spmi: Return meaningful errors in spmi_controller_alloc()

spmi_controller_alloc() currently returns NULL to all types of errors,
which can be improved.

Use appropriate error code in returns and pass the errors from used
functions where possible.
Signed-off-by: Fei Shao <fshao@chromium.org>
Link: https://lore.kernel.org/r/20230824104101.4083400-6-fshao@chromium.orgSigned-off-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20231206231733.4031901-8-sboyd@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/spmi/spmi-devres.c

@@ -20,9 +20,9 @@ struct spmi_controller *devm_spmi_controller_alloc(struct device *parent, size_t
 		return ERR_PTR(-ENOMEM);
 
 	ctrl = spmi_controller_alloc(parent, size);
-	if (!ctrl) {
+	if (IS_ERR(ctrl)) {
 		devres_free(ptr);
-		return ERR_PTR(-ENOMEM);
+		return ctrl;
 	}
 
 	*ptr = ctrl;

drivers/spmi/spmi.c

@@ -448,11 +448,11 @@ struct spmi_controller *spmi_controller_alloc(struct device *parent,
 	int id;
 
 	if (WARN_ON(!parent))
-		return NULL;
+		return ERR_PTR(-EINVAL);
 
 	ctrl = kzalloc(sizeof(*ctrl) + size, GFP_KERNEL);
 	if (!ctrl)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	device_initialize(&ctrl->dev);
 	ctrl->dev.type = &spmi_ctrl_type;
@@ -466,7 +466,7 @@ struct spmi_controller *spmi_controller_alloc(struct device *parent,
 		dev_err(parent,
 			"unable to allocate SPMI controller identifier.\n");
 		spmi_controller_put(ctrl);
-		return NULL;
+		return ERR_PTR(id);
 	}
 
 	ctrl->nr = id;