kolibrios-gitea/drivers/video/drm/i2c/i2c-core.c
Sergey Semyonov (Serge) 3c7b2b4679 init modeset
git-svn-id: svn://kolibrios.org@1125 a494cfbc-eb01-0410-851d-a64ba20cac60
2009-07-04 13:29:02 +00:00

109 lines
4.0 KiB
C

/* i2c-core.c - a device driver for the iic-bus interface */
/* ------------------------------------------------------------------------- */
/* Copyright (C) 1995-99 Simon G. Vogl
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>.
All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
Jean Delvare <khali@linux-fr.org> */
#include <types.h>
#include <list.h>
#include <errno.h>
#include <linux/i2c.h>
#include <syscall.h>
/**
* i2c_transfer - execute a single or combined I2C message
* @adap: Handle to I2C bus
* @msgs: One or more messages to execute before STOP is issued to
* terminate the operation; each message begins with a START.
* @num: Number of messages to be executed.
*
* Returns negative errno, else the number of messages executed.
*
* Note that there is no requirement that each message be sent to
* the same slave address, although that is the most common model.
*/
int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
unsigned long orig_jiffies;
int ret, try;
/* REVISIT the fault reporting model here is weak:
*
* - When we get an error after receiving N bytes from a slave,
* there is no way to report "N".
*
* - When we get a NAK after transmitting N bytes to a slave,
* there is no way to report "N" ... or to let the master
* continue executing the rest of this combined message, if
* that's the appropriate response.
*
* - When for example "num" is two and we successfully complete
* the first message but get an error part way through the
* second, it's unclear whether that should be reported as
* one (discarding status on the second message) or errno
* (discarding status on the first one).
*/
if (adap->algo->master_xfer) {
#ifdef DEBUG
for (ret = 0; ret < num; ret++) {
dev_dbg(&adap->dev, "master_xfer[%d] %c, addr=0x%02x, "
"len=%d%s\n", ret, (msgs[ret].flags & I2C_M_RD)
? 'R' : 'W', msgs[ret].addr, msgs[ret].len,
(msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
}
#endif
// if (in_atomic() || irqs_disabled()) {
// ret = mutex_trylock(&adap->bus_lock);
// if (!ret)
// /* I2C activity is ongoing. */
// return -EAGAIN;
// } else {
// mutex_lock_nested(&adap->bus_lock, adap->level);
// }
/* Retry automatically on arbitration loss */
// orig_jiffies = jiffies;
for (ret = 0, try = 0; try <= adap->retries; try++) {
ret = adap->algo->master_xfer(adap, msgs, num);
if (ret != -EAGAIN)
break;
// if (time_after(jiffies, orig_jiffies + adap->timeout))
// break;
delay(1);
}
// mutex_unlock(&adap->bus_lock);
return ret;
} else {
// dev_dbg(&adap->dev, "I2C level transfers not supported\n");
return -EOPNOTSUPP;
}
}
EXPORT_SYMBOL(i2c_transfer);