freebsd-dev/sys/dev/iicbus/iiconf.c
Ian Lepore 34199ee049 Add support for tracking nested calls to iicbus_request/release_bus().
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.
2017-07-26 21:06:26 +00:00

518 lines
12 KiB
C

/*-
* Copyright (c) 1998 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/bus.h>
#include <dev/iicbus/iiconf.h>
#include <dev/iicbus/iicbus.h>
#include "iicbus_if.h"
/*
* Translate IIC_Exxxxx status values to vaguely-equivelent errno values.
*/
int
iic2errno(int iic_status)
{
switch (iic_status) {
case IIC_NOERR: return (0);
case IIC_EBUSERR: return (EALREADY);
case IIC_ENOACK: return (EIO);
case IIC_ETIMEOUT: return (ETIMEDOUT);
case IIC_EBUSBSY: return (EWOULDBLOCK);
case IIC_ESTATUS: return (EPROTO);
case IIC_EUNDERFLOW: return (EIO);
case IIC_EOVERFLOW: return (EOVERFLOW);
case IIC_ENOTSUPP: return (EOPNOTSUPP);
case IIC_ENOADDR: return (EADDRNOTAVAIL);
case IIC_ERESOURCE: return (ENOMEM);
default: return (EIO);
}
}
/*
* iicbus_intr()
*/
void
iicbus_intr(device_t bus, int event, char *buf)
{
struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
/* call owner's intr routine */
if (sc->owner)
IICBUS_INTR(sc->owner, event, buf);
return;
}
static int
iicbus_poll(struct iicbus_softc *sc, int how)
{
int error;
IICBUS_ASSERT_LOCKED(sc);
switch (how) {
case IIC_WAIT | IIC_INTR:
error = mtx_sleep(sc, &sc->lock, IICPRI|PCATCH, "iicreq", 0);
break;
case IIC_WAIT | IIC_NOINTR:
error = mtx_sleep(sc, &sc->lock, IICPRI, "iicreq", 0);
break;
default:
return (IIC_EBUSBSY);
}
return (error);
}
/*
* iicbus_request_bus()
*
* Allocate the device to perform transfers.
*
* how : IIC_WAIT or IIC_DONTWAIT
*/
int
iicbus_request_bus(device_t bus, device_t dev, int how)
{
struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
int error = 0;
IICBUS_LOCK(sc);
while (error == 0 && sc->owner != NULL && sc->owner != dev)
error = iicbus_poll(sc, how);
if (error == 0) {
++sc->owncount;
if (sc->owner == NULL) {
sc->owner = dev;
/*
* Drop the lock around the call to the bus driver, it
* should be allowed to sleep in the IIC_WAIT case.
* Drivers might also need to grab locks that would
* cause a LOR if our lock is held.
*/
IICBUS_UNLOCK(sc);
/* Ask the underlying layers if the request is ok */
error = IICBUS_CALLBACK(device_get_parent(bus),
IIC_REQUEST_BUS, (caddr_t)&how);
IICBUS_LOCK(sc);
if (error != 0) {
sc->owner = NULL;
sc->owncount = 0;
wakeup_one(sc);
}
}
}
IICBUS_UNLOCK(sc);
return (error);
}
/*
* iicbus_release_bus()
*
* Release the device allocated with iicbus_request_dev()
*/
int
iicbus_release_bus(device_t bus, device_t dev)
{
struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
IICBUS_LOCK(sc);
if (sc->owner != dev) {
IICBUS_UNLOCK(sc);
return (IIC_EBUSBSY);
}
if (--sc->owncount == 0) {
/* Drop the lock while informing the low-level driver. */
IICBUS_UNLOCK(sc);
IICBUS_CALLBACK(device_get_parent(bus), IIC_RELEASE_BUS, NULL);
IICBUS_LOCK(sc);
sc->owner = NULL;
wakeup_one(sc);
}
IICBUS_UNLOCK(sc);
return (0);
}
/*
* iicbus_started()
*
* Test if the iicbus is started by the controller
*/
int
iicbus_started(device_t bus)
{
struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
return (sc->started);
}
/*
* iicbus_start()
*
* Send start condition to the slave addressed by 'slave'
*/
int
iicbus_start(device_t bus, u_char slave, int timeout)
{
struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
int error = 0;
if (sc->started)
return (IIC_ESTATUS); /* protocol error, bus already started */
if (!(error = IICBUS_START(device_get_parent(bus), slave, timeout)))
sc->started = slave;
else
sc->started = 0;
return (error);
}
/*
* iicbus_repeated_start()
*
* Send start condition to the slave addressed by 'slave'
*/
int
iicbus_repeated_start(device_t bus, u_char slave, int timeout)
{
struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
int error = 0;
if (!sc->started)
return (IIC_ESTATUS); /* protocol error, bus not started */
if (!(error = IICBUS_REPEATED_START(device_get_parent(bus), slave, timeout)))
sc->started = slave;
else
sc->started = 0;
return (error);
}
/*
* iicbus_stop()
*
* Send stop condition to the bus
*/
int
iicbus_stop(device_t bus)
{
struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
int error = 0;
if (!sc->started)
return (IIC_ESTATUS); /* protocol error, bus not started */
error = IICBUS_STOP(device_get_parent(bus));
/* refuse any further access */
sc->started = 0;
return (error);
}
/*
* iicbus_write()
*
* Write a block of data to the slave previously started by
* iicbus_start() call
*/
int
iicbus_write(device_t bus, const char *buf, int len, int *sent, int timeout)
{
struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
/* a slave must have been started for writing */
if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) != 0))
return (IIC_ESTATUS);
return (IICBUS_WRITE(device_get_parent(bus), buf, len, sent, timeout));
}
/*
* iicbus_read()
*
* Read a block of data from the slave previously started by
* iicbus_read() call
*/
int
iicbus_read(device_t bus, char *buf, int len, int *read, int last, int delay)
{
struct iicbus_softc *sc = (struct iicbus_softc *)device_get_softc(bus);
/* a slave must have been started for reading */
if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) == 0))
return (IIC_ESTATUS);
return (IICBUS_READ(device_get_parent(bus), buf, len, read, last, delay));
}
/*
* iicbus_write_byte()
*
* Write a byte to the slave previously started by iicbus_start() call
*/
int
iicbus_write_byte(device_t bus, char byte, int timeout)
{
struct iicbus_softc *sc = device_get_softc(bus);
char data = byte;
int sent;
/* a slave must have been started for writing */
if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) != 0))
return (IIC_ESTATUS);
return (iicbus_write(bus, &data, 1, &sent, timeout));
}
/*
* iicbus_read_byte()
*
* Read a byte from the slave previously started by iicbus_start() call
*/
int
iicbus_read_byte(device_t bus, char *byte, int timeout)
{
struct iicbus_softc *sc = device_get_softc(bus);
int read;
/* a slave must have been started for reading */
if (sc->started == 0 || (sc->strict != 0 && (sc->started & LSB) == 0))
return (IIC_ESTATUS);
return (iicbus_read(bus, byte, 1, &read, IIC_LAST_READ, timeout));
}
/*
* iicbus_block_write()
*
* Write a block of data to slave ; start/stop protocol managed
*/
int
iicbus_block_write(device_t bus, u_char slave, char *buf, int len, int *sent)
{
u_char addr = slave & ~LSB;
int error;
if ((error = iicbus_start(bus, addr, 0)))
return (error);
error = iicbus_write(bus, buf, len, sent, 0);
iicbus_stop(bus);
return (error);
}
/*
* iicbus_block_read()
*
* Read a block of data from slave ; start/stop protocol managed
*/
int
iicbus_block_read(device_t bus, u_char slave, char *buf, int len, int *read)
{
u_char addr = slave | LSB;
int error;
if ((error = iicbus_start(bus, addr, 0)))
return (error);
error = iicbus_read(bus, buf, len, read, IIC_LAST_READ, 0);
iicbus_stop(bus);
return (error);
}
/*
* iicbus_transfer()
*
* Do an aribtrary number of transfers on the iicbus. We pass these
* raw requests to the bridge driver. If the bridge driver supports
* them directly, then it manages all the details. If not, it can use
* the helper function iicbus_transfer_gen() which will do the
* transfers at a low level.
*
* Pointers passed in as part of iic_msg must be kernel pointers.
* Callers that have user addresses to manage must do so on their own.
*/
int
iicbus_transfer(device_t bus, struct iic_msg *msgs, uint32_t nmsgs)
{
return (IICBUS_TRANSFER(device_get_parent(bus), msgs, nmsgs));
}
int
iicbus_transfer_excl(device_t dev, struct iic_msg *msgs, uint32_t nmsgs,
int how)
{
device_t bus;
int error;
bus = device_get_parent(dev);
error = iicbus_request_bus(bus, dev, how);
if (error == 0)
error = IICBUS_TRANSFER(bus, msgs, nmsgs);
iicbus_release_bus(bus, dev);
return (error);
}
/*
* Generic version of iicbus_transfer that calls the appropriate
* routines to accomplish this. See note above about acceptable
* buffer addresses.
*/
int
iicbus_transfer_gen(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
{
int i, error, lenread, lenwrote, nkid, rpstart, addr;
device_t *children, bus;
bool nostop, started;
if ((error = device_get_children(dev, &children, &nkid)) != 0)
return (IIC_ERESOURCE);
if (nkid != 1) {
free(children, M_TEMP);
return (IIC_ENOTSUPP);
}
bus = children[0];
rpstart = 0;
free(children, M_TEMP);
nostop = iicbus_get_nostop(dev);
started = false;
for (i = 0, error = 0; i < nmsgs && error == 0; i++) {
addr = msgs[i].slave;
if (msgs[i].flags & IIC_M_RD)
addr |= LSB;
else
addr &= ~LSB;
if (!(msgs[i].flags & IIC_M_NOSTART)) {
if (rpstart)
error = iicbus_repeated_start(bus, addr, 0);
else
error = iicbus_start(bus, addr, 0);
if (error != 0)
break;
started = true;
}
if (msgs[i].flags & IIC_M_RD)
error = iicbus_read(bus, msgs[i].buf, msgs[i].len,
&lenread, IIC_LAST_READ, 0);
else
error = iicbus_write(bus, msgs[i].buf, msgs[i].len,
&lenwrote, 0);
if (error != 0)
break;
if ((msgs[i].flags & IIC_M_NOSTOP) != 0 ||
(nostop && i + 1 < nmsgs)) {
rpstart = 1; /* Next message gets repeated start */
} else {
rpstart = 0;
iicbus_stop(bus);
}
}
if (error != 0 && started)
iicbus_stop(bus);
return (error);
}
int
iicdev_readfrom(device_t slavedev, uint8_t regaddr, void *buffer,
uint16_t buflen, int waithow)
{
struct iic_msg msgs[2];
uint8_t slaveaddr;
/*
* Two transfers back to back with a repeat-start between them; first we
* write the address-within-device, then we read from the device.
*/
slaveaddr = iicbus_get_addr(slavedev);
msgs[0].slave = slaveaddr;
msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP;
msgs[0].len = 1;
msgs[0].buf = &regaddr;
msgs[1].slave = slaveaddr;
msgs[1].flags = IIC_M_RD;
msgs[1].len = buflen;
msgs[1].buf = buffer;
return (iicbus_transfer_excl(slavedev, msgs, nitems(msgs), waithow));
}
int iicdev_writeto(device_t slavedev, uint8_t regaddr, void *buffer,
uint16_t buflen, int waithow)
{
struct iic_msg msgs[2];
uint8_t slaveaddr;
/*
* Two transfers back to back with no stop or start between them; first
* we write the address then we write the data to that address, all in a
* single transfer from two scattered buffers.
*/
slaveaddr = iicbus_get_addr(slavedev);
msgs[0].slave = slaveaddr;
msgs[0].flags = IIC_M_WR | IIC_M_NOSTOP;
msgs[0].len = 1;
msgs[0].buf = &regaddr;
msgs[1].slave = slaveaddr;
msgs[1].flags = IIC_M_WR | IIC_M_NOSTART;
msgs[1].len = buflen;
msgs[1].buf = buffer;
return (iicbus_transfer_excl(slavedev, msgs, nitems(msgs), waithow));
}