1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface
  4 *
  5 * Author: James Chapman <jchapman@katalix.com>
  6 *
  7 * Platform-specific setup code should configure the dog to generate
  8 * interrupt or reset as required.  This code only enables/disables
  9 * and services the watchdog.
 10 *
 11 * Derived from mpc8xx_wdt.c, with the following copyright.
 12 *
 13 * 2002 (c) Florian Schirmer <jolt@tuxbox.org>
 14 */
 15
 16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 17
 18#include <linux/fs.h>
 19#include <linux/init.h>
 20#include <linux/kernel.h>
 21#include <linux/miscdevice.h>
 22#include <linux/module.h>
 23#include <linux/watchdog.h>
 24#include <linux/platform_device.h>
 25#include <linux/mv643xx.h>
 26#include <linux/uaccess.h>
 27#include <linux/io.h>
 28
 29#define MV64x60_WDT_WDC_OFFSET	0
 30
 31/*
 32 * The watchdog configuration register contains a pair of 2-bit fields,
 33 *   1.  a reload field, bits 27-26, which triggers a reload of
 34 *       the countdown register, and
 35 *   2.  an enable field, bits 25-24, which toggles between
 36 *       enabling and disabling the watchdog timer.
 37 * Bit 31 is a read-only field which indicates whether the
 38 * watchdog timer is currently enabled.
 39 *
 40 * The low 24 bits contain the timer reload value.
 41 */
 42#define MV64x60_WDC_ENABLE_SHIFT	24
 43#define MV64x60_WDC_SERVICE_SHIFT	26
 44#define MV64x60_WDC_ENABLED_SHIFT	31
 45
 46#define MV64x60_WDC_ENABLED_TRUE	1
 47#define MV64x60_WDC_ENABLED_FALSE	0
 48
 49/* Flags bits */
 50#define MV64x60_WDOG_FLAG_OPENED	0
 51
 52static unsigned long wdt_flags;
 53static int wdt_status;
 54static void __iomem *mv64x60_wdt_regs;
 55static int mv64x60_wdt_timeout;
 56static int mv64x60_wdt_count;
 57static unsigned int bus_clk;
 58static char expect_close;
 59static DEFINE_SPINLOCK(mv64x60_wdt_spinlock);
 60
 61static bool nowayout = WATCHDOG_NOWAYOUT;
 62module_param(nowayout, bool, 0);
 63MODULE_PARM_DESC(nowayout,
 64		"Watchdog cannot be stopped once started (default="
 65				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 66
 67static int mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift)
 68{
 69	u32 data;
 70	u32 enabled;
 71	int ret = 0;
 72
 73	spin_lock(&mv64x60_wdt_spinlock);
 74	data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
 75	enabled = (data >> MV64x60_WDC_ENABLED_SHIFT) & 1;
 76
 77	/* only toggle the requested field if enabled state matches predicate */
 78	if ((enabled ^ enabled_predicate) == 0) {
 79		/* We write a 1, then a 2 -- to the appropriate field */
 80		data = (1 << field_shift) | mv64x60_wdt_count;
 81		writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
 82
 83		data = (2 << field_shift) | mv64x60_wdt_count;
 84		writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
 85		ret = 1;
 86	}
 87	spin_unlock(&mv64x60_wdt_spinlock);
 88
 89	return ret;
 90}
 91
 92static void mv64x60_wdt_service(void)
 93{
 94	mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
 95			       MV64x60_WDC_SERVICE_SHIFT);
 96}
 97
 98static void mv64x60_wdt_handler_enable(void)
 99{
100	if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE,
101				   MV64x60_WDC_ENABLE_SHIFT)) {
102		mv64x60_wdt_service();
103		pr_notice("watchdog activated\n");
104	}
105}
106
107static void mv64x60_wdt_handler_disable(void)
108{
109	if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
110				   MV64x60_WDC_ENABLE_SHIFT))
111		pr_notice("watchdog deactivated\n");
112}
113
114static void mv64x60_wdt_set_timeout(unsigned int timeout)
115{
116	/* maximum bus cycle count is 0xFFFFFFFF */
117	if (timeout > 0xFFFFFFFF / bus_clk)
118		timeout = 0xFFFFFFFF / bus_clk;
119
120	mv64x60_wdt_count = timeout * bus_clk >> 8;
121	mv64x60_wdt_timeout = timeout;
122}
123
124static int mv64x60_wdt_open(struct inode *inode, struct file *file)
125{
126	if (test_and_set_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags))
127		return -EBUSY;
128
129	if (nowayout)
130		__module_get(THIS_MODULE);
131
132	mv64x60_wdt_handler_enable();
133
134	return stream_open(inode, file);
135}
136
137static int mv64x60_wdt_release(struct inode *inode, struct file *file)
138{
139	if (expect_close == 42)
140		mv64x60_wdt_handler_disable();
141	else {
142		pr_crit("unexpected close, not stopping timer!\n");
143		mv64x60_wdt_service();
144	}
145	expect_close = 0;
146
147	clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags);
148
149	return 0;
150}
151
152static ssize_t mv64x60_wdt_write(struct file *file, const char __user *data,
153				 size_t len, loff_t *ppos)
154{
155	if (len) {
156		if (!nowayout) {
157			size_t i;
158
159			expect_close = 0;
160
161			for (i = 0; i != len; i++) {
162				char c;
163				if (get_user(c, data + i))
164					return -EFAULT;
165				if (c == 'V')
166					expect_close = 42;
167			}
168		}
169		mv64x60_wdt_service();
170	}
171
172	return len;
173}
174
175static long mv64x60_wdt_ioctl(struct file *file,
176					unsigned int cmd, unsigned long arg)
177{
178	int timeout;
179	int options;
180	void __user *argp = (void __user *)arg;
181	static const struct watchdog_info info = {
182		.options =	WDIOF_SETTIMEOUT	|
183				WDIOF_MAGICCLOSE	|
184				WDIOF_KEEPALIVEPING,
185		.firmware_version = 0,
186		.identity = "MV64x60 watchdog",
187	};
188
189	switch (cmd) {
190	case WDIOC_GETSUPPORT:
191		if (copy_to_user(argp, &info, sizeof(info)))
192			return -EFAULT;
193		break;
194
195	case WDIOC_GETSTATUS:
196	case WDIOC_GETBOOTSTATUS:
197		if (put_user(wdt_status, (int __user *)argp))
198			return -EFAULT;
199		wdt_status &= ~WDIOF_KEEPALIVEPING;
200		break;
201
202	case WDIOC_GETTEMP:
203		return -EOPNOTSUPP;
204
205	case WDIOC_SETOPTIONS:
206		if (get_user(options, (int __user *)argp))
207			return -EFAULT;
208
209		if (options & WDIOS_DISABLECARD)
210			mv64x60_wdt_handler_disable();
211
212		if (options & WDIOS_ENABLECARD)
213			mv64x60_wdt_handler_enable();
214		break;
215
216	case WDIOC_KEEPALIVE:
217		mv64x60_wdt_service();
218		wdt_status |= WDIOF_KEEPALIVEPING;
219		break;
220
221	case WDIOC_SETTIMEOUT:
222		if (get_user(timeout, (int __user *)argp))
223			return -EFAULT;
224		mv64x60_wdt_set_timeout(timeout);
225		/* Fall through */
226
227	case WDIOC_GETTIMEOUT:
228		if (put_user(mv64x60_wdt_timeout, (int __user *)argp))
229			return -EFAULT;
230		break;
231
232	default:
233		return -ENOTTY;
234	}
235
236	return 0;
237}
238
239static const struct file_operations mv64x60_wdt_fops = {
240	.owner = THIS_MODULE,
241	.llseek = no_llseek,
242	.write = mv64x60_wdt_write,
243	.unlocked_ioctl = mv64x60_wdt_ioctl,
244	.open = mv64x60_wdt_open,
245	.release = mv64x60_wdt_release,
246};
247
248static struct miscdevice mv64x60_wdt_miscdev = {
249	.minor = WATCHDOG_MINOR,
250	.name = "watchdog",
251	.fops = &mv64x60_wdt_fops,
252};
253
254static int mv64x60_wdt_probe(struct platform_device *dev)
255{
256	struct mv64x60_wdt_pdata *pdata = dev_get_platdata(&dev->dev);
257	struct resource *r;
258	int timeout = 10;
259
260	bus_clk = 133;			/* in MHz */
261	if (pdata) {
262		timeout = pdata->timeout;
263		bus_clk = pdata->bus_clk;
264	}
265
266	/* Since bus_clk is truncated MHz, actual frequency could be
267	 * up to 1MHz higher.  Round up, since it's better to time out
268	 * too late than too soon.
269	 */
270	bus_clk++;
271	bus_clk *= 1000000;		/* convert to Hz */
272
273	r = platform_get_resource(dev, IORESOURCE_MEM, 0);
274	if (!r)
275		return -ENODEV;
276
277	mv64x60_wdt_regs = devm_ioremap(&dev->dev, r->start, resource_size(r));
278	if (mv64x60_wdt_regs == NULL)
279		return -ENOMEM;
280
281	mv64x60_wdt_set_timeout(timeout);
282
283	mv64x60_wdt_handler_disable();	/* in case timer was already running */
284
285	return misc_register(&mv64x60_wdt_miscdev);
286}
287
288static int mv64x60_wdt_remove(struct platform_device *dev)
289{
290	misc_deregister(&mv64x60_wdt_miscdev);
291
292	mv64x60_wdt_handler_disable();
293
294	return 0;
295}
296
297static struct platform_driver mv64x60_wdt_driver = {
298	.probe = mv64x60_wdt_probe,
299	.remove = mv64x60_wdt_remove,
300	.driver = {
301		.name = MV64x60_WDT_NAME,
302	},
303};
304
305static int __init mv64x60_wdt_init(void)
306{
307	pr_info("MV64x60 watchdog driver\n");
308
309	return platform_driver_register(&mv64x60_wdt_driver);
310}
311
312static void __exit mv64x60_wdt_exit(void)
313{
314	platform_driver_unregister(&mv64x60_wdt_driver);
315}
316
317module_init(mv64x60_wdt_init);
318module_exit(mv64x60_wdt_exit);
319
320MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
321MODULE_DESCRIPTION("MV64x60 watchdog driver");
322MODULE_LICENSE("GPL");
323MODULE_ALIAS("platform:" MV64x60_WDT_NAME);