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path: root/drivers/serial/ip22zilog.h
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#ifndef _IP22_ZILOG_H
#define _IP22_ZILOG_H

#include <asm/byteorder.h>

struct zilog_channel {
#ifdef __BIG_ENDIAN
	volatile unsigned char unused0[3];
	volatile unsigned char control;
	volatile unsigned char unused1[3];
	volatile unsigned char data;
#else /* __LITTLE_ENDIAN */
	volatile unsigned char control;
	volatile unsigned char unused0[3];
	volatile unsigned char data;
	volatile unsigned char unused1[3];
#endif
};

struct zilog_layout {
	struct zilog_channel channelB;
	struct zilog_channel channelA;
};

#define NUM_ZSREGS    16

/* Conversion routines to/from brg time constants from/to bits
 * per second.
 */
#define BRG_TO_BPS(brg, freq) ((freq) / 2 / ((brg) + 2))
#define BPS_TO_BRG(bps, freq) ((((freq) + (bps)) / (2 * (bps))) - 2)

/* The Zilog register set */

#define	FLAG	0x7e

/* Write Register 0 */
#define	R0	0		/* Register selects */
#define	R1	1
#define	R2	2
#define	R3	3
#define	R4	4
#define	R5	5
#define	R6	6
#define	R7	7
#define	R8	8
#define	R9	9
#define	R10	10
#define	R11	11
#define	R12	12
#define	R13	13
#define	R14	14
#define	R15	15

#define	NULLCODE	0	/* Null Code */
#define	POINT_HIGH	0x8	/* Select upper half of registers */
#define	RES_EXT_INT	0x10	/* Reset Ext. Status Interrupts */
#define	SEND_ABORT	0x18	/* HDLC Abort */
#define	RES_RxINT_FC	0x20	/* Reset RxINT on First Character */
#define	RES_Tx_P	0x28	/* Reset TxINT Pending */
#define	ERR_RES		0x30	/* Error Reset */
#define	RES_H_IUS	0x38	/* Reset highest IUS */

#define	RES_Rx_CRC	0x40	/* Reset Rx CRC Checker */
#define	RES_Tx_CRC	0x80	/* Reset Tx CRC Checker */
#define	RES_EOM_L	0xC0	/* Reset EOM latch */

/* Write Register 1 */

#define	EXT_INT_ENAB	0x1	/* Ext Int Enable */
#define	TxINT_ENAB	0x2	/* Tx Int Enable */
#define	PAR_SPEC	0x4	/* Parity is special condition */

#define	RxINT_DISAB	0	/* Rx Int Disable */
#define	RxINT_FCERR	0x8	/* Rx Int on First Character Only or Error */
#define	INT_ALL_Rx	0x10	/* Int on all Rx Characters or error */
#define	INT_ERR_Rx	0x18	/* Int on error only */
#define RxINT_MASK	0x18

#define	WT_RDY_RT	0x20	/* Wait/Ready on R/T */
#define	WT_FN_RDYFN	0x40	/* Wait/FN/Ready FN */
#define	WT_RDY_ENAB	0x80	/* Wait/Ready Enable */

/* Write Register #2 (Interrupt Vector) */

/* Write Register 3 */

#define	RxENAB  	0x1	/* Rx Enable */
#define	SYNC_L_INH	0x2	/* Sync Character Load Inhibit */
#define	ADD_SM		0x4	/* Address Search Mode (SDLC) */
#define	RxCRC_ENAB	0x8	/* Rx CRC Enable */
#define	ENT_HM		0x10	/* Enter Hunt Mode */
#define	AUTO_ENAB	0x20	/* Auto Enables */
#define	Rx5		0x0	/* Rx 5 Bits/Character */
#define	Rx7		0x40	/* Rx 7 Bits/Character */
#define	Rx6		0x80	/* Rx 6 Bits/Character */
#define	Rx8		0xc0	/* Rx 8 Bits/Character */
#define RxN_MASK	0xc0

/* Write Register 4 */

#define	PAR_ENAB	0x1	/* Parity Enable */
#define	PAR_EVEN	0x2	/* Parity Even/Odd* */

#define	SYNC_ENAB	0	/* Sync Modes Enable */
#define	SB1		0x4	/* 1 stop bit/char */
#define	SB15		0x8	/* 1.5 stop bits/char */
#define	SB2		0xc	/* 2 stop bits/char */

#define	MONSYNC		0	/* 8 Bit Sync character */
#define	BISYNC		0x10	/* 16 bit sync character */
#define	SDLC		0x20	/* SDLC Mode (01111110 Sync Flag) */
#define	EXTSYNC		0x30	/* External Sync Mode */

#define	X1CLK		0x0	/* x1 clock mode */
#define	X16CLK		0x40	/* x16 clock mode */
#define	X32CLK		0x80	/* x32 clock mode */
#define	X64CLK		0xC0	/* x64 clock mode */
#define XCLK_MASK	0xC0

/* Write Register 5 */

#define	TxCRC_ENAB	0x1	/* Tx CRC Enable */
#define	RTS		0x2	/* RTS */
#define	SDLC_CRC	0x4	/* SDLC/CRC-16 */
#define	TxENAB		0x8	/* Tx Enable */
#define	SND_BRK		0x10	/* Send Break */
#define	Tx5		0x0	/* Tx 5 bits (or less)/character */
#define	Tx7		0x20	/* Tx 7 bits/character */
#define	Tx6		0x40	/* Tx 6 bits/character */
#define	Tx8		0x60	/* Tx 8 bits/character */
#define TxN_MASK	0x60
#define	DTR		0x80	/* DTR */

/* Write Register 6 (Sync bits 0-7/SDLC Address Field) */

/* Write Register 7 (Sync bits 8-15/SDLC 01111110) */

/* Write Register 8 (transmit buffer) */

/* Write Register 9 (Master interrupt control) */
#define	VIS	1	/* Vector Includes Status */
#define	NV	2	/* No Vector */
#define	DLC	4	/* Disable Lower Chain */
#define	MIE	8	/* Master Interrupt Enable */
#define	STATHI	0x10	/* Status high */
#define	NORESET	0	/* No reset on write to R9 */
#define	CHRB	0x40	/* Reset channel B */
#define	CHRA	0x80	/* Reset channel A */
#define	FHWRES	0xc0	/* Force hardware reset */

/* Write Register 10 (misc control bits) */
#define	BIT6	1	/* 6 bit/8bit sync */
#define	LOOPMODE 2	/* SDLC Loop mode */
#define	ABUNDER	4	/* Abort/flag on SDLC xmit underrun */
#define	MARKIDLE 8	/* Mark/flag on idle */
#define	GAOP	0x10	/* Go active on poll */
#define	NRZ	0	/* NRZ mode */
#define	NRZI	0x20	/* NRZI mode */
#define	FM1	0x40	/* FM1 (transition = 1) */
#define	FM0	0x60	/* FM0 (transition = 0) */
#define	CRCPS	0x80	/* CRC Preset I/O */

/* Write Register 11 (Clock Mode control) */
#define	TRxCXT	0	/* TRxC = Xtal output */
#define	TRxCTC	1	/* TRxC = Transmit clock */
#define	TRxCBR	2	/* TRxC = BR Generator Output */
#define	TRxCDP	3	/* TRxC = DPLL output */
#define	TRxCOI	4	/* TRxC O/I */
#define	TCRTxCP	0	/* Transmit clock = RTxC pin */
#define	TCTRxCP	8	/* Transmit clock = TRxC pin */
#define	TCBR	0x10	/* Transmit clock = BR Generator output */
#define	TCDPLL	0x18	/* Transmit clock = DPLL output */
#define	RCRTxCP	0	/* Receive clock = RTxC pin */
#define	RCTRxCP	0x20	/* Receive clock = TRxC pin */
#define	RCBR	0x40	/* Receive clock = BR Generator output */
#define	RCDPLL	0x60	/* Receive clock = DPLL output */
#define	RTxCX	0x80	/* RTxC Xtal/No Xtal */

/* Write Register 12 (lower byte of baud rate generator time constant) */

/* Write Register 13 (upper byte of baud rate generator time constant) */

/* Write Register 14 (Misc control bits) */
#define	BRENAB 	1	/* Baud rate generator enable */
#define	BRSRC	2	/* Baud rate generator source */
#define	DTRREQ	4	/* DTR/Request function */
#define	AUTOECHO 8	/* Auto Echo */
#define	LOOPBAK	0x10	/* Local loopback */
#define	SEARCH	0x20	/* Enter search mode */
#define	RMC	0x40	/* Reset missing clock */
#define	DISDPLL	0x60	/* Disable DPLL */
#define	SSBR	0x80	/* Set DPLL source = BR generator */
#define	SSRTxC	0xa0	/* Set DPLL source = RTxC */
#define	SFMM	0xc0	/* Set FM mode */
#define	SNRZI	0xe0	/* Set NRZI mode */

/* Write Register 15 (external/status interrupt control) */
#define	ZCIE	2	/* Zero count IE */
#define	DCDIE	8	/* DCD IE */
#define	SYNCIE	0x10	/* Sync/hunt IE */
#define	CTSIE	0x20	/* CTS IE */
#define	TxUIE	0x40	/* Tx Underrun/EOM IE */
#define	BRKIE	0x80	/* Break/Abort IE */


/* Read Register 0 */
#define	Rx_CH_AV	0x1	/* Rx Character Available */
#define	ZCOUNT		0x2	/* Zero count */
#define	Tx_BUF_EMP	0x4	/* Tx Buffer empty */
#define	DCD		0x8	/* DCD */
#define	SYNC		0x10	/* Sync/hunt */
#define	CTS		0x20	/* CTS */
#define	TxEOM		0x40	/* Tx underrun */
#define	BRK_ABRT	0x80	/* Break/Abort */

/* Read Register 1 */
#define	ALL_SNT		0x1	/* All sent */
/* Residue Data for 8 Rx bits/char programmed */
#define	RES3		0x8	/* 0/3 */
#define	RES4		0x4	/* 0/4 */
#define	RES5		0xc	/* 0/5 */
#define	RES6		0x2	/* 0/6 */
#define	RES7		0xa	/* 0/7 */
#define	RES8		0x6	/* 0/8 */
#define	RES18		0xe	/* 1/8 */
#define	RES28		0x0	/* 2/8 */
/* Special Rx Condition Interrupts */
#define	PAR_ERR		0x10	/* Parity error */
#define	Rx_OVR		0x20	/* Rx Overrun Error */
#define	CRC_ERR		0x40	/* CRC/Framing Error */
#define	END_FR		0x80	/* End of Frame (SDLC) */

/* Read Register 2 (channel b only) - Interrupt vector */
#define CHB_Tx_EMPTY	0x00
#define CHB_EXT_STAT	0x02
#define CHB_Rx_AVAIL	0x04
#define CHB_SPECIAL	0x06
#define CHA_Tx_EMPTY	0x08
#define CHA_EXT_STAT	0x0a
#define CHA_Rx_AVAIL	0x0c
#define CHA_SPECIAL	0x0e
#define STATUS_MASK	0x0e

/* Read Register 3 (interrupt pending register) ch a only */
#define	CHBEXT	0x1		/* Channel B Ext/Stat IP */
#define	CHBTxIP	0x2		/* Channel B Tx IP */
#define	CHBRxIP	0x4		/* Channel B Rx IP */
#define	CHAEXT	0x8		/* Channel A Ext/Stat IP */
#define	CHATxIP	0x10		/* Channel A Tx IP */
#define	CHARxIP	0x20		/* Channel A Rx IP */

/* Read Register 8 (receive data register) */

/* Read Register 10  (misc status bits) */
#define	ONLOOP	2		/* On loop */
#define	LOOPSEND 0x10		/* Loop sending */
#define	CLK2MIS	0x40		/* Two clocks missing */
#define	CLK1MIS	0x80		/* One clock missing */

/* Read Register 12 (lower byte of baud rate generator constant) */

/* Read Register 13 (upper byte of baud rate generator constant) */

/* Read Register 15 (value of WR 15) */

/* Misc macros */
#define ZS_CLEARERR(channel)    do { writeb(ERR_RES, &channel->control); \
				     udelay(5); } while(0)

#define ZS_CLEARSTAT(channel)   do { writeb(RES_EXT_INT, &channel->control); \
				     udelay(5); } while(0)

#define ZS_CLEARFIFO(channel)   do { readb(&channel->data); \
				     udelay(2); \
				     readb(&channel->data); \
				     udelay(2); \
				     readb(&channel->data); \
				     udelay(2); } while(0)

#endif /* _IP22_ZILOG_H */
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/*
 *  fs/timerfd.c
 *
 *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
 *
 *
 *  Thanks to Thomas Gleixner for code reviews and useful comments.
 *
 */

#include <linux/alarmtimer.h>
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/time.h>
#include <linux/hrtimer.h>
#include <linux/anon_inodes.h>
#include <linux/timerfd.h>
#include <linux/syscalls.h>
#include <linux/compat.h>
#include <linux/rcupdate.h>

struct timerfd_ctx {
	union {
		struct hrtimer tmr;
		struct alarm alarm;
	} t;
	ktime_t tintv;
	ktime_t moffs;
	wait_queue_head_t wqh;
	u64 ticks;
	int clockid;
	short unsigned expired;
	short unsigned settime_flags;	/* to show in fdinfo */
	struct rcu_head rcu;
	struct list_head clist;
	spinlock_t cancel_lock;
	bool might_cancel;
};

static LIST_HEAD(cancel_list);
static DEFINE_SPINLOCK(cancel_lock);

static inline bool isalarm(struct timerfd_ctx *ctx)
{
	return ctx->clockid == CLOCK_REALTIME_ALARM ||
		ctx->clockid == CLOCK_BOOTTIME_ALARM;
}

/*
 * This gets called when the timer event triggers. We set the "expired"
 * flag, but we do not re-arm the timer (in case it's necessary,
 * tintv != 0) until the timer is accessed.
 */
static void timerfd_triggered(struct timerfd_ctx *ctx)
{
	unsigned long flags;

	spin_lock_irqsave(&ctx->wqh.lock, flags);
	ctx->expired = 1;
	ctx->ticks++;
	wake_up_locked(&ctx->wqh);
	spin_unlock_irqrestore(&ctx->wqh.lock, flags);
}

static enum hrtimer_restart timerfd_tmrproc(struct hrtimer *htmr)
{
	struct timerfd_ctx *ctx = container_of(htmr, struct timerfd_ctx,
					       t.tmr);
	timerfd_triggered(ctx);
	return HRTIMER_NORESTART;
}

static enum alarmtimer_restart timerfd_alarmproc(struct alarm *alarm,
	ktime_t now)
{
	struct timerfd_ctx *ctx = container_of(alarm, struct timerfd_ctx,
					       t.alarm);
	timerfd_triggered(ctx);
	return ALARMTIMER_NORESTART;
}

/*
 * Called when the clock was set to cancel the timers in the cancel
 * list. This will wake up processes waiting on these timers. The
 * wake-up requires ctx->ticks to be non zero, therefore we increment
 * it before calling wake_up_locked().
 */
void timerfd_clock_was_set(void)
{
	ktime_t moffs = ktime_mono_to_real(0);
	struct timerfd_ctx *ctx;
	unsigned long flags;

	rcu_read_lock();
	list_for_each_entry_rcu(ctx, &cancel_list, clist) {
		if (!ctx->might_cancel)
			continue;
		spin_lock_irqsave(&ctx->wqh.lock, flags);
		if (ctx->moffs != moffs) {
			ctx->moffs = KTIME_MAX;
			ctx->ticks++;
			wake_up_locked(&ctx->wqh);
		}
		spin_unlock_irqrestore(&ctx->wqh.lock, flags);
	}
	rcu_read_unlock();
}

static void __timerfd_remove_cancel(struct timerfd_ctx *ctx)
{
	if (ctx->might_cancel) {
		ctx->might_cancel = false;
		spin_lock(&cancel_lock);
		list_del_rcu(&ctx->clist);
		spin_unlock(&cancel_lock);
	}
}

static void timerfd_remove_cancel(struct timerfd_ctx *ctx)
{
	spin_lock(&ctx->cancel_lock);
	__timerfd_remove_cancel(ctx);
	spin_unlock(&ctx->cancel_lock);
}

static bool timerfd_canceled(struct timerfd_ctx *ctx)
{
	if (!ctx->might_cancel || ctx->moffs != KTIME_MAX)
		return false;
	ctx->moffs = ktime_mono_to_real(0);
	return true;
}

static void timerfd_setup_cancel(struct timerfd_ctx *ctx, int flags)
{
	spin_lock(&ctx->cancel_lock);
	if ((ctx->clockid == CLOCK_REALTIME ||
	     ctx->clockid == CLOCK_REALTIME_ALARM) &&
	    (flags & TFD_TIMER_ABSTIME) && (flags & TFD_TIMER_CANCEL_ON_SET)) {
		if (!ctx->might_cancel) {
			ctx->might_cancel = true;
			spin_lock(&cancel_lock);
			list_add_rcu(&ctx->clist, &cancel_list);
			spin_unlock(&cancel_lock);
		}
	} else {
		__timerfd_remove_cancel(ctx);
	}
	spin_unlock(&ctx->cancel_lock);
}

static ktime_t timerfd_get_remaining(struct timerfd_ctx *ctx)
{
	ktime_t remaining;

	if (isalarm(ctx))
		remaining = alarm_expires_remaining(&ctx->t.alarm);
	else
		remaining = hrtimer_expires_remaining_adjusted(&ctx->t.tmr);

	return remaining < 0 ? 0: remaining;
}

static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
			 const struct itimerspec *ktmr)
{
	enum hrtimer_mode htmode;
	ktime_t texp;
	int clockid = ctx->clockid;

	htmode = (flags & TFD_TIMER_ABSTIME) ?
		HRTIMER_MODE_ABS: HRTIMER_MODE_REL;

	texp = timespec_to_ktime(ktmr->it_value);
	ctx->expired = 0;
	ctx->ticks = 0;
	ctx->tintv = timespec_to_ktime(ktmr->it_interval);

	if (isalarm(ctx)) {
		alarm_init(&ctx->t.alarm,
			   ctx->clockid == CLOCK_REALTIME_ALARM ?
			   ALARM_REALTIME : ALARM_BOOTTIME,
			   timerfd_alarmproc);
	} else {
		hrtimer_init(&ctx->t.tmr, clockid, htmode);
		hrtimer_set_expires(&ctx->t.tmr, texp);
		ctx->t.tmr.function = timerfd_tmrproc;
	}

	if (texp != 0) {
		if (isalarm(ctx)) {
			if (flags & TFD_TIMER_ABSTIME)
				alarm_start(&ctx->t.alarm, texp);
			else
				alarm_start_relative(&ctx->t.alarm, texp);
		} else {
			hrtimer_start(&ctx->t.tmr, texp, htmode);
		}

		if (timerfd_canceled(ctx))
			return -ECANCELED;
	}

	ctx->settime_flags = flags & TFD_SETTIME_FLAGS;
	return 0;
}

static int timerfd_release(struct inode *inode, struct file *file)
{
	struct timerfd_ctx *ctx = file->private_data;

	timerfd_remove_cancel(ctx);

	if (isalarm(ctx))
		alarm_cancel(&ctx->t.alarm);
	else
		hrtimer_cancel(&ctx->t.tmr);
	kfree_rcu(ctx, rcu);
	return 0;
}

static unsigned int timerfd_poll(struct file *file, poll_table *wait)
{
	struct timerfd_ctx *ctx = file->private_data;
	unsigned int events = 0;
	unsigned long flags;

	poll_wait(file, &ctx->wqh, wait);

	spin_lock_irqsave(&ctx->wqh.lock, flags);
	if (ctx->ticks)
		events |= POLLIN;
	spin_unlock_irqrestore(&ctx->wqh.lock, flags);

	return events;
}

static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
			    loff_t *ppos)
{
	struct timerfd_ctx *ctx = file->private_data;
	ssize_t res;
	u64 ticks = 0;

	if (count < sizeof(ticks))
		return -EINVAL;
	spin_lock_irq(&ctx->wqh.lock);
	if (file->f_flags & O_NONBLOCK)
		res = -EAGAIN;
	else
		res = wait_event_interruptible_locked_irq(ctx->wqh, ctx->ticks);

	/*
	 * If clock has changed, we do not care about the
	 * ticks and we do not rearm the timer. Userspace must
	 * reevaluate anyway.
	 */
	if (timerfd_canceled(ctx)) {
		ctx->ticks = 0;
		ctx->expired = 0;
		res = -ECANCELED;
	}

	if (ctx->ticks) {
		ticks = ctx->ticks;

		if (ctx->expired && ctx->tintv) {
			/*
			 * If tintv != 0, this is a periodic timer that
			 * needs to be re-armed. We avoid doing it in the timer
			 * callback to avoid DoS attacks specifying a very
			 * short timer period.
			 */
			if (isalarm(ctx)) {
				ticks += alarm_forward_now(
					&ctx->t.alarm, ctx->tintv) - 1;
				alarm_restart(&ctx->t.alarm);
			} else {
				ticks += hrtimer_forward_now(&ctx->t.tmr,
							     ctx->tintv) - 1;
				hrtimer_restart(&ctx->t.tmr);
			}
		}
		ctx->expired = 0;
		ctx->ticks = 0;
	}
	spin_unlock_irq(&ctx->wqh.lock);
	if (ticks)
		res = put_user(ticks, (u64 __user *) buf) ? -EFAULT: sizeof(ticks);
	return res;
}

#ifdef CONFIG_PROC_FS
static void timerfd_show(struct seq_file *m, struct file *file)
{
	struct timerfd_ctx *ctx = file->private_data;
	struct itimerspec t;

	spin_lock_irq(&ctx->wqh.lock);
	t.it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
	t.it_interval = ktime_to_timespec(ctx->tintv);
	spin_unlock_irq(&ctx->wqh.lock);

	seq_printf(m,
		   "clockid: %d\n"
		   "ticks: %llu\n"
		   "settime flags: 0%o\n"
		   "it_value: (%llu, %llu)\n"
		   "it_interval: (%llu, %llu)\n",
		   ctx->clockid,
		   (unsigned long long)ctx->ticks,
		   ctx->settime_flags,
		   (unsigned long long)t.it_value.tv_sec,
		   (unsigned long long)t.it_value.tv_nsec,
		   (unsigned long long)t.it_interval.tv_sec,
		   (unsigned long long)t.it_interval.tv_nsec);
}
#else
#define timerfd_show NULL
#endif

#ifdef CONFIG_CHECKPOINT_RESTORE
static long timerfd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct timerfd_ctx *ctx = file->private_data;
	int ret = 0;

	switch (cmd) {
	case TFD_IOC_SET_TICKS: {
		u64 ticks;

		if (copy_from_user(&ticks, (u64 __user *)arg, sizeof(ticks)))
			return -EFAULT;
		if (!ticks)
			return -EINVAL;

		spin_lock_irq(&ctx->wqh.lock);
		if (!timerfd_canceled(ctx)) {
			ctx->ticks = ticks;
			wake_up_locked(&ctx->wqh);
		} else
			ret = -ECANCELED;
		spin_unlock_irq(&ctx->wqh.lock);
		break;
	}
	default:
		ret = -ENOTTY;
		break;
	}

	return ret;
}
#else
#define timerfd_ioctl NULL
#endif

static const struct file_operations timerfd_fops = {
	.release	= timerfd_release,
	.poll		= timerfd_poll,
	.read		= timerfd_read,
	.llseek		= noop_llseek,
	.show_fdinfo	= timerfd_show,
	.unlocked_ioctl	= timerfd_ioctl,
};

static int timerfd_fget(int fd, struct fd *p)
{
	struct fd f = fdget(fd);
	if (!f.file)
		return -EBADF;
	if (f.file->f_op != &timerfd_fops) {
		fdput(f);
		return -EINVAL;
	}
	*p = f;
	return 0;
}

SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags)
{
	int ufd;
	struct timerfd_ctx *ctx;

	/* Check the TFD_* constants for consistency.  */
	BUILD_BUG_ON(TFD_CLOEXEC != O_CLOEXEC);
	BUILD_BUG_ON(TFD_NONBLOCK != O_NONBLOCK);

	if ((flags & ~TFD_CREATE_FLAGS) ||
	    (clockid != CLOCK_MONOTONIC &&
	     clockid != CLOCK_REALTIME &&
	     clockid != CLOCK_REALTIME_ALARM &&
	     clockid != CLOCK_BOOTTIME &&
	     clockid != CLOCK_BOOTTIME_ALARM))
		return -EINVAL;

	if ((clockid == CLOCK_REALTIME_ALARM ||
	     clockid == CLOCK_BOOTTIME_ALARM) &&
	    !capable(CAP_WAKE_ALARM))
		return -EPERM;

	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
	if (!ctx)
		return -ENOMEM;

	init_waitqueue_head(&ctx->wqh);
	spin_lock_init(&ctx->cancel_lock);
	ctx->clockid = clockid;

	if (isalarm(ctx))
		alarm_init(&ctx->t.alarm,
			   ctx->clockid == CLOCK_REALTIME_ALARM ?
			   ALARM_REALTIME : ALARM_BOOTTIME,
			   timerfd_alarmproc);
	else
		hrtimer_init(&ctx->t.tmr, clockid, HRTIMER_MODE_ABS);

	ctx->moffs = ktime_mono_to_real(0);

	ufd = anon_inode_getfd("[timerfd]", &timerfd_fops, ctx,
			       O_RDWR | (flags & TFD_SHARED_FCNTL_FLAGS));
	if (ufd < 0)
		kfree(ctx);

	return ufd;
}

static int do_timerfd_settime(int ufd, int flags, 
		const struct itimerspec *new,
		struct itimerspec *old)
{
	struct fd f;
	struct timerfd_ctx *ctx;
	int ret;

	if ((flags & ~TFD_SETTIME_FLAGS) ||
	    !timespec_valid(&new->it_value) ||
	    !timespec_valid(&new->it_interval))
		return -EINVAL;

	ret = timerfd_fget(ufd, &f);
	if (ret)
		return ret;
	ctx = f.file->private_data;

	if (isalarm(ctx) && !capable(CAP_WAKE_ALARM)) {
		fdput(f);
		return -EPERM;
	}

	timerfd_setup_cancel(ctx, flags);

	/*
	 * We need to stop the existing timer before reprogramming
	 * it to the new values.
	 */
	for (;;) {
		spin_lock_irq(&ctx->wqh.lock);

		if (isalarm(ctx)) {
			if (alarm_try_to_cancel(&ctx->t.alarm) >= 0)
				break;
		} else {
			if (hrtimer_try_to_cancel(&ctx->t.tmr) >= 0)
				break;
		}
		spin_unlock_irq(&ctx->wqh.lock);
		cpu_relax();
	}

	/*
	 * If the timer is expired and it's periodic, we need to advance it
	 * because the caller may want to know the previous expiration time.
	 * We do not update "ticks" and "expired" since the timer will be
	 * re-programmed again in the following timerfd_setup() call.
	 */
	if (ctx->expired && ctx->tintv) {
		if (isalarm(ctx))
			alarm_forward_now(&ctx->t.alarm, ctx->tintv);
		else
			hrtimer_forward_now(&ctx->t.tmr, ctx->tintv);
	}

	old->it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
	old->it_interval = ktime_to_timespec(ctx->tintv);

	/*
	 * Re-program the timer to the new value ...
	 */
	ret = timerfd_setup(ctx, flags, new);

	spin_unlock_irq(&ctx->wqh.lock);
	fdput(f);
	return ret;
}

static int do_timerfd_gettime(int ufd, struct itimerspec *t)
{
	struct fd f;
	struct timerfd_ctx *ctx;
	int ret = timerfd_fget(ufd, &f);
	if (ret)
		return ret;
	ctx = f.file->private_data;

	spin_lock_irq(&ctx->wqh.lock);
	if (ctx->expired && ctx->tintv) {
		ctx->expired = 0;

		if (isalarm(ctx)) {
			ctx->ticks +=
				alarm_forward_now(
					&ctx->t.alarm, ctx->tintv) - 1;
			alarm_restart(&ctx->t.alarm);
		} else {
			ctx->ticks +=
				hrtimer_forward_now(&ctx->t.tmr, ctx->tintv)
				- 1;
			hrtimer_restart(&ctx->t.tmr);
		}
	}
	t->it_value = ktime_to_timespec(timerfd_get_remaining(ctx));
	t->it_interval = ktime_to_timespec(ctx->tintv);
	spin_unlock_irq(&ctx->wqh.lock);
	fdput(f);
	return 0;
}

SYSCALL_DEFINE4(timerfd_settime, int, ufd, int, flags,
		const struct itimerspec __user *, utmr,
		struct itimerspec __user *, otmr)
{
	struct itimerspec new, old;
	int ret;

	if (copy_from_user(&new, utmr, sizeof(new)))
		return -EFAULT;
	ret = do_timerfd_settime(ufd, flags, &new, &old);
	if (ret)
		return ret;
	if (otmr && copy_to_user(otmr, &old, sizeof(old)))
		return -EFAULT;

	return ret;
}

SYSCALL_DEFINE2(timerfd_gettime, int, ufd, struct itimerspec __user *, otmr)
{
	struct itimerspec kotmr;
	int ret = do_timerfd_gettime(ufd, &kotmr);
	if (ret)
		return ret;
	return copy_to_user(otmr, &kotmr, sizeof(kotmr)) ? -EFAULT: 0;
}

#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE4(timerfd_settime, int, ufd, int, flags,
		const struct compat_itimerspec __user *, utmr,
		struct compat_itimerspec __user *, otmr)
{
	struct itimerspec new, old;
	int ret;

	if (get_compat_itimerspec(&new, utmr))
		return -EFAULT;
	ret = do_timerfd_settime(ufd, flags, &new, &old);
	if (ret)
		return ret;
	if (otmr && put_compat_itimerspec(otmr, &old))
		return -EFAULT;
	return ret;
}

COMPAT_SYSCALL_DEFINE2(timerfd_gettime, int, ufd,
		struct compat_itimerspec __user *, otmr)
{
	struct itimerspec kotmr;
	int ret = do_timerfd_gettime(ufd, &kotmr);
	if (ret)
		return ret;
	return put_compat_itimerspec(otmr, &kotmr) ? -EFAULT: 0;
}
#endif