i2c.c

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/*
 * Helper module for board specific I2C bus registration
 *
 * Copyright (C) 2009 Nokia Corporation.
 *
 * 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.
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 */

#include <plat/i2c.h>
#include "common.h"
#include <plat/omap_hwmod.h>

#include "mux.h"

/* In register I2C_CON, Bit 15 is the I2C enable bit */
#define I2C_EN                  BIT(15)
#define OMAP2_I2C_CON_OFFSET            0x24
#define OMAP4_I2C_CON_OFFSET            0xA4

/* Maximum microseconds to wait for OMAP module to softreset */
#define MAX_MODULE_SOFTRESET_WAIT   10000

void __init omap2_i2c_mux_pins(int bus_id)
{
    char mux_name[sizeof("i2c2_scl.i2c2_scl")];

    /* First I2C bus is not muxable */
    if (bus_id == 1)
        return;

    sprintf(mux_name, "i2c%i_scl.i2c%i_scl", bus_id, bus_id);
    omap_mux_init_signal(mux_name, OMAP_PIN_INPUT);
    sprintf(mux_name, "i2c%i_sda.i2c%i_sda", bus_id, bus_id);
    omap_mux_init_signal(mux_name, OMAP_PIN_INPUT);
}

int omap_i2c_reset(struct omap_hwmod *oh)
{
    u32 v;
    u16 i2c_con;
    int c = 0;

    if (oh->class->rev == OMAP_I2C_IP_VERSION_2) {
        i2c_con = OMAP4_I2C_CON_OFFSET;
    } else if (oh->class->rev == OMAP_I2C_IP_VERSION_1) {
        i2c_con = OMAP2_I2C_CON_OFFSET;
    } else {
        WARN(1, "Cannot reset I2C block %s: unsupported revision\n",
             oh->name);
        return -EINVAL;
    }

    /* Disable I2C */
    v = omap_hwmod_read(oh, i2c_con);
    v &= ~I2C_EN;
    omap_hwmod_write(v, oh, i2c_con);

    /* Write to the SOFTRESET bit */
    omap_hwmod_softreset(oh);

    /* Enable I2C */
    v = omap_hwmod_read(oh, i2c_con);
    v |= I2C_EN;
    omap_hwmod_write(v, oh, i2c_con);

    /* Poll on RESETDONE bit */
    omap_test_timeout((omap_hwmod_read(oh,
                oh->class->sysc->syss_offs)
                & SYSS_RESETDONE_MASK),
                MAX_MODULE_SOFTRESET_WAIT, c);

    if (c == MAX_MODULE_SOFTRESET_WAIT)
        pr_warning("%s: %s: softreset failed (waited %d usec)\n",
            __func__, oh->name, MAX_MODULE_SOFTRESET_WAIT);
    else
        pr_debug("%s: %s: softreset in %d usec\n", __func__,
            oh->name, c);

    return 0;
}