/*
* i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
* Copyright (C) 2004 Arcom Control Systems
*
* 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 <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-pca.h>
#include "i2c-algo-pca.h"
#define DRIVER "i2c-algo-pca"
#define DEB1(fmt, args...) do { if (i2c_debug>=1) printk(fmt, ## args); } while(0)
#define DEB2(fmt, args...) do { if (i2c_debug>=2) printk(fmt, ## args); } while(0)
#define DEB3(fmt, args...) do { if (i2c_debug>=3) printk(fmt, ## args); } while(0)
static int i2c_debug;
#define pca_outw(adap, reg, val) adap->write_byte(adap, reg, val)
#define pca_inw(adap, reg) adap->read_byte(adap, reg)
#define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
#define pca_clock(adap) adap->get_clock(adap)
#define pca_own(adap) adap->get_own(adap)
#define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
#define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
#define pca_wait(adap) adap->wait_for_interrupt(adap)
/*
* Generate a start condition on the i2c bus.
*
* returns after the start condition has occurred
*/
static void pca_start(struct i2c_algo_pca_data *adap)
{
int sta = pca_get_con(adap);
DEB2("=== START\n");
sta |= I2C_PCA_CON_STA;
sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
pca_set_con(adap, sta);
pca_wait(adap);
}
/*
* Generate a repeated start condition on the i2c bus
*
* return after the repeated start condition has occurred
*/
static void pca_repeated_start(struct i2c_algo_pca_data *adap)
{
int sta = pca_get_con(adap);
DEB2("=== REPEATED START\n");
sta |= I2C_PCA_CON_STA;
sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
pca_set_con(adap, sta);
pca_wait(adap);
}
/*
* Generate a stop condition on the i2c bus
*
* returns after the stop condition has been generated
*
* STOPs do not generate an interrupt or set the SI flag, since the
* part returns the idle state (0xf8). Hence we don't need to
* pca_wait here.
*/
static void pca_stop(struct i2c_algo_pca_data *adap)
{
int sta = pca_get_con(adap);
DEB2("=== STOP\n");
sta |= I2C_PCA_CON_STO;
sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
pca_set_con(adap, sta);
}
/*
* Send the slave address and R/W bit
*
* returns after the address has been sent
*/
static void pca_address(struct i2c_algo_pca_data *adap,
struct i2c_msg *msg)
{
int sta = pca_get_con(adap);
int addr;
addr = ( (0x7f & msg->addr) << 1 );
if (msg->flags & I2C_M_RD )
addr |= 1;
DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
pca_outw(adap, I2C_PCA_DAT, addr);
sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
pca_set_con(adap, sta);
pca_wait(adap);
}
/*
* Transmit a byte.
*
* Returns after the byte has been transmitted
*/
static void pca_tx_byte(struct i2c_algo_pca_data *adap,
__u8 b)
{
int sta = pca_get_con(adap);
DEB2("=== WRITE %#04x\n", b);
pca_outw(adap, I2C_PCA_DAT, b);
sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
pca_set_con(adap, sta);
pca_wait(adap);
}
/*
* Receive a byte
*
* returns immediately.
*/
static void pca_rx_byte(struct i2c_algo_pca_data *adap,
__u8 *b, int ack)
{
*b = pca_inw(adap, I2C_PCA_DAT);
DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
}
/*
* Setup ACK or NACK for next received byte and wait for it to arrive.
*
* Returns after next byte has arrived.
*/
static void pca_rx_ack(struct i2c_algo_pca_data *adap,
int ack)
{
int sta = pca_get_con(adap);
sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
if ( ack )
sta |= I2C_PCA_CON_AA;
pca_set_con(adap, sta);
pca_wait(adap);
}
/*
* Reset the i2c bus / SIO
*/
static void pca_reset(struct i2c_algo_pca_data *adap)
{
/* apparently only an external reset will do it. not a lot can be done */
printk(KERN_ERR DRIVER ": Haven't figured out how to do a reset yet\n");
}
static int pca_xfer(struct i2c_adapter *i2c_adap,
struct i2c_msg *msgs,
int num)
{
struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
struct i2c_msg *msg = NULL;
int curmsg;
int numbytes = 0;
int state;
int ret;
int timeout = 100;
while ((state = pca_status(adap)) != 0xf8 && timeout--) {
msleep(10);
}
if (state != 0xf8) {
dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state);
return -EIO;
}
DEB1("{{{ XFER %d messages\n", num);
if (i2c_debug>=2) {
for (curmsg = 0; curmsg < num; curmsg++) {
int addr, i;
msg = &msgs[curmsg];
addr = (0x7f & msg->addr) ;
if (msg->flags & I2C_M_RD )
printk(KERN_INFO " [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
curmsg, msg->len, addr, (addr<<1) | 1);
else {
printk(KERN_INFO " [%02d] WR %d bytes to %#02x [%#02x%s",
curmsg, msg->len, addr, addr<<1,
msg->len == 0 ? "" : ", ");
for(i=0; i < msg->len; i++)
printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
printk("]\n");
}
}
}
curmsg = 0;
ret = -EREMOTEIO;
while (curmsg < num) {
state = pca_status(adap);
DEB3("STATE is 0x%02x\n", state);
msg = &msgs[curmsg];
switch (state) {
case 0xf8: /* On reset or stop the bus is idle */
pca_start(adap);
break;
case 0x08: /* A START condition has been transmitted */
case 0x10: /* A repeated start condition has been transmitted */
pca_address(adap, msg);
break;
case 0x18: /* SLA+W has been transmitted; ACK has been received */
case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
if (numbytes < msg->len) {
pca_tx_byte(adap, msg->buf[numbytes]);
numbytes++;
break;
}
curmsg++; numbytes = 0;
if (curmsg == num)
pca_stop(adap);
else
pca_repeated_start(adap);
break;
case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
DEB2("NOT ACK received after SLA+W\n");
pca_stop(adap);
goto out;
case 0x40: /* SLA+R has been transmitted; ACK has been received */
pca_rx_ack(adap, msg->len > 1);
break;
case 0x50: /* Data bytes has been received; ACK has been returned */
if (numbytes < msg->len) {
pca_rx_byte(adap, &msg->buf[numbytes], 1);
numbytes++;
pca_rx_ack(adap, numbytes < msg->len - 1);
break;
}
curmsg++; numbytes = 0;
if (curmsg == num)
pca_stop(adap);
else
pca_repeated_start(adap);
break;
case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
DEB2("NOT ACK received after SLA+R\n");
pca_stop(adap);
goto out;
case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
DEB2("NOT ACK received after data byte\n");
goto out;
case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
DEB2("Arbitration lost\n");
goto out;
case 0x58: /* Data byte has been received; NOT ACK has been returned */
if ( numbytes == msg->len - 1 ) {
pca_rx_byte(adap, &msg->buf[numbytes], 0);
curmsg++; numbytes = 0;
if (curmsg == num)
pca_stop(adap);
else
pca_repeated_start(adap);
} else {
DEB2("NOT ACK sent after data byte received. "
"Not final byte. numbytes %d. len %d\n",
numbytes, msg->len);
pca_stop(adap);
goto out;
}
break;
case 0x70: /* Bus error - SDA stuck low */
DEB2("BUS ERROR - SDA Stuck low\n");
pca_reset(adap);
goto out;
case 0x90: /* Bus error - SCL stuck low */
DEB2("BUS ERROR - SCL Stuck low\n");
pca_reset(adap);
goto out;
case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
DEB2("BUS ERROR - Illegal START or STOP\n");
pca_reset(adap);
goto out;
default:
printk(KERN_ERR DRIVER ": unhandled SIO state 0x%02x\n", state);
break;
}
}
ret = curmsg;
out:
DEB1(KERN_CRIT "}}} transfered %d/%d messages. "
"status is %#04x. control is %#04x\n",
curmsg, num, pca_status(adap),
pca_get_con(adap));
return ret;
}
static u32 pca_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static int pca_init(struct i2c_algo_pca_data *adap)
{
static int freqs[] = {330,288,217,146,88,59,44,36};
int own, clock;
own = pca_own(adap);
clock = pca_clock(adap);
DEB1(KERN_INFO DRIVER ": own address is %#04x\n", own);
DEB1(KERN_INFO DRIVER ": clock freqeuncy is %dkHz\n", freqs[clock]);
pca_outw(adap, I2C_PCA_ADR, own << 1);
pca_set_con(adap, I2C_PCA_CON_ENSIO | clock);
udelay(500); /* 500 µs for oscilator to stabilise */
return 0;
}
static const struct i2c_algorithm pca_algo = {
.master_xfer = pca_xfer,
.functionality = pca_func,
};
/*
* registering functions to load algorithms at runtime
*/
int i2c_pca_add_bus(struct i2c_adapter *adap)
{
struct i2c_algo_pca_data *pca_adap = adap->algo_data;
int rval;
/* register new adapter to i2c module... */
adap->algo = &pca_algo;
adap->timeout = 100; /* default values, should */
adap->retries = 3; /* be replaced by defines */
if ((rval = pca_init(pca_adap)))
return rval;
rval = i2c_add_adapter(adap);
return rval;
}
EXPORT_SYMBOL(i2c_pca_add_bus);
MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>");
MODULE_DESCRIPTION("I2C-Bus PCA9564 algorithm");
MODULE_LICENSE("GPL");
module_param(i2c_debug, int, 0);
