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    /*
     * Copyright (c) 2012 The Chromium OS Authors.
     *
     * This program is free software; you can redistribute it and/or
     * modify it under the terms of the GNU General Public License as
     * published by the Free Software Foundation; either version 2 of
     * the License, or (at your option) any later version.
     *
     * This program is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     * GNU General Public License for more details.
     *
     * You should have received a copy of the GNU General Public License
     * along with this program; if not, write to the Free Software
     * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
     * MA 02111-1307 USA
     */
    
    #include <common.h>
    #include <malloc.h>
    #include <asm/io.h>
    #include <asm/i8254.h>
    #include <asm/ibmpc.h>
    #include <asm/msr.h>
    #include <asm/u-boot-x86.h>
    
    DECLARE_GLOBAL_DATA_PTR;
    
    void timer_set_base(u64 base)
    {
    	gd->arch.tsc_base = base;
    }
    
    /*
     * Get the number of CPU time counter ticks since it was read first time after
     * restart. This yields a free running counter guaranteed to take almost 6
     * years to wrap around even at 100GHz clock rate.
     */
    u64 get_ticks(void)
    {
    	u64 now_tick = rdtsc();
    
    	/* We assume that 0 means the base hasn't been set yet */
    	if (!gd->arch.tsc_base)
    		panic("No tick base available");
    	return now_tick - gd->arch.tsc_base;
    }
    
    #define PLATFORM_INFO_MSR 0xce
    
    /* Get the speed of the TSC timer in MHz */
    unsigned long get_tbclk_mhz(void)
    {
    	u32 ratio;
    	u64 platform_info = native_read_msr(PLATFORM_INFO_MSR);
    
    	/* 100MHz times Max Non Turbo ratio */
    	ratio = (platform_info >> 8) & 0xff;
    	return 100 * ratio;
    }
    
    unsigned long get_tbclk(void)
    {
    	return get_tbclk_mhz() * 1000 * 1000;
    }
    
    static ulong get_ms_timer(void)
    {
    	return (get_ticks() * 1000) / get_tbclk();
    }
    
    ulong get_timer(ulong base)
    {
    	return get_ms_timer() - base;
    }
    
    ulong timer_get_us(void)
    {
    	return get_ticks() / get_tbclk_mhz();
    }
    
    ulong timer_get_boot_us(void)
    {
    	return timer_get_us();
    }
    
    void __udelay(unsigned long usec)
    {
    	u64 now = get_ticks();
    	u64 stop;
    
    	stop = now + usec * get_tbclk_mhz();
    
    	while ((int64_t)(stop - get_ticks()) > 0)
    		;
    }
    
    int timer_init(void)
    {
    	/* Nothing to do here - the timer needs no init */
    	return 0;
    }