path: root/drivers/media/dvb/dvb-usb/mxl111sf-i2c.c

/*
 *  mxl111sf-i2c.c - driver for the MaxLinear MXL111SF
 *
 *  Copyright (C) 2010 Michael Krufky <mkrufky@kernellabs.com>
 *
 *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "mxl111sf-i2c.h"
#include "mxl111sf.h"

/* SW-I2C ----------------------------------------------------------------- */

#define SW_I2C_ADDR		0x1a
#define SW_I2C_EN		0x02
#define SW_SCL_OUT		0x04
#define SW_SDA_OUT		0x08
#define SW_SDA_IN		0x04

#define SW_I2C_BUSY_ADDR	0x2f
#define SW_I2C_BUSY		0x02

static int mxl111sf_i2c_bitbang_sendbyte(struct mxl111sf_state *state,
					 u8 byte)
{
	int i, ret;
	u8 data = 0;

	mxl_i2c("(0x%02x)", byte);

	ret = mxl111sf_read_reg(state, SW_I2C_BUSY_ADDR, &data);
	if (mxl_fail(ret))
		goto fail;

	for (i = 0; i < 8; i++) {

		data = (byte & (0x80 >> i)) ? SW_SDA_OUT : 0;

		ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
					 0x10 | SW_I2C_EN | data);
		if (mxl_fail(ret))
			goto fail;

		ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
					 0x10 | SW_I2C_EN | data | SW_SCL_OUT);
		if (mxl_fail(ret))
			goto fail;

		ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
					 0x10 | SW_I2C_EN | data);
		if (mxl_fail(ret))
			goto fail;
	}

	/* last bit was 0 so we need to release SDA */
	if (!(byte & 1)) {
		ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
					 0x10 | SW_I2C_EN | SW_SDA_OUT);
		if (mxl_fail(ret))
			goto fail;
	}

	/* CLK high for ACK readback */
	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_I2C_EN | SW_SCL_OUT | SW_SDA_OUT);
	if (mxl_fail(ret))
		goto fail;

	ret = mxl111sf_read_reg(state, SW_I2C_BUSY_ADDR, &data);
	if (mxl_fail(ret))
		goto fail;

	/* drop the CLK after getting ACK, SDA will go high right away */
	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_I2C_EN | SW_SDA_OUT);
	if (mxl_fail(ret))
		goto fail;

	if (data & SW_SDA_IN)
		ret = -EIO;
fail:
	return ret;
}

static int mxl111sf_i2c_bitbang_recvbyte(struct mxl111sf_state *state,
					 u8 *pbyte)
{
	int i, ret;
	u8 byte = 0;
	u8 data = 0;

	mxl_i2c("()");

	*pbyte = 0;

	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_I2C_EN | SW_SDA_OUT);
	if (mxl_fail(ret))
		goto fail;

	for (i = 0; i < 8; i++) {
		ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
					 0x10 | SW_I2C_EN |
					 SW_SCL_OUT | SW_SDA_OUT);
		if (mxl_fail(ret))
			goto fail;

		ret = mxl111sf_read_reg(state, SW_I2C_BUSY_ADDR, &data);
		if (mxl_fail(ret))
			goto fail;

		if (data & SW_SDA_IN)
			byte |= (0x80 >> i);

		ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
					 0x10 | SW_I2C_EN | SW_SDA_OUT);
		if (mxl_fail(ret))
			goto fail;
	}
	*pbyte = byte;
fail:
	return ret;
}

static int mxl111sf_i2c_start(struct mxl111sf_state *state)
{
	int ret;

	mxl_i2c("()");

	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_I2C_EN | SW_SCL_OUT | SW_SDA_OUT);
	if (mxl_fail(ret))
		goto fail;

	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_I2C_EN | SW_SCL_OUT);
	if (mxl_fail(ret))
		goto fail;

	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_I2C_EN); /* start */
	mxl_fail(ret);
fail:
	return ret;
}

static int mxl111sf_i2c_stop(struct mxl111sf_state *state)
{
	int ret;

	mxl_i2c("()");

	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_I2C_EN); /* stop */
	if (mxl_fail(ret))
		goto fail;

	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_I2C_EN | SW_SCL_OUT);
	if (mxl_fail(ret))
		goto fail;

	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_I2C_EN | SW_SCL_OUT | SW_SDA_OUT);
	if (mxl_fail(ret))
		goto fail;

	ret = mxl111sf_write_reg(state, SW_I2C_ADDR,
				 0x10 | SW_SCL_OUT | SW_SDA_OUT);
	mxl_fail(ret);
fail