diff options
Diffstat (limited to 'arch/arm/kernel/smp_twd.c')
| -rw-r--r-- | arch/arm/kernel/smp_twd.c | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c new file mode 100644 index 00000000..31deb5ae --- /dev/null +++ b/arch/arm/kernel/smp_twd.c @@ -0,0 +1,223 @@ +/* + * 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 <linux/init.h> +#include <linux/kernel.h> +#include <linux/delay.h> +#include <linux/device.h> +#include <linux/smp.h> +#include <linux/jiffies.h> +#include <linux/clockchips.h> +#include <linux/irq.h> +#include <linux/io.h> +#include <linux/clk.h> +#include <linux/cpufreq.h> +#include <linux/err.h> + +#include <asm/smp_twd.h> +#include <asm/hardware/gic.h> + +/* set up by the platform code */ +void __iomem *twd_base; +static struct clk *twd_clk; + +static unsigned long twd_timer_rate; + +static struct clock_event_device __percpu **twd_evt; + +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; + __raw_writel(twd_timer_rate / HZ, twd_base + TWD_TIMER_LOAD); + gic_enable_ppi(clk->irq); + 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; + gic_enable_ppi(clk->irq); + break; + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_SHUTDOWN: + default: + ctrl = 0; + gic_disable_ppi(clk->irq); + } + + __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); + + ctrl |= TWD_TIMER_CONTROL_ENABLE; + + __raw_writel(evt, twd_base + TWD_TIMER_COUNTER); + __raw_writel(ctrl, 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 struct clk *twd_get_clock(void) +{ + return clk_get_sys("smp_twd", NULL); +} + +#ifdef CONFIG_CPU_FREQ +/* + * Updates clockevent frequency when the cpu frequency changes. + * Called on the cpu that is changing frequency with interrupts disabled. + */ +static void twd_update_frequency(void *data) +{ + twd_timer_rate = clk_get_rate(twd_clk); + + clockevents_update_freq(*__this_cpu_ptr(twd_evt), twd_timer_rate); +} + +static int twd_cpufreq_transition(struct notifier_block *nb, + unsigned long state, void *data) +{ + struct cpufreq_freqs *freqs = data; + + /* + * The twd clock events must be reprogrammed to account for the new + * frequency. The timer is local to a cpu, so cross-call to the + * changing cpu. + * + * Only wait for it to finish, if the cpu is active to avoid + * deadlock when cpu1 is spinning on while(!cpu_active(cpu1)) during + * booting of that cpu. + */ + if (state == CPUFREQ_POSTCHANGE || state == CPUFREQ_RESUMECHANGE) + smp_call_function_single(freqs->cpu, twd_update_frequency, + NULL, cpu_active(freqs->cpu)); + + return NOTIFY_OK; +} + +static struct notifier_block twd_cpufreq_nb = { + .notifier_call = twd_cpufreq_transition, +}; + +static int twd_cpufreq_init(void) +{ + if (twd_evt && *__this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk)) + return cpufreq_register_notifier(&twd_cpufreq_nb, + CPUFREQ_TRANSITION_NOTIFIER); + + return 0; +} +core_initcall(twd_cpufreq_init); + +#endif +static void __cpuinit twd_calibrate_rate(void) +{ + unsigned long 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(KERN_INFO "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 / 10000) % 100); + } +} + +/* + * Setup the local clock events for a CPU. + */ +void __cpuinit twd_timer_setup(struct clock_event_device *clk) +{ + struct clock_event_device **this_cpu_clk; + + if (!twd_evt) { + + twd_evt = alloc_percpu(struct clock_event_device *); + if (!twd_evt) { + pr_err("twd: can't allocate memory\n"); + return; + } + } + + if (!twd_clk) + twd_clk = twd_get_clock(); + + if (!IS_ERR_OR_NULL(twd_clk)) + twd_timer_rate = clk_get_rate(twd_clk); + else + twd_calibrate_rate(); + + clk->name = "local_timer"; + clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT | + CLOCK_EVT_FEAT_C3STOP; + clk->rating = 350; + clk->set_mode = twd_set_mode; + clk->set_next_event = twd_set_next_event; + + this_cpu_clk = __this_cpu_ptr(twd_evt); + *this_cpu_clk = clk; + + clockevents_config_and_register(clk, twd_timer_rate, + 0xf, 0xffffffff); + + /* Make sure our local interrupt controller has this enabled */ + gic_enable_ppi(clk->irq); +} |