firmware: arm_scpi: fix reading sensor values on pre-1.0 SCPI firmwares

The pre-1.0 SCPI firmwares are using single __le32 as sensor value,
while the SCPI v1.0 protocol uses two __le32 as sensor values(64bit)
split into 32bit upper and 32bit lower value.

Using an "struct sensor_value" to read the sensor value on a pre-1.0
SCPI firmware gives garbage in the "hi_val" field.

This patch fixes the issue by reading only the lower 32-bit value for
all pre-1.0 SCPI versions.

Suggested-by: Sudeep Holla <Sudeep.Holla@arm.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
[sudeep.holla@arm.com: updated the commit log to reflect the implementation]
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_scpi.c b/drivers/firmware/arm_scpi.c
index 70e13230d8db835ec201590762ea0ac5331f7ca2..9ad0b1934be9a31173ede1ed6c1c3705cc0c1e05 100644 (file)
--- a/drivers/firmware/arm_scpi.c
+++ b/drivers/firmware/arm_scpi.c
@@ -721,11 +721,17 @@ static int scpi_sensor_get_value(u16 sensor, u64 *val)
 
        ret = scpi_send_message(CMD_SENSOR_VALUE, &id, sizeof(id),
                                &buf, sizeof(buf));
-       if (!ret)
+       if (ret)
+               return ret;
+
+       if (scpi_info->is_legacy)
+               /* only 32-bits supported, hi_val can be junk */
+               *val = le32_to_cpu(buf.lo_val);
+       else
                *val = (u64)le32_to_cpu(buf.hi_val) << 32 |
                        le32_to_cpu(buf.lo_val);
 
-       return ret;
+       return 0;
 }
 
 static int scpi_device_get_power_state(u16 dev_id)