1/*
  2 * Copyright (C) 2008-2009 Avionic Design GmbH
  3 *
  4 * This program is free software; you can redistribute it and/or modify
  5 * it under the terms of the GNU General Public License version 2 as
  6 * published by the Free Software Foundation.
  7 */
  8
  9#include <linux/fs.h>
 10#include <linux/gfp.h>
 11#include <linux/io.h>
 12#include <linux/miscdevice.h>
 13#include <linux/module.h>
 14#include <linux/platform_device.h>
 15#include <linux/types.h>
 16#include <linux/uaccess.h>
 17#include <linux/watchdog.h>
 18
 19#define WATCHDOG_NAME "adx-wdt"
 20
 21/* register offsets */
 22#define	ADX_WDT_CONTROL		0x00
 23#define	ADX_WDT_CONTROL_ENABLE	(1 << 0)
 24#define	ADX_WDT_CONTROL_nRESET	(1 << 1)
 25#define	ADX_WDT_TIMEOUT		0x08
 26
 27static struct platform_device *adx_wdt_dev;
 28static unsigned long driver_open;
 29
 30#define	WDT_STATE_STOP	0
 31#define	WDT_STATE_START	1
 32
 33struct adx_wdt {
 34	void __iomem *base;
 35	unsigned long timeout;
 36	unsigned int state;
 37	unsigned int wake;
 38	spinlock_t lock;
 39};
 40
 41static const struct watchdog_info adx_wdt_info = {
 42	.identity = "Avionic Design Xanthos Watchdog",
 43	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 44};
 45
 46static void adx_wdt_start_locked(struct adx_wdt *wdt)
 47{
 48	u32 ctrl;
 49
 50	ctrl = readl(wdt->base + ADX_WDT_CONTROL);
 51	ctrl |= ADX_WDT_CONTROL_ENABLE;
 52	writel(ctrl, wdt->base + ADX_WDT_CONTROL);
 53	wdt->state = WDT_STATE_START;
 54}
 55
 56static void adx_wdt_start(struct adx_wdt *wdt)
 57{
 58	unsigned long flags;
 59
 60	spin_lock_irqsave(&wdt->lock, flags);
 61	adx_wdt_start_locked(wdt);
 62	spin_unlock_irqrestore(&wdt->lock, flags);
 63}
 64
 65static void adx_wdt_stop_locked(struct adx_wdt *wdt)
 66{
 67	u32 ctrl;
 68
 69	ctrl = readl(wdt->base + ADX_WDT_CONTROL);
 70	ctrl &= ~ADX_WDT_CONTROL_ENABLE;
 71	writel(ctrl, wdt->base + ADX_WDT_CONTROL);
 72	wdt->state = WDT_STATE_STOP;
 73}
 74
 75static void adx_wdt_stop(struct adx_wdt *wdt)
 76{
 77	unsigned long flags;
 78
 79	spin_lock_irqsave(&wdt->lock, flags);
 80	adx_wdt_stop_locked(wdt);
 81	spin_unlock_irqrestore(&wdt->lock, flags);
 82}
 83
 84static void adx_wdt_set_timeout(struct adx_wdt *wdt, unsigned long seconds)
 85{
 86	unsigned long timeout = seconds * 1000;
 87	unsigned long flags;
 88	unsigned int state;
 89
 90	spin_lock_irqsave(&wdt->lock, flags);
 91	state = wdt->state;
 92	adx_wdt_stop_locked(wdt);
 93	writel(timeout, wdt->base + ADX_WDT_TIMEOUT);
 94
 95	if (state == WDT_STATE_START)
 96		adx_wdt_start_locked(wdt);
 97
 98	wdt->timeout = timeout;
 99	spin_unlock_irqrestore(&wdt->lock, flags);
100}
101
102static void adx_wdt_get_timeout(struct adx_wdt *wdt, unsigned long *seconds)
103{
104	*seconds = wdt->timeout / 1000;
105}
106
107static void adx_wdt_keepalive(struct adx_wdt *wdt)
108{
109	unsigned long flags;
110
111	spin_lock_irqsave(&wdt->lock, flags);
112	writel(wdt->timeout, wdt->base + ADX_WDT_TIMEOUT);
113	spin_unlock_irqrestore(&wdt->lock, flags);
114}
115
116static int adx_wdt_open(struct inode *inode, struct file *file)
117{
118	struct adx_wdt *wdt = platform_get_drvdata(adx_wdt_dev);
119
120	if (test_and_set_bit(0, &driver_open))
121		return -EBUSY;
122
123	file->private_data = wdt;
124	adx_wdt_set_timeout(wdt, 30);
125	adx_wdt_start(wdt);
126
127	return nonseekable_open(inode, file);
128}
129
130static int adx_wdt_release(struct inode *inode, struct file *file)
131{
132	struct adx_wdt *wdt = file->private_data;
133
134	adx_wdt_stop(wdt);
135	clear_bit(0, &driver_open);
136
137	return 0;
138}
139
140static long adx_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
141{
142	struct adx_wdt *wdt = file->private_data;
143	void __user *argp = (void __user *)arg;
144	unsigned long __user *p = argp;
145	unsigned long seconds = 0;
146	unsigned int options;
147	long ret = -EINVAL;
148
149	switch (cmd) {
150	case WDIOC_GETSUPPORT:
151		if (copy_to_user(argp, &adx_wdt_info, sizeof(adx_wdt_info)))
152			return -EFAULT;
153		else
154			return 0;
155
156	case WDIOC_GETSTATUS:
157	case WDIOC_GETBOOTSTATUS:
158		return put_user(0, p);
159
160	case WDIOC_KEEPALIVE:
161		adx_wdt_keepalive(wdt);
162		return 0;
163
164	case WDIOC_SETTIMEOUT:
165		if (get_user(seconds, p))
166			return -EFAULT;
167
168		adx_wdt_set_timeout(wdt, seconds);
169
170		/* fallthrough */
171	case WDIOC_GETTIMEOUT:
172		adx_wdt_get_timeout(wdt, &seconds);
173		return put_user(seconds, p);
174
175	case WDIOC_SETOPTIONS:
176		if (copy_from_user(&options, argp, sizeof(options)))
177			return -EFAULT;
178
179		if (options & WDIOS_DISABLECARD) {
180			adx_wdt_stop(wdt);
181			ret = 0;
182		}
183
184		if (options & WDIOS_ENABLECARD) {
185			adx_wdt_start(wdt);
186			ret = 0;
187		}
188
189		return ret;
190
191	default:
192		break;
193	}
194
195	return -ENOTTY;
196}
197
198static ssize_t adx_wdt_write(struct file *file, const char __user *data,
199		size_t len, loff_t *ppos)
200{
201	struct adx_wdt *wdt = file->private_data;
202
203	if (len)
204		adx_wdt_keepalive(wdt);
205
206	return len;
207}
208
209static const struct file_operations adx_wdt_fops = {
210	.owner = THIS_MODULE,
211	.llseek = no_llseek,
212	.open = adx_wdt_open,
213	.release = adx_wdt_release,
214	.unlocked_ioctl = adx_wdt_ioctl,
215	.write = adx_wdt_write,
216};
217
218static struct miscdevice adx_wdt_miscdev = {
219	.minor = WATCHDOG_MINOR,
220	.name = "watchdog",
221	.fops = &adx_wdt_fops,
222};
223
224static int __devinit adx_wdt_probe(struct platform_device *pdev)
225{
226	struct resource *res;
227	struct adx_wdt *wdt;
228	int ret = 0;
229	u32 ctrl;
230
231	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
232	if (!wdt) {
233		dev_err(&pdev->dev, "cannot allocate WDT structure\n");
234		return -ENOMEM;
235	}
236
237	spin_lock_init(&wdt->lock);
238
239	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
240	if (!res) {
241		dev_err(&pdev->dev, "cannot obtain I/O memory region\n");
242		return -ENXIO;
243	}
244
245	res = devm_request_mem_region(&pdev->dev, res->start,
246			resource_size(res), res->name);
247	if (!res) {
248		dev_err(&pdev->dev, "cannot request I/O memory region\n");
249		return -ENXIO;
250	}
251
252	wdt->base = devm_ioremap_nocache(&pdev->dev, res->start,
253			resource_size(res));
254	if (!wdt->base) {
255		dev_err(&pdev->dev, "cannot remap I/O memory region\n");
256		return -ENXIO;
257	}
258
259	/* disable watchdog and reboot on timeout */
260	ctrl = readl(wdt->base + ADX_WDT_CONTROL);
261	ctrl &= ~ADX_WDT_CONTROL_ENABLE;
262	ctrl &= ~ADX_WDT_CONTROL_nRESET;
263	writel(ctrl, wdt->base + ADX_WDT_CONTROL);
264
265	platform_set_drvdata(pdev, wdt);
266	adx_wdt_dev = pdev;
267
268	ret = misc_register(&adx_wdt_miscdev);
269	if (ret) {
270		dev_err(&pdev->dev, "cannot register miscdev on minor %d "
271				"(err=%d)\n", WATCHDOG_MINOR, ret);
272		return ret;
273	}
274
275	return 0;
276}
277
278static int __devexit adx_wdt_remove(struct platform_device *pdev)
279{
280	struct adx_wdt *wdt = platform_get_drvdata(pdev);
281
282	misc_deregister(&adx_wdt_miscdev);
283	adx_wdt_stop(wdt);
284	platform_set_drvdata(pdev, NULL);
285
286	return 0;
287}
288
289static void adx_wdt_shutdown(struct platform_device *pdev)
290{
291	struct adx_wdt *wdt = platform_get_drvdata(pdev);
292	adx_wdt_stop(wdt);
293}
294
295#ifdef CONFIG_PM
296static int adx_wdt_suspend(struct device *dev)
297{
298	struct platform_device *pdev = to_platform_device(dev);
299	struct adx_wdt *wdt = platform_get_drvdata(pdev);
300
301	wdt->wake = (wdt->state == WDT_STATE_START) ? 1 : 0;
302	adx_wdt_stop(wdt);
303
304	return 0;
305}
306
307static int adx_wdt_resume(struct device *dev)
308{
309	struct platform_device *pdev = to_platform_device(dev);
310	struct adx_wdt *wdt = platform_get_drvdata(pdev);
311
312	if (wdt->wake)
313		adx_wdt_start(wdt);
314
315	return 0;
316}
317
318static const struct dev_pm_ops adx_wdt_pm_ops = {
319	.suspend = adx_wdt_suspend,
320	.resume = adx_wdt_resume,
321};
322
323#  define ADX_WDT_PM_OPS	(&adx_wdt_pm_ops)
324#else
325#  define ADX_WDT_PM_OPS	NULL
326#endif
327
328static struct platform_driver adx_wdt_driver = {
329	.probe = adx_wdt_probe,
330	.remove = __devexit_p(adx_wdt_remove),
331	.shutdown = adx_wdt_shutdown,
332	.driver = {
333		.name = WATCHDOG_NAME,
334		.owner = THIS_MODULE,
335		.pm = ADX_WDT_PM_OPS,
336	},
337};
338
339static int __init adx_wdt_init(void)
340{
341	return platform_driver_register(&adx_wdt_driver);
342}
343
344static void __exit adx_wdt_exit(void)
345{
346	platform_driver_unregister(&adx_wdt_driver);
347}
348
349module_init(adx_wdt_init);
350module_exit(adx_wdt_exit);
351
352MODULE_DESCRIPTION("Avionic Design Xanthos Watchdog Driver");
353MODULE_LICENSE("GPL v2");
354MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
355MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);