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
56static int timeout = WDT_TIMEOUT;
57module_param(timeout, int, 0);
58MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds, between 1 and 1023 "
59 "(default = " __MODULE_STRING(WDT_TIMEOUT) ")");
60
61static bool nowayout = WATCHDOG_NOWAYOUT;
62module_param(nowayout, bool, 0);
63MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
64 "(default = " __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
65
66static struct watchdog_device wdt_dev;
67static struct resource wdt_res;
68static void __iomem *wdt_mem;
69static unsigned int mmio;
70static void wdt_timer_tick(struct timer_list *unused);
71static DEFINE_TIMER(timer, wdt_timer_tick);
72 /* The timer that pings the watchdog */
73static unsigned long next_heartbeat; /* the next_heartbeat for the timer */
74
75static inline void wdt_reset(void)
76{
77 unsigned int ctl = readl(addr: wdt_mem);
78
79 writel(val: ctl | VIA_WDT_TRIGGER, addr: 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 */
91static void wdt_timer_tick(struct timer_list *unused)
92{
93 if (time_before(jiffies, next_heartbeat) ||
94 (!watchdog_active(wdd: &wdt_dev))) {
95 wdt_reset();
96 mod_timer(timer: &timer, expires: jiffies + WDT_HEARTBEAT);
97 } else
98 pr_crit("I will reboot your machine !\n");
99}
100
101static 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
108static int wdt_start(struct watchdog_device *wdd)
109{
110 unsigned int ctl = readl(addr: wdt_mem);
111
112 writel(val: wdd->timeout, addr: wdt_mem + VIA_WDT_COUNT);
113 writel(val: ctl | VIA_WDT_RUNNING | VIA_WDT_TRIGGER, addr: wdt_mem);
114 wdt_ping(wdd);
115 mod_timer(timer: &timer, expires: jiffies + WDT_HEARTBEAT);
116 return 0;
117}
118
119static int wdt_stop(struct watchdog_device *wdd)
120{
121 unsigned int ctl = readl(addr: wdt_mem);
122
123 writel(val: ctl & ~VIA_WDT_RUNNING, addr: wdt_mem);
124 return 0;
125}
126
127static int wdt_set_timeout(struct watchdog_device *wdd,
128 unsigned int new_timeout)
129{
130 writel(val: new_timeout, addr: wdt_mem + VIA_WDT_COUNT);
131 wdd->timeout = new_timeout;
132 return 0;
133}
134
135static 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
143static 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
151static 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
158static 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(dev: 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(root: &iomem_resource, new: &wdt_res, VIA_WDT_MMIO_LEN,
176 min: 0xf0000000, max: 0xffffff00, align: 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(dev: pdev, VIA_WDT_MMIO_BASE, val: wdt_res.start);
182 pci_read_config_byte(dev: pdev, VIA_WDT_CONF, val: &conf);
183 conf |= VIA_WDT_CONF_ENABLE | VIA_WDT_CONF_MMIO;
184 pci_write_config_byte(dev: pdev, VIA_WDT_CONF, val: conf);
185
186 pci_read_config_dword(dev: pdev, VIA_WDT_MMIO_BASE, val: &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(offset: 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(wdd: &wdt_dev, nowayout);
211 if (readl(addr: 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: &timer, expires: jiffies + WDT_HEARTBEAT);
220 return 0;
221
222err_out_iounmap:
223 iounmap(addr: wdt_mem);
224err_out_release:
225 release_mem_region(mmio, VIA_WDT_MMIO_LEN);
226err_out_resource:
227 release_resource(new: &wdt_res);
228err_out_disable_device:
229 pci_disable_device(dev: pdev);
230 return ret;
231}
232
233static void wdt_remove(struct pci_dev *pdev)
234{
235 watchdog_unregister_device(&wdt_dev);
236 del_timer_sync(timer: &timer);
237 iounmap(addr: wdt_mem);
238 release_mem_region(mmio, VIA_WDT_MMIO_LEN);
239 release_resource(new: &wdt_res);
240 pci_disable_device(dev: pdev);
241}
242
243static 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
250static 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
257module_pci_driver(wdt_driver);
258
259MODULE_AUTHOR("Marc Vertes");
260MODULE_DESCRIPTION("Driver for watchdog timer on VIA chipset");
261MODULE_LICENSE("GPL");
262

source code of linux/drivers/watchdog/via_wdt.c