regulator: scmi: add support for registering SCMI regulators by name

Add support to register SCMI regulator subnodes based on an SCMI Voltage Domain name specified via the 'regulator-name' device tree property. In doing so, make the 'reg' property optional with the constraint that at least one of 'reg' or 'regulator-name' must be specified. If both are specified, then both must match the Voltage Domain data exposed by the SCMI platform.

Name based SCMI regulator registration helps ensure that an SCMI agent doesn't need to be aware of the numbering scheme used for Voltage Domains by the SCMI platform. It also ensures that the correct Voltage Domain is selected for a given physical regulator. This cannot be guaranteed with numeric Voltage Domain IDs alone.

David Collins (2):
dt-bindings: firmware: arm,scmi: define support for name based
regulators
regulator: scmi: add support for registering SCMI regulators by name

 .../bindings/firmware/arm,scmi.yaml           | 11 +++-
 drivers/regulator/scmi-regulator.c            | 57 ++++++++++++++++++-
 2 files changed, 62 insertions(+), 6 deletions(-)

2.17.1

Allow SCMI regulator subnodes to be specified either by ID using the "reg" property or by name using the "regulator-name" property.

Name based SCMI regulator specification helps ensure that an SCMI agent doesn't need to be aware of the numbering scheme used for Voltage Domains by the SCMI platform. It also ensures that the correct Voltage Domain is selected for a given physical regulator. This cannot be guaranteed with numeric Voltage Domain IDs alone.

---
 .../devicetree/bindings/firmware/arm,scmi.yaml        | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

index 5c4c6782e052..bc4a84fe25d2 100644
@@ -155,7 +155,7 @@ properties:
           The list of all regulators provided by this SCMI controller.
 
         patternProperties:
-          '^regulators@[0-9a-f]+$':
+          '^regulator.+$':
             type: object
             $ref: "../regulator/regulator.yaml#"
 

@@ -164,8 +164,13 @@ properties:
                 maxItems: 1
                 description: Identifier for the voltage regulator.
 
-            required:
-              - reg
+              regulator-name: true
+
+            anyOf:
+              - required:
+                  - reg
+              - required:
+                  - regulator-name
 
 additionalProperties: false
 

2.17.1

Add support to register SCMI regulator subnodes based on an SCMI Voltage Domain name specified via the 'regulator-name' device tree property. In doing so, make the 'reg' property optional with the constraint that at least one of 'reg' or 'regulator-name' must be specified. If both are specified, then both must match the Voltage Domain data exposed by the SCMI platform.

Name based SCMI regulator registration helps ensure that an SCMI agent doesn't need to be aware of the numbering scheme used for Voltage Domains by the SCMI platform. It also ensures that the correct Voltage Domain is selected for a given physical regulator. This cannot be guaranteed with numeric Voltage Domain IDs alone.

---
 drivers/regulator/scmi-regulator.c | 57 ++++++++++++++++++++++++++++--
 1 file changed, 54 insertions(+), 3 deletions(-)

index 1f02f60ad136..c3287901975e 100644
@@ -31,6 +31,7 @@
 #include <linux/regulator/of_regulator.h>
 #include <linux/scmi_protocol.h>
 #include <linux/slab.h>
+#include <linux/string.h>
 #include <linux/types.h>
 
 static const struct scmi_voltage_proto_ops *voltage_ops;

@@ -252,16 +253,66 @@ static int scmi_regulator_common_init(struct scmi_regulator *sreg)
 	return 0;
 }
 
+static int scmi_regulator_map_name(struct scmi_protocol_handle *ph,
+				   struct scmi_regulator_info *rinfo,
+				   const char *name)
+{
+	const struct scmi_voltage_info *vinfo;
+	int i;
+
+	for (i = 0; i < rinfo->num_doms; i++) {
+		vinfo = voltage_ops->info_get(ph, i);
+		if (!vinfo)
+			continue;
+		if (!strncmp(vinfo->name, name, sizeof(vinfo->name)))
+			return i;
+	}
+
+	return -ENODEV;
+}
+
 static int process_scmi_regulator_of_node(struct scmi_device *sdev,
 					  struct scmi_protocol_handle *ph,
 					  struct device_node *np,
 					  struct scmi_regulator_info *rinfo)
 {
 	u32 dom, ret;
+	int name_dom;
+	const char *name;
 
-	ret = of_property_read_u32(np, "reg", &dom);
-	if (ret)
-		return ret;
+	dom = rinfo->num_doms;
+	if (of_find_property(np, "reg", NULL)) {
+		ret = of_property_read_u32(np, "reg", &dom);
+		if (ret)
+			return ret;
+
+		if (dom >= rinfo->num_doms)
+			return -ENODEV;
+	}
+
+	if (of_find_property(np, "regulator-name", NULL)) {
+		ret = of_property_read_string(np, "regulator-name", &name);
+		if (ret)
+			return ret;
+
+		name_dom = scmi_regulator_map_name(ph, rinfo, name);
+		if (name_dom < 0) {
+			dev_err(&sdev->dev,
+				"No SCMI Voltage Domain found named %s. Skipping: %s\n",
+				name, np->full_name);
+			return name_dom;
+		}
+
+		if (dom >= rinfo->num_doms)
+			dom = name_dom;
+
+		if (name_dom != dom) {
+			dev_err(&sdev->dev,
+				"SCMI Voltage Domain %s ID mismatch, %u (DT) != %d (firmware). Skipping: %s\n",
+				name, dom, name_dom, np->full_name);
+			return -EINVAL;
+		}
+	}
 
 	if (dom >= rinfo->num_doms)
 		return -ENODEV;

2.17.1