diff options
Diffstat (limited to 'arch/arm/mach-realview/localtimer.c')
| -rw-r--r-- | arch/arm/mach-realview/localtimer.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/arch/arm/mach-realview/localtimer.c b/arch/arm/mach-realview/localtimer.c new file mode 100644 index 000000000000..5e917e37d095 --- /dev/null +++ b/arch/arm/mach-realview/localtimer.c @@ -0,0 +1,130 @@ +/* + * linux/arch/arm/mach-realview/localtimer.c + * + * Copyright (C) 2002 ARM Ltd. + * All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/smp.h> + +#include <asm/mach/time.h> +#include <asm/hardware/arm_twd.h> +#include <asm/hardware/gic.h> +#include <asm/hardware.h> +#include <asm/io.h> +#include <asm/irq.h> + +#include "core.h" + +#define TWD_BASE(cpu) (__io_address(REALVIEW_TWD_BASE) + \ + ((cpu) * REALVIEW_TWD_SIZE)) + +static unsigned long mpcore_timer_rate; + +/* + * local_timer_ack: checks for a local timer interrupt. + * + * If a local timer interrupt has occured, acknowledge and return 1. + * Otherwise, return 0. + */ +int local_timer_ack(void) +{ + void __iomem *base = TWD_BASE(smp_processor_id()); + + if (__raw_readl(base + TWD_TIMER_INTSTAT)) { + __raw_writel(1, base + TWD_TIMER_INTSTAT); + return 1; + } + + return 0; +} + +void __cpuinit local_timer_setup(unsigned int cpu) +{ + void __iomem *base = TWD_BASE(cpu); + unsigned int load, offset; + u64 waitjiffies; + unsigned int count; + + /* + * If this is the first time round, we need to work out how fast + * the timer ticks + */ + if (mpcore_timer_rate == 0) { + printk("Calibrating local timer... "); + + /* Wait for a tick to start */ + waitjiffies = get_jiffies_64() + 1; + + while (get_jiffies_64() < waitjiffies) + udelay(10); + + /* OK, now the tick has started, let's get the timer going */ + waitjiffies += 5; + + /* enable, no interrupt or reload */ + __raw_writel(0x1, base + TWD_TIMER_CONTROL); + + /* maximum value */ + __raw_writel(0xFFFFFFFFU, base + TWD_TIMER_COUNTER); + + while (get_jiffies_64() < waitjiffies) + udelay(10); + + count = __raw_readl(base + TWD_TIMER_COUNTER); + + mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5); + + printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000, + (mpcore_timer_rate / 100000) % 100); + } + + load = mpcore_timer_rate / HZ; + + __raw_writel(load, base + TWD_TIMER_LOAD); + __raw_writel(0x7, base + TWD_TIMER_CONTROL); + + /* + * Now maneuver our local tick into the right part of the jiffy. + * Start by working out where within the tick our local timer + * interrupt should go. + */ + offset = ((mpcore_timer_rate / HZ) / (NR_CPUS + 1)) * (cpu + 1); + + /* + * gettimeoffset() will return a number of us since the last tick. + * Convert this number of us to a local timer tick count. + * Be careful of integer overflow whilst keeping maximum precision. + * + * with HZ=100 and 1MHz (fpga) ~ 1GHz processor: + * load = 1 ~ 10,000 + * mpcore_timer_rate/10000 = 100 ~ 100,000 + * + * so the multiply value will be less than 10^9 always. + */ + load = (system_timer->offset() * (mpcore_timer_rate / 10000)) / 100; + + /* Add on our offset to get the load value */ + load = (load + offset) % (mpcore_timer_rate / HZ); + + __raw_writel(load, base + TWD_TIMER_COUNTER); + + /* Make sure our local interrupt controller has this enabled */ + __raw_writel(1 << IRQ_LOCALTIMER, + __io_address(REALVIEW_GIC_DIST_BASE) + GIC_DIST_ENABLE_SET); +} + +/* + * take a local timer down + */ +void __cpuexit local_timer_stop(unsigned int cpu) +{ + __raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL); +} |