484 lines
11 KiB
C
484 lines
11 KiB
C
/* $NetBSD: i2c_exec.c,v 1.18 2022/10/24 10:17:27 riastradh Exp $ */
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/*
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* Copyright (c) 2003 Wasabi Systems, Inc.
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* All rights reserved.
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*
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* Written by Jason R. Thorpe for Wasabi Systems, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed for the NetBSD Project by
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* Wasabi Systems, Inc.
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* 4. The name of Wasabi Systems, Inc. may not be used to endorse
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* or promote products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: i2c_exec.c,v 1.18 2022/10/24 10:17:27 riastradh Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/cpu.h>
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#include <sys/device.h>
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#include <sys/module.h>
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#include <sys/event.h>
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#include <sys/conf.h>
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#include <sys/kernel.h>
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#define _I2C_PRIVATE
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#include <dev/i2c/i2cvar.h>
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static uint8_t iic_smbus_crc8(uint16_t);
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static uint8_t iic_smbus_pec(int, uint8_t *, uint8_t *);
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static int i2cexec_modcmd(modcmd_t, void *);
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static inline int
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iic_op_flags(int flags)
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{
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return flags | ((cold || shutting_down) ? I2C_F_POLL : 0);
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}
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/*
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* iic_tag_init:
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*
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* Perform some basic initialization of the i2c controller tag.
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*/
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void
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iic_tag_init(i2c_tag_t tag)
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{
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memset(tag, 0, sizeof(*tag));
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mutex_init(&tag->ic_bus_lock, MUTEX_DEFAULT, IPL_NONE);
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}
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/*
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* iic_tag_fini:
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*
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* Teardown of the i2c controller tag.
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*/
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void
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iic_tag_fini(i2c_tag_t tag)
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{
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mutex_destroy(&tag->ic_bus_lock);
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}
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/*
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* iic_acquire_bus:
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*
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* Acquire the I2C bus for use by a client.
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*/
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int
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iic_acquire_bus(i2c_tag_t tag, int flags)
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{
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#if 0 /* XXX Not quite ready for this yet. */
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KASSERT(!cpu_intr_p());
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#endif
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flags = iic_op_flags(flags);
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if (flags & I2C_F_POLL) {
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/*
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* Polling should only be used in rare and/or
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* extreme circumstances; most i2c clients
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* should be allowed to sleep.
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*
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* Really, the ONLY user of I2C_F_POLL should be
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* "when cold", i.e. during early autoconfiguration
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* when there is only proc0, and we might have to
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* read SEEPROMs, etc. There should be no other
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* users interfering with our access of the i2c bus
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* in that case.
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*/
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if (mutex_tryenter(&tag->ic_bus_lock) == 0) {
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return EBUSY;
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}
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} else {
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/*
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* N.B. We implement this as a mutex that we hold across
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* across a series of requests beause we'd like to get the
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* priority boost if a higher-priority process wants the
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* i2c bus while we're asleep waiting for the controller
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* to perform the I/O.
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*
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* XXXJRT Disable preemption here? We'd like to keep
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* the CPU while holding this resource, unless we release
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* it voluntarily (which should only happen while waiting
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* for a controller to complete I/O).
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*/
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mutex_enter(&tag->ic_bus_lock);
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}
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int error = 0;
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if (tag->ic_acquire_bus) {
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error = (*tag->ic_acquire_bus)(tag->ic_cookie, flags);
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}
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if (__predict_false(error)) {
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mutex_exit(&tag->ic_bus_lock);
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}
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return error;
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}
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/*
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* iic_release_bus:
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*
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* Release the I2C bus, allowing another client to use it.
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*/
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void
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iic_release_bus(i2c_tag_t tag, int flags)
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{
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#if 0 /* XXX Not quite ready for this yet. */
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KASSERT(!cpu_intr_p());
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#endif
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flags = iic_op_flags(flags);
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if (tag->ic_release_bus) {
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(*tag->ic_release_bus)(tag->ic_cookie, flags);
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}
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mutex_exit(&tag->ic_bus_lock);
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}
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/*
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* iic_exec:
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*
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* Simplified I2C client interface engine.
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*
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* This and the SMBus routines are the preferred interface for
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* client access to I2C/SMBus, since many automated controllers
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* do not provide access to the low-level primitives of the I2C
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* bus protocol.
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*/
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int
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iic_exec(i2c_tag_t tag, i2c_op_t op, i2c_addr_t addr, const void *vcmd,
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size_t cmdlen, void *vbuf, size_t buflen, int flags)
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{
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const uint8_t *cmd = vcmd;
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uint8_t *buf = vbuf;
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int error;
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size_t len;
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#if 0 /* XXX Not quite ready for this yet. */
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KASSERT(!cpu_intr_p());
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#endif
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flags = iic_op_flags(flags);
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if ((flags & I2C_F_PEC) && cmdlen > 0 && tag->ic_exec != NULL) {
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uint8_t data[33]; /* XXX */
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uint8_t b[3];
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b[0] = addr << 1;
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b[1] = cmd[0];
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switch (buflen) {
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case 0:
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data[0] = iic_smbus_pec(2, b, NULL);
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buflen++;
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break;
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case 1:
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b[2] = buf[0];
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data[0] = iic_smbus_pec(3, b, NULL);
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data[1] = b[2];
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buflen++;
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break;
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case 2:
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break;
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default:
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KASSERT(buflen+1 < sizeof(data));
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memcpy(data, vbuf, buflen);
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data[buflen] = iic_smbus_pec(2, b, data);
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buflen++;
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break;
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}
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return ((*tag->ic_exec)(tag->ic_cookie, op, addr, cmd,
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cmdlen, data, buflen, flags));
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}
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/*
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* Defer to the controller if it provides an exec function. Use
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* it if it does.
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*/
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if (tag->ic_exec != NULL)
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return ((*tag->ic_exec)(tag->ic_cookie, op, addr, cmd,
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cmdlen, buf, buflen, flags));
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if ((len = cmdlen) != 0) {
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if ((error = iic_initiate_xfer(tag, addr, flags)) != 0)
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goto bad;
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while (len--) {
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if ((error = iic_write_byte(tag, *cmd++, flags)) != 0)
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goto bad;
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}
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} else if (buflen == 0) {
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/*
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* This is a quick_read()/quick_write() command with
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* neither command nor data bytes
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*/
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if (I2C_OP_STOP_P(op))
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flags |= I2C_F_STOP;
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if (I2C_OP_READ_P(op))
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flags |= I2C_F_READ;
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if ((error = iic_initiate_xfer(tag, addr, flags)) != 0)
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goto bad;
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}
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if (I2C_OP_READ_P(op))
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flags |= I2C_F_READ;
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len = buflen;
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while (len--) {
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if (len == 0 && I2C_OP_STOP_P(op))
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flags |= I2C_F_STOP;
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if (I2C_OP_READ_P(op)) {
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/* Send REPEATED START. */
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if ((len + 1) == buflen &&
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(error = iic_initiate_xfer(tag, addr, flags)) != 0)
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goto bad;
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/* NACK on last byte. */
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if (len == 0)
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flags |= I2C_F_LAST;
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if ((error = iic_read_byte(tag, buf++, flags)) != 0)
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goto bad;
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} else {
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/* Maybe send START. */
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if ((len + 1) == buflen && cmdlen == 0 &&
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(error = iic_initiate_xfer(tag, addr, flags)) != 0)
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goto bad;
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if ((error = iic_write_byte(tag, *buf++, flags)) != 0)
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goto bad;
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}
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}
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return (0);
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bad:
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iic_send_stop(tag, flags);
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return (error);
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}
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/*
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* iic_smbus_write_byte:
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*
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* Perform an SMBus "write byte" operation.
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*/
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int
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iic_smbus_write_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
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uint8_t val, int flags)
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{
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return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, &cmd, 1,
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&val, 1, flags));
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}
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/*
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* iic_smbus_write_word:
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*
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* Perform an SMBus "write word" operation.
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*/
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int
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iic_smbus_write_word(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
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uint16_t val, int flags)
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{
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uint8_t vbuf[2];
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vbuf[0] = val & 0xff;
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vbuf[1] = (val >> 8) & 0xff;
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return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, &cmd, 1,
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vbuf, 2, flags));
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}
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/*
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* iic_smbus_read_byte:
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*
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* Perform an SMBus "read byte" operation.
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*/
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int
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iic_smbus_read_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
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uint8_t *valp, int flags)
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{
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return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, &cmd, 1,
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valp, 1, flags));
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}
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/*
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* iic_smbus_read_word:
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*
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* Perform an SMBus "read word" operation.
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*/
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int
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iic_smbus_read_word(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
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uint16_t *valp, int flags)
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{
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return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, &cmd, 1,
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(uint8_t *)valp, 2, flags));
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}
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/*
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* iic_smbus_receive_byte:
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*
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* Perform an SMBus "receive byte" operation.
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*/
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int
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iic_smbus_receive_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t *valp,
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int flags)
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{
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return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, NULL, 0,
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valp, 1, flags));
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}
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/*
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* iic_smbus_send_byte:
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*
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* Perform an SMBus "send byte" operation.
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*/
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int
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iic_smbus_send_byte(i2c_tag_t tag, i2c_addr_t addr, uint8_t val, int flags)
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{
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return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, NULL, 0,
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&val, 1, flags));
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}
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/*
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* iic_smbus_quick_read:
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*
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* Perform an SMBus "quick read" operation.
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*/
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int
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iic_smbus_quick_read(i2c_tag_t tag, i2c_addr_t addr, int flags)
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{
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return (iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, NULL, 0,
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NULL, 0, flags));
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}
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/*
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* iic_smbus_quick_write:
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*
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* Perform an SMBus "quick write" operation.
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*/
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int
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iic_smbus_quick_write(i2c_tag_t tag, i2c_addr_t addr, int flags)
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{
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return (iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, NULL, 0,
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NULL, 0, flags));
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}
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/*
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* iic_smbus_block_read:
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*
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* Perform an SMBus "block read" operation.
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*/
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int
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iic_smbus_block_read(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
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uint8_t *vbuf, size_t buflen, int flags)
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{
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return (iic_exec(tag, I2C_OP_READ_BLOCK, addr, &cmd, 1,
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vbuf, buflen, flags));
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}
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/*
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* iic_smbus_block_write:
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*
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* Perform an SMBus "block write" operation.
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*/
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int
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iic_smbus_block_write(i2c_tag_t tag, i2c_addr_t addr, uint8_t cmd,
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uint8_t *vbuf, size_t buflen, int flags)
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{
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return (iic_exec(tag, I2C_OP_WRITE_BLOCK, addr, &cmd, 1,
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vbuf, buflen, flags));
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}
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/*
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* iic_smbus_crc8
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*
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* Private helper for calculating packet error checksum
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*/
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static uint8_t
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iic_smbus_crc8(uint16_t data)
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{
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int i;
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for (i = 0; i < 8; i++) {
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if (data & 0x8000)
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data = data ^ (0x1070U << 3);
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data = data << 1;
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}
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return (uint8_t)(data >> 8);
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}
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/*
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* iic_smbus_pec
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*
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* Private function for calculating packet error checking on SMBus
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* packets.
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*/
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static uint8_t
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iic_smbus_pec(int count, uint8_t *s, uint8_t *r)
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{
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int i;
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uint8_t crc = 0;
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for (i = 0; i < count; i++)
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crc = iic_smbus_crc8((crc ^ s[i]) << 8);
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if (r != NULL)
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for (i = 0; i <= r[0]; i++)
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crc = iic_smbus_crc8((crc ^ r[i]) << 8);
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return crc;
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}
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MODULE(MODULE_CLASS_MISC, i2cexec, NULL);
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static int
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i2cexec_modcmd(modcmd_t cmd, void *opaque)
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{
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switch (cmd) {
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case MODULE_CMD_INIT:
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case MODULE_CMD_FINI:
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return 0;
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break;
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default:
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return ENOTTY;
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}
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}
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