1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *	Watchdog driver for the SA11x0/PXA2xx
4  *
5  *	(c) Copyright 2000 Oleg Drokin <green@crimea.edu>
6  *	    Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
7  *
8  *	Neither Oleg Drokin nor iXcelerator.com admit liability nor provide
9  *	warranty for any of this software. This material is provided
10  *	"AS-IS" and at no charge.
11  *
12  *	(c) Copyright 2000           Oleg Drokin <green@crimea.edu>
13  *
14  *	27/11/2000 Initial release
15  */
16 
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18 
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/clk.h>
22 #include <linux/types.h>
23 #include <linux/kernel.h>
24 #include <linux/fs.h>
25 #include <linux/platform_device.h>
26 #include <linux/miscdevice.h>
27 #include <linux/watchdog.h>
28 #include <linux/init.h>
29 #include <linux/io.h>
30 #include <linux/bitops.h>
31 #include <linux/uaccess.h>
32 #include <linux/timex.h>
33 
34 #define REG_OSMR0  	0x0000  /* OS timer Match Reg. 0 */
35 #define REG_OSMR1  	0x0004  /* OS timer Match Reg. 1 */
36 #define REG_OSMR2  	0x0008  /* OS timer Match Reg. 2 */
37 #define REG_OSMR3  	0x000c  /* OS timer Match Reg. 3 */
38 #define REG_OSCR   	0x0010  /* OS timer Counter Reg. */
39 #define REG_OSSR   	0x0014  /* OS timer Status Reg. */
40 #define REG_OWER   	0x0018  /* OS timer Watch-dog Enable Reg. */
41 #define REG_OIER  	0x001C  /* OS timer Interrupt Enable Reg. */
42 
43 #define OSSR_M3		(1 << 3)	/* Match status channel 3 */
44 #define OSSR_M2		(1 << 2)	/* Match status channel 2 */
45 #define OSSR_M1		(1 << 1)	/* Match status channel 1 */
46 #define OSSR_M0		(1 << 0)	/* Match status channel 0 */
47 
48 #define OWER_WME	(1 << 0)	/* Watchdog Match Enable */
49 
50 #define OIER_E3		(1 << 3)	/* Interrupt enable channel 3 */
51 #define OIER_E2		(1 << 2)	/* Interrupt enable channel 2 */
52 #define OIER_E1		(1 << 1)	/* Interrupt enable channel 1 */
53 #define OIER_E0		(1 << 0)	/* Interrupt enable channel 0 */
54 
55 static unsigned long oscr_freq;
56 static unsigned long sa1100wdt_users;
57 static unsigned int pre_margin;
58 static int boot_status;
59 static void __iomem *reg_base;
60 
sa1100_wr(u32 val,u32 offset)61 static inline void sa1100_wr(u32 val, u32 offset)
62 {
63 	writel_relaxed(val, reg_base + offset);
64 }
65 
sa1100_rd(u32 offset)66 static inline u32 sa1100_rd(u32 offset)
67 {
68 	return readl_relaxed(reg_base + offset);
69 }
70 
71 /*
72  *	Allow only one person to hold it open
73  */
sa1100dog_open(struct inode * inode,struct file * file)74 static int sa1100dog_open(struct inode *inode, struct file *file)
75 {
76 	if (test_and_set_bit(1, &sa1100wdt_users))
77 		return -EBUSY;
78 
79 	/* Activate SA1100 Watchdog timer */
80 	sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
81 	sa1100_wr(OSSR_M3, REG_OSSR);
82 	sa1100_wr(OWER_WME, REG_OWER);
83 	sa1100_wr(sa1100_rd(REG_OIER) | OIER_E3, REG_OIER);
84 	return stream_open(inode, file);
85 }
86 
87 /*
88  * The watchdog cannot be disabled.
89  *
90  * Previous comments suggested that turning off the interrupt by
91  * clearing REG_OIER[E3] would prevent the watchdog timing out but this
92  * does not appear to be true (at least on the PXA255).
93  */
sa1100dog_release(struct inode * inode,struct file * file)94 static int sa1100dog_release(struct inode *inode, struct file *file)
95 {
96 	pr_crit("Device closed - timer will not stop\n");
97 	clear_bit(1, &sa1100wdt_users);
98 	return 0;
99 }
100 
sa1100dog_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)101 static ssize_t sa1100dog_write(struct file *file, const char __user *data,
102 						size_t len, loff_t *ppos)
103 {
104 	if (len)
105 		/* Refresh OSMR3 timer. */
106 		sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
107 	return len;
108 }
109 
110 static const struct watchdog_info ident = {
111 	.options	= WDIOF_CARDRESET | WDIOF_SETTIMEOUT
112 				| WDIOF_KEEPALIVEPING,
113 	.identity	= "SA1100/PXA255 Watchdog",
114 	.firmware_version	= 1,
115 };
116 
sa1100dog_ioctl(struct file * file,unsigned int cmd,unsigned long arg)117 static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
118 							unsigned long arg)
119 {
120 	int ret = -ENOTTY;
121 	int time;
122 	void __user *argp = (void __user *)arg;
123 	int __user *p = argp;
124 
125 	switch (cmd) {
126 	case WDIOC_GETSUPPORT:
127 		ret = copy_to_user(argp, &ident,
128 				   sizeof(ident)) ? -EFAULT : 0;
129 		break;
130 
131 	case WDIOC_GETSTATUS:
132 		ret = put_user(0, p);
133 		break;
134 
135 	case WDIOC_GETBOOTSTATUS:
136 		ret = put_user(boot_status, p);
137 		break;
138 
139 	case WDIOC_KEEPALIVE:
140 		sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
141 		ret = 0;
142 		break;
143 
144 	case WDIOC_SETTIMEOUT:
145 		ret = get_user(time, p);
146 		if (ret)
147 			break;
148 
149 		if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
150 			ret = -EINVAL;
151 			break;
152 		}
153 
154 		pre_margin = oscr_freq * time;
155 		sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
156 		fallthrough;
157 
158 	case WDIOC_GETTIMEOUT:
159 		ret = put_user(pre_margin / oscr_freq, p);
160 		break;
161 	}
162 	return ret;
163 }
164 
165 static const struct file_operations sa1100dog_fops = {
166 	.owner		= THIS_MODULE,
167 	.llseek		= no_llseek,
168 	.write		= sa1100dog_write,
169 	.unlocked_ioctl	= sa1100dog_ioctl,
170 	.compat_ioctl	= compat_ptr_ioctl,
171 	.open		= sa1100dog_open,
172 	.release	= sa1100dog_release,
173 };
174 
175 static struct miscdevice sa1100dog_miscdev = {
176 	.minor		= WATCHDOG_MINOR,
177 	.name		= "watchdog",
178 	.fops		= &sa1100dog_fops,
179 };
180 
181 static int margin = 60;		/* (secs) Default is 1 minute */
182 static struct clk *clk;
183 
sa1100dog_probe(struct platform_device * pdev)184 static int sa1100dog_probe(struct platform_device *pdev)
185 {
186 	int ret;
187 	int *platform_data;
188 	struct resource *res;
189 
190 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
191 	if (!res)
192 		return -ENXIO;
193 	reg_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
194 	ret = PTR_ERR_OR_ZERO(reg_base);
195 	if (ret)
196 		return ret;
197 
198 	clk = clk_get(NULL, "OSTIMER0");
199 	if (IS_ERR(clk)) {
200 		pr_err("SA1100/PXA2xx Watchdog Timer: clock not found: %d\n",
201 		       (int) PTR_ERR(clk));
202 		return PTR_ERR(clk);
203 	}
204 
205 	ret = clk_prepare_enable(clk);
206 	if (ret) {
207 		pr_err("SA1100/PXA2xx Watchdog Timer: clock failed to prepare+enable: %d\n",
208 		       ret);
209 		goto err;
210 	}
211 
212 	oscr_freq = clk_get_rate(clk);
213 
214 	platform_data = pdev->dev.platform_data;
215 	if (platform_data && *platform_data)
216 		boot_status = WDIOF_CARDRESET;
217 	pre_margin = oscr_freq * margin;
218 
219 	ret = misc_register(&sa1100dog_miscdev);
220 	if (ret == 0) {
221 		pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
222 			margin);
223 		return 0;
224 	}
225 
226 	clk_disable_unprepare(clk);
227 err:
228 	clk_put(clk);
229 	return ret;
230 }
231 
sa1100dog_remove(struct platform_device * pdev)232 static int sa1100dog_remove(struct platform_device *pdev)
233 {
234 	misc_deregister(&sa1100dog_miscdev);
235 	clk_disable_unprepare(clk);
236 	clk_put(clk);
237 
238 	return 0;
239 }
240 
241 static struct platform_driver sa1100dog_driver = {
242 	.driver.name = "sa1100_wdt",
243 	.probe	  = sa1100dog_probe,
244 	.remove	  = sa1100dog_remove,
245 };
246 module_platform_driver(sa1100dog_driver);
247 
248 MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
249 MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
250 
251 module_param(margin, int, 0);
252 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
253 
254 MODULE_LICENSE("GPL");
255