kernel/reboot.c
 138          * - If the received "cmd" is not supported, use the default mode.
 139          */
 140         if (boot_cmd) {
 141                 if (boot_cmd[0] == 'h')
 142                         mode = REBOOT_HARD;
 143                 else if (boot_cmd[0] == 's')
 144                         mode = REBOOT_SOFT;
 145         }
 146
 147         if (mode == REBOOT_SOFT) {
 148                 /* Force match output active */
 149                 writel(EXT_MATCH0, WDTIM_EMR(wdt_base));
 150                 /* Internal reset on match output (RESOUT_N not asserted) */
 151                 writel(M_RES1, WDTIM_MCTRL(wdt_base));
 152         } else {
 153                 /* Instant assert of RESETOUT_N with pulse length 1mS */
 154                 writel(13000, WDTIM_PULSE(wdt_base));
 155                 writel(M_RES2 | RESFRC1 | RESFRC2, WDTIM_MCTRL(wdt_base));
 156         }
 157
 158         /* Wait for watchdog to reset system */
 159         mdelay(1000);
 160
 161         return NOTIFY_DONE;
 162 }
 163
 164 static const struct watchdog_info pnx4008_wdt_ident = {
 165         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
 166             WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 167         .identity = "PNX4008 Watchdog",
 168 };
 169
 170 static const struct watchdog_ops pnx4008_wdt_ops = {
 171         .owner = THIS_MODULE,
 172         .start = pnx4008_wdt_start,
 173         .stop = pnx4008_wdt_stop,
 174         .set_timeout = pnx4008_wdt_set_timeout,
 175         .restart = pnx4008_restart_handler,
 176 };
 177
 178 static struct watchdog_device pnx4008_wdd = {
 179         .info = &pnx4008_wdt_ident,
 180         .ops = &pnx4008_wdt_ops,
 181         .timeout = DEFAULT_HEARTBEAT,
 182         .min_timeout = 1,
 183         .max_timeout = MAX_HEARTBEAT,
 184 };
 185
 186 static int pnx4008_wdt_probe(struct platform_device *pdev)
 187 {
 188         struct resource *r;
 189         int ret = 0;
 190
 191         watchdog_init_timeout(&pnx4008_wdd, heartbeat, &pdev->dev);
 192
 193         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 194         wdt_base = devm_ioremap_resource(&pdev->dev, r);
 195         if (IS_ERR(wdt_base))
 196                 return PTR_ERR(wdt_base);
 197
 198         wdt_clk = devm_clk_get(&pdev->dev, NULL);
 199         if (IS_ERR(wdt_clk))
 200                 return PTR_ERR(wdt_clk);
 201
 202         ret = clk_prepare_enable(wdt_clk);
 203         if (ret)
 204                 return ret;
 205
 206         pnx4008_wdd.bootstatus = (readl(WDTIM_RES(wdt_base)) & WDOG_RESET) ?
 207                         WDIOF_CARDRESET : 0;
 208         pnx4008_wdd.parent = &pdev->dev;
 209         watchdog_set_nowayout(&pnx4008_wdd, nowayout);
 210         watchdog_set_restart_priority(&pnx4008_wdd, 128);
 211
 212         pnx4008_wdt_stop(&pnx4008_wdd); /* disable for now */
 213
 214         ret = watchdog_register_device(&pnx4008_wdd);
 215         if (ret < 0) {
 216                 dev_err(&pdev->dev, "cannot register watchdog device\n");
 217                 goto disable_clk;
 218         }
 219
 220         dev_info(&pdev->dev, "heartbeat %d sec\n", pnx4008_wdd.timeout);
 221
 222         return 0;
 223
 224 disable_clk:
 225         clk_disable_unprepare(wdt_clk);
 226         return ret;
 227 }
 228
 229 static int pnx4008_wdt_remove(struct platform_device *pdev)
 230 {
 231         watchdog_unregister_device(&pnx4008_wdd);
 232
 233         clk_disable_unprepare(wdt_clk);
 234
 235         return 0;
 236 }
 237
 238 #ifdef CONFIG_OF
 239 static const struct of_device_id pnx4008_wdt_match[] = {
 240         { .compatible = "nxp,pnx4008-wdt" },
 241         { }
 242 };
 243 MODULE_DEVICE_TABLE(of, pnx4008_wdt_match);
 244 #endif
 245
 246 static struct platform_driver platform_wdt_driver = {
 247         .driver = {
 248                 .name = "pnx4008-watchdog",
 249                 .of_match_table = of_match_ptr(pnx4008_wdt_match),
 250         },
 251         .probe = pnx4008_wdt_probe,
 252         .remove = pnx4008_wdt_remove,
 253 };
 254
 255 module_platform_driver(platform_wdt_driver);
 256
 257 MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
 258 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
 259 MODULE_DESCRIPTION("PNX4008 Watchdog Driver");
 260
 261 module_param(heartbeat, uint, 0);
 262 MODULE_PARM_DESC(heartbeat,
 263                  "Watchdog heartbeat period in seconds from 1 to "
 264                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 265                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 266
 267 module_param(nowayout, bool, 0);
 268 MODULE_PARM_DESC(nowayout,
 269                  "Set to 1 to keep watchdog running after device release");
 270
 271 MODULE_LICENSE("GPL");
 272 MODULE_ALIAS("platform:pnx4008-watchdog");