/*
* 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.
*/
/*
* iic_tag_fini:
*
* Teardown of the i2c controller tag.
*/
void
iic_tag_fini(i2c_tag_t tag)
{
mutex_destroy(&tag->ic_bus_lock);
}
/*
* iic_acquire_bus:
*
* Acquire the I2C bus for use by a client.
*/
int
iic_acquire_bus(i2c_tag_t tag, int flags)
{
#if 0 /* XXX Not quite ready for this yet. */
KASSERT(!cpu_intr_p());
#endif
flags = iic_op_flags(flags);
if (flags & I2C_F_POLL) {
/*
* Polling should only be used in rare and/or
* extreme circumstances; most i2c clients
* should be allowed to sleep.
*
* Really, the ONLY user of I2C_F_POLL should be
* "when cold", i.e. during early autoconfiguration
* when there is only proc0, and we might have to
* read SEEPROMs, etc. There should be no other
* users interfering with our access of the i2c bus
* in that case.
*/
if (mutex_tryenter(&tag->ic_bus_lock) == 0) {
return EBUSY;
}
} else {
/*
* N.B. We implement this as a mutex that we hold across
* across a series of requests beause we'd like to get the
* priority boost if a higher-priority process wants the
* i2c bus while we're asleep waiting for the controller
* to perform the I/O.
*
* XXXJRT Disable preemption here? We'd like to keep
* the CPU while holding this resource, unless we release
* it voluntarily (which should only happen while waiting
* for a controller to complete I/O).
*/
mutex_enter(&tag->ic_bus_lock);
}
int error = 0;
if (tag->ic_acquire_bus) {
error = (*tag->ic_acquire_bus)(tag->ic_cookie, flags);
}
if (__predict_false(error)) {
mutex_exit(&tag->ic_bus_lock);
}
return error;
}
/*
* iic_release_bus:
*
* Release the I2C bus, allowing another client to use it.
*/
void
iic_release_bus(i2c_tag_t tag, int flags)
{
#if 0 /* XXX Not quite ready for this yet. */
KASSERT(!cpu_intr_p());
#endif
flags = iic_op_flags(flags);
if (tag->ic_release_bus) {
(*tag->ic_release_bus)(tag->ic_cookie, flags);
}
mutex_exit(&tag->ic_bus_lock);
}
/*
* 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 0 /* XXX Not quite ready for this yet. */
KASSERT(!cpu_intr_p());
#endif
/*
* 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;
}
}
/*
* 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;
}
MODULE(MODULE_CLASS_MISC, i2cexec, NULL);
static int
i2cexec_modcmd(modcmd_t cmd, void *opaque)
{
switch (cmd) {
case MODULE_CMD_INIT:
case MODULE_CMD_FINI:
return 0;
break;
default:
return ENOTTY;
}
}
