On 3/14/24 11:45 AM, 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 perfectly legal
> according to the ACPI spec.
>
> Add support for reading/writing such values.
>
> Tested on a Dell Inspiron 3505 and a Asus Prime B650-Plus.
>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
> ---
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> Chnages since v4:
> - spelling fix
> - fix checkpatch warning
>
> 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 | 54 +++++++++++++++++++++++++++++---------
> 1 file changed, 41 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
> index 1920e115da89..9602658711cf 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;
> +}
> +
> +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;
> +}
> +
> /*
> * WMI can have EmbeddedControl access regions. In which case, we just want to
> * hand these off to the EC driver.
> @@ -1162,27 +1190,27 @@ 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 ((address > 0xFF) || !value)
> + if (!value)
> + return AE_NULL_ENTRY;
> +
> + 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)
> + if (function != ACPI_READ && function != ACPI_WRITE)
> return AE_BAD_PARAMETER;
>
> - if (function == ACPI_READ) {
> - result = ec_read(address, &temp);
> - *value = temp;
> - } else {
> - temp = 0xff & *value;
> - result = ec_write(address, temp);
> - }
> + if (function == ACPI_READ)
> + ret = ec_read_multiple(address, (u8 *)value, bytes);
> + else
> + ret = ec_write_multiple(address, (u8 *)value, bytes);
>
> - switch (result) {
> + switch (ret) {
> case -EINVAL:
> return AE_BAD_PARAMETER;
> case -ENODEV:
> --
> 2.39.2
>
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
