Re: [PATCH 1/2] firmware: arm_scmi: Fetch and store sensor scale

[Guenter Roeck]

On 5/6/19 3:41 PM, Florian Fainelli wrote:

In preparation for dealing with scales within the SCMI HWMON driver,
fetch and store the sensor unit scale into the scmi_sensor_info
structure.

Signed-off-by: Florian Fainelli <f.faine...@gmail.com>
---
  drivers/firmware/arm_scmi/sensors.c | 7 ++++++-
  include/linux/scmi_protocol.h       | 1 +
  2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_scmi/sensors.c 
b/drivers/firmware/arm_scmi/sensors.c
index b53d5cc9c9f6..f324f0a13ebe 100644
--- a/drivers/firmware/arm_scmi/sensors.c
+++ b/drivers/firmware/arm_scmi/sensors.c
@@ -33,7 +33,8 @@ struct scmi_msg_resp_sensor_description {
  #define NUM_TRIP_POINTS(x)    (((x) >> 4) & 0xff)
                __le32 attributes_high;
  #define SENSOR_TYPE(x)                ((x) & 0xff)
-#define SENSOR_SCALE(x)                (((x) >> 11) & 0x3f)
+#define SENSOR_SCALE_MASK      0x3f
+#define SENSOR_SCALE(x)                (((x) >> 11) & SENSOR_SCALE_MASK)
  #define SENSOR_UPDATE_SCALE(x)        (((x) >> 22) & 0x1f)
  #define SENSOR_UPDATE_BASE(x) (((x) >> 27) & 0x1f)
                    u8 name[SCMI_MAX_STR_SIZE];
@@ -140,6 +141,10 @@ static int scmi_sensor_description_get(const struct 
scmi_handle *handle,
                        s = &si->sensors[desc_index + cnt];
                        s->id = le32_to_cpu(buf->desc[cnt].id);
                        s->type = SENSOR_TYPE(attrh);
+                       s->scale = SENSOR_SCALE(attrh);
+                       /* Sign extend to a full u8 */
+                       if (s->scale & ((SENSOR_SCALE_MASK + 1) >> 1))

The logic here is quite confusing. I think it would be better to define,
say, SENSOR_SCALE_SIGN and use it.

+                               s->scale |= GENMASK(7, 6);
                        strlcpy(s->name, buf->desc[cnt].name, 
SCMI_MAX_STR_SIZE);
                }

diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h

index 3105055c00a7..7746f171f108 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -144,6 +144,7 @@ struct scmi_power_ops {
  struct scmi_sensor_info {
        u32 id;
        u8 type;
+       u8 scale;

Why not s8 if this is a signed value ?

Thanks,
Guenter

        char name[SCMI_MAX_STR_SIZE];
  };