34199ee049
Usually it is sufficient to use iicbus_transfer_excl(), or one of the higher-level convenience functions that use it, to reserve the bus for the duration of each register access. Occasionally it is important that a series of accesses or read-modify-write operations must be done without any other intervening access to the device, to prevent corrupting state. Without support for nested request/release, slave device drivers would have to stop using high-level convenience functions and resort to working with arrays of iic_msg structs just for a few operations (often involving one-time device setup or infrequent configuration changes). The changes here appear large from a glance at the diff, but in fact they're nearly trivial, and the large diff is because of changes in indentation and the re-wrapping of comments caused by that. One notable change is that iicbus_release_bus() now ignores the IICBUS_CALLBACK(IIC_RELEASE_BUS) return value. The old error handling left the bus in a kind of limbo state where it was still owned at the iicbus layer, but drivers rarely check the return of the release call, and it's unclear what they would do to recover from an error return anyway. No existing low-level drivers return any kind of error from IIC_RELEASE_BUS except one EINVAL for "you don't own the bus", to which the right response is probably to carry on with the process of releasing the reference to the bus anyway.
518 lines
12 KiB
C
518 lines
12 KiB
C
/*-
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* Copyright (c) 1998 Nicolas Souchu
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* All rights reserved.
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/module.h>
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#include <sys/mutex.h>
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#include <sys/bus.h>
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#include <dev/iicbus/iiconf.h>
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#include <dev/iicbus/iicbus.h>
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#include "iicbus_if.h"
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/*
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* Translate IIC_Exxxxx status values to vaguely-equivelent errno values.
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*/
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int
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iic2errno(int iic_status)
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{
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switch (iic_status) {
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case IIC_NOERR: return (0);
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case IIC_EBUSERR: return (EALREADY);
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case IIC_ENOACK: return (EIO);
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case IIC_ETIMEOUT: return (ETIMEDOUT);
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case IIC_EBUSBSY: return (EWOULDBLOCK);
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case IIC_ESTATUS: return (EPROTO);
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case IIC_EUNDERFLOW: return (EIO);
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case IIC_EOVERFLOW: return (EOVERFLOW);
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case IIC_ENOTSUPP: return (EOPNOTSUPP);
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case IIC_ENOADDR: return (EADDRNOTAVAIL);
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case IIC_ERESOURCE: return (ENOMEM);
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default: return (EIO);
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}
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}
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/*
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* iicbus_intr()
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*/
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void
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iicbus_intr(device_t bus, int event, char *buf)
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{
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struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
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/* call owner's intr routine */
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if (sc->owner)
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IICBUS_INTR(sc->owner, event, buf);
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return;
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}
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static int
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iicbus_poll(struct iicbus_softc *sc, int how)
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{
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int error;
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IICBUS_ASSERT_LOCKED(sc);
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switch (how) {
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case IIC_WAIT | IIC_INTR:
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error = mtx_sleep(sc, &sc->lock, IICPRI|PCATCH, "iicreq", 0);
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break;
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case IIC_WAIT | IIC_NOINTR:
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error = mtx_sleep(sc, &sc->lock, IICPRI, "iicreq", 0);
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break;
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default:
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return (IIC_EBUSBSY);
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}
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return (error);
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}
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/*
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* iicbus_request_bus()
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*
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* Allocate the device to perform transfers.
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*
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* how : IIC_WAIT or IIC_DONTWAIT
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*/
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int
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iicbus_request_bus(device_t bus, device_t dev, int how)
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{
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struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
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int error = 0;
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IICBUS_LOCK(sc);
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while (error == 0 && sc->owner != NULL && sc->owner != dev)
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error = iicbus_poll(sc, how);
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if (error == 0) {
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++sc->owncount;
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if (sc->owner == NULL) {
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sc->owner = dev;
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/*
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* Drop the lock around the call to the bus driver, it
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* should be allowed to sleep in the IIC_WAIT case.
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* Drivers might also need to grab locks that would
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* cause a LOR if our lock is held.
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*/
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IICBUS_UNLOCK(sc);
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/* Ask the underlying layers if the request is ok */
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error = IICBUS_CALLBACK(device_get_parent(bus),
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IIC_REQUEST_BUS, (caddr_t)&how);
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IICBUS_LOCK(sc);
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if (error != 0) {
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sc->owner = NULL;
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sc->owncount = 0;
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wakeup_one(sc);
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}
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}
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}
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IICBUS_UNLOCK(sc);
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return (error);
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}
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/*
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* iicbus_release_bus()
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*
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* Release the device allocated with iicbus_request_dev()
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*/
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int
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iicbus_release_bus(device_t bus, device_t dev)
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{
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struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
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IICBUS_LOCK(sc);
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if (sc->owner != dev) {
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IICBUS_UNLOCK(sc);
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return (IIC_EBUSBSY);
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}
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if (--sc->owncount == 0) {
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/* Drop the lock while informing the low-level driver. */
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IICBUS_UNLOCK(sc);
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IICBUS_CALLBACK(device_get_parent(bus), IIC_RELEASE_BUS, NULL);
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IICBUS_LOCK(sc);
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sc->owner = NULL;
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wakeup_one(sc);
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}
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IICBUS_UNLOCK(sc);
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return (0);
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}
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/*
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* iicbus_started()
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*
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* Test if the iicbus is started by the controller
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*/
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int
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iicbus_started(device_t bus)
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{
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struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
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return (sc->started);
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}
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/*
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* iicbus_start()
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*
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* Send start condition to the slave addressed by 'slave'
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*/
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int
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iicbus_start(device_t bus, u_char slave, int timeout)
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{
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struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
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int error = 0;
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if (sc->started)
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return (IIC_ESTATUS); /* protocol error, bus already started */
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if (!(error = IICBUS_START(device_get_parent(bus), slave, timeout)))
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sc->started = slave;
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else
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sc->started = 0;
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return (error);
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}
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/*
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* iicbus_repeated_start()
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*
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* Send start condition to the slave addressed by 'slave'
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*/
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int
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iicbus_repeated_start(device_t bus, u_char slave, int timeout)
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{
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struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
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int error = 0;
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if (!sc->started)
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return (IIC_ESTATUS); /* protocol error, bus not started */
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if (!(error = IICBUS_REPEATED_START(device_get_parent(bus), slave, timeout)))
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sc->started = slave;
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else
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sc->started = 0;
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return (error);
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}
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/*
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* iicbus_stop()
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*
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* Send stop condition to the bus
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*/
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int
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iicbus_stop(device_t bus)
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{
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struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
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int error = 0;
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if (!sc->started)
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return (IIC_ESTATUS); /* protocol error, bus not started */
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error = IICBUS_STOP(device_get_parent(bus));
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/* refuse any further access */
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sc->started = 0;
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return (error);
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}
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/*
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* iicbus_write()
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*
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* Write a block of data to the slave previously started by
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* iicbus_start() call
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*/
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int
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iicbus_write(device_t bus, const char *buf, int len, int *sent, int timeout)
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{
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struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
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/* a slave must have been started for writing */
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if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) != 0))
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return (IIC_ESTATUS);
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return (IICBUS_WRITE(device_get_parent(bus), buf, len, sent, timeout));
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}
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/*
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* iicbus_read()
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*
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* Read a block of data from the slave previously started by
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* iicbus_read() call
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*/
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int
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iicbus_read(device_t bus, char *buf, int len, int *read, int last, int delay)
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{
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struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
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/* a slave must have been started for reading */
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if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) == 0))
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return (IIC_ESTATUS);
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return (IICBUS_READ(device_get_parent(bus), buf, len, read, last, delay));
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}
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/*
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* iicbus_write_byte()
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*
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* Write a byte to the slave previously started by iicbus_start() call
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*/
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int
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iicbus_write_byte(device_t bus, char byte, int timeout)
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{
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struct iicbus_softc *sc = device_get_softc(bus);
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char data = byte;
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int sent;
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/* a slave must have been started for writing */
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if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) != 0))
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return (IIC_ESTATUS);
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return (iicbus_write(bus, &data, 1, &sent, timeout));
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}
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/*
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* iicbus_read_byte()
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*
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* Read a byte from the slave previously started by iicbus_start() call
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*/
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int
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iicbus_read_byte(device_t bus, char *byte, int timeout)
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{
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struct iicbus_softc *sc = device_get_softc(bus);
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int read;
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/* a slave must have been started for reading */
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if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) == 0))
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return (IIC_ESTATUS);
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return (iicbus_read(bus, byte, 1, &read, IIC_LAST_READ, timeout));
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}
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/*
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* iicbus_block_write()
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*
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* Write a block of data to slave ; start/stop protocol managed
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*/
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int
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iicbus_block_write(device_t bus, u_char slave, char *buf, int len, int *sent)
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{
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u_char addr = slave & ~LSB;
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int error;
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if ((error = iicbus_start(bus, addr, 0)))
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return (error);
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error = iicbus_write(bus, buf, len, sent, 0);
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iicbus_stop(bus);
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return (error);
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}
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/*
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* iicbus_block_read()
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*
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* Read a block of data from slave ; start/stop protocol managed
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*/
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int
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iicbus_block_read(device_t bus, u_char slave, char *buf, int len, int *read)
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{
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u_char addr = slave | LSB;
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int error;
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if ((error = iicbus_start(bus, addr, 0)))
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return (error);
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error = iicbus_read(bus, buf, len, read, IIC_LAST_READ, 0);
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iicbus_stop(bus);
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return (error);
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}
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/*
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* iicbus_transfer()
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*
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* Do an aribtrary number of transfers on the iicbus. We pass these
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* raw requests to the bridge driver. If the bridge driver supports
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* them directly, then it manages all the details. If not, it can use
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* the helper function iicbus_transfer_gen() which will do the
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* transfers at a low level.
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*
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* Pointers passed in as part of iic_msg must be kernel pointers.
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* Callers that have user addresses to manage must do so on their own.
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*/
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int
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iicbus_transfer(device_t bus, struct iic_msg *msgs, uint32_t nmsgs)
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{
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return (IICBUS_TRANSFER(device_get_parent(bus), msgs, nmsgs));
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}
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int
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iicbus_transfer_excl(device_t dev, struct iic_msg *msgs, uint32_t nmsgs,
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int how)
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{
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device_t bus;
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int error;
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bus = device_get_parent(dev);
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error = iicbus_request_bus(bus, dev, how);
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if (error == 0)
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error = IICBUS_TRANSFER(bus, msgs, nmsgs);
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iicbus_release_bus(bus, dev);
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return (error);
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}
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/*
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* Generic version of iicbus_transfer that calls the appropriate
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* routines to accomplish this. See note above about acceptable
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* buffer addresses.
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*/
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int
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iicbus_transfer_gen(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
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{
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int i, error, lenread, lenwrote, nkid, rpstart, addr;
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device_t *children, bus;
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bool nostop, started;
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if ((error = device_get_children(dev, &children, &nkid)) != 0)
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return (IIC_ERESOURCE);
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if (nkid != 1) {
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free(children, M_TEMP);
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return (IIC_ENOTSUPP);
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}
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bus = children[0];
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rpstart = 0;
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free(children, M_TEMP);
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nostop = iicbus_get_nostop(dev);
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started = false;
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for (i = 0, error = 0; i < nmsgs && error == 0; i++) {
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addr = msgs[i].slave;
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if (msgs[i].flags & IIC_M_RD)
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addr |= LSB;
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else
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addr &= ~LSB;
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if (!(msgs[i].flags & IIC_M_NOSTART)) {
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if (rpstart)
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error = iicbus_repeated_start(bus, addr, 0);
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else
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error = iicbus_start(bus, addr, 0);
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if (error != 0)
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break;
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started = true;
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}
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if (msgs[i].flags & IIC_M_RD)
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error = iicbus_read(bus, msgs[i].buf, msgs[i].len,
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&lenread, IIC_LAST_READ, 0);
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else
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error = iicbus_write(bus, msgs[i].buf, msgs[i].len,
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&lenwrote, 0);
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if (error != 0)
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break;
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if ((msgs[i].flags & IIC_M_NOSTOP) != 0 ||
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(nostop && i + 1 < nmsgs)) {
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rpstart = 1; /* Next message gets repeated start */
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} else {
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rpstart = 0;
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iicbus_stop(bus);
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}
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}
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if (error != 0 && started)
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iicbus_stop(bus);
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return (error);
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}
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int
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iicdev_readfrom(device_t slavedev, uint8_t regaddr, void *buffer,
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uint16_t buflen, int waithow)
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{
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struct iic_msg msgs[2];
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uint8_t slaveaddr;
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/*
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* Two transfers back to back with a repeat-start between them; first we
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* write the address-within-device, then we read from the device.
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*/
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slaveaddr = iicbus_get_addr(slavedev);
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msgs[0].slave = slaveaddr;
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msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP;
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msgs[0].len = 1;
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msgs[0].buf = ®addr;
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msgs[1].slave = slaveaddr;
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msgs[1].flags = IIC_M_RD;
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msgs[1].len = buflen;
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msgs[1].buf = buffer;
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return (iicbus_transfer_excl(slavedev, msgs, nitems(msgs), waithow));
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}
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int iicdev_writeto(device_t slavedev, uint8_t regaddr, void *buffer,
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uint16_t buflen, int waithow)
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{
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struct iic_msg msgs[2];
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uint8_t slaveaddr;
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/*
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* Two transfers back to back with no stop or start between them; first
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* we write the address then we write the data to that address, all in a
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* single transfer from two scattered buffers.
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*/
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slaveaddr = iicbus_get_addr(slavedev);
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msgs[0].slave = slaveaddr;
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msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP;
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msgs[0].len = 1;
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msgs[0].buf = ®addr;
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msgs[1].slave = slaveaddr;
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msgs[1].flags = IIC_M_WR | IIC_M_NOSTART;
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msgs[1].len = buflen;
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|
msgs[1].buf = buffer;
|
|
|
|
return (iicbus_transfer_excl(slavedev, msgs, nitems(msgs), waithow));
|
|
}
|