freebsd-dev/sys/dev/iicbus/iic.c
Jason A. Harmening 0afebee290 Fix numerous issues in iic(4) and iicbus(4):
--Allow multiple open iic fds by storing addressing state in cdevpriv
--Fix, as much as possible, the baked-in race conditions in the iic
ioctl interface by requesting bus ownership on I2CSTART, releasing it on
I2CSTOP/I2CRSTCARD, and requiring bus ownership by the current cdevpriv
to use the I/O ioctls
--Reduce internal iic buffer size and remove 1K read/write limit by
iteratively calling iicbus_read/iicbus_write
--Eliminate dynamic allocation in I2CWRITE/I2CREAD
--Move handling of I2CRDWR to separate function and improve error handling
--Add new I2CSADDR ioctl to store address in current cdevpriv so that
I2CSTART is not needed for read(2)/write(2) to work
--Redesign iicbus_request_bus() and iicbus_release_bus():
    --iicbus_request_bus() no longer falls through if the bus is already
owned by the requesting device.  Multiple threads on the same device may
want exclusive access.  Also, iicbus_release_bus() was never
device-recursive anyway.
    --Previously, if IICBUS_CALLBACK failed in iicbus_release_bus(), but
the following iicbus_poll() call succeeded, IICBUS_CALLBACK would not be
issued again
    --Do not hold iicbus mtx during IICBUS_CALLBACK call.  There are
several drivers that may sleep in IICBUS_CALLBACK, if IIC_WAIT is passed.
    --Do not loop in iicbus_request_bus if IICBUS_CALLBACK returns
EWOULDBLOCK; instead pass that to the caller so that it can retry if so
desired.

Differential Revision:	https://reviews.freebsd.org/D2140
Reviewed by:	imp, jhb, loos
Approved by:	kib (mentor)
2015-04-21 11:50:31 +00:00

493 lines
11 KiB
C

/*-
* Copyright (c) 1998, 2001 Nicolas Souchu
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR OR CONTRIBUTORS 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.
*
* $FreeBSD$
*
*/
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/sx.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/errno.h>
#include <dev/iicbus/iiconf.h>
#include <dev/iicbus/iicbus.h>
#include <dev/iicbus/iic.h>
#include "iicbus_if.h"
struct iic_softc {
device_t sc_dev;
struct cdev *sc_devnode;
};
struct iic_cdevpriv {
struct sx lock;
struct iic_softc *sc;
bool started;
uint8_t addr;
};
#define IIC_LOCK(cdp) sx_xlock(&(cdp)->lock)
#define IIC_UNLOCK(cdp) sx_xunlock(&(cdp)->lock)
static MALLOC_DEFINE(M_IIC, "iic", "I2C device data");
static int iic_probe(device_t);
static int iic_attach(device_t);
static int iic_detach(device_t);
static void iic_identify(driver_t *driver, device_t parent);
static void iicdtor(void *data);
static int iicuio_move(struct iic_cdevpriv *priv, struct uio *uio, int last);
static int iicuio(struct cdev *dev, struct uio *uio, int ioflag);
static int iicrdwr(struct iic_cdevpriv *priv, struct iic_rdwr_data *d, int flags);
static devclass_t iic_devclass;
static device_method_t iic_methods[] = {
/* device interface */
DEVMETHOD(device_identify, iic_identify),
DEVMETHOD(device_probe, iic_probe),
DEVMETHOD(device_attach, iic_attach),
DEVMETHOD(device_detach, iic_detach),
/* iicbus interface */
DEVMETHOD(iicbus_intr, iicbus_generic_intr),
{ 0, 0 }
};
static driver_t iic_driver = {
"iic",
iic_methods,
sizeof(struct iic_softc),
};
static d_open_t iicopen;
static d_ioctl_t iicioctl;
static struct cdevsw iic_cdevsw = {
.d_version = D_VERSION,
.d_open = iicopen,
.d_read = iicuio,
.d_write = iicuio,
.d_ioctl = iicioctl,
.d_name = "iic",
};
static void
iic_identify(driver_t *driver, device_t parent)
{
if (device_find_child(parent, "iic", -1) == NULL)
BUS_ADD_CHILD(parent, 0, "iic", -1);
}
static int
iic_probe(device_t dev)
{
if (iicbus_get_addr(dev) > 0)
return (ENXIO);
device_set_desc(dev, "I2C generic I/O");
return (0);
}
static int
iic_attach(device_t dev)
{
struct iic_softc *sc;
sc = device_get_softc(dev);
sc->sc_dev = dev;
sc->sc_devnode = make_dev(&iic_cdevsw, device_get_unit(dev),
UID_ROOT, GID_WHEEL,
0600, "iic%d", device_get_unit(dev));
if (sc->sc_devnode == NULL) {
device_printf(dev, "failed to create character device\n");
return (ENXIO);
}
sc->sc_devnode->si_drv1 = sc;
return (0);
}
static int
iic_detach(device_t dev)
{
struct iic_softc *sc;
sc = device_get_softc(dev);
if (sc->sc_devnode)
destroy_dev(sc->sc_devnode);
return (0);
}
static int
iicopen(struct cdev *dev, int flags, int fmt, struct thread *td)
{
struct iic_cdevpriv *priv;
int error;
priv = malloc(sizeof(*priv), M_IIC, M_WAITOK | M_ZERO);
sx_init(&priv->lock, "iic");
priv->sc = dev->si_drv1;
error = devfs_set_cdevpriv(priv, iicdtor);
if (error != 0)
free(priv, M_IIC);
return (error);
}
static void
iicdtor(void *data)
{
device_t iicdev, parent;
struct iic_cdevpriv *priv;
priv = data;
KASSERT(priv != NULL, ("iic cdevpriv should not be NULL!"));
iicdev = priv->sc->sc_dev;
parent = device_get_parent(iicdev);
if (priv->started) {
iicbus_stop(parent);
iicbus_reset(parent, IIC_UNKNOWN, 0, NULL);
iicbus_release_bus(parent, iicdev);
}
sx_destroy(&priv->lock);
free(priv, M_IIC);
}
static int
iicuio_move(struct iic_cdevpriv *priv, struct uio *uio, int last)
{
device_t parent;
int error, num_bytes, transferred_bytes, written_bytes;
char buffer[128];
parent = device_get_parent(priv->sc->sc_dev);
error = 0;
/*
* We can only transfer up to sizeof(buffer) bytes in 1 shot, so loop until
* everything has been transferred.
*/
while ((error == 0) && (uio->uio_resid > 0)) {
num_bytes = MIN(uio->uio_resid, sizeof(buffer));
transferred_bytes = 0;
if (uio->uio_rw == UIO_WRITE) {
error = uiomove(buffer, num_bytes, uio);
while ((error == 0) && (transferred_bytes < num_bytes)) {
written_bytes = 0;
error = iicbus_write(parent, &buffer[transferred_bytes],
num_bytes - transferred_bytes, &written_bytes, 0);
transferred_bytes += written_bytes;
}
} else if (uio->uio_rw == UIO_READ) {
error = iicbus_read(parent, buffer,
num_bytes, &transferred_bytes,
((uio->uio_resid <= sizeof(buffer)) ? last : 0), 0);
if (error == 0)
error = uiomove(buffer, transferred_bytes, uio);
}
}
return (error);
}
static int
iicuio(struct cdev *dev, struct uio *uio, int ioflag)
{
device_t parent;
struct iic_cdevpriv *priv;
int error;
uint8_t addr;
priv = NULL;
error = devfs_get_cdevpriv((void**)&priv);
if (error != 0)
return (error);
KASSERT(priv != NULL, ("iic cdevpriv should not be NULL!"));
IIC_LOCK(priv);
if (priv->started || (priv->addr == 0)) {
IIC_UNLOCK(priv);
return (ENXIO);
}
parent = device_get_parent(priv->sc->sc_dev);
error = iicbus_request_bus(parent, priv->sc->sc_dev,
(ioflag & O_NONBLOCK) ? IIC_DONTWAIT : (IIC_WAIT | IIC_INTR));
if (error != 0) {
IIC_UNLOCK(priv);
return (error);
}
if (uio->uio_rw == UIO_READ)
addr = priv->addr | LSB;
else
addr = priv->addr & ~LSB;
error = iicbus_start(parent, addr, 0);
if (error != 0)
{
iicbus_release_bus(parent, priv->sc->sc_dev);
IIC_UNLOCK(priv);
return (error);
}
error = iicuio_move(priv, uio, IIC_LAST_READ);
iicbus_stop(parent);
iicbus_release_bus(parent, priv->sc->sc_dev);
IIC_UNLOCK(priv);
return (error);
}
static int
iicrdwr(struct iic_cdevpriv *priv, struct iic_rdwr_data *d, int flags)
{
struct iic_msg *buf, *m;
void **usrbufs;
device_t iicdev, parent;
int error, i;
iicdev = priv->sc->sc_dev;
parent = device_get_parent(iicdev);
error = 0;
buf = malloc(sizeof(*d->msgs) * d->nmsgs, M_IIC, M_WAITOK);
error = copyin(d->msgs, buf, sizeof(*d->msgs) * d->nmsgs);
/* Alloc kernel buffers for userland data, copyin write data */
usrbufs = malloc(sizeof(void *) * d->nmsgs, M_IIC, M_WAITOK | M_ZERO);
for (i = 0; i < d->nmsgs; i++) {
m = &(buf[i]);
usrbufs[i] = m->buf;
/*
* At least init the buffer to NULL so we can safely free() it later.
* If the copyin() to buf failed, don't try to malloc bogus m->len.
*/
m->buf = NULL;
if (error != 0)
continue;
m->buf = malloc(m->len, M_IIC, M_WAITOK);
if (!(m->flags & IIC_M_RD))
error = copyin(usrbufs[i], m->buf, m->len);
}
if (error == 0)
error = iicbus_request_bus(parent, iicdev,
(flags & O_NONBLOCK) ? IIC_DONTWAIT : (IIC_WAIT | IIC_INTR));
if (error == 0) {
error = iicbus_transfer(iicdev, buf, d->nmsgs);
iicbus_release_bus(parent, iicdev);
}
/* Copyout all read segments, free up kernel buffers */
for (i = 0; i < d->nmsgs; i++) {
m = &(buf[i]);
if ((error == 0) && (m->flags & IIC_M_RD))
error = copyout(m->buf, usrbufs[i], m->len);
free(m->buf, M_IIC);
}
free(usrbufs, M_IIC);
free(buf, M_IIC);
return (error);
}
static int
iicioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, struct thread *td)
{
device_t parent, iicdev;
struct iiccmd *s;
struct uio ubuf;
struct iovec uvec;
struct iic_cdevpriv *priv;
int error;
s = (struct iiccmd *)data;
error = devfs_get_cdevpriv((void**)&priv);
if (error != 0)
return (error);
KASSERT(priv != NULL, ("iic cdevpriv should not be NULL!"));
iicdev = priv->sc->sc_dev;
parent = device_get_parent(iicdev);
IIC_LOCK(priv);
switch (cmd) {
case I2CSTART:
if (priv->started) {
error = EINVAL;
break;
}
error = iicbus_request_bus(parent, iicdev,
(flags & O_NONBLOCK) ? IIC_DONTWAIT : (IIC_WAIT | IIC_INTR));
if (error == 0)
error = iicbus_start(parent, s->slave, 0);
if (error == 0) {
priv->addr = s->slave;
priv->started = true;
} else
iicbus_release_bus(parent, iicdev);
break;
case I2CSTOP:
if (priv->started) {
error = iicbus_stop(parent);
iicbus_release_bus(parent, iicdev);
priv->started = false;
}
break;
case I2CRSTCARD:
/*
* Bus should be owned before we reset it.
* We allow the bus to be already owned as the result of an in-progress
* sequence; however, bus reset will always be followed by release
* (a new start is presumably needed for I/O anyway). */
if (!priv->started)
error = iicbus_request_bus(parent, iicdev,
(flags & O_NONBLOCK) ? IIC_DONTWAIT : (IIC_WAIT | IIC_INTR));
if (error == 0) {
error = iicbus_reset(parent, IIC_UNKNOWN, 0, NULL);
/*
* Ignore IIC_ENOADDR as it only means we have a master-only
* controller.
*/
if (error == IIC_ENOADDR)
error = 0;
iicbus_release_bus(parent, iicdev);
priv->started = false;
}
break;
case I2CWRITE:
if (!priv->started) {
error = EINVAL;
break;
}
uvec.iov_base = s->buf;
uvec.iov_len = s->count;
ubuf.uio_iov = &uvec;
ubuf.uio_iovcnt = 1;
ubuf.uio_segflg = UIO_USERSPACE;
ubuf.uio_td = td;
ubuf.uio_resid = s->count;
ubuf.uio_offset = 0;
ubuf.uio_rw = UIO_WRITE;
error = iicuio_move(priv, &ubuf, 0);
break;
case I2CREAD:
if (!priv->started) {
error = EINVAL;
break;
}
uvec.iov_base = s->buf;
uvec.iov_len = s->count;
ubuf.uio_iov = &uvec;
ubuf.uio_iovcnt = 1;
ubuf.uio_segflg = UIO_USERSPACE;
ubuf.uio_td = td;
ubuf.uio_resid = s->count;
ubuf.uio_offset = 0;
ubuf.uio_rw = UIO_READ;
error = iicuio_move(priv, &ubuf, s->last);
break;
case I2CRDWR:
/*
* The rdwr list should be a self-contained set of
* transactions. Fail if another transaction is in progress.
*/
if (priv->started) {
error = EINVAL;
break;
}
error = iicrdwr(priv, (struct iic_rdwr_data *)data, flags);
break;
case I2CRPTSTART:
if (!priv->started) {
error = EINVAL;
break;
}
error = iicbus_repeated_start(parent, s->slave, 0);
break;
case I2CSADDR:
priv->addr = *((uint8_t*)data);
break;
default:
error = ENOTTY;
}
IIC_UNLOCK(priv);
return (error);
}
DRIVER_MODULE(iic, iicbus, iic_driver, iic_devclass, 0, 0);
MODULE_DEPEND(iic, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
MODULE_VERSION(iic, 1);