csrc-octeon.c

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/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2007 by Ralf Baechle
 * Copyright (C) 2009, 2012 Cavium, Inc.
 */
#include <linux/clocksource.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/smp.h>

#include <asm/cpu-info.h>
#include <asm/time.h>

#include <asm/octeon/octeon.h>
#include <asm/octeon/cvmx-ipd-defs.h>
#include <asm/octeon/cvmx-mio-defs.h>


static u64 f;
static u64 rdiv;
static u64 sdiv;
static u64 octeon_udelay_factor;
static u64 octeon_ndelay_factor;

void __init octeon_setup_delays(void)
{
    octeon_udelay_factor = octeon_get_clock_rate() / 1000000;
    /*
     * For __ndelay we divide by 2^16, so the factor is multiplied
     * by the same amount.
     */
    octeon_ndelay_factor = (octeon_udelay_factor * 0x10000ull) / 1000ull;

    preset_lpj = octeon_get_clock_rate() / HZ;

    if (current_cpu_type() == CPU_CAVIUM_OCTEON2) {
        union cvmx_mio_rst_boot rst_boot;
        rst_boot.u64 = cvmx_read_csr(CVMX_MIO_RST_BOOT);
        rdiv = rst_boot.s.c_mul;    /* CPU clock */
        sdiv = rst_boot.s.pnr_mul;  /* I/O clock */
        f = (0x8000000000000000ull / sdiv) * 2;
    }
}

/*
 * Set the current core's cvmcount counter to the value of the
 * IPD_CLK_COUNT.  We do this on all cores as they are brought
 * on-line.  This allows for a read from a local cpu register to
 * access a synchronized counter.
 *
 * On CPU_CAVIUM_OCTEON2 the IPD_CLK_COUNT is scaled by rdiv/sdiv.
 */
void octeon_init_cvmcount(void)
{
    unsigned long flags;
    unsigned loops = 2;

    /* Clobber loops so GCC will not unroll the following while loop. */
    asm("" : "+r" (loops));

    local_irq_save(flags);
    /*
     * Loop several times so we are executing from the cache,
     * which should give more deterministic timing.
     */
    while (loops--) {
        u64 ipd_clk_count = cvmx_read_csr(CVMX_IPD_CLK_COUNT);
        if (rdiv != 0) {
            ipd_clk_count *= rdiv;
            if (f != 0) {
                asm("dmultu\t%[cnt],%[f]\n\t"
                    "mfhi\t%[cnt]"
                    : [cnt] "+r" (ipd_clk_count)
                    : [f] "r" (f)
                    : "hi", "lo");
            }
        }
        write_c0_cvmcount(ipd_clk_count);
    }
    local_irq_restore(flags);
}

static cycle_t octeon_cvmcount_read(struct clocksource *cs)
{
    return read_c0_cvmcount();
}

static struct clocksource clocksource_mips = {
    .name       = "OCTEON_CVMCOUNT",
    .read       = octeon_cvmcount_read,
    .mask       = CLOCKSOURCE_MASK(64),
    .flags      = CLOCK_SOURCE_IS_CONTINUOUS,
};

unsigned long long notrace sched_clock(void)
{
    /* 64-bit arithmatic can overflow, so use 128-bit.  */
    u64 t1, t2, t3;
    unsigned long long rv;
    u64 mult = clocksource_mips.mult;
    u64 shift = clocksource_mips.shift;
    u64 cnt = read_c0_cvmcount();

    asm (
        "dmultu\t%[cnt],%[mult]\n\t"
        "nor\t%[t1],$0,%[shift]\n\t"
        "mfhi\t%[t2]\n\t"
        "mflo\t%[t3]\n\t"
        "dsll\t%[t2],%[t2],1\n\t"
        "dsrlv\t%[rv],%[t3],%[shift]\n\t"
        "dsllv\t%[t1],%[t2],%[t1]\n\t"
        "or\t%[rv],%[t1],%[rv]\n\t"
        : [rv] "=&r" (rv), [t1] "=&r" (t1), [t2] "=&r" (t2), [t3] "=&r" (t3)
        : [cnt] "r" (cnt), [mult] "r" (mult), [shift] "r" (shift)
        : "hi", "lo");
    return rv;
}

void __init plat_time_init(void)
{
    clocksource_mips.rating = 300;
    clocksource_register_hz(&clocksource_mips, octeon_get_clock_rate());
}

void __udelay(unsigned long us)
{
    u64 cur, end, inc;

    cur = read_c0_cvmcount();

    inc = us * octeon_udelay_factor;
    end = cur + inc;

    while (end > cur)
        cur = read_c0_cvmcount();
}
EXPORT_SYMBOL(__udelay);

void __ndelay(unsigned long ns)
{
    u64 cur, end, inc;

    cur = read_c0_cvmcount();

    inc = ((ns * octeon_ndelay_factor) >> 16);
    end = cur + inc;

    while (end > cur)
        cur = read_c0_cvmcount();
}
EXPORT_SYMBOL(__ndelay);

void __delay(unsigned long loops)
{
    u64 cur, end;

    cur = read_c0_cvmcount();
    end = cur + loops;

    while (end > cur)
        cur = read_c0_cvmcount();
}
EXPORT_SYMBOL(__delay);


void octeon_io_clk_delay(unsigned long count)
{
    u64 cur, end;

    cur = read_c0_cvmcount();
    if (rdiv != 0) {
        end = count * rdiv;
        if (f != 0) {
            asm("dmultu\t%[cnt],%[f]\n\t"
                "mfhi\t%[cnt]"
                : [cnt] "+r" (end)
                : [f] "r" (f)
                : "hi", "lo");
        }
        end = cur + end;
    } else {
        end = cur + count;
    }
    while (end > cur)
        cur = read_c0_cvmcount();
}
EXPORT_SYMBOL(octeon_io_clk_delay);