drivers/watchdog/pnx4008_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * drivers/char/watchdog/pnx4008_wdt.c
   4  *
   5  * Watchdog driver for PNX4008 board
   6  *
   7  * Authors: Dmitry Chigirev <source@mvista.com>,
   8  *          Vitaly Wool <vitalywool@gmail.com>
   9  * Based on sa1100 driver,
  10  * Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  11  *
  12  * 2005-2006 (c) MontaVista Software, Inc.
  13  *
  14  * (C) 2012 Wolfram Sang, Pengutronix
  15  */
  16
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/types.h>
  22 #include <linux/kernel.h>
  23 #include <linux/watchdog.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/clk.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/io.h>
  28 #include <linux/slab.h>
  29 #include <linux/err.h>
  30 #include <linux/of.h>
  31 #include <linux/delay.h>
  32 #include <linux/reboot.h>
  33
  34 /* WatchDog Timer - Chapter 23 Page 207 */
  35
  36 #define DEFAULT_HEARTBEAT 19
  37 #define MAX_HEARTBEAT     60
  38
  39 /* Watchdog timer register set definition */
  40 #define WDTIM_INT(p)     ((p) + 0x0)
  41 #define WDTIM_CTRL(p)    ((p) + 0x4)
  42 #define WDTIM_COUNTER(p) ((p) + 0x8)
  43 #define WDTIM_MCTRL(p)   ((p) + 0xC)
  44 #define WDTIM_MATCH0(p)  ((p) + 0x10)
  45 #define WDTIM_EMR(p)     ((p) + 0x14)
  46 #define WDTIM_PULSE(p)   ((p) + 0x18)
  47 #define WDTIM_RES(p)     ((p) + 0x1C)
  48
  49 /* WDTIM_INT bit definitions */
  50 #define MATCH_INT      1
  51
  52 /* WDTIM_CTRL bit definitions */
  53 #define COUNT_ENAB     1
  54 #define RESET_COUNT    (1 << 1)
  55 #define DEBUG_EN       (1 << 2)
  56
  57 /* WDTIM_MCTRL bit definitions */
  58 #define MR0_INT        1
  59 #undef  RESET_COUNT0
  60 #define RESET_COUNT0   (1 << 2)
  61 #define STOP_COUNT0    (1 << 2)
  62 #define M_RES1         (1 << 3)
  63 #define M_RES2         (1 << 4)
  64 #define RESFRC1        (1 << 5)
  65 #define RESFRC2        (1 << 6)
  66
  67 /* WDTIM_EMR bit definitions */
  68 #define EXT_MATCH0      1
  69 #define MATCH_OUTPUT_HIGH (2 << 4)      /*a MATCH_CTRL setting */
  70
  71 /* WDTIM_RES bit definitions */
  72 #define WDOG_RESET      1       /* read only */
  73
  74 #define WDOG_COUNTER_RATE 13000000      /*the counter clock is 13 MHz fixed */
  75
  76 static bool nowayout = WATCHDOG_NOWAYOUT;
  77 static unsigned int heartbeat;
  78
  79 static DEFINE_SPINLOCK(io_lock);
  80 static void __iomem     *wdt_base;
  81 static struct clk       *wdt_clk;
  82
  83 static int pnx4008_wdt_start(struct watchdog_device *wdd)
  84 {
  85         spin_lock(&io_lock);
  86
  87         /* stop counter, initiate counter reset */
  88         writel(RESET_COUNT, WDTIM_CTRL(wdt_base));
  89         /*wait for reset to complete. 100% guarantee event */
  90         while (readl(WDTIM_COUNTER(wdt_base)))
  91                 cpu_relax();
  92         /* internal and external reset, stop after that */
  93         writel(M_RES2 | STOP_COUNT0 | RESET_COUNT0, WDTIM_MCTRL(wdt_base));
  94         /* configure match output */
  95         writel(MATCH_OUTPUT_HIGH, WDTIM_EMR(wdt_base));
  96         /* clear interrupt, just in case */
  97         writel(MATCH_INT, WDTIM_INT(wdt_base));
  98         /* the longest pulse period 65541/(13*10^6) seconds ~ 5 ms. */
  99         writel(0xFFFF, WDTIM_PULSE(wdt_base));
 100         writel(wdd->timeout * WDOG_COUNTER_RATE, WDTIM_MATCH0(wdt_base));
 101         /*enable counter, stop when debugger active */
 102         writel(COUNT_ENAB | DEBUG_EN, WDTIM_CTRL(wdt_base));
 103
 104         spin_unlock(&io_lock);
 105         return 0;
 106 }
 107
 108 static int pnx4008_wdt_stop(struct watchdog_device *wdd)
 109 {
 110         spin_lock(&io_lock);
 111
 112         writel(0, WDTIM_CTRL(wdt_base));        /*stop counter */
 113
 114         spin_unlock(&io_lock);
 115         return 0;
 116 }
 117
 118 static int pnx4008_wdt_set_timeout(struct watchdog_device *wdd,
 119                                     unsigned int new_timeout)
 120 {
 121         wdd->timeout = new_timeout;
 122         return 0;
 123 }
 124
 125 static int pnx4008_restart_handler(struct watchdog_device *wdd,
 126                                    unsigned long mode, void *cmd)
 127 {
 128         const char *boot_cmd = cmd;
 129
 130         /*
 131          * Verify if a "cmd" passed from the userspace program rebooting
 132          * the system; if available, handle it.
 133          * - For details, see the 'reboot' syscall in kernel/reboot.c
 134          * - If the received "cmd" is not supported, use the default mode.
 135          */
 136         if (boot_cmd) {
 137                 if (boot_cmd[0] == 'h')
 138                         mode = REBOOT_HARD;
 139                 else if (boot_cmd[0] == 's')
 140                         mode = REBOOT_SOFT;
 141         }
 142
 143         if (mode == REBOOT_SOFT) {
 144                 /* Force match output active */
 145                 writel(EXT_MATCH0, WDTIM_EMR(wdt_base));
 146                 /* Internal reset on match output (RESOUT_N not asserted) */
 147                 writel(M_RES1, WDTIM_MCTRL(wdt_base));
 148         } else {
 149                 /* Instant assert of RESETOUT_N with pulse length 1mS */
 150                 writel(13000, WDTIM_PULSE(wdt_base));
 151                 writel(M_RES2 | RESFRC1 | RESFRC2, WDTIM_MCTRL(wdt_base));
 152         }
 153
 154         /* Wait for watchdog to reset system */
 155         mdelay(1000);
 156
 157         return NOTIFY_DONE;
 158 }
 159
 160 static const struct watchdog_info pnx4008_wdt_ident = {
 161         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
 162             WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 163         .identity = "PNX4008 Watchdog",
 164 };
 165
 166 static const struct watchdog_ops pnx4008_wdt_ops = {
 167         .owner = THIS_MODULE,
 168         .start = pnx4008_wdt_start,
 169         .stop = pnx4008_wdt_stop,
 170         .set_timeout = pnx4008_wdt_set_timeout,
 171         .restart = pnx4008_restart_handler,
 172 };
 173
 174 static struct watchdog_device pnx4008_wdd = {
 175         .info = &pnx4008_wdt_ident,
 176         .ops = &pnx4008_wdt_ops,
 177         .timeout = DEFAULT_HEARTBEAT,
 178         .min_timeout = 1,
 179         .max_timeout = MAX_HEARTBEAT,
 180 };
 181
 182 static void pnx4008_clk_disable_unprepare(void *data)
 183 {
 184         clk_disable_unprepare(data);
 185 }
 186
 187 static int pnx4008_wdt_probe(struct platform_device *pdev)
 188 {
 189         struct device *dev = &pdev->dev;
 190         int ret = 0;
 191
 192         watchdog_init_timeout(&pnx4008_wdd, heartbeat, dev);
 193
 194         wdt_base = devm_platform_ioremap_resource(pdev, 0);
 195         if (IS_ERR(wdt_base))
 196                 return PTR_ERR(wdt_base);
 197
 198         wdt_clk = devm_clk_get(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         ret = devm_add_action_or_reset(dev, pnx4008_clk_disable_unprepare,
 206                                        wdt_clk);
 207         if (ret)
 208                 return ret;
 209
 210         pnx4008_wdd.bootstatus = (readl(WDTIM_RES(wdt_base)) & WDOG_RESET) ?
 211                         WDIOF_CARDRESET : 0;
 212         pnx4008_wdd.parent = dev;
 213         watchdog_set_nowayout(&pnx4008_wdd, nowayout);
 214         watchdog_set_restart_priority(&pnx4008_wdd, 128);
 215
 216         if (readl(WDTIM_CTRL(wdt_base)) & COUNT_ENAB)
 217                 set_bit(WDOG_HW_RUNNING, &pnx4008_wdd.status);
 218
 219         ret = devm_watchdog_register_device(dev, &pnx4008_wdd);
 220         if (ret < 0)
 221                 return ret;
 222
 223         dev_info(dev, "heartbeat %d sec\n", pnx4008_wdd.timeout);
 224
 225         return 0;
 226 }
 227
 228 #ifdef CONFIG_OF
 229 static const struct of_device_id pnx4008_wdt_match[] = {
 230         { .compatible = "nxp,pnx4008-wdt" },
 231         { }
 232 };
 233 MODULE_DEVICE_TABLE(of, pnx4008_wdt_match);
 234 #endif
 235
 236 static struct platform_driver platform_wdt_driver = {
 237         .driver = {
 238                 .name = "pnx4008-watchdog",
 239                 .of_match_table = of_match_ptr(pnx4008_wdt_match),
 240         },
 241         .probe = pnx4008_wdt_probe,
 242 };
 243
 244 module_platform_driver(platform_wdt_driver);
 245
 246 MODULE_AUTHOR("MontaVista Software, Inc. <source@mvista.com>");
 247 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
 248 MODULE_DESCRIPTION("PNX4008 Watchdog Driver");
 249
 250 module_param(heartbeat, uint, 0);
 251 MODULE_PARM_DESC(heartbeat,
 252                  "Watchdog heartbeat period in seconds from 1 to "
 253                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 254                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 255
 256 module_param(nowayout, bool, 0);
 257 MODULE_PARM_DESC(nowayout,
 258                  "Set to 1 to keep watchdog running after device release");
 259
 260 MODULE_LICENSE("GPL");
 261 MODULE_ALIAS("platform:pnx4008-watchdog");