/* * 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/clk.h> #include <linux/cpu.h> #include <linux/delay.h> #include <linux/device.h> #include <linux/err.h> #include <linux/smp.h> #include <linux/jiffies.h> #include <linux/clockchips.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/of_irq.h> #include <linux/of_address.h> #include <asm/smp_plat.h> #include <asm/smp_twd.h> /* set up by the platform code */ static void __iomem *twd_base; static struct clk *twd_clk; static unsigned long twd_timer_rate; static DEFINE_PER_CPU(bool, percpu_setup_called); static struct clock_event_device __percpu *twd_evt; static int twd_ppi; 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: ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_PERIODIC; writel_relaxed(DIV_ROUND_CLOSEST(twd_timer_rate, HZ), twd_base + TWD_TIMER_LOAD); 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; } writel_relaxed(ctrl, twd_base + TWD_TIMER_CONTROL); } static int twd_set_next_event(unsigned long evt, struct clock_event_device *unused) { unsigned long ctrl = readl_relaxed(twd_base + TWD_TIMER_CONTROL); ctrl |= TWD_TIMER_CONTROL_ENABLE; writel_relaxed(evt, twd_base + TWD_TIMER_COUNTER); writel_relaxed(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. */ static int twd_timer_ack(void) { if (readl_relaxed(twd_base + TWD_TIMER_INTSTAT)) { writel_relaxed(1, twd_base + TWD_TIMER_INTSTAT); return 1; } return 0; } static void twd_timer_stop(void) { struct clock_event_device *clk = __this_cpu_ptr(twd_evt); twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk); disable_percpu_irq(clk->irq); } #ifdef CONFIG_COMMON_CLK /* * 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 *new_rate) { twd_timer_rate = *((unsigned long *) new_rate); clockevents_update_freq(__this_cpu_ptr(twd_evt), twd_timer_rate); } static int twd_rate_change(struct notifier_block *nb, unsigned long flags, void *data) { struct clk_notifier_data *cnd = 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. */ if (flags == POST_RATE_CHANGE) on_each_cpu(twd_update_frequency, (void *)&cnd->new_rate, 1); return NOTIFY_OK; } static struct notifier_block twd_clk_nb = { .notifier_call = twd_rate_change, }; static int twd_clk_init(void) { if (twd_evt && __this_cpu_ptr(twd_evt) && !IS_ERR(twd_clk)) return clk_notifier_register(twd_clk, &twd_clk_nb); return 0; } core_initcall(twd_clk_init); #elif defined (CONFIG_CPU_FREQ) #include <linux/cpufreq.h> /* * 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. */ if (state == CPUFREQ_POSTCHANGE) smp_call_function_single(freqs->cpu, twd_update_frequency, NULL, 1); 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 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 */ writel_relaxed(0x1, twd_base + TWD_TIMER_CONTROL); /* maximum value */ writel_relaxed(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER); while (get_jiffies_64() < waitjiffies) udelay(10); count = readl_relaxed(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); } } static irqreturn_t twd_handler(int irq, void *dev_id) { struct clock_event_device *evt = dev_id; if (twd_timer_ack()) { evt->event_handler(evt); return IRQ_HANDLED; } return IRQ_NONE; } static void twd_get_clock(struct device_node *np) { int err; if (np) twd_clk = of_clk_get(np, 0); else twd_clk = clk_get_sys("smp_twd", NULL); if (IS_ERR(twd_clk)) { pr_err("smp_twd: clock not found %d\n", (int) PTR_ERR(twd_clk)); return; } err = clk_prepare_enable(twd_clk); if (err) { pr_err("smp_twd: clock failed to prepare+enable: %d\n", err); clk_put(twd_clk); return; } twd_timer_rate = clk_get_rate(twd_clk); } /* * Setup the local clock events for a CPU. */ static void twd_timer_setup(void) { struct clock_event_device *clk = __this_cpu_ptr(twd_evt); int cpu = smp_processor_id(); /* * If the basic setup for this CPU has been done before don't * bother with the below. */ if (per_cpu(percpu_setup_called, cpu)) { writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); clockevents_register_device(clk); enable_percpu_irq(clk->irq, 0); return; } per_cpu(percpu_setup_called, cpu) = true; twd_calibrate_rate(); /* * The following is done once per CPU the first time .setup() is * called. */ writel_relaxed(0, twd_base + TWD_TIMER_CONTROL); 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; clk->irq = twd_ppi; clk->cpumask = cpumask_of(cpu); clockevents_config_and_register(clk, twd_timer_rate, 0xf, 0xffffffff); enable_percpu_irq(clk->irq, 0); } static int twd_timer_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { switch (action & ~CPU_TASKS_FROZEN) { case CPU_STARTING: twd_timer_setup(); break; case CPU_DYING: twd_timer_stop(); break; } return NOTIFY_OK; } static struct notifier_block twd_timer_cpu_nb = { .notifier_call = twd_timer_cpu_notify, }; static int __init twd_local_timer_common_register(struct device_node *np) { int err; twd_evt = alloc_percpu(struct clock_event_device); if (!twd_evt) { err = -ENOMEM; goto out_free; } err = request_percpu_irq(twd_ppi, twd_handler, "twd", twd_evt); if (err) { pr_err("twd: can't register interrupt %d (%d)\n", twd_ppi, err); goto out_free; } err = register_cpu_notifier(&twd_timer_cpu_nb); if (err) goto out_irq; twd_get_clock(np); /* * Immediately configure the timer on the boot CPU, unless we need * jiffies to be incrementing to calibrate the rate in which case * setup the timer in late_time_init. */ if (twd_timer_rate) twd_timer_setup(); else late_time_init = twd_timer_setup; return 0; out_irq: free_percpu_irq(twd_ppi, twd_evt); out_free: iounmap(twd_base); twd_base = NULL; free_percpu(twd_evt); return err; } int __init twd_local_timer_register(struct twd_local_timer *tlt) { if (twd_base || twd_evt) return -EBUSY; twd_ppi = tlt->res[1].start; twd_base = ioremap(tlt->res[0].start, resource_size(&tlt->res[0])); if (!twd_base) return -ENOMEM; return twd_local_timer_common_register(NULL); } #ifdef CONFIG_OF static void __init twd_local_timer_of_register(struct device_node *np) { int err; if (!is_smp() || !setup_max_cpus) return; twd_ppi = irq_of_parse_and_map(np, 0); if (!twd_ppi) { err = -EINVAL; goto out; } twd_base = of_iomap(np, 0); if (!twd_base) { err = -ENOMEM; goto out; } err = twd_local_timer_common_register(np); out: WARN(err, "twd_local_timer_of_register failed (%d)\n", err); } CLOCKSOURCE_OF_DECLARE(arm_twd_a9, "arm,cortex-a9-twd-timer", twd_local_timer_of_register); CLOCKSOURCE_OF_DECLARE(arm_twd_a5, "arm,cortex-a5-twd-timer", twd_local_timer_of_register); CLOCKSOURCE_OF_DECLARE(arm_twd_11mp, "arm,arm11mp-twd-timer", twd_local_timer_of_register); #endif