ARM SCMI fixes for v5.14

A small set of fixes:
 - adding check for presence of probe while registering the driver to
   prevent NULL pointer access
 - dropping the duplicate check as the driver core already takes care of it
 - fix for possible scmi_linux_errmap buffer overflow
 - fix to avoid sensor message structure padding
 - fix the range check for the maximum number of pending SCMI messages
 - fix for various kernel-doc warnings
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Merge tag 'scmi-fixes-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into arm/fixes

ARM SCMI fixes for v5.14

A small set of fixes:
- adding check for presence of probe while registering the driver to
  prevent NULL pointer access
- dropping the duplicate check as the driver core already takes care of it
- fix for possible scmi_linux_errmap buffer overflow
- fix to avoid sensor message structure padding
- fix the range check for the maximum number of pending SCMI messages
- fix for various kernel-doc warnings

* tag 'scmi-fixes-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux:
  firmware: arm_scmi: Fix range check for the maximum number of pending messages
  firmware: arm_scmi: Avoid padding in sensor message structure
  firmware: arm_scmi: Fix kernel doc warnings about return values
  firmware: arm_scpi: Fix kernel doc warnings
  firmware: arm_scmi: Fix kernel doc warnings
  firmware: arm_scmi: Fix possible scmi_linux_errmap buffer overflow
  firmware: arm_scmi: Ensure drivers provide a probe function
  firmware: arm_scmi: Simplify device probe function on the bus

Link: https://lore.kernel.org/r/20210714165831.2617437-1-sudeep.holla@arm.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/firmware/arm_scmi/bus.c

@@ -104,11 +104,6 @@ static int scmi_dev_probe(struct device *dev)
 {
 	struct scmi_driver *scmi_drv = to_scmi_driver(dev->driver);
 	struct scmi_device *scmi_dev = to_scmi_dev(dev);
-	const struct scmi_device_id *id;
-
-	id = scmi_dev_match_id(scmi_dev, scmi_drv);
-	if (!id)
-		return -ENODEV;
 
 	if (!scmi_dev->handle)
 		return -EPROBE_DEFER;
@@ -139,6 +134,9 @@ int scmi_driver_register(struct scmi_driver *driver, struct module *owner,
 {
 	int retval;
 
+	if (!driver->probe)
+		return -EINVAL;
+
 	retval = scmi_protocol_device_request(driver->id_table);
 	if (retval)
 		return retval;

drivers/firmware/arm_scmi/driver.c

@@ -47,7 +47,6 @@ enum scmi_error_codes {
 	SCMI_ERR_GENERIC = -8,	/* Generic Error */
 	SCMI_ERR_HARDWARE = -9,	/* Hardware Error */
 	SCMI_ERR_PROTOCOL = -10,/* Protocol Error */
-	SCMI_ERR_MAX
 };
 
 /* List of all SCMI devices active in system */
@@ -166,8 +165,10 @@ static const int scmi_linux_errmap[] = {
 
 static inline int scmi_to_linux_errno(int errno)
 {
-	if (errno < SCMI_SUCCESS && errno > SCMI_ERR_MAX)
-		return scmi_linux_errmap[-errno];
+	int err_idx = -errno;
+
+	if (err_idx >= SCMI_SUCCESS && err_idx < ARRAY_SIZE(scmi_linux_errmap))
+		return scmi_linux_errmap[err_idx];
 	return -EIO;
 }
 
@@ -1025,8 +1026,9 @@ static int __scmi_xfer_info_init(struct scmi_info *sinfo,
 	const struct scmi_desc *desc = sinfo->desc;
 
 	/* Pre-allocated messages, no more than what hdr.seq can support */
-	if (WARN_ON(desc->max_msg >= MSG_TOKEN_MAX)) {
-		dev_err(dev, "Maximum message of %d exceeds supported %ld\n",
+	if (WARN_ON(!desc->max_msg || desc->max_msg > MSG_TOKEN_MAX)) {
+		dev_err(dev,
+			"Invalid maximum messages %d, not in range [1 - %lu]\n",
 			desc->max_msg, MSG_TOKEN_MAX);
 		return -EINVAL;
 	}
@@ -1137,6 +1139,8 @@ scmi_txrx_setup(struct scmi_info *info, struct device *dev, int prot_id)
  * @proto_id and @name: if device was still not existent it is created as a
  * child of the specified SCMI instance @info and its transport properly
  * initialized as usual.
+ *
+ * Return: A properly initialized scmi device, NULL otherwise.
  */
 static inline struct scmi_device *
 scmi_get_protocol_device(struct device_node *np, struct scmi_info *info,

drivers/firmware/arm_scmi/notify.c

@@ -1457,6 +1457,8 @@ static void scmi_devm_release_notifier(struct device *dev, void *res)
  *
  * Generic devres managed helper to register a notifier_block against a
  * protocol event.
+ *
+ * Return: 0 on Success
  */
 static int scmi_devm_notifier_register(struct scmi_device *sdev,
 				       u8 proto_id, u8 evt_id,
@@ -1523,6 +1525,8 @@ static int scmi_devm_notifier_match(struct device *dev, void *res, void *data)
  * Generic devres managed helper to explicitly un-register a notifier_block
  * against a protocol event, which was previously registered using the above
  * @scmi_devm_notifier_register.
+ *
+ * Return: 0 on Success
  */
 static int scmi_devm_notifier_unregister(struct scmi_device *sdev,
 					 u8 proto_id, u8 evt_id,

drivers/firmware/arm_scmi/sensors.c

@@ -166,7 +166,8 @@ struct scmi_msg_sensor_reading_get {
 
 struct scmi_resp_sensor_reading_complete {
 	__le32 id;
-	__le64 readings;
+	__le32 readings_low;
+	__le32 readings_high;
 };
 
 struct scmi_sensor_reading_resp {
@@ -717,7 +718,8 @@ static int scmi_sensor_reading_get(const struct scmi_protocol_handle *ph,
 
 			resp = t->rx.buf;
 			if (le32_to_cpu(resp->id) == sensor_id)
-				*value = get_unaligned_le64(&resp->readings);
+				*value =
+					get_unaligned_le64(&resp->readings_low);
 			else
 				ret = -EPROTO;
 		}

include/linux/scmi_protocol.h

@@ -101,6 +101,10 @@ struct scmi_clk_proto_ops {
  *	to sustained performance level mapping
  * @est_power_get: gets the estimated power cost for a given performance domain
  *	at a given frequency
+ * @fast_switch_possible: indicates if fast DVFS switching is possible or not
+ *	for a given device
+ * @power_scale_mw_get: indicates if the power values provided are in milliWatts
+ *	or in some other (abstract) scale
  */
 struct scmi_perf_proto_ops {
 	int (*limits_set)(const struct scmi_protocol_handle *ph, u32 domain,
@@ -153,7 +157,7 @@ struct scmi_power_proto_ops {
 };
 
 /**
- * scmi_sensor_reading  - represent a timestamped read
+ * struct scmi_sensor_reading  - represent a timestamped read
  *
  * Used by @reading_get_timestamped method.
  *
@@ -167,7 +171,7 @@ struct scmi_sensor_reading {
 };
 
 /**
- * scmi_range_attrs  - specifies a sensor or axis values' range
+ * struct scmi_range_attrs  - specifies a sensor or axis values' range
  * @min_range: The minimum value which can be represented by the sensor/axis.
  * @max_range: The maximum value which can be represented by the sensor/axis.
  */
@@ -177,7 +181,7 @@ struct scmi_range_attrs {
 };
 
 /**
- * scmi_sensor_axis_info  - describes one sensor axes
+ * struct scmi_sensor_axis_info  - describes one sensor axes
  * @id: The axes ID.
  * @type: Axes type. Chosen amongst one of @enum scmi_sensor_class.
  * @scale: Power-of-10 multiplier applied to the axis unit.
@@ -205,8 +209,8 @@ struct scmi_sensor_axis_info {
 };
 
 /**
- * scmi_sensor_intervals_info  - describes number and type of available update
- * intervals
+ * struct scmi_sensor_intervals_info  - describes number and type of available
+ *	update intervals
  * @segmented: Flag for segmented intervals' representation. When True there
  *	       will be exactly 3 intervals in @desc, with each entry
  *	       representing a member of a segment in this order:

include/linux/scpi_protocol.h

@@ -51,6 +51,14 @@ struct scpi_sensor_info {
  *	OPP is an index to the list return by @dvfs_get_info
  * @dvfs_get_info: returns the DVFS capabilities of the given power
  *	domain. It includes the OPP list and the latency information
+ * @device_domain_id: gets the scpi domain id for a given device
+ * @get_transition_latency: gets the DVFS transition latency for a given device
+ * @add_opps_to_device: adds all the OPPs for a given device
+ * @sensor_get_capability: get the list of capabilities for the sensors
+ * @sensor_get_info: get the information of the specified sensor
+ * @sensor_get_value: gets the current value of the sensor
+ * @device_get_power_state: gets the power state of a power domain
+ * @device_set_power_state: sets the power state of a power domain
  */
 struct scpi_ops {
 	u32 (*get_version)(void);