From 730b77ed17f637237c16579ad9849b2a994b61a3 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Tue, 21 Jul 2009 12:50:43 +0200 Subject: [PATCH] 070-s3c24xx-time.patch --- arch/arm/plat-s3c24xx/time.c | 480 ++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 480 insertions(+), 0 deletions(-) create mode 100644 arch/arm/plat-s3c24xx/time.c diff --git a/arch/arm/plat-s3c24xx/time.c b/arch/arm/plat-s3c24xx/time.c new file mode 100644 index 0000000..713a6bc --- /dev/null +++ b/arch/arm/plat-s3c24xx/time.c @@ -0,0 +1,480 @@ +/* linux/arch/arm/plat-s3c24xx/time.c + * + * Copyright (C) 2003-2005 Simtec Electronics + * Ben Dooks, + * + * 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 +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +#include +#include +#include +#include +#include +#include + +#include +#include + +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 +}; -- 1.5.6.5