1 // SPDX-License-Identifier: GPL-2.0-only
3  * PIKA FPGA based Watchdog Timer
19 #include <linux/watchdog.h>
22 #include <linux/timer.h>
29 #define DRV_NAME "PIKA-WDT"
34 /* Timer heartbeat (500ms) */
41 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
46 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
51 	unsigned long next_heartbeat;	/* the next_heartbeat for the timer */
55 	struct timer_list timer;	/* The timer that pings the watchdog */  member
67  * Reload the watchdog timer.  (ie, pat the watchdog)
71 	/* -- FPGA: Reset Control Register (32bit R/W) (Offset: 0x14) --  in pikawdt_reset()
72 	 * Bit 7,    WTCHDG_EN: When set to 1, the watchdog timer is enabled.  in pikawdt_reset()
73 	 *           Once enabled, it cannot be disabled. The watchdog can be  in pikawdt_reset()
76 	 * Bit 8-11, WTCHDG_TIMEOUT_SEC: Sets the watchdog timeout value in  in pikawdt_reset()
81 	/* enable with max timeout - 15 seconds */  in pikawdt_reset()
87  * Timer tick
94 		mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);  in pikawdt_ping()
108 	mod_timer(&pikawdt_private.timer, jiffies + WDT_TIMEOUT);  in pikawdt_start()
112  * Watchdog device is opened, and watchdog starts running.
116 	/* /dev/watchdog can only be opened once */  in pikawdt_open()
118 		return -EBUSY;  in pikawdt_open()
126  * Close the watchdog device.
132 		del_timer(&pikawdt_private.timer);  in pikawdt_release()
140  * Pat the watchdog whenever device is written to.
157 				return -EFAULT;  in pikawdt_write()
171  * Handle commands from user-space.
182 		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;  in pikawdt_ioctl()
196 			return -EFAULT;  in pikawdt_ioctl()
206 	return -ENOTTY;  in pikawdt_ioctl()
221 	.name	= "watchdog",
235 		return -ENOENT;  in pikawdt_init()
242 		return -ENOMEM;  in pikawdt_init()
248 	np = of_find_compatible_node(NULL, NULL, "pika,fpga-sd");  in pikawdt_init()
250 		pr_err("Unable to find fpga-sd\n");  in pikawdt_init()
251 		ret = -ENOENT;  in pikawdt_init()
258 		pr_err("Unable to map fpga-sd\n");  in pikawdt_init()
259 		ret = -ENOMEM;  in pikawdt_init()
263 	/* -- FPGA: POST Test Results Register 1 (32bit R/W) (Offset: 0x4040) --  in pikawdt_init()
264 	 * Bit 31,   WDOG: Set to 1 when the last reset was caused by a watchdog  in pikawdt_init()
273 	timer_setup(&pikawdt_private.timer, pikawdt_ping, 0);  in pikawdt_init()
301 MODULE_DESCRIPTION("PIKA FPGA based Watchdog Timer");