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|
/*
* i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters
*
* Copyright (C) 1995-1997 Simon G. Vogl
* 1998-2000 Hans Berglund
*
* 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.
*
* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
* Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
* <mbailey@littlefeet-inc.com>
*
* Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
* messages, proper stop/repstart signaling during receive, added detect code
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-pcf.h>
#include "i2c-algo-pcf.h"
#define DEB2(x) if (i2c_debug >= 2) x
#define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
#define DEBPROTO(x) if (i2c_debug >= 9) x;
/* debug the protocol by showing transferred bits */
#define DEF_TIMEOUT 16
/*
* module parameters:
*/
static int i2c_debug;
/* setting states on the bus with the right timing: */
#define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
#define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
#define get_own(adap) adap->getown(adap->data)
#define get_clock(adap) adap->getclock(adap->data)
#define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
#define i2c_inb(adap) adap->getpcf(adap->data, 0)
/* other auxiliary functions */
static void i2c_start(struct i2c_algo_pcf_data *adap)
{
DEBPROTO(printk(KERN_DEBUG "S "));
set_pcf(adap, 1, I2C_PCF_START);
}
static void i2c_repstart(struct i2c_algo_pcf_data *adap)
{
DEBPROTO(printk(" Sr "));
set_pcf(adap, 1, I2C_PCF_REPSTART);
}
static void i2c_stop(struct i2c_algo_pcf_data *adap)
{
DEBPROTO(printk("P\n"));
set_pcf(adap, 1, I2C_PCF_STOP);
}
static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
{
DEB2(printk(KERN_INFO
"i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
*status));
/*
* Cleanup from LAB -- reset and enable ESO.
* This resets the PCF8584; since we've lost the bus, no
* further attempts should be made by callers to clean up
* (no i2c_stop() etc.)
*/
set_pcf(adap, 1, I2C_PCF_PIN);
set_pcf(adap, 1, I2C_PCF_ESO);
/*
* We pause for a time period sufficient for any running
* I2C transaction to complete -- the arbitration logic won't
* work properly until the next START is seen.
* It is assumed the bus driver or client has set a proper value.
*
* REVISIT: should probably use msleep instead of mdelay if we
* know we can sleep.
*/
if (adap->lab_mdelay)
mdelay(adap->lab_mdelay);
DEB2(printk(KERN_INFO
"i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
get_pcf(adap, 1)));
}
static int wait_for_bb(struct i2c_algo_pcf_data *adap)
{
int timeout = DEF_TIMEOUT;
int status;
status = get_pcf(adap, 1);
while (!(status & I2C_PCF_BB) && --timeout) {
udelay(100); /* wait for 100 us */
status = get_pcf(adap, 1);
}
if (timeout == 0) {
printk(KERN_ERR "Timeout waiting for Bus Busy\n");
return -ETIMEDOUT;
}
return 0;
}
static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
{
int timeout = DEF_TIMEOUT;
*status = get_pcf(adap, 1);
while ((*status & I2C_PCF_PIN) && --timeout) {
adap->waitforpin(adap->data);
*status = get_pcf(adap, 1);
}
if (*status & I2C_PCF_LAB) {
handle_lab(adap, status);
return -EINTR;
}
if (timeout == 0)
return -ETIMEDOUT;
return 0;
}
/*
* This should perform the 'PCF8584 initialization sequence' as described
* in the Philips IC12 data book (1995, Aug 29).
* There should be a 30 clock cycle wait after reset, I assume this
* has been fulfilled.
* There should be a delay at the end equal to the longest I2C message
* to synchronize the BB-bit (in multimaster systems). How long is
* this? I assume 1 second is always long enough.
*
* vdovikin: added detect code for PCF8584
*/
static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
{
unsigned char temp;
DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",
get_pcf(adap, 1)));
/* S1=0x80: S0 selected, serial interface off */
set_pcf(adap, 1, I2C_PCF_PIN);
/*
* check to see S1 now used as R/W ctrl -
* PCF8584 does that when ESO is zero
*/
if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
return -ENXIO; /* definitely not PCF8584 */
}
/* load own address in S0, effective address is (own << 1) */
i2c_outb(adap, get_own(adap));
/* check it's really written */
if ((temp = i2c_inb(adap)) != get_own(adap)) {
DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
return -ENXIO;
}
/* S1=0xA0, next byte in S2 */
set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
/* check to see S2 now selected */
if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
return -ENXIO;
}
/* load clock register S2 */
i2c_outb(adap, get_clock(adap));
/* check it's really written, the only 5 lowest bits does matter */
if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
return -ENXIO;
}
/* Enable serial interface, idle, S0 selected */
set_pcf(adap, 1, I2C_PCF_IDLE);
/* check to see PCF is really idled and we can access status register */
if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
return -ENXIO;
}
printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
return 0;
}
static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
int count, int last)
{
struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
int wrcount, status, timeout;
for (wrcount=0; wrcount<count; ++wrcount) {
DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
buf[wrcount] & 0xff));
i2c_outb(adap, buf[wrcount]);
timeout = wait_for_pin(adap, &status);
if (timeout) {
if (timeout == -EINTR)
return -EINTR; /* arbitration lost */
i2c_stop(adap);
dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
return -EREMOTEIO; /* got a better one ?? */
}
if (status & I2C_PCF_LRB) {
i2c_stop(adap);
dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
return -EREMOTEIO; /* got a better one ?? */
}
}
if (last)
i2c_stop(adap);
else
i2c_repstart(adap);
return wrcount;
}
static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
int count, int last)
{
int i, status;
struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
int wfp;
/* increment number of bytes to read by one -- read dummy byte */
for (i = 0; i <= count; i++) {
if ((wfp = wait_for_pin(adap, &status))) {
if (wfp == -EINTR)
return -EINTR; /* arbitration lost */
i2c_stop(adap);
dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
return -1;
}
if ((status & I2C_PCF_LRB) && (i != count)) {
i2c_stop(adap);
dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
return -1;
}
if (i == count - 1) {
set_pcf(adap, 1, I2C_PCF_ESO);
} else if (i == count) {
if (last)
i2c_stop(adap);
else
i2c_repstart(adap);
}
if (i)
buf[i<
|