| /* |
| * 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 <asm/smp_twd.h> |
| #include <asm/hardware/gic.h> |
| |
| #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); |
| |
| 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 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(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 / 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); |
| } |
| |
| #ifdef CONFIG_HOTPLUG_CPU |
| /* |
| * take a local timer down |
| */ |
| void twd_timer_stop(void) |
| { |
| __raw_writel(0, twd_base + TWD_TIMER_CONTROL); |
| } |
| #endif |