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NetBSD/sys/dev/i2c/i2c_exec.c

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/* $NetBSD: i2c_exec.c,v 1.9 2013/09/12 20:30:58 martin Exp $ */
/*
* Copyright (c) 2003 Wasabi Systems, Inc.
* All rights reserved.
*
* Written by Jason R. Thorpe for Wasabi Systems, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed for the NetBSD Project by
* Wasabi Systems, Inc.
* 4. The name of Wasabi Systems, Inc. may not be used to endorse
* or promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: i2c_exec.c,v 1.9 2013/09/12 20:30:58 martin Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/event.h>
#include <sys/conf.h>
#define _I2C_PRIVATE
#include <dev/i2c/i2cvar.h>
static uint8_t iic_smbus_crc8(uint16_t);
static uint8_t iic_smbus_pec(int, uint8_t *, uint8_t *);
/*
* iic_exec:
*
* Simplified I2C client interface engine.
*
* This and the SMBus routines are the preferred interface for
* client access to I2C/SMBus, since many automated controllers
* do not provide access to the low-level primitives of the I2C
* bus protocol.
*/
int
iic_exec(i2c_tag_t tag, i2c_op_t op, i2c_addr_t addr, const void *vcmd,
size_t cmdlen, void *vbuf, size_t buflen, int flags)
{
const uint8_t *cmd = vcmd;
uint8_t *buf = vbuf;
int error;
size_t len;
if ((flags & I2C_F_PEC) && cmdlen > 0 && tag->ic_exec != NULL) {
uint8_t data[33]; /* XXX */
uint8_t b[3];
b[0] = addr << 1;
b[1] = cmd[0];
switch (buflen) {
case 0:
data[0] = iic_smbus_pec(2, b, NULL);
buflen++;
break;
case 1:
b[2] = buf[0];
data[0] = iic_smbus_pec(3, b, NULL);
data[1] = b[2];
buflen++;
break;
case 2:
break;
default:
KASSERT(buflen+1 < sizeof(data));
memcpy(data, vbuf, buflen);
data[buflen] = iic_smbus_pec(2, b, data);
buflen++;
break;
}
return ((*tag->ic_exec)(tag->ic_cookie, op, addr, cmd,
cmdlen, data, buflen, flags));
}
/*
* Defer to the controller if it provides an exec function. Use
* it if it does.
*/
if (tag->ic_exec != NULL)
return ((*tag->ic_exec)(tag->ic_cookie, op, addr, cmd,
cmdlen, buf, buflen, flags));
if ((len = cmdlen) != 0) {
if ((error = iic_initiate_xfer(tag, addr, flags)) != 0)
goto bad;
while (len--) {
if ((error = iic_write_byte(tag, *cmd++, flags)) != 0)
goto bad;
}
} else if (buflen == 0) {
/*
* This is a quick_read()/quick_write() command with
* neither command nor data bytes
*/
if (I2C_OP_STOP_P(op))
flags |= I2C_F_STOP;
if (I2C_OP_READ_P(op))
flags |= I2C_F_READ;
if ((error = iic_initiate_xfer(tag, addr, flags)) != 0)
goto bad;
}
if (I2C_OP_READ_P(op))
flags |= I2C_F_READ;
len = buflen;
while (len--) {
if (len == 0 && I2C_OP_STOP_P(op))
flags |= I2C_F_STOP;
if (I2C_OP_READ_P(op)) {
/* Send REPEATED START. */
if ((len + 1) == buflen &&
(error = iic_initiate_xfer(tag, addr, flags)) != 0)
goto bad;
/* NACK on last byte. */
if (len == 0)
flags |= I2C_F_LAST;
if ((error = iic_read_byte(tag, buf++, flags)) != 0)
goto bad;
} else {
/* Maybe send START. */
if ((len + 1) == buflen && cmdlen == 0 &&
(error = iic_initiate_xfer(tag, addr, flags)) != 0)
goto bad;
if ((error = iic_write_byte(tag, *buf++, flags)) != 0)
goto bad;
}
}
return (0);
bad:
iic_send_stop(tag, flags);
return (error);
}
/*
* iic_smbus_write_byte:
*
* Perform an SMBus "write byte" operation.
*/
int
iic_smbus_write_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
uint8_t val, int flags)
{
return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, &cmd, 1,
&val, 1, flags));
}
/*
* iic_smbus_write_word:
*
* Perform an SMBus "write word" operation.
*/
int
iic_smbus_write_word(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
uint16_t val, int flags)
{
uint8_t vbuf[2];
vbuf[0] = val & 0xff;
vbuf[1] = (val >> 8) & 0xff;
return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, &cmd, 1,
vbuf, 2, flags));
}
/*
* iic_smbus_read_byte:
*
* Perform an SMBus "read byte" operation.
*/
int
iic_smbus_read_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
uint8_t *valp, int flags)
{
return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, &cmd, 1,
valp, 1, flags));
}
/*
* iic_smbus_read_word:
*
* Perform an SMBus "read word" operation.
*/
int
iic_smbus_read_word(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
uint16_t *valp, int flags)
{
return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, &cmd, 1,
(uint8_t *)valp, 2, flags));
}
/*
* iic_smbus_receive_byte:
*
* Perform an SMBus "receive byte" operation.
*/
int
iic_smbus_receive_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t *valp,
int flags)
{
return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, NULL, 0,
valp, 1, flags));
}
/*
* iic_smbus_send_byte:
*
* Perform an SMBus "send byte" operation.
*/
int
iic_smbus_send_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t val, int flags)
{
return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, NULL, 0,
&val, 1, flags));
}
/*
* iic_smbus_quick_read:
*
* Perform an SMBus "quick read" operation.
*/
int
iic_smbus_quick_read(i2c_tag_t tag, i2c_addr_t addr, int flags)
{
return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, NULL, 0,
NULL, 0, flags));
}
/*
* iic_smbus_quick_write:
*
* Perform an SMBus "quick write" operation.
*/
int
iic_smbus_quick_write(i2c_tag_t tag, i2c_addr_t addr, int flags)
{
return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, NULL, 0,
NULL, 0, flags));
}
/*
* iic_smbus_block_read:
*
* Perform an SMBus "block read" operation.
*/
int
iic_smbus_block_read(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
uint8_t *vbuf, size_t buflen, int flags)
{
return (iic_exec(tag, I2C_OP_READ_BLOCK, addr, &cmd, 1,
vbuf, buflen, flags));
}
/*
* iic_smbus_block_write:
*
* Perform an SMBus "block write" operation.
*/
int
iic_smbus_block_write(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
uint8_t *vbuf, size_t buflen, int flags)
{
return (iic_exec(tag, I2C_OP_WRITE_BLOCK, addr, &cmd, 1,
vbuf, buflen, flags));
}
/*
* iic_smbus_crc8
*
* Private helper for calculating packet error checksum
*/
static uint8_t
iic_smbus_crc8(uint16_t data)
{
int i;
for (i = 0; i < 8; i++) {
if (data & 0x8000)
data = data ^ (0x1070U << 3);
data = data << 1;
}
return (uint8_t)(data >> 8);
}
/*
* iic_smbus_pec
*
* Private function for calculating packet error checking on SMBus
* packets.
*/
static uint8_t
iic_smbus_pec(int count, uint8_t *s, uint8_t *r)
{
int i;
uint8_t crc = 0;
for (i = 0; i < count; i++)
crc = iic_smbus_crc8((crc ^ s[i]) << 8);
if (r != NULL)
for (i = 0; i <= r[0]; i++)
crc = iic_smbus_crc8((crc ^ r[i]) << 8);
return crc;
}
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