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From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Date: Mon, 11 Mar 2024 16:03:26 +0200 (EET)
To: Armin Wolf <W_Armin@gmx.de>
cc: Hans de Goede <hdegoede@redhat.com>, 
    "Rafael J. Wysocki" <rafael@kernel.org>, lenb@kernel.org, 
    mario.limonciello@amd.com, linux-acpi@vger.kernel.org, 
    platform-driver-x86@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 1/2] platform/x86: wmi: Support reading/writing 16
 bit EC values
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Message-ID: <891f6a46-fb6c-b366-d17e-64d26cb6f4a2@linux.intel.com>
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On Fri, 8 Mar 2024, 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
> according to the ACPI spec.
>=20
> Add support for reading/writing such values.
>=20
> Tested on a Dell Inspiron 3505 and a Asus Prime B650-Plus.
>=20
> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> ---
> Changes since v3:
> - change type of variable i to size_t
>=20
> Changes since v2:
> - fix address overflow check
>=20
> 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(-)
>=20
> 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, s=
truct platform_device *pdev)
>  =09return 0;
>  }
>=20
> +static int ec_read_multiple(u8 address, u8 *buffer, size_t bytes)
> +{
> +=09size_t i;
> +=09int ret;
> +
> +=09for (i =3D 0; i < bytes; i++) {
> +=09=09ret =3D ec_read(address + i, &buffer[i]);
> +=09=09if (ret < 0)
> +=09=09=09return ret;
> +=09}
> +
> +=09return 0;
> +}
> +
> +static int ec_write_multiple(u8 address, u8 *buffer, size_t bytes)
> +{
> +=09size_t i;
> +=09int ret;
> +
> +=09for (i =3D 0; i < bytes; i++) {
> +=09=09ret =3D ec_write(address + i, buffer[i]);
> +=09=09if (ret < 0)
> +=09=09=09return ret;
> +=09}
> +
> +=09return 0;
> +}
> +
>  /*
>   * WMI can have EmbeddedControl access regions. In which case, we just w=
ant to
>   * hand these off to the EC driver.
> @@ -1162,27 +1190,28 @@ acpi_wmi_ec_space_handler(u32 function, acpi_phys=
ical_address address,
>  =09=09=09  u32 bits, u64 *value,
>  =09=09=09  void *handler_context, void *region_context)
>  {
> -=09int result =3D 0;
> -=09u8 temp =3D 0;
> +=09int bytes =3D bits / BITS_PER_BYTE;
> +=09int ret;
> +
> +=09if (!value)
> +=09=09return AE_NULL_ENTRY;
>=20
> -=09if ((address > 0xFF) || !value)
> +=09if (!bytes || bytes > sizeof(*value))
>  =09=09return AE_BAD_PARAMETER;
>=20
> -=09if (function !=3D ACPI_READ && function !=3D ACPI_WRITE)
> +=09if (address > U8_MAX || address + bytes - 1 > U8_MAX)
>  =09=09return AE_BAD_PARAMETER;
>=20
> -=09if (bits !=3D 8)
> +=09if (function !=3D ACPI_READ && function !=3D ACPI_WRITE)
>  =09=09return AE_BAD_PARAMETER;
>=20
>  =09if (function =3D=3D ACPI_READ) {
> -=09=09result =3D ec_read(address, &temp);
> -=09=09*value =3D temp;
> +=09=09ret =3D ec_read_multiple(address, (u8 *)value, bytes);
>  =09} else {
> -=09=09temp =3D 0xff & *value;
> -=09=09result =3D ec_write(address, temp);
> +=09=09ret =3D ec_write_multiple(address, (u8 *)value, bytes);
>  =09}
>=20
> -=09switch (result) {
> +=09switch (ret) {
>  =09case -EINVAL:
>  =09=09return AE_BAD_PARAMETER;
>  =09case -ENODEV:

Seems okay now, thanks.

Reviewed-by: Ilpo J=E4rvinen <ilpo.jarvinen@linux.intel.com>

--=20
 i.
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