Re: [PATCH v3 1/2] platform/x86: wmi: Support reading/writing 16 bit EC values

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On 3/8/2024 13:50, 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@xxxxxx>
---
Chnages 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 | 47 ++++++++++++++++++++++++++++++--------
  1 file changed, 37 insertions(+), 10 deletions(-)

diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index 1920e115da89..e6cab1cf611a 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++) {

To make sure that you're comparing against the same size data you should either i "size_t" instead of "int".

+		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++) {

Same comment as above.

+		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 || 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;
+		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







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