1/*
2 * mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface
3 *
4 * Author: James Chapman <jchapman@katalix.com>
5 *
6 * Platform-specific setup code should configure the dog to generate
7 * interrupt or reset as required.  This code only enables/disables
8 * and services the watchdog.
9 *
10 * Derived from mpc8xx_wdt.c, with the following copyright.
11 *
12 * 2002 (c) Florian Schirmer <jolt@tuxbox.org> This file is licensed under
13 * the terms of the GNU General Public License version 2. This program
14 * is licensed "as is" without any warranty of any kind, whether express
15 * or implied.
16 */
17
18#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19
20#include <linux/fs.h>
21#include <linux/init.h>
22#include <linux/kernel.h>
23#include <linux/miscdevice.h>
24#include <linux/module.h>
25#include <linux/watchdog.h>
26#include <linux/platform_device.h>
27#include <linux/mv643xx.h>
28#include <linux/uaccess.h>
29#include <linux/io.h>
30
31#define MV64x60_WDT_WDC_OFFSET	0
32
33/*
34 * The watchdog configuration register contains a pair of 2-bit fields,
35 *   1.  a reload field, bits 27-26, which triggers a reload of
36 *       the countdown register, and
37 *   2.  an enable field, bits 25-24, which toggles between
38 *       enabling and disabling the watchdog timer.
39 * Bit 31 is a read-only field which indicates whether the
40 * watchdog timer is currently enabled.
41 *
42 * The low 24 bits contain the timer reload value.
43 */
44#define MV64x60_WDC_ENABLE_SHIFT	24
45#define MV64x60_WDC_SERVICE_SHIFT	26
46#define MV64x60_WDC_ENABLED_SHIFT	31
47
48#define MV64x60_WDC_ENABLED_TRUE	1
49#define MV64x60_WDC_ENABLED_FALSE	0
50
51/* Flags bits */
52#define MV64x60_WDOG_FLAG_OPENED	0
53
54static unsigned long wdt_flags;
55static int wdt_status;
56static void __iomem *mv64x60_wdt_regs;
57static int mv64x60_wdt_timeout;
58static int mv64x60_wdt_count;
59static unsigned int bus_clk;
60static char expect_close;
61static DEFINE_SPINLOCK(mv64x60_wdt_spinlock);
62
63static bool nowayout = WATCHDOG_NOWAYOUT;
64module_param(nowayout, bool, 0);
65MODULE_PARM_DESC(nowayout,
66		"Watchdog cannot be stopped once started (default="
67				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
68
69static int mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift)
70{
71	u32 data;
72	u32 enabled;
73	int ret = 0;
74
75	spin_lock(&mv64x60_wdt_spinlock);
76	data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
77	enabled = (data >> MV64x60_WDC_ENABLED_SHIFT) & 1;
78
79	/* only toggle the requested field if enabled state matches predicate */
80	if ((enabled ^ enabled_predicate) == 0) {
81		/* We write a 1, then a 2 -- to the appropriate field */
82		data = (1 << field_shift) | mv64x60_wdt_count;
83		writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
84
85		data = (2 << field_shift) | mv64x60_wdt_count;
86		writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
87		ret = 1;
88	}
89	spin_unlock(&mv64x60_wdt_spinlock);
90
91	return ret;
92}
93
94static void mv64x60_wdt_service(void)
95{
96	mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
97			       MV64x60_WDC_SERVICE_SHIFT);
98}
99
100static void mv64x60_wdt_handler_enable(void)
101{
102	if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE,
103				   MV64x60_WDC_ENABLE_SHIFT)) {
104		mv64x60_wdt_service();
105		pr_notice("watchdog activated\n");
106	}
107}
108
109static void mv64x60_wdt_handler_disable(void)
110{
111	if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
112				   MV64x60_WDC_ENABLE_SHIFT))
113		pr_notice("watchdog deactivated\n");
114}
115
116static void mv64x60_wdt_set_timeout(unsigned int timeout)
117{
118	/* maximum bus cycle count is 0xFFFFFFFF */
119	if (timeout > 0xFFFFFFFF / bus_clk)
120		timeout = 0xFFFFFFFF / bus_clk;
121
122	mv64x60_wdt_count = timeout * bus_clk >> 8;
123	mv64x60_wdt_timeout = timeout;
124}
125
126static int mv64x60_wdt_open(struct inode *inode, struct file *file)
127{
128	if (test_and_set_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags))
129		return -EBUSY;
130
131	if (nowayout)
132		__module_get(THIS_MODULE);
133
134	mv64x60_wdt_handler_enable();
135
136	return nonseekable_open(inode, file);
137}
138
139static int mv64x60_wdt_release(struct inode *inode, struct file *file)
140{
141	if (expect_close == 42)
142		mv64x60_wdt_handler_disable();
143	else {
144		pr_crit("unexpected close, not stopping timer!\n");
145		mv64x60_wdt_service();
146	}
147	expect_close = 0;
148
149	clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags);
150
151	return 0;
152}
153
154static ssize_t mv64x60_wdt_write(struct file *file, const char __user *data,
155				 size_t len, loff_t *ppos)
156{
157	if (len) {
158		if (!nowayout) {
159			size_t i;
160
161			expect_close = 0;
162
163			for (i = 0; i != len; i++) {
164				char c;
165				if (get_user(c, data + i))
166					return -EFAULT;
167				if (c == 'V')
168					expect_close = 42;
169			}
170		}
171		mv64x60_wdt_service();
172	}
173
174	return len;
175}
176
177static long mv64x60_wdt_ioctl(struct file *file,
178					unsigned int cmd, unsigned long arg)
179{
180	int timeout;
181	int options;
182	void __user *argp = (void __user *)arg;
183	static const struct watchdog_info info = {
184		.options =	WDIOF_SETTIMEOUT	|
185				WDIOF_MAGICCLOSE	|
186				WDIOF_KEEPALIVEPING,
187		.firmware_version = 0,
188		.identity = "MV64x60 watchdog",
189	};
190
191	switch (cmd) {
192	case WDIOC_GETSUPPORT:
193		if (copy_to_user(argp, &info, sizeof(info)))
194			return -EFAULT;
195		break;
196
197	case WDIOC_GETSTATUS:
198	case WDIOC_GETBOOTSTATUS:
199		if (put_user(wdt_status, (int __user *)argp))
200			return -EFAULT;
201		wdt_status &= ~WDIOF_KEEPALIVEPING;
202		break;
203
204	case WDIOC_GETTEMP:
205		return -EOPNOTSUPP;
206
207	case WDIOC_SETOPTIONS:
208		if (get_user(options, (int __user *)argp))
209			return -EFAULT;
210
211		if (options & WDIOS_DISABLECARD)
212			mv64x60_wdt_handler_disable();
213
214		if (options & WDIOS_ENABLECARD)
215			mv64x60_wdt_handler_enable();
216		break;
217
218	case WDIOC_KEEPALIVE:
219		mv64x60_wdt_service();
220		wdt_status |= WDIOF_KEEPALIVEPING;
221		break;
222
223	case WDIOC_SETTIMEOUT:
224		if (get_user(timeout, (int __user *)argp))
225			return -EFAULT;
226		mv64x60_wdt_set_timeout(timeout);
227		/* Fall through */
228
229	case WDIOC_GETTIMEOUT:
230		if (put_user(mv64x60_wdt_timeout, (int __user *)argp))
231			return -EFAULT;
232		break;
233
234	default:
235		return -ENOTTY;
236	}
237
238	return 0;
239}
240
241static const struct file_operations mv64x60_wdt_fops = {
242	.owner = THIS_MODULE,
243	.llseek = no_llseek,
244	.write = mv64x60_wdt_write,
245	.unlocked_ioctl = mv64x60_wdt_ioctl,
246	.open = mv64x60_wdt_open,
247	.release = mv64x60_wdt_release,
248};
249
250static struct miscdevice mv64x60_wdt_miscdev = {
251	.minor = WATCHDOG_MINOR,
252	.name = "watchdog",
253	.fops = &mv64x60_wdt_fops,
254};
255
256static int mv64x60_wdt_probe(struct platform_device *dev)
257{
258	struct mv64x60_wdt_pdata *pdata = dev_get_platdata(&dev->dev);
259	struct resource *r;
260	int timeout = 10;
261
262	bus_clk = 133;			/* in MHz */
263	if (pdata) {
264		timeout = pdata->timeout;
265		bus_clk = pdata->bus_clk;
266	}
267
268	/* Since bus_clk is truncated MHz, actual frequency could be
269	 * up to 1MHz higher.  Round up, since it's better to time out
270	 * too late than too soon.
271	 */
272	bus_clk++;
273	bus_clk *= 1000000;		/* convert to Hz */
274
275	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
276	if (!r)
277		return -ENODEV;
278
279	mv64x60_wdt_regs = devm_ioremap(&dev->dev, r->start, resource_size(r));
280	if (mv64x60_wdt_regs == NULL)
281		return -ENOMEM;
282
283	mv64x60_wdt_set_timeout(timeout);
284
285	mv64x60_wdt_handler_disable();	/* in case timer was already running */
286
287	return misc_register(&mv64x60_wdt_miscdev);
288}
289
290static int mv64x60_wdt_remove(struct platform_device *dev)
291{
292	misc_deregister(&mv64x60_wdt_miscdev);
293
294	mv64x60_wdt_handler_disable();
295
296	return 0;
297}
298
299static struct platform_driver mv64x60_wdt_driver = {
300	.probe = mv64x60_wdt_probe,
301	.remove = mv64x60_wdt_remove,
302	.driver = {
303		.name = MV64x60_WDT_NAME,
304	},
305};
306
307static int __init mv64x60_wdt_init(void)
308{
309	pr_info("MV64x60 watchdog driver\n");
310
311	return platform_driver_register(&mv64x60_wdt_driver);
312}
313
314static void __exit mv64x60_wdt_exit(void)
315{
316	platform_driver_unregister(&mv64x60_wdt_driver);
317}
318
319module_init(mv64x60_wdt_init);
320module_exit(mv64x60_wdt_exit);
321
322MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
323MODULE_DESCRIPTION("MV64x60 watchdog driver");
324MODULE_LICENSE("GPL");
325MODULE_ALIAS("platform:" MV64x60_WDT_NAME);
326