2 * VIA Chipset Watchdog Driver
4 * Copyright (C) 2011 Sigfox
5 * License terms: GNU General Public License (GPL) version 2
6 * Author: Marc Vertes <marc.vertes@sigfox.com>
7 * Based on a preliminary version from Harald Welte <HaraldWelte@viatech.com>
8 * Timer code by Wim Van Sebroeck <wim@iguana.be>
10 * Caveat: PnP must be enabled in BIOS to allow full access to watchdog
11 * control registers. If not, the watchdog must be configured in BIOS manually.
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
16 #include <linux/device.h>
18 #include <linux/jiffies.h>
19 #include <linux/module.h>
20 #include <linux/pci.h>
21 #include <linux/timer.h>
22 #include <linux/watchdog.h>
24 /* Configuration registers relative to the pci device */
25 #define VIA_WDT_MMIO_BASE 0xe8 /* MMIO region base address */
26 #define VIA_WDT_CONF 0xec /* watchdog enable state */
28 /* Relevant bits for the VIA_WDT_CONF register */
29 #define VIA_WDT_CONF_ENABLE 0x01 /* 1: enable watchdog */
30 #define VIA_WDT_CONF_MMIO 0x02 /* 1: enable watchdog MMIO */
33 * The MMIO region contains the watchog control register and the
34 * hardware timer counter.
36 #define VIA_WDT_MMIO_LEN 8 /* MMIO region length in bytes */
37 #define VIA_WDT_CTL 0 /* MMIO addr+0: state/control reg. */
38 #define VIA_WDT_COUNT 4 /* MMIO addr+4: timer counter reg. */
40 /* Bits for the VIA_WDT_CTL register */
41 #define VIA_WDT_RUNNING 0x01 /* 0: stop, 1: running */
42 #define VIA_WDT_FIRED 0x02 /* 1: restarted by expired watchdog */
43 #define VIA_WDT_PWROFF 0x04 /* 0: reset, 1: poweroff */
44 #define VIA_WDT_DISABLED 0x08 /* 1: timer is disabled */
45 #define VIA_WDT_TRIGGER 0x80 /* 1: start a new countdown */
47 /* Hardware heartbeat in seconds */
48 #define WDT_HW_HEARTBEAT 1
50 /* Timer heartbeat (500ms) */
51 #define WDT_HEARTBEAT (HZ/2) /* should be <= ((WDT_HW_HEARTBEAT*HZ)/2) */
53 /* User space timeout in seconds */
54 #define WDT_TIMEOUT_MAX 1023 /* approx. 17 min. */
55 #define WDT_TIMEOUT 60
56 static int timeout = WDT_TIMEOUT;
57 module_param(timeout, int, 0);
58 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds, between 1 and 1023 "
59 "(default = " __MODULE_STRING(WDT_TIMEOUT) ")");
61 static bool nowayout = WATCHDOG_NOWAYOUT;
62 module_param(nowayout, bool, 0);
63 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
64 "(default = " __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
66 static struct watchdog_device wdt_dev;
67 static struct resource wdt_res;
68 static void __iomem *wdt_mem;
69 static unsigned int mmio;
70 static void wdt_timer_tick(unsigned long data);
71 static DEFINE_TIMER(timer, wdt_timer_tick, 0, 0);
72 /* The timer that pings the watchdog */
73 static unsigned long next_heartbeat; /* the next_heartbeat for the timer */
75 static inline void wdt_reset(void)
77 unsigned int ctl = readl(wdt_mem);
79 writel(ctl | VIA_WDT_TRIGGER, wdt_mem);
83 * Timer tick: the timer will make sure that the watchdog timer hardware
84 * is being reset in time. The conditions to do this are:
85 * 1) the watchog timer has been started and /dev/watchdog is open
86 * and there is still time left before userspace should send the
87 * next heartbeat/ping. (note: the internal heartbeat is much smaller
88 * then the external/userspace heartbeat).
89 * 2) the watchdog timer has been stopped by userspace.
91 static void wdt_timer_tick(unsigned long data)
93 if (time_before(jiffies, next_heartbeat) ||
94 (!watchdog_active(&wdt_dev))) {
96 mod_timer(&timer, jiffies + WDT_HEARTBEAT);
98 pr_crit("I will reboot your machine !\n");
101 static int wdt_ping(struct watchdog_device *wdd)
103 /* calculate when the next userspace timeout will be */
104 next_heartbeat = jiffies + wdd->timeout * HZ;
108 static int wdt_start(struct watchdog_device *wdd)
110 unsigned int ctl = readl(wdt_mem);
112 writel(wdd->timeout, wdt_mem + VIA_WDT_COUNT);
113 writel(ctl | VIA_WDT_RUNNING | VIA_WDT_TRIGGER, wdt_mem);
115 mod_timer(&timer, jiffies + WDT_HEARTBEAT);
119 static int wdt_stop(struct watchdog_device *wdd)
121 unsigned int ctl = readl(wdt_mem);
123 writel(ctl & ~VIA_WDT_RUNNING, wdt_mem);
127 static int wdt_set_timeout(struct watchdog_device *wdd,
128 unsigned int new_timeout)
130 writel(new_timeout, wdt_mem + VIA_WDT_COUNT);
131 wdd->timeout = new_timeout;
135 static const struct watchdog_info wdt_info = {
136 .identity = "VIA watchdog",
137 .options = WDIOF_CARDRESET |
143 static const struct watchdog_ops wdt_ops = {
144 .owner = THIS_MODULE,
148 .set_timeout = wdt_set_timeout,
151 static struct watchdog_device wdt_dev = {
155 .max_timeout = WDT_TIMEOUT_MAX,
158 static int wdt_probe(struct pci_dev *pdev,
159 const struct pci_device_id *ent)
164 if (pci_enable_device(pdev)) {
165 dev_err(&pdev->dev, "cannot enable PCI device\n");
170 * Allocate a MMIO region which contains watchdog control register
171 * and counter, then configure the watchdog to use this region.
172 * This is possible only if PnP is properly enabled in BIOS.
173 * If not, the watchdog must be configured in BIOS manually.
175 if (allocate_resource(&iomem_resource, &wdt_res, VIA_WDT_MMIO_LEN,
176 0xf0000000, 0xffffff00, 0xff, NULL, NULL)) {
177 dev_err(&pdev->dev, "MMIO allocation failed\n");
178 goto err_out_disable_device;
181 pci_write_config_dword(pdev, VIA_WDT_MMIO_BASE, wdt_res.start);
182 pci_read_config_byte(pdev, VIA_WDT_CONF, &conf);
183 conf |= VIA_WDT_CONF_ENABLE | VIA_WDT_CONF_MMIO;
184 pci_write_config_byte(pdev, VIA_WDT_CONF, conf);
186 pci_read_config_dword(pdev, VIA_WDT_MMIO_BASE, &mmio);
188 dev_info(&pdev->dev, "VIA Chipset watchdog MMIO: %x\n", mmio);
190 dev_err(&pdev->dev, "MMIO setting failed. Check BIOS.\n");
191 goto err_out_resource;
194 if (!request_mem_region(mmio, VIA_WDT_MMIO_LEN, "via_wdt")) {
195 dev_err(&pdev->dev, "MMIO region busy\n");
196 goto err_out_resource;
199 wdt_mem = ioremap(mmio, VIA_WDT_MMIO_LEN);
200 if (wdt_mem == NULL) {
201 dev_err(&pdev->dev, "cannot remap VIA wdt MMIO registers\n");
202 goto err_out_release;
205 if (timeout < 1 || timeout > WDT_TIMEOUT_MAX)
206 timeout = WDT_TIMEOUT;
208 wdt_dev.timeout = timeout;
209 watchdog_set_nowayout(&wdt_dev, nowayout);
210 if (readl(wdt_mem) & VIA_WDT_FIRED)
211 wdt_dev.bootstatus |= WDIOF_CARDRESET;
213 ret = watchdog_register_device(&wdt_dev);
215 goto err_out_iounmap;
217 /* start triggering, in case of watchdog already enabled by BIOS */
218 mod_timer(&timer, jiffies + WDT_HEARTBEAT);
224 release_mem_region(mmio, VIA_WDT_MMIO_LEN);
226 release_resource(&wdt_res);
227 err_out_disable_device:
228 pci_disable_device(pdev);
232 static void wdt_remove(struct pci_dev *pdev)
234 watchdog_unregister_device(&wdt_dev);
235 del_timer_sync(&timer);
237 release_mem_region(mmio, VIA_WDT_MMIO_LEN);
238 release_resource(&wdt_res);
239 pci_disable_device(pdev);
242 static const struct pci_device_id wdt_pci_table[] = {
243 { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_CX700) },
244 { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VX800) },
245 { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VX855) },
249 static struct pci_driver wdt_driver = {
251 .id_table = wdt_pci_table,
253 .remove = wdt_remove,
256 module_pci_driver(wdt_driver);
258 MODULE_AUTHOR("Marc Vertes");
259 MODULE_DESCRIPTION("Driver for watchdog timer on VIA chipset");
260 MODULE_LICENSE("GPL");