Author: loos
Date: Fri Oct 31 19:15:14 2014
New Revision: 273917
URL: https://svnweb.freebsd.org/changeset/base/273917
Log:
Fix the gpiobus locking by using a more sane model where it isn't necessary
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.
Modified:
head/sys/dev/gpio/gpiobus.c
head/sys/dev/gpio/gpiobus_if.m
head/sys/dev/gpio/gpiobusvar.h
head/sys/dev/gpio/gpioiic.c
head/sys/dev/gpio/gpioled.c
Modified: head/sys/dev/gpio/gpiobus.c
==============================================================================
--- head/sys/dev/gpio/gpiobus.c Fri Oct 31 18:53:16 2014 (r273916)
+++ head/sys/dev/gpio/gpiobus.c Fri Oct 31 19:15:14 2014 (r273917)
@@ -53,9 +53,7 @@ static void gpiobus_hinted_child(device_
/*
* 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
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);
+ 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);
-}
-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.");
- sc->sc_owner = child;
+ return (0);
}
static void
@@ -365,14 +352,15 @@ gpiobus_release_bus(device_t busdev, dev
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),
Modified: head/sys/dev/gpio/gpiobus_if.m
==============================================================================
--- head/sys/dev/gpio/gpiobus_if.m Fri Oct 31 18:53:16 2014
(r273916)
+++ head/sys/dev/gpio/gpiobus_if.m Fri Oct 31 19:15:14 2014
(r273917)
@@ -32,25 +32,12 @@
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;
};
#
Modified: head/sys/dev/gpio/gpiobusvar.h
==============================================================================
--- head/sys/dev/gpio/gpiobusvar.h Fri Oct 31 18:53:16 2014
(r273916)
+++ head/sys/dev/gpio/gpiobusvar.h Fri Oct 31 19:15:14 2014
(r273917)
@@ -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 */
Modified: head/sys/dev/gpio/gpioiic.c
==============================================================================
--- head/sys/dev/gpio/gpioiic.c Fri Oct 31 18:53:16 2014 (r273916)
+++ head/sys/dev/gpio/gpioiic.c Fri Oct 31 19:15:14 2014 (r273917)
@@ -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;
Modified: head/sys/dev/gpio/gpioled.c
==============================================================================
--- head/sys/dev/gpio/gpioled.c Fri Oct 31 18:53:16 2014 (r273916)
+++ head/sys/dev/gpio/gpioled.c Fri Oct 31 19:15:14 2014 (r273917)
@@ -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);
}
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