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Martyn Welch3268b562008-11-10 12:31:26 +00001/*
Martyn Welchcda61c92010-03-01 17:06:20 +00002 * GE watchdog userspace interface
Martyn Welch3268b562008-11-10 12:31:26 +00003 *
Martyn Welchcda61c92010-03-01 17:06:20 +00004 * Author: Martyn Welch <martyn.welch@ge.com>
Martyn Welch3268b562008-11-10 12:31:26 +00005 *
Martyn Welchcda61c92010-03-01 17:06:20 +00006 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
Martyn Welch3268b562008-11-10 12:31:26 +00007 *
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License as published by the
10 * Free Software Foundation; either version 2 of the License, or (at your
11 * option) any later version.
12 *
13 * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
14 * Author: James Chapman <jchapman@katalix.com>
15 */
16
17/* TODO:
18 * This driver does not provide support for the hardwares capability of sending
19 * an interrupt at a programmable threshold.
20 *
21 * This driver currently can only support 1 watchdog - there are 2 in the
22 * hardware that this driver supports. Thus one could be configured as a
23 * process-based watchdog (via /dev/watchdog), the second (using the interrupt
24 * capabilities) a kernel-based watchdog.
25 */
26
Joe Perches27c766a2012-02-15 15:06:19 -080027#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28
Martyn Welch3268b562008-11-10 12:31:26 +000029#include <linux/kernel.h>
30#include <linux/compiler.h>
31#include <linux/init.h>
32#include <linux/module.h>
33#include <linux/miscdevice.h>
34#include <linux/watchdog.h>
Wolfram Sang & Martyn Welchf6e07222010-12-02 00:11:16 +010035#include <linux/fs.h>
Martyn Welch3268b562008-11-10 12:31:26 +000036#include <linux/of.h>
Rob Herring5af50732013-09-17 14:28:33 -050037#include <linux/of_address.h>
Martyn Welch3268b562008-11-10 12:31:26 +000038#include <linux/of_platform.h>
39#include <linux/io.h>
40#include <linux/uaccess.h>
41
42#include <sysdev/fsl_soc.h>
43
44/*
45 * The watchdog configuration register contains a pair of 2-bit fields,
46 * 1. a reload field, bits 27-26, which triggers a reload of
47 * the countdown register, and
48 * 2. an enable field, bits 25-24, which toggles between
49 * enabling and disabling the watchdog timer.
50 * Bit 31 is a read-only field which indicates whether the
51 * watchdog timer is currently enabled.
52 *
53 * The low 24 bits contain the timer reload value.
54 */
55#define GEF_WDC_ENABLE_SHIFT 24
56#define GEF_WDC_SERVICE_SHIFT 26
57#define GEF_WDC_ENABLED_SHIFT 31
58
59#define GEF_WDC_ENABLED_TRUE 1
60#define GEF_WDC_ENABLED_FALSE 0
61
62/* Flags bits */
63#define GEF_WDOG_FLAG_OPENED 0
64
65static unsigned long wdt_flags;
66static int wdt_status;
67static void __iomem *gef_wdt_regs;
68static int gef_wdt_timeout;
69static int gef_wdt_count;
70static unsigned int bus_clk;
71static char expect_close;
72static DEFINE_SPINLOCK(gef_wdt_spinlock);
73
Wim Van Sebroeck86a1e182012-03-05 16:51:11 +010074static bool nowayout = WATCHDOG_NOWAYOUT;
75module_param(nowayout, bool, 0);
Martyn Welch3268b562008-11-10 12:31:26 +000076MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
77 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
78
79
80static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
81{
82 u32 data;
83 u32 enabled;
84 int ret = 0;
85
86 spin_lock(&gef_wdt_spinlock);
87 data = ioread32be(gef_wdt_regs);
88 enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
89
90 /* only toggle the requested field if enabled state matches predicate */
91 if ((enabled ^ enabled_predicate) == 0) {
92 /* We write a 1, then a 2 -- to the appropriate field */
93 data = (1 << field_shift) | gef_wdt_count;
94 iowrite32be(data, gef_wdt_regs);
95
96 data = (2 << field_shift) | gef_wdt_count;
97 iowrite32be(data, gef_wdt_regs);
98 ret = 1;
99 }
100 spin_unlock(&gef_wdt_spinlock);
101
102 return ret;
103}
104
105static void gef_wdt_service(void)
106{
107 gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
108 GEF_WDC_SERVICE_SHIFT);
109}
110
111static void gef_wdt_handler_enable(void)
112{
113 if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
114 GEF_WDC_ENABLE_SHIFT)) {
115 gef_wdt_service();
Joe Perches27c766a2012-02-15 15:06:19 -0800116 pr_notice("watchdog activated\n");
Martyn Welch3268b562008-11-10 12:31:26 +0000117 }
118}
119
120static void gef_wdt_handler_disable(void)
121{
122 if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
123 GEF_WDC_ENABLE_SHIFT))
Joe Perches27c766a2012-02-15 15:06:19 -0800124 pr_notice("watchdog deactivated\n");
Martyn Welch3268b562008-11-10 12:31:26 +0000125}
126
127static void gef_wdt_set_timeout(unsigned int timeout)
128{
129 /* maximum bus cycle count is 0xFFFFFFFF */
130 if (timeout > 0xFFFFFFFF / bus_clk)
131 timeout = 0xFFFFFFFF / bus_clk;
132
133 /* Register only holds upper 24 bits, bit shifted into lower 24 */
134 gef_wdt_count = (timeout * bus_clk) >> 8;
135 gef_wdt_timeout = timeout;
136}
137
138
139static ssize_t gef_wdt_write(struct file *file, const char __user *data,
140 size_t len, loff_t *ppos)
141{
142 if (len) {
143 if (!nowayout) {
144 size_t i;
145
146 expect_close = 0;
147
148 for (i = 0; i != len; i++) {
149 char c;
150 if (get_user(c, data + i))
151 return -EFAULT;
152 if (c == 'V')
153 expect_close = 42;
154 }
155 }
156 gef_wdt_service();
157 }
158
159 return len;
160}
161
162static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
163 unsigned long arg)
164{
165 int timeout;
166 int options;
167 void __user *argp = (void __user *)arg;
Wim Van Sebroeck42747d72009-12-26 18:55:22 +0000168 static const struct watchdog_info info = {
Martyn Welch3268b562008-11-10 12:31:26 +0000169 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
170 WDIOF_KEEPALIVEPING,
171 .firmware_version = 0,
Martyn Welchcda61c92010-03-01 17:06:20 +0000172 .identity = "GE watchdog",
Martyn Welch3268b562008-11-10 12:31:26 +0000173 };
174
175 switch (cmd) {
176 case WDIOC_GETSUPPORT:
177 if (copy_to_user(argp, &info, sizeof(info)))
178 return -EFAULT;
179 break;
180
181 case WDIOC_GETSTATUS:
182 case WDIOC_GETBOOTSTATUS:
183 if (put_user(wdt_status, (int __user *)argp))
184 return -EFAULT;
185 wdt_status &= ~WDIOF_KEEPALIVEPING;
186 break;
187
188 case WDIOC_SETOPTIONS:
189 if (get_user(options, (int __user *)argp))
190 return -EFAULT;
191
192 if (options & WDIOS_DISABLECARD)
193 gef_wdt_handler_disable();
194
195 if (options & WDIOS_ENABLECARD)
196 gef_wdt_handler_enable();
197 break;
198
199 case WDIOC_KEEPALIVE:
200 gef_wdt_service();
201 wdt_status |= WDIOF_KEEPALIVEPING;
202 break;
203
204 case WDIOC_SETTIMEOUT:
205 if (get_user(timeout, (int __user *)argp))
206 return -EFAULT;
207 gef_wdt_set_timeout(timeout);
208 /* Fall through */
209
210 case WDIOC_GETTIMEOUT:
211 if (put_user(gef_wdt_timeout, (int __user *)argp))
212 return -EFAULT;
213 break;
214
215 default:
216 return -ENOTTY;
217 }
218
219 return 0;
220}
221
222static int gef_wdt_open(struct inode *inode, struct file *file)
223{
224 if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
225 return -EBUSY;
226
227 if (nowayout)
228 __module_get(THIS_MODULE);
229
230 gef_wdt_handler_enable();
231
232 return nonseekable_open(inode, file);
233}
234
235static int gef_wdt_release(struct inode *inode, struct file *file)
236{
237 if (expect_close == 42)
238 gef_wdt_handler_disable();
239 else {
Joe Perches27c766a2012-02-15 15:06:19 -0800240 pr_crit("unexpected close, not stopping timer!\n");
Martyn Welch3268b562008-11-10 12:31:26 +0000241 gef_wdt_service();
242 }
243 expect_close = 0;
244
245 clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
246
247 return 0;
248}
249
250static const struct file_operations gef_wdt_fops = {
251 .owner = THIS_MODULE,
252 .llseek = no_llseek,
253 .write = gef_wdt_write,
254 .unlocked_ioctl = gef_wdt_ioctl,
255 .open = gef_wdt_open,
256 .release = gef_wdt_release,
257};
258
259static struct miscdevice gef_wdt_miscdev = {
260 .minor = WATCHDOG_MINOR,
261 .name = "watchdog",
262 .fops = &gef_wdt_fops,
263};
264
265
Bill Pemberton2d991a12012-11-19 13:21:41 -0500266static int gef_wdt_probe(struct platform_device *dev)
Martyn Welch3268b562008-11-10 12:31:26 +0000267{
268 int timeout = 10;
269 u32 freq;
270
271 bus_clk = 133; /* in MHz */
272
273 freq = fsl_get_sys_freq();
Roel Kluin26952662009-03-03 15:10:05 +0100274 if (freq != -1)
Martyn Welch3268b562008-11-10 12:31:26 +0000275 bus_clk = freq;
276
277 /* Map devices registers into memory */
Anatolij Gustschinb74dbf22010-06-03 03:30:31 +0200278 gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
Martyn Welch3268b562008-11-10 12:31:26 +0000279 if (gef_wdt_regs == NULL)
280 return -ENOMEM;
281
282 gef_wdt_set_timeout(timeout);
283
284 gef_wdt_handler_disable(); /* in case timer was already running */
285
286 return misc_register(&gef_wdt_miscdev);
287}
288
Bill Pemberton4b12b892012-11-19 13:26:24 -0500289static int gef_wdt_remove(struct platform_device *dev)
Martyn Welch3268b562008-11-10 12:31:26 +0000290{
291 misc_deregister(&gef_wdt_miscdev);
292
293 gef_wdt_handler_disable();
294
295 iounmap(gef_wdt_regs);
296
297 return 0;
298}
299
300static const struct of_device_id gef_wdt_ids[] = {
301 {
302 .compatible = "gef,fpga-wdt",
303 },
304 {},
305};
306
Grant Likely1c48a5c2011-02-17 02:43:24 -0700307static struct platform_driver gef_wdt_driver = {
Grant Likely40182942010-04-13 16:13:02 -0700308 .driver = {
309 .name = "gef_wdt",
Grant Likely40182942010-04-13 16:13:02 -0700310 .of_match_table = gef_wdt_ids,
311 },
Martyn Welch3268b562008-11-10 12:31:26 +0000312 .probe = gef_wdt_probe,
Devendra Naga67371762012-11-02 14:15:39 -0400313 .remove = gef_wdt_remove,
Martyn Welch3268b562008-11-10 12:31:26 +0000314};
315
316static int __init gef_wdt_init(void)
317{
Joe Perches27c766a2012-02-15 15:06:19 -0800318 pr_info("GE watchdog driver\n");
Grant Likely1c48a5c2011-02-17 02:43:24 -0700319 return platform_driver_register(&gef_wdt_driver);
Martyn Welch3268b562008-11-10 12:31:26 +0000320}
321
322static void __exit gef_wdt_exit(void)
323{
Grant Likely1c48a5c2011-02-17 02:43:24 -0700324 platform_driver_unregister(&gef_wdt_driver);
Martyn Welch3268b562008-11-10 12:31:26 +0000325}
326
327module_init(gef_wdt_init);
328module_exit(gef_wdt_exit);
329
Martyn Welchcda61c92010-03-01 17:06:20 +0000330MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
331MODULE_DESCRIPTION("GE watchdog driver");
Martyn Welch3268b562008-11-10 12:31:26 +0000332MODULE_LICENSE("GPL");
Axel Linae2a0062011-06-27 22:37:16 +0800333MODULE_ALIAS("platform:gef_wdt");