path: root/target/linux/s3c24xx/patches-2.6.30/070-s3c24xx-time.patch

Index: linux-2.6.30-rc6/arch/arm/plat-s3c24xx/time.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.30-rc6/arch/arm/plat-s3c24xx/time.c	2009-05-18 19:08:34.000000000 +0200
@@ -0,0 +1,480 @@
+/* linux/arch/arm/plat-s3c24xx/time.c
+ *
+ * Copyright (C) 2003-2005 Simtec Electronics
+ *	Ben Dooks, <ben@simtec.co.uk>
+ *
+ * dyn_tick support by Andrzej Zaborowski based on omap_dyn_tick_timer.
+ *
+ * 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/kernel.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.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 <mach/map.h>
+#include <asm/plat-s3c/regs-timer.h>
+#include <mach/regs-irq.h>
+#include <asm/mach/time.h>
+
+#include <asm/plat-s3c24xx/clock.h>
+#include <asm/plat-s3c24xx/cpu.h>
+
+static unsigned long timer_startval;
+static unsigned long timer_usec_ticks;
+static struct work_struct resume_work;
+
+unsigned long pclk;
+struct clk *clk;
+
+#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))
+
+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)
+{
+	timer_tick();
+	return IRQ_HANDLED;
+}
+
+static struct irqaction s3c2410_timer_irq = {
+	.name		= "S3C2410 Timer Tick",
+	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+	.handler	= s3c2410_timer_interrupt,
+};
+
+#define use_tclk1_12() ( \
+	machine_is_bast()	|| \
+	machine_is_vr1000()	|| \
+	machine_is_anubis()	|| \
+	machine_is_osiris() )
+
+/*
+ * 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 (use_tclk1_12()) {
+		/* 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 {
+		/* 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)
+		 */
+
+		/* configure clock tick */
+		timer_usec_ticks = timer_mask_usec_ticks(6, pclk);
+		printk("timer_usec_ticks = %lu\n", timer_usec_ticks);
+
+		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);
+
+	__raw_writel(__raw_readl(S3C2410_INTMSK) & (~(1UL << 14)),
+		     S3C2410_INTMSK);
+
+}
+
+struct sys_timer s3c24xx_timer;
+static void timer_resume_work(struct work_struct *work)
+{
+	clk_enable(clk);
+
+#ifdef CONFIG_NO_IDLE_HZ
+	if (s3c24xx_timer.dyn_tick->state & DYN_TICK_ENABLED)
+		s3c24xx_timer.dyn_tick->enable();
+	else
+#endif
+		s3c2410_timer_setup();
+}
+
+static void __init s3c2410_timer_init (void)
+{
+	if (!use_tclk1_12()) {
+		/* for the h1940 (and others), we use the pclk from the core
+		 * to generate the timer values.
+		 */
+
+		/* 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);
+		printk("pclk = %lu\n", pclk);
+	}
+
+	INIT_WORK(&resume_work, timer_resume_work);
+	s3c2410_timer_setup();
+	setup_irq(IRQ_TIMER4, &s3c2410_timer_irq);
+}
+
+static void s3c2410_timer_resume_work(struct work_struct *work)
+{
+	s3c2410_timer_setup();
+}
+
+static void s3c2410_timer_resume(void)
+{
+	static DECLARE_WORK(work, s3c2410_timer_resume_work);
+	int res;
+
+	res = schedule_work(&work);
+	if (!res)
+		printk(KERN_ERR
+		    "s3c2410_timer_resume_work already queued ???\n");
+}
+
+#ifdef CONFIG_NO_IDLE_HZ
+/*
+ * We'll set a constant prescaler so we don't have to bother setting it
+ * when reprogramming and so that we avoid costly divisions.
+ *
+ * (2 * HZ) << INPUT_FREQ_SHIFT is the desired frequency after prescaler.
+ * At HZ == 200, HZ * 1024 should work for PCLKs of up to ~53.5 MHz.
+ */
+#define INPUT_FREQ_SHIFT	9
+
+static int ticks_last;
+static int ticks_left;
+static uint32_t tcnto_last;
+
+static inline int s3c24xx_timer_read(void)
+{
+	uint32_t tcnto = __raw_readl(S3C2410_TCNTO(4));
+
+	/*
+	 * WARNING: sometimes we get called before TCNTB has been
+	 * loaded into the counter and TCNTO then returns its previous
+	 * value and kill us, so don't do anything before counter is
+	 * reloaded.
+	 */
+	if (unlikely(tcnto == tcnto_last))
+		return ticks_last;
+
+	tcnto_last = -1;
+	return tcnto <<
+		((__raw_readl(S3C2410_TCFG1) >> S3C2410_TCFG1_MUX4_SHIFT) & 3);
+}
+
+static inline void s3c24xx_timer_program(int ticks)
+{
+	uint32_t tcon = __raw_readl(S3C2410_TCON) & ~(7 << 20);
+	uint32_t tcfg1 = __raw_readl(S3C2410_TCFG1) & ~S3C2410_TCFG1_MUX4_MASK;
+
+	/* Just make sure the timer is stopped.  */
+	__raw_writel(tcon, S3C2410_TCON);
+
+	/* TODO: add likely()ies / unlikely()ies */
+	if (ticks >> 18) {
+		ticks_last = min(ticks, 0xffff << 3);
+		ticks_left = ticks - ticks_last;
+		__raw_writel(tcfg1 | S3C2410_TCFG1_MUX4_DIV16, S3C2410_TCFG1);
+		__raw_writel(ticks_last >> 3, S3C2410_TCNTB(4));
+	} else if (ticks >> 17) {
+		ticks_last = ticks;
+		ticks_left = 0;
+		__raw_writel(tcfg1 | S3C2410_TCFG1_MUX4_DIV8, S3C2410_TCFG1);
+		__raw_writel(ticks_last >> 2, S3C2410_TCNTB(4));
+	} else if (ticks >> 16) {
+		ticks_last = ticks;
+		ticks_left = 0;
+		__raw_writel(tcfg1 | S3C2410_TCFG1_MUX4_DIV4, S3C2410_TCFG1);
+		__raw_writel(ticks_last >> 1, S3C2410_TCNTB(4));
+	} else {
+		ticks_last = ticks;
+		ticks_left = 0;
+		__raw_writel(tcfg1 | S3C2410_TCFG1_MUX4_DIV2, S3C2410_TCFG1);
+		__raw_writel(ticks_last >> 0, S3C2410_TCNTB(4));
+	}
+
+	tcnto_last = __raw_readl(S3C2410_TCNTO(4));
+	__raw_writel(tcon | S3C2410_TCON_T4MANUALUPD,
+			S3C2410_TCON);
+	__raw_writel(tcon | S3C2410_TCON_T4START,
+			S3C2410_TCON);
+}
+
+/*
+ * If we have already waited all the time we were supposed to wait,
+ * kick the timer, setting the longest allowed timeout value just
+ * for time-keeping.
+ */
+static inline void s3c24xx_timer_program_idle(void)
+{
+	s3c24xx_timer_program(0xffff << 3);
+}
+
+static inline void s3c24xx_timer_update(int restart)
+{
+	int ticks_cur = s3c24xx_timer_read();
+	int jiffies_elapsed = (ticks_last - ticks_cur) >> INPUT_FREQ_SHIFT;
+	int subjiffy = ticks_last - (jiffies_elapsed << INPUT_FREQ_SHIFT);
+
+	if (restart) {
+		if (ticks_left >= (1 << INPUT_FREQ_SHIFT))
+			s3c24xx_timer_program(ticks_left);
+		else
+			s3c24xx_timer_program_idle();
+		ticks_last += subjiffy;
+	} else
+		ticks_last = subjiffy;
+
+	while (jiffies_elapsed --)
+		timer_tick();
+}
+
+/* Called when the timer expires.  */
+static irqreturn_t s3c24xx_timer_handler(int irq, void *dev_id)
+{
+	tcnto_last = -1;
+	s3c24xx_timer_update(1);
+
+	return IRQ_HANDLED;
+}
+
+/* Called to update jiffies with time elapsed.  */
+static irqreturn_t s3c24xx_timer_handler_dyn_tick(int irq, void *dev_id)
+{
+	s3c24xx_timer_update(0);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Programs the next timer interrupt needed.  Called when dynamic tick is
+ * enabled, and to reprogram the ticks to skip from pm_idle.  The CPU goes
+ * to sleep directly after this.
+ */
+static void s3c24xx_timer_reprogram_dyn_tick(unsigned long next_jiffies)
+{
+	int subjiffy_left = ticks_last - s3c24xx_timer_read();
+
+	s3c24xx_timer_program(max((int) next_jiffies, 1) << INPUT_FREQ_SHIFT);
+	ticks_last += subjiffy_left;
+}
+
+static unsigned long s3c24xx_timer_offset_dyn_tick(void)
+{
+	/* TODO */
+	return 0;
+}
+
+static int s3c24xx_timer_enable_dyn_tick(void)
+{
+	/* Set our constant prescaler.  */
+	uint32_t tcfg0 = __raw_readl(S3C2410_TCFG0);
+	int prescaler =
+		max(min(256, (int) pclk / (HZ << (INPUT_FREQ_SHIFT + 1))), 1);
+
+	tcfg0 &= ~S3C2410_TCFG_PRESCALER1_MASK;
+	tcfg0 |= (prescaler - 1) << S3C2410_TCFG_PRESCALER1_SHIFT;
+	__raw_writel(tcfg0, S3C2410_TCFG0);
+
+	/* Override handlers.  */
+	s3c2410_timer_irq.handler = s3c24xx_timer_handler;
+	s3c24xx_timer.offset = s3c24xx_timer_offset_dyn_tick;
+
+	printk(KERN_INFO "dyn_tick enabled on s3c24xx timer 4, "
+			"%li Hz pclk with prescaler %i\n", pclk, prescaler);
+
+	s3c24xx_timer_program_idle();
+
+	return 0;
+}
+
+static int s3c24xx_timer_disable_dyn_tick(void)
+{
+	s3c2410_timer_irq.handler = s3c2410_timer_interrupt;
+	s3c24xx_timer.offset = s3c2410_gettimeoffset;
+	s3c2410_timer_setup();
+
+	return 0;
+}
+
+static struct dyn_tick_timer s3c24xx_dyn_tick_timer = {
+	.enable		= s3c24xx_timer_enable_dyn_tick,
+	.disable	= s3c24xx_timer_disable_dyn_tick,
+	.reprogram	= s3c24xx_timer_reprogram_dyn_tick,
+	.handler	= s3c24xx_timer_handler_dyn_tick,
+};
+#endif	/* CONFIG_NO_IDLE_HZ */
+
+struct sys_timer s3c24xx_timer = {
+	.init		= s3c2410_timer_init,
+	.offset		= s3c2410_gettimeoffset,
+	.resume		= s3c2410_timer_resume,
+#ifdef CONFIG_NO_IDLE_HZ
+	.dyn_tick	= &s3c24xx_dyn_tick_timer,
+#endif
+};