diff options
| author | uwe <uwe@NetBSD.org> | 2022-03-17 23:05:01 +0000 |
|---|---|---|
| committer | uwe <uwe@NetBSD.org> | 2022-03-17 23:05:01 +0000 |
| commit | 8044878026e31114ed91f4419e84331ebcdda7bd (patch) | |
| tree | 3f8b5958810442f391a790c4b7341d01d0dd021d /sys/dev | |
| parent | 687f794943c36621f8ee905561ba8b83bd8294d1 (diff) | |
virtio_pci_bus_space_write_8: don't use bus_space_write_8.
The standard says:
4.1.3.1 Driver Requirements: PCI Device Layout
For device configuration access, the driver MUST use ... 32-bit
wide and aligned accesses for ... 64-bit wide fields. For 64-bit
fields, the driver MAY access each of the high and low 32-bit parts
of the field independently.
NB: "MAY" in this text refers to "independently" (i.e. the order of
accesses) not "32-bit" (which is restricted by the earlier "MUST").
Note also that virtio_{read,write}_device_config_8 in virtio.c already
uses two 32-bit accesses.
Diffstat (limited to 'sys/dev')
| -rw-r--r-- | sys/dev/pci/virtio_pci.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/sys/dev/pci/virtio_pci.c b/sys/dev/pci/virtio_pci.c index 992f5022caa..79318dab964 100644 --- a/sys/dev/pci/virtio_pci.c +++ b/sys/dev/pci/virtio_pci.c @@ -1,4 +1,4 @@ -/* $NetBSD: virtio_pci.c,v 1.35 2022/03/17 22:53:13 uwe Exp $ */ +/* $NetBSD: virtio_pci.c,v 1.36 2022/03/17 23:05:01 uwe Exp $ */ /* * Copyright (c) 2020 The NetBSD Foundation, Inc. @@ -28,7 +28,7 @@ */ #include <sys/cdefs.h> -__KERNEL_RCSID(0, "$NetBSD: virtio_pci.c,v 1.35 2022/03/17 22:53:13 uwe Exp $"); +__KERNEL_RCSID(0, "$NetBSD: virtio_pci.c,v 1.36 2022/03/17 23:05:01 uwe Exp $"); #include <sys/param.h> #include <sys/systm.h> @@ -694,21 +694,22 @@ virtio_pci_read_queue_size_10(struct virtio_softc *sc, uint16_t idx) } /* - * By definition little endian only in v1.0 and 8 byters are allowed to be - * written as two 4 byters + * By definition little endian only in v1.0. NB: "MAY" in the text + * below refers to "independently" (i.e. the order of accesses) not + * "32-bit" (which is restricted by the earlier "MUST"). * - * This is not a general purpose function that can be used in any - * driver. Virtio specifically allows the 8 byte bus transaction - * to be split into two 4 byte transactions. Do not copy/use it - * in other device drivers unless you know that the device accepts it. + * 4.1.3.1 Driver Requirements: PCI Device Layout + * + * For device configuration access, the driver MUST use ... 32-bit + * wide and aligned accesses for ... 64-bit wide fields. For 64-bit + * fields, the driver MAY access each of the high and low 32-bit parts + * of the field independently. */ static __inline void virtio_pci_bus_space_write_8(bus_space_tag_t iot, bus_space_handle_t ioh, bus_size_t offset, uint64_t value) { -#if defined(__HAVE_BUS_SPACE_8) - bus_space_write_8(iot, ioh, offset, value); -#elif _QUAD_HIGHWORD +#if _QUAD_HIGHWORD bus_space_write_4(iot, ioh, offset, BUS_ADDR_LO32(value)); bus_space_write_4(iot, ioh, offset + 4, BUS_ADDR_HI32(value)); #else |
