From f32f4ce25745209f16a5a6cef7442144b596c68a Mon Sep 17 00:00:00 2001 From: Russell King Date: Sat, 16 May 2009 12:14:21 +0100 Subject: [ARM] smp: allow re-use of realview localtimer TWD support Signed-off-by: Russell King --- arch/arm/kernel/Makefile | 1 + arch/arm/kernel/smp_twd.c | 173 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 174 insertions(+) create mode 100644 arch/arm/kernel/smp_twd.c (limited to 'arch/arm/kernel') diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index 90ffbaf23b4..ff89d0b3abc 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -23,6 +23,7 @@ obj-$(CONFIG_ISA_DMA) += dma-isa.o obj-$(CONFIG_PCI) += bios32.o isa.o obj-$(CONFIG_SMP) += smp.o obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o +obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o obj-$(CONFIG_KPROBES) += kprobes.o kprobes-decode.o diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c new file mode 100644 index 00000000000..aabd62d6bd1 --- /dev/null +++ b/arch/arm/kernel/smp_twd.c @@ -0,0 +1,173 @@ +/* + * linux/arch/arm/kernel/smp_twd.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 +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +#define TWD_TIMER_LOAD 0x00 +#define TWD_TIMER_COUNTER 0x04 +#define TWD_TIMER_CONTROL 0x08 +#define TWD_TIMER_INTSTAT 0x0C + +#define TWD_WDOG_LOAD 0x20 +#define TWD_WDOG_COUNTER 0x24 +#define TWD_WDOG_CONTROL 0x28 +#define TWD_WDOG_INTSTAT 0x2C +#define TWD_WDOG_RESETSTAT 0x30 +#define TWD_WDOG_DISABLE 0x34 + +#define TWD_TIMER_CONTROL_ENABLE (1 << 0) +#define TWD_TIMER_CONTROL_ONESHOT (0 << 1) +#define TWD_TIMER_CONTROL_PERIODIC (1 << 1) +#define TWD_TIMER_CONTROL_IT_ENABLE (1 << 2) + +/* set up by the platform code */ +void __iomem *twd_base; + +static unsigned long twd_timer_rate; + +static void twd_set_mode(enum clock_event_mode mode, + struct clock_event_device *clk) +{ + unsigned long ctrl; + + switch(mode) { + case CLOCK_EVT_MODE_PERIODIC: + /* timer load already set up */ + ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE + | TWD_TIMER_CONTROL_PERIODIC; + break; + case CLOCK_EVT_MODE_ONESHOT: + /* period set, and timer enabled in 'next_event' hook */ + ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT; + break; + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + default: + ctrl = 0; + } + + __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL); +} + +static int twd_set_next_event(unsigned long evt, + struct clock_event_device *unused) +{ + unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL); + + __raw_writel(evt, twd_base + TWD_TIMER_COUNTER); + __raw_writel(ctrl | TWD_TIMER_CONTROL_ENABLE, twd_base + TWD_TIMER_CONTROL); + + return 0; +} + +/* + * local_timer_ack: checks for a local timer interrupt. + * + * If a local timer interrupt has occurred, acknowledge and return 1. + * Otherwise, return 0. + */ +int twd_timer_ack(void) +{ + if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) { + __raw_writel(1, twd_base + TWD_TIMER_INTSTAT); + return 1; + } + + return 0; +} + +static void __cpuinit twd_calibrate_rate(void) +{ + unsigned long load, count; + u64 waitjiffies; + + /* + * If this is the first time round, we need to work out how fast + * the timer ticks + */ + if (twd_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, twd_base + TWD_TIMER_CONTROL); + + /* maximum value */ + __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER); + + while (get_jiffies_64() < waitjiffies) + udelay(10); + + count = __raw_readl(twd_base + TWD_TIMER_COUNTER); + + twd_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5); + + printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000, + (twd_timer_rate / 100000) % 100); + } + + load = twd_timer_rate / HZ; + + __raw_writel(load, twd_base + TWD_TIMER_LOAD); +} + +/* + * Setup the local clock events for a CPU. + */ +void __cpuinit twd_timer_setup(struct clock_event_device *clk) +{ + unsigned long flags; + + twd_calibrate_rate(); + + clk->name = "local_timer"; + clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; + clk->rating = 350; + clk->set_mode = twd_set_mode; + clk->set_next_event = twd_set_next_event; + clk->shift = 20; + clk->mult = div_sc(twd_timer_rate, NSEC_PER_SEC, clk->shift); + clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk); + clk->min_delta_ns = clockevent_delta2ns(0xf, clk); + + /* Make sure our local interrupt controller has this enabled */ + local_irq_save(flags); + get_irq_chip(clk->irq)->unmask(clk->irq); + local_irq_restore(flags); + + clockevents_register_device(clk); +} + +/* + * take a local timer down + */ +void __cpuexit twd_timer_stop(void) +{ + __raw_writel(0, twd_base + TWD_TIMER_CONTROL); +} -- cgit v1.2.3