Root/drivers/watchdog/mv64x60_wdt.c

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 __devinit mv64x60_wdt_probe(struct platform_device *dev)
257{
258    struct mv64x60_wdt_pdata *pdata = dev->dev.platform_data;
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 = ioremap(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 __devexit mv64x60_wdt_remove(struct platform_device *dev)
291{
292    misc_deregister(&mv64x60_wdt_miscdev);
293
294    mv64x60_wdt_handler_disable();
295
296    iounmap(mv64x60_wdt_regs);
297
298    return 0;
299}
300
301static struct platform_driver mv64x60_wdt_driver = {
302    .probe = mv64x60_wdt_probe,
303    .remove = __devexit_p(mv64x60_wdt_remove),
304    .driver = {
305        .owner = THIS_MODULE,
306        .name = MV64x60_WDT_NAME,
307    },
308};
309
310static int __init mv64x60_wdt_init(void)
311{
312    pr_info("MV64x60 watchdog driver\n");
313
314    return platform_driver_register(&mv64x60_wdt_driver);
315}
316
317static void __exit mv64x60_wdt_exit(void)
318{
319    platform_driver_unregister(&mv64x60_wdt_driver);
320}
321
322module_init(mv64x60_wdt_init);
323module_exit(mv64x60_wdt_exit);
324
325MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
326MODULE_DESCRIPTION("MV64x60 watchdog driver");
327MODULE_LICENSE("GPL");
328MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
329MODULE_ALIAS("platform:" MV64x60_WDT_NAME);
330

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