[linux-block.git] / arch / arm / mach-s3c2410 / time.c

/* linux/arch/arm/mach-s3c2410/time.c
 *
 * Copyright (C) 2003-2005 Simtec Electronics
 *	Ben Dooks, <ben@simtec.co.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/clk.h>

#include <asm/system.h>
#include <asm/leds.h>
#include <asm/mach-types.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/arch/map.h>
#include <asm/arch/regs-timer.h>
#include <asm/arch/regs-irq.h>
#include <asm/mach/time.h>

#include "clock.h"
#include "cpu.h"

static unsigned long timer_startval;
static unsigned long timer_usec_ticks;

#define TIMER_USEC_SHIFT 16

/* we use the shifted arithmetic to work out the ratio of timer ticks
 * to usecs, as often the peripheral clock is not a nice even multiple
 * of 1MHz.
 *
 * shift of 14 and 15 are too low for the 12MHz, 16 seems to be ok
 * for the current HZ value of 200 without producing overflows.
 *
 * Original patch by Dimitry Andric, updated by Ben Dooks
*/


/* timer_mask_usec_ticks
 *
 * given a clock and divisor, make the value to pass into timer_ticks_to_usec
 * to scale the ticks into usecs
*/

static inline unsigned long
timer_mask_usec_ticks(unsigned long scaler, unsigned long pclk)
{
	unsigned long den = pclk / 1000;

	return ((1000 << TIMER_USEC_SHIFT) * scaler + (den >> 1)) / den;
}

/* timer_ticks_to_usec
 *
 * convert timer ticks to usec.
*/

static inline unsigned long timer_ticks_to_usec(unsigned long ticks)
{
	unsigned long res;

	res = ticks * timer_usec_ticks;
	res += 1 << (TIMER_USEC_SHIFT - 4);	/* round up slightly */

	return res >> TIMER_USEC_SHIFT;
}

/***
 * Returns microsecond  since last clock interrupt.  Note that interrupts
 * will have been disabled by do_gettimeoffset()
 * IRQs are disabled before entering here from do_gettimeofday()
 */

#define SRCPND_TIMER4 (1<<(IRQ_TIMER4 - IRQ_EINT0))

static unsigned long s3c2410_gettimeoffset (void)
{
	unsigned long tdone;
	unsigned long irqpend;
	unsigned long tval;

	/* work out how many ticks have gone since last timer interrupt */

        tval =  __raw_readl(S3C2410_TCNTO(4));
	tdone = timer_startval - tval;

	/* check to see if there is an interrupt pending */

	irqpend = __raw_readl(S3C2410_SRCPND);
	if (irqpend & SRCPND_TIMER4) {
		/* re-read the timer, and try and fix up for the missed
		 * interrupt. Note, the interrupt may go off before the
		 * timer has re-loaded from wrapping.
		 */

		tval =  __raw_readl(S3C2410_TCNTO(4));
		tdone = timer_startval - tval;

		if (tval != 0)
			tdone += timer_startval;
	}

	return timer_ticks_to_usec(tdone);
}


/*
 * IRQ handler for the timer
 */
static irqreturn_t
s3c2410_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	write_seqlock(&xtime_lock);
	timer_tick(regs);
	write_sequnlock(&xtime_lock);
	return IRQ_HANDLED;
}

static struct irqaction s3c2410_timer_irq = {
	.name		= "S3C2410 Timer Tick",
	.flags		= SA_INTERRUPT | SA_TIMER,
	.handler	= s3c2410_timer_interrupt,
};

/*
 * Set up timer interrupt, and return the current time in seconds.
 *
 * Currently we only use timer4, as it is the only timer which has no
 * other function that can be exploited externally
 */
static void s3c2410_timer_setup (void)
{
	unsigned long tcon;
	unsigned long tcnt;
	unsigned long tcfg1;
	unsigned long tcfg0;

	tcnt = 0xffff;  /* default value for tcnt */

	/* read the current timer configuration bits */

	tcon = __raw_readl(S3C2410_TCON);
	tcfg1 = __raw_readl(S3C2410_TCFG1);
	tcfg0 = __raw_readl(S3C2410_TCFG0);

	/* configure the system for whichever machine is in use */

	if (machine_is_bast() || machine_is_vr1000() || machine_is_anubis()) {
		/* timer is at 12MHz, scaler is 1 */
		timer_usec_ticks = timer_mask_usec_ticks(1, 12000000);
		tcnt = 12000000 / HZ;

		tcfg1 &= ~S3C2410_TCFG1_MUX4_MASK;
		tcfg1 |= S3C2410_TCFG1_MUX4_TCLK1;
	} else {
		unsigned long pclk;
		struct clk *clk;

		/* for the h1940 (and others), we use the pclk from the core
		 * to generate the timer values. since values around 50 to
		 * 70MHz are not values we can directly generate the timer
		 * value from, we need to pre-scale and divide before using it.
		 *
		 * for instance, using 50.7MHz and dividing by 6 gives 8.45MHz
		 * (8.45 ticks per usec)
		 */

		/* this is used as default if no other timer can be found */

		clk = clk_get(NULL, "timers");
		if (IS_ERR(clk))
			panic("failed to get clock for system timer");

		clk_enable(clk);

		pclk = clk_get_rate(clk);

		/* configure clock tick */

		timer_usec_ticks = timer_mask_usec_ticks(6, pclk);

		tcfg1 &= ~S3C2410_TCFG1_MUX4_MASK;
		tcfg1 |= S3C2410_TCFG1_MUX4_DIV2;

		tcfg0 &= ~S3C2410_TCFG_PRESCALER1_MASK;
		tcfg0 |= ((6 - 1) / 2) << S3C2410_TCFG_PRESCALER1_SHIFT;

		tcnt = (pclk / 6) / HZ;
	}

	/* timers reload after counting zero, so reduce the count by 1 */

	tcnt--;

	printk("timer tcon=%08lx, tcnt %04lx, tcfg %08lx,%08lx, usec %08lx\n",
	       tcon, tcnt, tcfg0, tcfg1, timer_usec_ticks);

	/* check to see if timer is within 16bit range... */
	if (tcnt > 0xffff) {
		panic("setup_timer: HZ is too small, cannot configure timer!");
		return;
	}

	__raw_writel(tcfg1, S3C2410_TCFG1);
	__raw_writel(tcfg0, S3C2410_TCFG0);

	timer_startval = tcnt;
	__raw_writel(tcnt, S3C2410_TCNTB(4));

	/* ensure timer is stopped... */

	tcon &= ~(7<<20);
	tcon |= S3C2410_TCON_T4RELOAD;
	tcon |= S3C2410_TCON_T4MANUALUPD;

	__raw_writel(tcon, S3C2410_TCON);
	__raw_writel(tcnt, S3C2410_TCNTB(4));
	__raw_writel(tcnt, S3C2410_TCMPB(4));

	/* start the timer running */
	tcon |= S3C2410_TCON_T4START;
	tcon &= ~S3C2410_TCON_T4MANUALUPD;
	__raw_writel(tcon, S3C2410_TCON);
}

static void __init s3c2410_timer_init (void)
{
	s3c2410_timer_setup();
	setup_irq(IRQ_TIMER4, &s3c2410_timer_irq);
}

struct sys_timer s3c24xx_timer = {
	.init		= s3c2410_timer_init,
	.offset		= s3c2410_gettimeoffset,
	.resume		= s3c2410_timer_setup
};
Commit	Line	Data
1da177e4 LT	1	/* linux/arch/arm/mach-s3c2410/time.c
	2	*
	3	* Copyright (C) 2003-2005 Simtec Electronics
	4	* Ben Dooks, <ben@simtec.co.uk>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	19	*/
	20
	21	#include <linux/config.h>
	22	#include <linux/kernel.h>
	23	#include <linux/sched.h>
	24	#include <linux/init.h>
	25	#include <linux/interrupt.h>
	26	#include <linux/err.h>
f8ce2547	27	#include <linux/clk.h>
1da177e4 LT	28
	29	#include <asm/system.h>
	30	#include <asm/leds.h>
	31	#include <asm/mach-types.h>
	32
	33	#include <asm/io.h>
	34	#include <asm/irq.h>
	35	#include <asm/arch/map.h>
	36	#include <asm/arch/regs-timer.h>
	37	#include <asm/arch/regs-irq.h>
	38	#include <asm/mach/time.h>
1da177e4 LT	39
1da177e4 LT	40	#include "clock.h"
0eea3c0b	41	#include "cpu.h"
1da177e4 LT	42
	43	static unsigned long timer_startval;
	44	static unsigned long timer_usec_ticks;
	45
	46	#define TIMER_USEC_SHIFT 16
	47
	48	/* we use the shifted arithmetic to work out the ratio of timer ticks
	49	* to usecs, as often the peripheral clock is not a nice even multiple
	50	* of 1MHz.
	51	*
	52	* shift of 14 and 15 are too low for the 12MHz, 16 seems to be ok
	53	* for the current HZ value of 200 without producing overflows.
	54	*
	55	* Original patch by Dimitry Andric, updated by Ben Dooks
	56	*/
	57
	58
	59	/* timer_mask_usec_ticks
	60	*
	61	* given a clock and divisor, make the value to pass into timer_ticks_to_usec
	62	* to scale the ticks into usecs
	63	*/
	64
	65	static inline unsigned long
	66	timer_mask_usec_ticks(unsigned long scaler, unsigned long pclk)
	67	{
	68	unsigned long den = pclk / 1000;
	69
	70	return ((1000 << TIMER_USEC_SHIFT) * scaler + (den >> 1)) / den;
	71	}
	72
	73	/* timer_ticks_to_usec
	74	*
	75	* convert timer ticks to usec.
	76	*/
	77
	78	static inline unsigned long timer_ticks_to_usec(unsigned long ticks)
	79	{
	80	unsigned long res;
	81
	82	res = ticks * timer_usec_ticks;
	83	res += 1 << (TIMER_USEC_SHIFT - 4); /* round up slightly */
	84
	85	return res >> TIMER_USEC_SHIFT;
	86	}
	87
	88	/***
	89	* Returns microsecond since last clock interrupt. Note that interrupts
	90	* will have been disabled by do_gettimeoffset()
	91	* IRQs are disabled before entering here from do_gettimeofday()
	92	*/
	93
	94	#define SRCPND_TIMER4 (1<<(IRQ_TIMER4 - IRQ_EINT0))
	95
	96	static unsigned long s3c2410_gettimeoffset (void)
	97	{
	98	unsigned long tdone;
	99	unsigned long irqpend;
	100	unsigned long tval;
	101
	102	/* work out how many ticks have gone since last timer interrupt */
	103
	104	tval = __raw_readl(S3C2410_TCNTO(4));
	105	tdone = timer_startval - tval;
106
107	/* check to see if there is an interrupt pending */
108
109	irqpend = __raw_readl(S3C2410_SRCPND);
110	if (irqpend & SRCPND_TIMER4) {
111	/* re-read the timer, and try and fix up for the missed
112	* interrupt. Note, the interrupt may go off before the
113	* timer has re-loaded from wrapping.
114	*/
115
116	tval = __raw_readl(S3C2410_TCNTO(4));
117	tdone = timer_startval - tval;
118
119	if (tval != 0)
120	tdone += timer_startval;
121	}
122
123	return timer_ticks_to_usec(tdone);
124	}
125
126
127	/*
128	* IRQ handler for the timer
129	*/
130	static irqreturn_t
131	s3c2410_timer_interrupt(int irq, void dev_id, struct pt_regs regs)
132	{
133	write_seqlock(&xtime_lock);
134	timer_tick(regs);
135	write_sequnlock(&xtime_lock);
136	return IRQ_HANDLED;
137	}
138
139	static struct irqaction s3c2410_timer_irq = {
140	.name = "S3C2410 Timer Tick",
09b8b5f8 RK	141	.flags = SA_INTERRUPT \| SA_TIMER,
09b8b5f8 RK	142	.handler = s3c2410_timer_interrupt,
1da177e4 LT	143	};
	144
	145	/*
	146	* Set up timer interrupt, and return the current time in seconds.
	147	*
	148	* Currently we only use timer4, as it is the only timer which has no
	149	* other function that can be exploited externally
	150	*/
	151	static void s3c2410_timer_setup (void)
	152	{
	153	unsigned long tcon;
	154	unsigned long tcnt;
	155	unsigned long tcfg1;
	156	unsigned long tcfg0;
	157
	158	tcnt = 0xffff; /* default value for tcnt */
	159
	160	/* read the current timer configuration bits */
	161
	162	tcon = __raw_readl(S3C2410_TCON);
	163	tcfg1 = __raw_readl(S3C2410_TCFG1);
	164	tcfg0 = __raw_readl(S3C2410_TCFG0);
	165
	166	/* configure the system for whichever machine is in use */
	167
7efb833d	168	if (machine_is_bast() \|\| machine_is_vr1000() \|\| machine_is_anubis()) {
1da177e4 LT	169	/* timer is at 12MHz, scaler is 1 */
	170	timer_usec_ticks = timer_mask_usec_ticks(1, 12000000);
	171	tcnt = 12000000 / HZ;
	172
	173	tcfg1 &= ~S3C2410_TCFG1_MUX4_MASK;
	174	tcfg1 \|= S3C2410_TCFG1_MUX4_TCLK1;
	175	} else {
	176	unsigned long pclk;
	177	struct clk *clk;
	178
	179	/* for the h1940 (and others), we use the pclk from the core
	180	* to generate the timer values. since values around 50 to
	181	* 70MHz are not values we can directly generate the timer
	182	* value from, we need to pre-scale and divide before using it.
	183	*
	184	* for instance, using 50.7MHz and dividing by 6 gives 8.45MHz
	185	* (8.45 ticks per usec)
	186	*/
	187
	188	/* this is used as default if no other timer can be found */
	189
	190	clk = clk_get(NULL, "timers");
	191	if (IS_ERR(clk))
	192	panic("failed to get clock for system timer");
	193
1da177e4 LT	194	clk_enable(clk);
	195
	196	pclk = clk_get_rate(clk);
	197
	198	/* configure clock tick */
	199
	200	timer_usec_ticks = timer_mask_usec_ticks(6, pclk);
	201
	202	tcfg1 &= ~S3C2410_TCFG1_MUX4_MASK;
	203	tcfg1 \|= S3C2410_TCFG1_MUX4_DIV2;
	204
	205	tcfg0 &= ~S3C2410_TCFG_PRESCALER1_MASK;
	206	tcfg0 \|= ((6 - 1) / 2) << S3C2410_TCFG_PRESCALER1_SHIFT;
	207
	208	tcnt = (pclk / 6) / HZ;
	209	}
	210
	211	/* timers reload after counting zero, so reduce the count by 1 */
	212
	213	tcnt--;
	214
	215	printk("timer tcon=%08lx, tcnt %04lx, tcfg %08lx,%08lx, usec %08lx\n",
	216	tcon, tcnt, tcfg0, tcfg1, timer_usec_ticks);
	217
	218	/* check to see if timer is within 16bit range... */
	219	if (tcnt > 0xffff) {
	220	panic("setup_timer: HZ is too small, cannot configure timer!");
	221	return;
	222	}
	223
	224	__raw_writel(tcfg1, S3C2410_TCFG1);
	225	__raw_writel(tcfg0, S3C2410_TCFG0);
	226
	227	timer_startval = tcnt;
	228	__raw_writel(tcnt, S3C2410_TCNTB(4));
	229
	230	/* ensure timer is stopped... */
	231
	232	tcon &= ~(7<<20);
	233	tcon \|= S3C2410_TCON_T4RELOAD;
	234	tcon \|= S3C2410_TCON_T4MANUALUPD;
	235
	236	__raw_writel(tcon, S3C2410_TCON);
	237	__raw_writel(tcnt, S3C2410_TCNTB(4));
	238	__raw_writel(tcnt, S3C2410_TCMPB(4));
	239
	240	/* start the timer running */
	241	tcon \|= S3C2410_TCON_T4START;
	242	tcon &= ~S3C2410_TCON_T4MANUALUPD;
	243	__raw_writel(tcon, S3C2410_TCON);
	244	}
	245
	246	static void __init s3c2410_timer_init (void)
	247	{
	248	s3c2410_timer_setup();
	249	setup_irq(IRQ_TIMER4, &s3c2410_timer_irq);
	250	}
	251
	252	struct sys_timer s3c24xx_timer = {
	253	.init = s3c2410_timer_init,
	254	.offset = s3c2410_gettimeoffset,
	255	.resume = s3c2410_timer_setup
	256	};