intel_i2c.c

Go to the documentation of this file.

/*
 * Copyright © 2006-2007 Intel Corporation
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 *
 * Authors:
 *  Eric Anholt <[email protected]>
 */
#include <linux/export.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>

#include "psb_drv.h"
#include "psb_intel_reg.h"

/*
 * Intel GPIO access functions
 */

#define I2C_RISEFALL_TIME 20

static int get_clock(void *data)
{
    struct psb_intel_i2c_chan *chan = data;
    struct drm_device *dev = chan->drm_dev;
    u32 val;

    val = REG_READ(chan->reg);
    return (val & GPIO_CLOCK_VAL_IN) != 0;
}

static int get_data(void *data)
{
    struct psb_intel_i2c_chan *chan = data;
    struct drm_device *dev = chan->drm_dev;
    u32 val;

    val = REG_READ(chan->reg);
    return (val & GPIO_DATA_VAL_IN) != 0;
}

static void set_clock(void *data, int state_high)
{
    struct psb_intel_i2c_chan *chan = data;
    struct drm_device *dev = chan->drm_dev;
    u32 reserved = 0, clock_bits;

    /* On most chips, these bits must be preserved in software. */
    reserved =
            REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
                       GPIO_CLOCK_PULLUP_DISABLE);

    if (state_high)
        clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK;
    else
        clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK |
            GPIO_CLOCK_VAL_MASK;
    REG_WRITE(chan->reg, reserved | clock_bits);
    udelay(I2C_RISEFALL_TIME);  /* wait for the line to change state */
}

static void set_data(void *data, int state_high)
{
    struct psb_intel_i2c_chan *chan = data;
    struct drm_device *dev = chan->drm_dev;
    u32 reserved = 0, data_bits;

    /* On most chips, these bits must be preserved in software. */
    reserved =
            REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
                       GPIO_CLOCK_PULLUP_DISABLE);

    if (state_high)
        data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK;
    else
        data_bits =
            GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK |
            GPIO_DATA_VAL_MASK;

    REG_WRITE(chan->reg, reserved | data_bits);
    udelay(I2C_RISEFALL_TIME);  /* wait for the line to change state */
}

struct psb_intel_i2c_chan *psb_intel_i2c_create(struct drm_device *dev,
                    const u32 reg, const char *name)
{
    struct psb_intel_i2c_chan *chan;

    chan = kzalloc(sizeof(struct psb_intel_i2c_chan), GFP_KERNEL);
    if (!chan)
        goto out_free;

    chan->drm_dev = dev;
    chan->reg = reg;
    snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name);
    chan->adapter.owner = THIS_MODULE;
    chan->adapter.algo_data = &chan->algo;
    chan->adapter.dev.parent = &dev->pdev->dev;
    chan->algo.setsda = set_data;
    chan->algo.setscl = set_clock;
    chan->algo.getsda = get_data;
    chan->algo.getscl = get_clock;
    chan->algo.udelay = 20;
    chan->algo.timeout = usecs_to_jiffies(2200);
    chan->algo.data = chan;

    i2c_set_adapdata(&chan->adapter, chan);

    if (i2c_bit_add_bus(&chan->adapter))
        goto out_free;

    /* JJJ:  raise SCL and SDA? */
    set_data(chan, 1);
    set_clock(chan, 1);
    udelay(20);

    return chan;

out_free:
    kfree(chan);
    return NULL;
}

void psb_intel_i2c_destroy(struct psb_intel_i2c_chan *chan)
{
    if (!chan)
        return;

    i2c_del_adapter(&chan->adapter);
    kfree(chan);
}