From 8917c34a825ea59b8c3b1bc7ae9a3a8e356a27f1 Mon Sep 17 00:00:00 2001 From: Ian Lepore Date: Wed, 24 Jan 2018 03:09:56 +0000 Subject: [PATCH] Follow changes in r328307 by using new IIC_RECURSIVE flag. The driver now ensures only one thread at a time is running in the API functions (clock_gettime() and clock_settime()) by specifically requesting ownership of the i2c bus without using IIC_RECURSIVE, then it does all IO using IIC_RECURSIVE so that each individual IO operation doesn't try to re-acquire the bus. The other IO done by the driver happens at attach or intr_config_hooks time, when there can't be multiple threads running with the same device instance. So, the IIC_RECURSIVE flag can be safely ORed into the wait flags for all IO done by the driver, because it's all either done in a single-threaded environment, or protected within a block bounded by explict iicbus_acquire_bus() and iicbus_release_bus() calls. --- sys/dev/iicbus/nxprtc.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/sys/dev/iicbus/nxprtc.c b/sys/dev/iicbus/nxprtc.c index 898daa77f925..27890a0fcca5 100644 --- a/sys/dev/iicbus/nxprtc.c +++ b/sys/dev/iicbus/nxprtc.c @@ -197,6 +197,15 @@ struct nxprtc_softc { #define SC_F_CPOL (1 << 0) /* Century bit means 19xx */ +/* + * When doing i2c IO, indicate that we need to wait for exclusive bus ownership, + * but that we should not wait if we already own the bus. This lets us put + * iicbus_acquire_bus() calls with a non-recursive wait at the entry of our API + * functions to ensure that only one client at a time accesses the hardware for + * the entire series of operations it takes to read or write the clock. + */ +#define WAITFLAGS (IIC_WAIT | IIC_RECURSIVE) + /* * We use the compat_data table to look up hint strings in the non-FDT case, so * define the struct locally when we don't get it from ofw_bus_subr.h. @@ -230,14 +239,14 @@ static int read_reg(struct nxprtc_softc *sc, uint8_t reg, uint8_t *val) { - return (iicdev_readfrom(sc->dev, reg, val, sizeof(*val), IIC_WAIT)); + return (iicdev_readfrom(sc->dev, reg, val, sizeof(*val), WAITFLAGS)); } static int write_reg(struct nxprtc_softc *sc, uint8_t reg, uint8_t val) { - return (iicdev_writeto(sc->dev, reg, &val, sizeof(val), IIC_WAIT)); + return (iicdev_writeto(sc->dev, reg, &val, sizeof(val), WAITFLAGS)); } static int @@ -264,7 +273,7 @@ read_timeregs(struct nxprtc_softc *sc, struct time_regs *tregs, uint8_t *tmr) continue; } if ((err = iicdev_readfrom(sc->dev, sc->secaddr, tregs, - sizeof(*tregs), IIC_WAIT)) != 0) + sizeof(*tregs), WAITFLAGS)) != 0) break; } while (sc->use_timer && tregs->sec != sec); @@ -294,7 +303,7 @@ write_timeregs(struct nxprtc_softc *sc, struct time_regs *tregs) { return (iicdev_writeto(sc->dev, sc->secaddr, tregs, - sizeof(*tregs), IIC_WAIT)); + sizeof(*tregs), WAITFLAGS)); } static int @@ -557,14 +566,15 @@ nxprtc_gettime(device_t dev, struct timespec *ts) * bit is not set in the control reg. The latter can happen if there * was an error when setting the time. */ - if ((err = read_timeregs(sc, &tregs, &tmrcount)) != 0) { - device_printf(dev, "cannot read RTC time\n"); - return (err); + if ((err = iicbus_request_bus(sc->busdev, sc->dev, IIC_WAIT)) == 0) { + if ((err = read_timeregs(sc, &tregs, &tmrcount)) == 0) { + err = read_reg(sc, PCF85xx_R_CS1, &cs1); + } + iicbus_release_bus(sc->busdev, sc->dev); } - if ((err = read_reg(sc, PCF85xx_R_CS1, &cs1)) != 0) { - device_printf(dev, "cannot read RTC time\n"); + if (err != 0) return (err); - } + if ((tregs.sec & PCF85xx_B_SECOND_OS) || (cs1 & PCF85xx_B_CS1_STOP)) { device_printf(dev, "RTC clock not running\n"); return (EINVAL); /* hardware is good, time is not. */