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