HPET: create /dev/hpetN as a way to access HPET from userland.
In some cases, TSC is broken and special applications might benefit from memory mapping HPET and reading the registers to count time. Most often the main HPET counter is 32-bit only[1], so this only gives the application a 300 second window based on the default HPET interval. Other applications, such as Intel's DPDK, expect /dev/hpet to be present and use it to count time as well. Although we have an almost userland version of gettimeofday() which uses rdtsc in userland, it's not always possible to use it, depending on how broken the multi-socket hardware is. Install the acpi_hpet.h so that applications can use the HPET register definitions. [1] I haven't found a system where HPET's main counter uses more than 32 bit. There seems to be a discrepancy in the Intel documentation (claiming it's a 64-bit counter) and the actual implementation (a 32-bit counter in a 64-bit memory area). MFC after: 1 week Relnotes: yes
This commit is contained in:
parent
ca807c8a88
commit
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=273598
@ -159,6 +159,8 @@ copies:
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cd ${.CURDIR}/../sys/dev/acpica; \
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cd ${.CURDIR}/../sys/dev/acpica; \
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${INSTALL} -C -o ${BINOWN} -g ${BINGRP} -m 444 acpiio.h \
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${INSTALL} -C -o ${BINOWN} -g ${BINGRP} -m 444 acpiio.h \
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${DESTDIR}${INCLUDEDIR}/dev/acpica
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${DESTDIR}${INCLUDEDIR}/dev/acpica
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${INSTALL} -C -o ${BINOWN} -g ${BINGRP} -m 444 acpi_hpet.h \
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${DESTDIR}${INCLUDEDIR}/dev/acpica
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cd ${.CURDIR}/../sys/dev/agp; \
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cd ${.CURDIR}/../sys/dev/agp; \
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${INSTALL} -C -o ${BINOWN} -g ${BINGRP} -m 444 agpreg.h \
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${INSTALL} -C -o ${BINOWN} -g ${BINGRP} -m 444 agpreg.h \
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${DESTDIR}${INCLUDEDIR}/dev/agp
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${DESTDIR}${INCLUDEDIR}/dev/agp
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@ -243,7 +245,7 @@ symlinks:
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done
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done
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.endfor
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.endfor
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cd ${.CURDIR}/../sys/dev/acpica; \
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cd ${.CURDIR}/../sys/dev/acpica; \
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for h in acpiio.h; do \
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for h in acpiio.h acpi_hpet.h; do \
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ln -fs ../../../../sys/dev/acpica/$$h \
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ln -fs ../../../../sys/dev/acpica/$$h \
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${DESTDIR}${INCLUDEDIR}/dev/acpica; \
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${DESTDIR}${INCLUDEDIR}/dev/acpica; \
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done
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done
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@ -35,11 +35,13 @@ __FBSDID("$FreeBSD$");
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#include "opt_apic.h"
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#include "opt_apic.h"
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#endif
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#endif
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#include <sys/param.h>
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#include <sys/param.h>
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#include <sys/conf.h>
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#include <sys/bus.h>
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#include <sys/bus.h>
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#include <sys/kernel.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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#include <sys/module.h>
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#include <sys/proc.h>
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#include <sys/proc.h>
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#include <sys/rman.h>
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#include <sys/rman.h>
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#include <sys/mman.h>
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#include <sys/time.h>
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#include <sys/time.h>
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#include <sys/smp.h>
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#include <sys/smp.h>
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#include <sys/sysctl.h>
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#include <sys/sysctl.h>
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@ -106,6 +108,23 @@ struct hpet_softc {
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char name[8];
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char name[8];
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} t[32];
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} t[32];
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int num_timers;
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int num_timers;
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struct cdev *pdev;
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int mmap_allow;
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int mmap_allow_write;
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int devinuse;
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};
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static d_open_t hpet_open;
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static d_close_t hpet_close;
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static d_mmap_t hpet_mmap;
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static struct cdevsw hpet_cdevsw = {
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.d_version = D_VERSION,
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.d_flags = D_TRACKCLOSE,
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.d_name = "hpet",
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.d_open = hpet_open,
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.d_close = hpet_close,
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.d_mmap = hpet_mmap,
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};
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};
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static u_int hpet_get_timecount(struct timecounter *tc);
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static u_int hpet_get_timecount(struct timecounter *tc);
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@ -317,6 +336,47 @@ hpet_find_irq_rid(device_t dev, u_long start, u_long end)
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}
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}
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}
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}
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static int
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hpet_open(struct cdev *cdev, int oflags, int devtype, struct thread *td)
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{
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struct hpet_softc *sc;
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sc = cdev->si_drv1;
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if (!sc->mmap_allow)
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return (EPERM);
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if (atomic_cmpset_32(&sc->devinuse, 0, 1) == 0)
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return (EBUSY);
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else
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return (0);
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}
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static int
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hpet_close(struct cdev *cdev, int fflag, int devtype, struct thread *td)
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{
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struct hpet_softc *sc;
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sc = cdev->si_drv1;
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sc->devinuse = 0;
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return (0);
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}
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static int
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hpet_mmap(struct cdev *cdev, vm_ooffset_t offset, vm_paddr_t *paddr,
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int nprot, vm_memattr_t *memattr)
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{
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struct hpet_softc *sc;
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sc = cdev->si_drv1;
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if (offset > rman_get_size(sc->mem_res))
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return (EINVAL);
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if (!sc->mmap_allow_write && (nprot & PROT_WRITE))
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return (EPERM);
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*paddr = rman_get_start(sc->mem_res) + offset;
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return (0);
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}
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/* Discover the HPET via the ACPI table of the same name. */
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/* Discover the HPET via the ACPI table of the same name. */
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static void
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static void
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hpet_identify(driver_t *driver, device_t parent)
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hpet_identify(driver_t *driver, device_t parent)
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@ -701,6 +761,26 @@ hpet_attach(device_t dev)
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maxhpetet++;
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maxhpetet++;
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}
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}
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}
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}
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sc->pdev = make_dev(&hpet_cdevsw, 0, UID_ROOT, GID_WHEEL,
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0600, "hpet%d", device_get_unit(dev));
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if (sc->pdev) {
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sc->pdev->si_drv1 = sc;
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sc->mmap_allow = 1;
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TUNABLE_INT_FETCH("hw.acpi.hpet.mmap_allow",
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&sc->mmap_allow);
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sc->mmap_allow_write = 1;
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TUNABLE_INT_FETCH("hw.acpi.hpet.mmap_allow_write",
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&sc->mmap_allow_write);
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SYSCTL_ADD_INT(device_get_sysctl_ctx(dev),
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SYSCTL_CHILDREN(device_get_sysctl_tree(dev)),
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OID_AUTO, "mmap_allow",
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CTLFLAG_RW, &sc->mmap_allow, 0,
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"Allow userland to memory map HPET");
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} else
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device_printf(dev, "could not create /dev/hpet%d\n",
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device_get_unit(dev));
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return (0);
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return (0);
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}
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}
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