cpwatchdog.c

该文件是rt_linux

/* cpwatchdog.c - driver implementation for hardware watchdog
 * timers found on Sun Microsystems CP1400 and CP1500 boards.
 *
 * This device supports both the generic Linux watchdog 
 * interface and Solaris-compatible ioctls as best it is
 * able.
 *
 * NOTE: 	CP1400 systems appear to have a defective intr_mask
 * 			register on the PLD, preventing the disabling of
 * 			timer interrupts.  We use a timer to periodically 
 * 			reset 'stopped' watchdogs on affected platforms.
 *
 * TODO:	DevFS support (/dev/watchdogs/0 ... /dev/watchdogs/2)
 *
 * Copyright (c) 2000 Eric Brower ([e-mail])
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/major.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/timer.h>
#include <asm/irq.h>
#include <asm/ebus.h>
#include <asm/oplib.h>
#include <asm/uaccess.h>

#include <asm/watchdog.h>

#define WD_OBPNAME	"watchdog"
#define WD_BADMODEL "SUNW,501-5336"
#define WD_BTIMEOUT	(jiffies + (HZ * 1000))
#define WD_BLIMIT	0xFFFF

#define WD0_DEVNAME "watchdog0"
#define WD1_DEVNAME "watchdog1"
#define WD2_DEVNAME "watchdog2"

#define WD0_MINOR	212
#define WD1_MINOR	213	
#define WD2_MINOR	214	


/* Internal driver definitions
 */
#define WD0_ID			0		/* Watchdog0						*/
#define WD1_ID			1		/* Watchdog1						*/
#define WD2_ID			2		/* Watchdog2						*/
#define WD_NUMDEVS		3		/* Device contains 3 timers			*/

#define WD_INTR_OFF		0		/* Interrupt disable value			*/
#define WD_INTR_ON		1		/* Interrupt enable value			*/

#define WD_STAT_INIT	0x01	/* Watchdog timer is initialized	*/
#define WD_STAT_BSTOP	0x02	/* Watchdog timer is brokenstopped	*/
#define WD_STAT_SVCD	0x04	/* Watchdog interrupt occurred		*/

/* Register value definitions
 */
#define WD0_INTR_MASK	0x01	/* Watchdog device interrupt masks	*/
#define WD1_INTR_MASK	0x02
#define WD2_INTR_MASK	0x04

#define WD_S_RUNNING	0x01	/* Watchdog device status running	*/
#define WD_S_EXPIRED	0x02	/* Watchdog device status expired	*/

/* Sun uses Altera PLD EPF8820ATC144-4 
 * providing three hardware watchdogs:
 *
 * 	1) RIC - sends an interrupt when triggered
 * 	2) XIR - asserts XIR_B_RESET when triggered, resets CPU
 * 	3) POR - asserts POR_B_RESET when triggered, resets CPU, backplane, board
 *
 *** Timer register block definition (struct wd_timer_regblk)
 *
 * dcntr and limit registers (halfword access):      
 * -------------------
 * | 15 | ...| 1 | 0 |
 * -------------------
 * |-  counter val  -|
 * -------------------
 * dcntr - 	Current 16-bit downcounter value.
 * 			When downcounter reaches '0' watchdog expires.
 * 			Reading this register resets downcounter with 'limit' value.
 * limit - 	16-bit countdown value in 1/10th second increments.
 * 			Writing this register begins countdown with input value.
 * 			Reading from this register does not affect counter.
 * NOTES:	After watchdog reset, dcntr and limit contain '1'
 *
 * status register (byte access):
 * ---------------------------
 * | 7 | ... | 2 |  1  |  0  |
 * --------------+------------
 * |-   UNUSED  -| EXP | RUN |
 * ---------------------------
 * status-	Bit 0 - Watchdog is running
 * 			Bit 1 - Watchdog has expired
 *
 *** PLD register block definition (struct wd_pld_regblk)
 *
 * intr_mask register (byte access):
 * ---------------------------------
 * | 7 | ... | 3 |  2  |  1  |  0  |
 * +-------------+------------------
 * |-   UNUSED  -| WD3 | WD2 | WD1 |
 * ---------------------------------
 * WD3 -  1 == Interrupt disabled for watchdog 3
 * WD2 -  1 == Interrupt disabled for watchdog 2
 * WD1 -  1 == Interrupt disabled for watchdog 1
 *
 * pld_status register (byte access):
 * UNKNOWN, MAGICAL MYSTERY REGISTER
 *
 */
struct wd_timer_regblk {
	volatile __u16	dcntr;		/* down counter		- hw	*/
	volatile __u16	dcntr_pad;
	volatile __u16	limit;		/* limit register	- hw	*/
	volatile __u16	limit_pad;
	volatile __u8	status;		/* status register	- b		*/
	volatile __u8	status_pad;
	volatile __u16	status_pad2;
	volatile __u32	pad32;		/* yet more padding			*/
};

struct wd_pld_regblk {
	volatile __u8	intr_mask;	/* interrupt mask	- b		*/
	volatile __u8	intr_mask_pad;
	volatile __u16	intr_mask_pad2;
	volatile __u8	status;		/* device status	- b		*/
	volatile __u8	status_pad;
	volatile __u16	status_pad2;
};

struct wd_regblk {
	volatile struct wd_timer_regblk		wd0_regs;
	volatile struct wd_timer_regblk		wd1_regs;
	volatile struct wd_timer_regblk		wd2_regs;
	volatile struct wd_pld_regblk		pld_regs;
};

/* Individual timer structure 
 */
struct wd_timer {
	__u16			timeout;
	__u8			intr_mask;
	unsigned char	runstatus;
	volatile struct wd_timer_regblk* regs;
};

/* Device structure
 */
struct wd_device {
	int				irq;
	spinlock_t		lock;
	unsigned char	isbaddoggie;	/* defective PLD */
	unsigned char	opt_enable;
	unsigned char	opt_reboot;
	unsigned short	opt_timeout;
	unsigned char	initialized;
	struct wd_timer	watchdog[WD_NUMDEVS];
	volatile struct	wd_regblk* regs;
};

static struct wd_device wd_dev = { 
		0, SPIN_LOCK_UNLOCKED, 0, 0, 0, 0,
};

static struct timer_list wd_timer;

static int wd0_timeout = 0;
static int wd1_timeout = 0;
static int wd2_timeout = 0;

#ifdef MODULE
EXPORT_NO_SYMBOLS;

MODULE_PARM		(wd0_timeout, "i");
MODULE_PARM_DESC(wd0_timeout, "Default watchdog0 timeout in 1/10secs");
MODULE_PARM 	(wd1_timeout, "i");
MODULE_PARM_DESC(wd1_timeout, "Default watchdog1 timeout in 1/10secs");
MODULE_PARM 	(wd2_timeout, "i");
MODULE_PARM_DESC(wd2_timeout, "Default watchdog2 timeout in 1/10secs");

MODULE_AUTHOR
	("Eric Brower <[e-mail]>");
MODULE_DESCRIPTION
	("Hardware watchdog driver for Sun Microsystems CP1400/1500");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE
	("watchdog");
#endif /* ifdef MODULE */

/* Forward declarations of internal methods
 */
#ifdef WD_DEBUG
static void wd_dumpregs(void);
#endif
static void wd_interrupt(int irq, void *dev_id, struct pt_regs *regs);
static void wd_toggleintr(struct wd_timer* pTimer, int enable);
static void wd_pingtimer(struct wd_timer* pTimer);
static void wd_starttimer(struct wd_timer* pTimer);
static void wd_resetbrokentimer(struct wd_timer* pTimer);
static void wd_stoptimer(struct wd_timer* pTimer);
static void wd_brokentimer(unsigned long data);
static int  wd_getstatus(struct wd_timer* pTimer);

/* PLD expects words to be written in LSB format,
 * so we must flip all words prior to writing them to regs
 */
static inline unsigned short flip_word(unsigned short word)
{
	return ((word & 0xff) << 8) | ((word >> 8) & 0xff);
}

#define wd_writew(val, addr) 	(writew(flip_word(val), addr))
#define wd_readw(addr) 			(flip_word(readw(addr)))
#define wd_writeb(val, addr) 	(writeb(val, addr))
#define wd_readb(addr) 			(readb(addr))


/* CP1400s seem to have broken PLD implementations--
 * the interrupt_mask register cannot be written, so
 * no timer interrupts can be masked within the PLD.
 */
static inline int wd_isbroken(void)
{
	/* we could test this by read/write/read/restore
	 * on the interrupt mask register only if OBP
	 * 'watchdog-enable?' == FALSE, but it seems 
	 * ubiquitous on CP1400s
	 */
	char val[32];
	prom_getproperty(prom_root_node, "model", val, sizeof(val));
	return((!strcmp(val, WD_BADMODEL)) ? 1 : 0);
}
		
/* Retrieve watchdog-enable? option from OBP
 * Returns 0 if false, 1 if true
 */
static inline int wd_opt_enable(void)
{
	int opt_node;

	opt_node = prom_getchild(prom_root_node);
	opt_node = prom_searchsiblings(opt_node, "options");
	return((-1 == prom_getint(opt_node, "watchdog-enable?")) ? 0 : 1);
}

/* Retrieve watchdog-reboot? option from OBP
 * Returns 0 if false, 1 if true
 */
static inline int wd_opt_reboot(void)
{
	int opt_node;

	opt_node = prom_getchild(prom_root_node);
	opt_node = prom_searchsiblings(opt_node, "options");
	return((-1 == prom_getint(opt_node, "watchdog-reboot?")) ? 0 : 1);
}

/* Retrieve watchdog-timeout option from OBP
 * Returns OBP value, or 0 if not located
 */
static inline int wd_opt_timeout(void)
{
	int opt_node;
	char value[32];
	char *p = value;

	opt_node = prom_getchild(prom_root_node);
	opt_node = prom_searchsiblings(opt_node, "options");
	opt_node = prom_getproperty(opt_node, 
								"watchdog-timeout", 
								value, 
								sizeof(value));
	if(-1 != opt_node) {
		/* atoi implementation */
		for(opt_node = 0; /* nop */; p++) {
			if(*p >= '0' && *p <= '9') {
				opt_node = (10*opt_node)+(*p-'0');
			}
			else {
				break;
			}
		}
	}
	return((-1 == opt_node) ? (0) : (opt_node)); 
}

static int wd_open(struct inode *inode, struct file *f)
{
	switch(MINOR(inode->i_rdev))
	{
		case WD0_MINOR:
			f->private_data = &wd_dev.watchdog[WD0_ID];
			break;
		case WD1_MINOR:
			f->private_data = &wd_dev.watchdog[WD1_ID];
			break;
		case WD2_MINOR:
			f->private_data = &wd_dev.watchdog[WD2_ID];
			break;
		default:
			return(-ENODEV);
	}

	/* Register IRQ on first open of device */
	if(0 == wd_dev.initialized)
	{	
		if (request_irq(wd_dev.irq, 
						&wd_interrupt, 
						SA_SHIRQ,
						WD_OBPNAME,
						(void *)wd_dev.regs)) {
			printk("%s: Cannot register IRQ %s\n", 
				WD_OBPNAME, __irq_itoa(wd_dev.irq));
			return(-EBUSY);
		}
		wd_dev.initialized = 1;
	}

	MOD_INC_USE_COUNT;
	return(0);
}

static int wd_release(struct inode *inode, struct file *file)
{
	MOD_DEC_USE_COUNT;
	return 0;
}

static int wd_ioctl(struct inode *inode, struct file *file, 
		     unsigned int cmd, unsigned long arg)
{
	int 	setopt 				= 0;
	struct 	wd_timer* pTimer 	= (struct wd_timer*)file->private_data;
	struct 	watchdog_info info 	= {
		0,
		0,
		"Altera EPF8820ATC144-4"
	};

	if(NULL == pTimer) {
		return(-EINVAL);
	}

	switch(cmd)
	{
		/* Generic Linux IOCTLs */
		case WDIOC_GETSUPPORT:
			if(copy_to_user((struct watchdog_info *)arg, 
							(struct watchdog_info *)&info, 
							sizeof(struct watchdog_info))) {
				return(-EFAULT);
			}
			break;
		case WDIOC_GETSTATUS:
		case WDIOC_GETBOOTSTATUS:
			if (put_user(0, (int *) arg))
				return -EFAULT;
			break;
		case WDIOC_KEEPALIVE:
			wd_pingtimer(pTimer);
			break;
		case WDIOC_SETOPTIONS:
			if(copy_from_user(&setopt, (void*) arg, sizeof(unsigned int))) {
				return -EFAULT;
			}
			if(setopt & WDIOS_DISABLECARD) {
				if(wd_dev.opt_enable) {
					printk(
						"%s: cannot disable watchdog in ENABLED mode\n",
						WD_OBPNAME);
					return(-EINVAL);
				}
				wd_stoptimer(pTimer);
			}
			else if(setopt & WDIOS_ENABLECARD) {
				wd_starttimer(pTimer);
			}
			else {
				return(-EINVAL);
			}	
			break;
		/* Solaris-compatible IOCTLs */
		case WIOCGSTAT:
			setopt = wd_getstatus(pTimer);
			if(copy_to_user((void*)arg, &setopt, sizeof(unsigned int))) {
				return(-EFAULT);
			}
			break;
		case WIOCSTART:
			wd_starttimer(pTimer);
			break;
		case WIOCSTOP:
			if(wd_dev.opt_enable) {
				printk("%s: cannot disable watchdog in ENABLED mode\n",
					WD_OBPNAME);
				return(-EINVAL);
			}
			wd_stoptimer(pTimer);
			break;
		default:
			return(-EINVAL);
	}
	return(0);
}

static ssize_t wd_write(	struct file 	*file, 
							const char		*buf, 
							size_t 			count, 
							loff_t 			*ppos)
{
	struct wd_timer* pTimer = (struct wd_timer*)file->private_data;

	if(NULL == pTimer) {
		return(-EINVAL);
	}

	if (ppos != &file->f_pos)