1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * VIA Chipset Watchdog Driver
4 *
5 * Copyright (C) 2011 Sigfox
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>
9 *
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.
12 */
13
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16 #include <linux/device.h>
17 #include <linux/io.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>
23
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 */
27
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 */
31
32 /*
33 * The MMIO region contains the watchdog control register and the
34 * hardware timer counter.
35 */
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. */
39
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 */
46
47 /* Hardware heartbeat in seconds */
48 #define WDT_HW_HEARTBEAT 1
49
50 /* Timer heartbeat (500ms) */
51 #define WDT_HEARTBEAT (HZ/2) /* should be <= ((WDT_HW_HEARTBEAT*HZ)/2) */
52
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) ")");
60
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) ")");
65
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(struct timer_list *unused);
71 static DEFINE_TIMER(timer, wdt_timer_tick);
72 /* The timer that pings the watchdog */
73 static unsigned long next_heartbeat; /* the next_heartbeat for the timer */
74
wdt_reset(void)75 static inline void wdt_reset(void)
76 {
77 unsigned int ctl = readl(wdt_mem);
78
79 writel(ctl | VIA_WDT_TRIGGER, wdt_mem);
80 }
81
82 /*
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 watchdog 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.
90 */
wdt_timer_tick(struct timer_list * unused)91 static void wdt_timer_tick(struct timer_list *unused)
92 {
93 if (time_before(jiffies, next_heartbeat) ||
94 (!watchdog_active(&wdt_dev))) {
95 wdt_reset();
96 mod_timer(&timer, jiffies + WDT_HEARTBEAT);
97 } else
98 pr_crit("I will reboot your machine !\n");
99 }
100
wdt_ping(struct watchdog_device * wdd)101 static int wdt_ping(struct watchdog_device *wdd)
102 {
103 /* calculate when the next userspace timeout will be */
104 next_heartbeat = jiffies + wdd->timeout * HZ;
105 return 0;
106 }
107
wdt_start(struct watchdog_device * wdd)108 static int wdt_start(struct watchdog_device *wdd)
109 {
110 unsigned int ctl = readl(wdt_mem);
111
112 writel(wdd->timeout, wdt_mem + VIA_WDT_COUNT);
113 writel(ctl | VIA_WDT_RUNNING | VIA_WDT_TRIGGER, wdt_mem);
114 wdt_ping(wdd);
115 mod_timer(&timer, jiffies + WDT_HEARTBEAT);
116 return 0;
117 }
118
wdt_stop(struct watchdog_device * wdd)119 static int wdt_stop(struct watchdog_device *wdd)
120 {
121 unsigned int ctl = readl(wdt_mem);
122
123 writel(ctl & ~VIA_WDT_RUNNING, wdt_mem);
124 return 0;
125 }
126
wdt_set_timeout(struct watchdog_device * wdd,unsigned int new_timeout)127 static int wdt_set_timeout(struct watchdog_device *wdd,
128 unsigned int new_timeout)
129 {
130 writel(new_timeout, wdt_mem + VIA_WDT_COUNT);
131 wdd->timeout = new_timeout;
132 return 0;
133 }
134
135 static const struct watchdog_info wdt_info = {
136 .identity = "VIA watchdog",
137 .options = WDIOF_CARDRESET |
138 WDIOF_SETTIMEOUT |
139 WDIOF_MAGICCLOSE |
140 WDIOF_KEEPALIVEPING,
141 };
142
143 static const struct watchdog_ops wdt_ops = {
144 .owner = THIS_MODULE,
145 .start = wdt_start,
146 .stop = wdt_stop,
147 .ping = wdt_ping,
148 .set_timeout = wdt_set_timeout,
149 };
150
151 static struct watchdog_device wdt_dev = {
152 .info = &wdt_info,
153 .ops = &wdt_ops,
154 .min_timeout = 1,
155 .max_timeout = WDT_TIMEOUT_MAX,
156 };
157
wdt_probe(struct pci_dev * pdev,const struct pci_device_id * ent)158 static int wdt_probe(struct pci_dev *pdev,
159 const struct pci_device_id *ent)
160 {
161 unsigned char conf;
162 int ret = -ENODEV;
163
164 if (pci_enable_device(pdev)) {
165 dev_err(&pdev->dev, "cannot enable PCI device\n");
166 return -ENODEV;
167 }
168
169 /*
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.
174 */
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;
179 }
180
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);
185
186 pci_read_config_dword(pdev, VIA_WDT_MMIO_BASE, &mmio);
187 if (mmio) {
188 dev_info(&pdev->dev, "VIA Chipset watchdog MMIO: %x\n", mmio);
189 } else {
190 dev_err(&pdev->dev, "MMIO setting failed. Check BIOS.\n");
191 goto err_out_resource;
192 }
193
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;
197 }
198
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;
203 }
204
205 if (timeout < 1 || timeout > WDT_TIMEOUT_MAX)
206 timeout = WDT_TIMEOUT;
207
208 wdt_dev.timeout = timeout;
209 wdt_dev.parent = &pdev->dev;
210 watchdog_set_nowayout(&wdt_dev, nowayout);
211 if (readl(wdt_mem) & VIA_WDT_FIRED)
212 wdt_dev.bootstatus |= WDIOF_CARDRESET;
213
214 ret = watchdog_register_device(&wdt_dev);
215 if (ret)
216 goto err_out_iounmap;
217
218 /* start triggering, in case of watchdog already enabled by BIOS */
219 mod_timer(&timer, jiffies + WDT_HEARTBEAT);
220 return 0;
221
222 err_out_iounmap:
223 iounmap(wdt_mem);
224 err_out_release:
225 release_mem_region(mmio, VIA_WDT_MMIO_LEN);
226 err_out_resource:
227 release_resource(&wdt_res);
228 err_out_disable_device:
229 pci_disable_device(pdev);
230 return ret;
231 }
232
wdt_remove(struct pci_dev * pdev)233 static void wdt_remove(struct pci_dev *pdev)
234 {
235 watchdog_unregister_device(&wdt_dev);
236 del_timer_sync(&timer);
237 iounmap(wdt_mem);
238 release_mem_region(mmio, VIA_WDT_MMIO_LEN);
239 release_resource(&wdt_res);
240 pci_disable_device(pdev);
241 }
242
243 static const struct pci_device_id wdt_pci_table[] = {
244 { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_CX700) },
245 { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VX800) },
246 { PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VX855) },
247 { 0 }
248 };
249
250 static struct pci_driver wdt_driver = {
251 .name = "via_wdt",
252 .id_table = wdt_pci_table,
253 .probe = wdt_probe,
254 .remove = wdt_remove,
255 };
256
257 module_pci_driver(wdt_driver);
258
259 MODULE_AUTHOR("Marc Vertes");
260 MODULE_DESCRIPTION("Driver for watchdog timer on VIA chipset");
261 MODULE_LICENSE("GPL");
262