On Sat, Mar 9, 2024 at 11:17 AM Armin Wolf <W_Armin@xxxxxx> wrote:
>
> Am 09.03.24 um 18:07 schrieb Kuppuswamy Sathyanarayanan:
>
> > On 3/8/24 1:05 PM, Armin Wolf wrote:
> >> The ACPI EC address space handler currently only supports
> >> reading/writing 8 bit values. Some firmware implementations however
> >> want to access for example 16 bit values, which is prefectly legal
/s/prefectly/perfectly
> >> according to the ACPI spec.
> >>
> >> Add support for reading/writing such values.
> >>
> >> Tested on a Dell Inspiron 3505 and a Asus Prime B650-Plus.
> >>
> >> Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
> >> ---
> >> Changes since v3:
> >> - change type of variable i to size_t
> >>
> >> Changes since v2:
> >> - fix address overflow check
> >>
> >> Changes since v1:
> >> - use BITS_PER_BYTE
> >> - validate that number of bytes to read/write does not overflow the
> >> address
> >> ---
> >> drivers/platform/x86/wmi.c | 49 ++++++++++++++++++++++++++++++--------
> >> 1 file changed, 39 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
> >> index 1920e115da89..d9bf6d452b3a 100644
> >> --- a/drivers/platform/x86/wmi.c
> >> +++ b/drivers/platform/x86/wmi.c
> >> @@ -1153,6 +1153,34 @@ static int parse_wdg(struct device *wmi_bus_dev, struct platform_device *pdev)
> >> return 0;
> >> }
> >>
> >> +static int ec_read_multiple(u8 address, u8 *buffer, size_t bytes)
> >> +{
> >> + size_t i;
> >> + int ret;
> >> +
> >> + for (i = 0; i < bytes; i++) {
> >> + ret = ec_read(address + i, &buffer[i]);
> >> + if (ret < 0)
> >> + return ret;
> >> + }
> >> +
> >> + return 0;
> >> +}
> > Why not use ec_transaction?
>
> Hi,
>
> because ec_transaction() is meant to send raw commands to the EC. And AFAIK read/write transactions can only transfer a
> single byte at once, so using ec_transaction() would yield no benefit here.
>From the implementation, I don't see any length restriction. If it is
a functional restriction, then fine.
int ec_transaction(u8 command,
const u8 *wdata, unsigned wdata_len,
u8 *rdata, unsigned rdata_len)
{
struct transaction t = {.command = command,
.wdata = wdata, .rdata = rdata,
.wlen = wdata_len, .rlen = rdata_len};
if (!first_ec)
return -ENODEV;
return acpi_ec_transaction(first_ec, &t);
}
EXPORT_SYMBOL(ec_transaction);
>
> >
> >> +
> >> +static int ec_write_multiple(u8 address, u8 *buffer, size_t bytes)
> >> +{
> >> + size_t i;
> >> + int ret;
> >> +
> >> + for (i = 0; i < bytes; i++) {
> >> + ret = ec_write(address + i, buffer[i]);
> >> + if (ret < 0)
> >> + return ret;
> >> + }
> >> +
> >> + return 0;
> >> +}
> > Same as above.
> >> +
> >> /*
> >> * WMI can have EmbeddedControl access regions. In which case, we just want to
> >> * hand these off to the EC driver.
> >> @@ -1162,27 +1190,28 @@ acpi_wmi_ec_space_handler(u32 function, acpi_physical_address address,
> >> u32 bits, u64 *value,
> >> void *handler_context, void *region_context)
> >> {
> >> - int result = 0;
> >> - u8 temp = 0;
> >> + int bytes = bits / BITS_PER_BYTE;
> >> + int ret;
> >> +
> >> + if (!value)
> >> + return AE_NULL_ENTRY;
> >>
> >> - if ((address > 0xFF) || !value)
> >> + if (!bytes || bytes > sizeof(*value))
> >> return AE_BAD_PARAMETER;
> >>
> >> - if (function != ACPI_READ && function != ACPI_WRITE)
> >> + if (address > U8_MAX || address + bytes - 1 > U8_MAX)
> >> return AE_BAD_PARAMETER;
> >>
> >> - if (bits != 8)
> > Since you want to support only 16 bit reads/writes, can you check for >16
>
> The 16 bit reads/writes where meant as an example, ACPI code can request much larger values.
> The WMI EC handler should be able to handle those, just like the regular ACPI EC handler.
>
Got it.
> Thanks,
> Armin Wolf
>
> >> + if (function != ACPI_READ && function != ACPI_WRITE)
> >> return AE_BAD_PARAMETER;
> >>
> >> if (function == ACPI_READ) {
> >> - result = ec_read(address, &temp);
> >> - *value = temp;
> >> + ret = ec_read_multiple(address, (u8 *)value, bytes);
> >> } else {
> >> - temp = 0xff & *value;
> >> - result = ec_write(address, temp);
> >> + ret = ec_write_multiple(address, (u8 *)value, bytes);
> >> }
> >>
> >> - switch (result) {
> >> + switch (ret) {
> >> case -EINVAL:
> >> return AE_BAD_PARAMETER;
> >> case -ENODEV:
> >> --
> >> 2.39.2
> >>
> >>
