Jon, You might want to take a look at using the acpi_read and acpi_write ACPICA interfaces that accept a GAS structure and handle the access width (etc.) automatically. Bob > -----Original Message----- > From: Jon Mason [mailto:jon.mason@xxxxxxxxxxxx] > Sent: Thursday, May 4, 2017 8:06 AM > To: Rafael Wysocki <rjw@xxxxxxxxxxxxx>; Len Brown <lenb@xxxxxxxxxx>; > Moore, Robert <robert.moore@xxxxxxxxx>; Zheng, Lv <lv.zheng@xxxxxxxxx> > Cc: linux-acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > devel@xxxxxxxxxx; bcm-kernel-feedback-list@xxxxxxxxxxxx > Subject: [PATCH] ACPI: SPCR: Use access width to determine mmio usage > > The current SPCR code does not check the access width of the mmio, and > uses a default of 8bit register accesses. This prevents devices that > only do 16 or 32bit register accesses from working. By simply checking > this field and setting the mmio string appropriately, this issue can be > corrected. To prevent any legacy issues, the code will default to 8bit > accesses if the value is anything but 16 or 32. > > Signed-off-by: Jon Mason <jon.mason@xxxxxxxxxxxx> > --- > drivers/acpi/spcr.c | 18 ++++++++++++++++-- > include/acpi/acrestyp.h | 7 +++++++ > 2 files changed, 23 insertions(+), 2 deletions(-) > > diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c index > 01c9466..11233f6 100644 > --- a/drivers/acpi/spcr.c > +++ b/drivers/acpi/spcr.c > @@ -74,8 +74,22 @@ int __init parse_spcr(bool earlycon) > goto done; > } > > - iotype = table->serial_port.space_id == > ACPI_ADR_SPACE_SYSTEM_MEMORY ? > - "mmio" : "io"; > + if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) { > + switch (table->serial_port.access_width) { > + default: > + pr_err("Unexpected SPCR Access Width. Defaulting to > byte size\n"); > + case ACPI_ACCESS_SIZE_BYTE: > + iotype = "mmio"; > + break; > + case ACPI_ACCESS_SIZE_WORD: > + iotype = "mmio16"; > + break; > + case ACPI_ACCESS_SIZE_DWORD: > + iotype = "mmio32"; > + break; > + } > + } else > + iotype = "io"; > > switch (table->interface_type) { > case ACPI_DBG2_ARM_SBSA_32BIT: > diff --git a/include/acpi/acrestyp.h b/include/acpi/acrestyp.h index > f0f7403..781cb55 100644 > --- a/include/acpi/acrestyp.h > +++ b/include/acpi/acrestyp.h > @@ -372,6 +372,13 @@ struct acpi_resource_generic_register { > u64 address; > }; > > +/* Generic Address Space Access Sizes */ > +#define ACPI_ACCESS_SIZE_UNDEFINED 0 > +#define ACPI_ACCESS_SIZE_BYTE 1 > +#define ACPI_ACCESS_SIZE_WORD 2 > +#define ACPI_ACCESS_SIZE_DWORD 3 > +#define ACPI_ACCESS_SIZE_QWORD 4 > + > struct acpi_resource_gpio { > u8 revision_id; > u8 connection_type; > -- > 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
