linux-imx

/*

 * I2C multiplexer driver for PCA9541 bus master selector

 *

 * Copyright (c) 2010 Ericsson AB.

 *

 * Author: Guenter Roeck <linux@roeck-us.net>

 *

 * Derived from:

 *  pca954x.c

 *

 *  Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>

 *  Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>

 *

 * This file is licensed under the terms of the GNU General Public

 * License version 2. This program is licensed "as is" without any

 * warranty of any kind, whether express or implied.

 */

​

#include <linux/delay.h>

#include <linux/device.h>

#include <linux/i2c.h>

#include <linux/i2c-mux.h>

#include <linux/jiffies.h>

#include <linux/module.h>

#include <linux/slab.h>

​

/*

 * The PCA9541 is a bus master selector. It supports two I2C masters connected

 * to a single slave bus.

 *

 * Before each bus transaction, a master has to acquire bus ownership. After the

 * transaction is complete, bus ownership has to be released. This fits well

 * into the I2C multiplexer framework, which provides select and release

 * functions for this purpose. For this reason, this driver is modeled as

 * single-channel I2C bus multiplexer.

 *

 * This driver assumes that the two bus masters are controlled by two different

 * hosts. If a single host controls both masters, platform code has to ensure

 * that only one of the masters is instantiated at any given time.

 */

​

#define PCA9541_CONTROL     0x01

#define PCA9541_ISTAT       0x02

​

#define PCA9541_CTL_MYBUS   (1 << 0)

#define PCA9541_CTL_NMYBUS  (1 << 1)

#define PCA9541_CTL_BUSON   (1 << 2)

#define PCA9541_CTL_NBUSON  (1 << 3)

#define PCA9541_CTL_BUSINIT (1 << 4)

#define PCA9541_CTL_TESTON  (1 << 6)

#define PCA9541_CTL_NTESTON (1 << 7)

​

#define PCA9541_ISTAT_INTIN (1 << 0)

#define PCA9541_ISTAT_BUSINIT   (1 << 1)

#define PCA9541_ISTAT_BUSOK (1 << 2)

#define PCA9541_ISTAT_BUSLOST   (1 << 3)

#define PCA9541_ISTAT_MYTEST    (1 << 6)

#define PCA9541_ISTAT_NMYTEST   (1 << 7)

​

#define BUSON       (PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)

#define MYBUS       (PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)

#define mybus(x)    (!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)

#define busoff(x)   (!((x) & BUSON) || ((x) & BUSON) == BUSON)