[PATCH v2 1/2] platform/x86: wmi: Support reading/writing 16 bit EC values

[PATCH v2 1/2] platform/x86: wmi: Support reading/writing 16 bit EC values

[Armin Wolf]

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.

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@gmx.de>
---
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 | 47 ++++++++++++++++++++++++++++++--------
 1 file changed, 37 insertions(+), 10 deletions(-)

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 1920e115da89..e542aef825a3 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -1153,6 +1153,32 @@ 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)
+{
+	int i, 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)
+{
+	int i, 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 +1188,28 @@ 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 > sizeof(*value))
 		return AE_BAD_PARAMETER;

-	if (function != ACPI_READ && function != ACPI_WRITE)
+	if (address > U8_MAX || address + bytes > 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;
+		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

[PATCH v2 2/2] platform/x86: wmi: Avoid returning AE_OK upon unknown error

[Armin Wolf]

If an error code other than EINVAL, ENODEV or ETIME is returned
by ec_read()/ec_write(), then AE_OK is wrongly returned.

Fix this by only returning AE_OK if the return code is 0, and
return AE_ERROR otherwise.

Tested on a Dell Inspiron 3505 and a Asus Prime B650-Plus.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 drivers/platform/x86/wmi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index e542aef825a3..ad82a96ed145 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -1216,8 +1216,10 @@ acpi_wmi_ec_space_handler(u32 function, acpi_physical_address address,
 		return AE_NOT_FOUND;
 	case -ETIME:
 		return AE_TIME;
-	default:
+	case 0:
 		return AE_OK;
+	default:
+		return AE_ERROR;
 	}
 }

--
2.39.2

Re: [PATCH v2 1/2] platform/x86: wmi: Support reading/writing 16 bit EC values

[Ilpo Järvinen]

On Thu, 7 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.
> 
> 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@gmx.de>

> @@ -1162,27 +1188,28 @@ 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 > sizeof(*value))
>  		return AE_BAD_PARAMETER;
> 
> -	if (function != ACPI_READ && function != ACPI_WRITE)
> +	if (address > U8_MAX || address + bytes > U8_MAX)

This doesn't look correct. With address = 0xff and bits = 8 this will 
return AE_BAD_PARAMETER, is that intensional?

-- 
 i.

Re: [PATCH v2 1/2] platform/x86: wmi: Support reading/writing 16 bit EC values

[Armin Wolf]

Am 08.03.24 um 09:01 schrieb Ilpo Järvinen:

> On Thu, 7 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.
>>
>> 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@gmx.de>
>> @@ -1162,27 +1188,28 @@ 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 > sizeof(*value))
>>   		return AE_BAD_PARAMETER;
>>
>> -	if (function != ACPI_READ && function != ACPI_WRITE)
>> +	if (address > U8_MAX || address + bytes > U8_MAX)
> This doesn't look correct. With address = 0xff and bits = 8 this will
> return AE_BAD_PARAMETER, is that intensional?
>
You are absolutely correct, i will send an updated series soon.

Thanks,
Armin Wolf