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Fix the gpiobus locking by using a more sane model where it isn't necessary

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hold the gpiobus lock between the gpio calls.

gpiobus_acquire_lock() now accepts a third parameter which tells gpiobus
what to do when the bus is already busy.

When GPIOBUS_WAIT wait is used, the calling thread will be put to sleep
until the bus became free.

With GPIOBUS_DONTWAIT the calling thread will receive EWOULDBLOCK right
away and then it can act upon.

This fixes the gpioiic(4) locking issues that arises when doing multiple
concurrent access on the bus.
This commit is contained in:
loos 2014-10-31 19:15:14 +00:00
parent 2ccd430671
commit 7106eeab9b
5 changed files with 45 additions and 62 deletions
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52
sys/dev/gpio/gpiobus.c
View File

@ -53,9 +53,7 @@ static void gpiobus_hinted_child(device_t, const char *, int);
/*
* GPIOBUS interface
*/
static void gpiobus_lock_bus(device_t);
static void gpiobus_unlock_bus(device_t);
static void gpiobus_acquire_bus(device_t, device_t);
static int gpiobus_acquire_bus(device_t, device_t, int);
static void gpiobus_release_bus(device_t, device_t);
static int gpiobus_pin_setflags(device_t, device_t, uint32_t, uint32_t);
static int gpiobus_pin_getflags(device_t, device_t, uint32_t, uint32_t*);
@ -326,37 +324,26 @@ gpiobus_hinted_child(device_t bus, const char *dname, int dunit)
device_delete_child(bus, child);
}
static void
gpiobus_lock_bus(device_t busdev)
static int
gpiobus_acquire_bus(device_t busdev, device_t child, int how)
{
struct gpiobus_softc *sc;
sc = device_get_softc(busdev);
GPIOBUS_ASSERT_UNLOCKED(sc);
GPIOBUS_LOCK(sc);
}
static void
gpiobus_unlock_bus(device_t busdev)
{
struct gpiobus_softc *sc;
sc = device_get_softc(busdev);
GPIOBUS_ASSERT_LOCKED(sc);
GPIOBUS_UNLOCK(sc);
}
static void
gpiobus_acquire_bus(device_t busdev, device_t child)
{
struct gpiobus_softc *sc;
sc = device_get_softc(busdev);
GPIOBUS_ASSERT_LOCKED(sc);
if (sc->sc_owner)
panic("gpiobus: cannot serialize the access to device.");
if (sc->sc_owner != NULL) {
if (how == GPIOBUS_DONTWAIT) {
GPIOBUS_UNLOCK(sc);
return (EWOULDBLOCK);
}
while (sc->sc_owner != NULL)
mtx_sleep(sc, &sc->sc_mtx, 0, "gpiobuswait", 0);
}
sc->sc_owner = child;
GPIOBUS_UNLOCK(sc);
return (0);
}
static void
@ -365,14 +352,15 @@ gpiobus_release_bus(device_t busdev, device_t child)
struct gpiobus_softc *sc;
sc = device_get_softc(busdev);
GPIOBUS_ASSERT_LOCKED(sc);
if (!sc->sc_owner)
GPIOBUS_ASSERT_UNLOCKED(sc);
GPIOBUS_LOCK(sc);
if (sc->sc_owner == NULL)
panic("gpiobus: releasing unowned bus.");
if (sc->sc_owner != child)
panic("gpiobus: you don't own the bus. game over.");
sc->sc_owner = NULL;
wakeup(sc);
GPIOBUS_UNLOCK(sc);
}
static int
@ -469,8 +457,6 @@ static device_method_t gpiobus_methods[] = {
DEVMETHOD(bus_hinted_child, gpiobus_hinted_child),
/* GPIO protocol */
DEVMETHOD(gpiobus_lock_bus, gpiobus_lock_bus),
DEVMETHOD(gpiobus_unlock_bus, gpiobus_unlock_bus),
DEVMETHOD(gpiobus_acquire_bus, gpiobus_acquire_bus),
DEVMETHOD(gpiobus_release_bus, gpiobus_release_bus),
DEVMETHOD(gpiobus_pin_getflags, gpiobus_pin_getflags),

17
sys/dev/gpio/gpiobus_if.m
View File

@ -31,26 +31,13 @@
INTERFACE gpiobus;
#
# Lock the gpio bus
#
METHOD void lock_bus {
device_t busdev;
};
#
# Unlock the gpio bus
#
METHOD void unlock_bus {
device_t busdev;
};
#
# Dedicate the gpio bus control for a child
#
METHOD void acquire_bus {
METHOD int acquire_bus {
device_t busdev;
device_t dev;
int how;
};
#

3
sys/dev/gpio/gpiobusvar.h
View File

@ -56,6 +56,9 @@
#define GPIOBUS_ASSERT_LOCKED(_sc) mtx_assert(&_sc->sc_mtx, MA_OWNED)
#define GPIOBUS_ASSERT_UNLOCKED(_sc) mtx_assert(&_sc->sc_mtx, MA_NOTOWNED)
#define GPIOBUS_WAIT 1
#define GPIOBUS_DONTWAIT 2
struct gpiobus_softc
{
struct mtx sc_mtx; /* bus mutex */

12
sys/dev/gpio/gpioiic.c
View File

@ -154,18 +154,18 @@ static int
gpioiic_callback(device_t dev, int index, caddr_t data)
{
struct gpioiic_softc *sc = device_get_softc(dev);
int error = 0;
int error, how;
how = GPIOBUS_DONTWAIT;
if (data != NULL && (int)*data == IIC_WAIT)
how = GPIOBUS_WAIT;
error = 0;
switch (index) {
case IIC_REQUEST_BUS:
GPIOBUS_LOCK_BUS(sc->sc_busdev);
GPIOBUS_ACQUIRE_BUS(sc->sc_busdev, sc->sc_dev);
GPIOBUS_UNLOCK_BUS(sc->sc_busdev);
error = GPIOBUS_ACQUIRE_BUS(sc->sc_busdev, sc->sc_dev, how);
break;
case IIC_RELEASE_BUS:
GPIOBUS_LOCK_BUS(sc->sc_busdev);
GPIOBUS_RELEASE_BUS(sc->sc_busdev, sc->sc_dev);
GPIOBUS_UNLOCK_BUS(sc->sc_busdev);
break;
default:
error = EINVAL;

23
sys/dev/gpio/gpioled.c
View File

@ -79,16 +79,23 @@ static int gpioled_detach(device_t);
static void
gpioled_control(void *priv, int onoff)
{
struct gpioled_softc *sc = priv;
int error;
struct gpioled_softc *sc;
sc = (struct gpioled_softc *)priv;
GPIOLED_LOCK(sc);
GPIOBUS_LOCK_BUS(sc->sc_busdev);
GPIOBUS_ACQUIRE_BUS(sc->sc_busdev, sc->sc_dev);
GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev, GPIOLED_PIN,
GPIO_PIN_OUTPUT);
GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev, GPIOLED_PIN,
onoff ? GPIO_PIN_HIGH : GPIO_PIN_LOW);
error = GPIOBUS_ACQUIRE_BUS(sc->sc_busdev, sc->sc_dev,
GPIOBUS_DONTWAIT);
if (error != 0) {
GPIOLED_UNLOCK(sc);
return;
}
error = GPIOBUS_PIN_SETFLAGS(sc->sc_busdev, sc->sc_dev,
GPIOLED_PIN, GPIO_PIN_OUTPUT);
if (error == 0)
GPIOBUS_PIN_SET(sc->sc_busdev, sc->sc_dev, GPIOLED_PIN,
onoff ? GPIO_PIN_HIGH : GPIO_PIN_LOW);
GPIOBUS_RELEASE_BUS(sc->sc_busdev, sc->sc_dev);
GPIOBUS_UNLOCK_BUS(sc->sc_busdev);
GPIOLED_UNLOCK(sc);
}