Date: Thu, 19 Mar 2009 12:39:13 +0000 (UTC) From: Dag-Erling Smorgrav <des@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r190030 - head/sys/dev/ichwd Message-ID: <200903191239.n2JCdD2K061097@svn.freebsd.org>
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Author: des Date: Thu Mar 19 12:39:13 2009 New Revision: 190030 URL: http://svn.freebsd.org/changeset/base/190030 Log: Rename two functions to make their purpose clearer. Add tons of comments. Generated code is identical after stripping .comment section. Suggested by: Andriy Gapon <avg@icyb.net.ua> MFC after: 2 weeks Modified: head/sys/dev/ichwd/ichwd.c Modified: head/sys/dev/ichwd/ichwd.c ============================================================================== --- head/sys/dev/ichwd/ichwd.c Thu Mar 19 12:33:37 2009 (r190029) +++ head/sys/dev/ichwd/ichwd.c Thu Mar 19 12:39:13 2009 (r190030) @@ -141,26 +141,55 @@ static devclass_t ichwd_devclass; device_printf(dev, __VA_ARGS__);\ } while (0) +/* + * Disable the watchdog timeout SMI handler. + * + * Apparently, some BIOSes install handlers that reset or disable the + * watchdog timer instead of resetting the system, so we disable the SMI + * (by clearing the SMI_TCO_EN bit of the SMI_EN register) to prevent this + * from happening. + */ static __inline void -ichwd_intr_enable(struct ichwd_softc *sc) +ichwd_smi_disable(struct ichwd_softc *sc) { ichwd_write_smi_4(sc, SMI_EN, ichwd_read_smi_4(sc, SMI_EN) & ~SMI_TCO_EN); } +/* + * Enable the watchdog timeout SMI handler. See above for details. + */ static __inline void -ichwd_intr_disable(struct ichwd_softc *sc) +ichwd_smi_enable(struct ichwd_softc *sc) { ichwd_write_smi_4(sc, SMI_EN, ichwd_read_smi_4(sc, SMI_EN) | SMI_TCO_EN); } +/* + * Reset the watchdog status bits. + */ static __inline void ichwd_sts_reset(struct ichwd_softc *sc) { + /* + * The watchdog status bits are set to 1 by the hardware to + * indicate various conditions. They can be cleared by software + * by writing a 1, not a 0. + */ ichwd_write_tco_2(sc, TCO1_STS, TCO_TIMEOUT); + /* + * XXX The datasheet says that TCO_SECOND_TO_STS must be cleared + * before TCO_BOOT_STS, not the other way around. + */ ichwd_write_tco_2(sc, TCO2_STS, TCO_BOOT_STS); ichwd_write_tco_2(sc, TCO2_STS, TCO_SECOND_TO_STS); } +/* + * Enable the watchdog timer by clearing the TCO_TMR_HALT bit in the + * TCO1_CNT register. This is complicated by the need to preserve bit 9 + * of that same register, and the requirement that all other bits must be + * written back as zero. + */ static __inline void ichwd_tmr_enable(struct ichwd_softc *sc) { @@ -172,6 +201,9 @@ ichwd_tmr_enable(struct ichwd_softc *sc) ichwd_verbose_printf(sc->device, "timer enabled\n"); } +/* + * Disable the watchdog timer. See above for details. + */ static __inline void ichwd_tmr_disable(struct ichwd_softc *sc) { @@ -183,6 +215,11 @@ ichwd_tmr_disable(struct ichwd_softc *sc ichwd_verbose_printf(sc->device, "timer disabled\n"); } +/* + * Reload the watchdog timer: writing anything to any of the lower five + * bits of the TCO_RLD register reloads the timer from the last value + * written to TCO_TMR. + */ static __inline void ichwd_tmr_reload(struct ichwd_softc *sc) { @@ -194,6 +231,10 @@ ichwd_tmr_reload(struct ichwd_softc *sc) ichwd_verbose_printf(sc->device, "timer reloaded\n"); } +/* + * Set the initial timeout value. Note that this must always be followed + * by a reload. + */ static __inline void ichwd_tmr_set(struct ichwd_softc *sc, unsigned int timeout) { @@ -262,7 +303,8 @@ ichwd_clear_noreboot(struct ichwd_softc } /* - * Watchdog event handler. + * Watchdog event handler - called by the framework to enable or disable + * the watchdog or change the initial timeout value. */ static void ichwd_event(void *arg, unsigned int cmd, int *error) @@ -426,6 +468,13 @@ ichwd_attach(device_t dev) device_printf(dev, "%s (ICH%d or equivalent)\n", device_get_desc(dev), sc->ich_version); + /* + * XXX we should check the status registers (specifically, the + * TCO_SECOND_TO_STS bit in the TCO2_STS register) to see if we + * just came back from a watchdog-induced reset, and let the user + * know. + */ + /* reset the watchdog status registers */ ichwd_sts_reset(sc); @@ -435,8 +484,8 @@ ichwd_attach(device_t dev) /* register the watchdog event handler */ sc->ev_tag = EVENTHANDLER_REGISTER(watchdog_list, ichwd_event, sc, 0); - /* enable watchdog timeout interrupts */ - ichwd_intr_enable(sc); + /* disable the SMI handler */ + ichwd_smi_disable(sc); return (0); fail: @@ -466,8 +515,8 @@ ichwd_detach(device_t dev) if (sc->active) ichwd_tmr_disable(sc); - /* disable watchdog timeout interrupts */ - ichwd_intr_disable(sc); + /* enable the SMI handler */ + ichwd_smi_enable(sc); /* deregister event handler */ if (sc->ev_tag != NULL)
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