firmware: qcom: scm: Introduce pas_metadata context

Starting with Qualcomm SM8450, some new security enhancements has been
done in the secure world, which results in the requirement to keep the
metadata segment accessible by the secure world from init_image() until
auth_and_reset().

Introduce a "PAS metadata context" object that can be passed to
init_image() for tracking the mapped memory and a related release
function for client drivers to release the mapping once either
auth_and_reset() has been invoked or in error handling paths on the way
there.
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20220128025513.97188-2-bjorn.andersson@linaro.org

drivers/firmware/qcom_scm.c

@@ -432,10 +432,16 @@ static void qcom_scm_set_download_mode(bool enable)
  *		and optional blob of data used for authenticating the metadata
  *		and the rest of the firmware
  * @size:	size of the metadata
+ * @ctx:	optional metadata context
  *
- * Returns 0 on success.
+ * Return: 0 on success.
+ *
+ * Upon successful return, the PAS metadata context (@ctx) will be used to
+ * track the metadata allocation, this needs to be released by invoking
+ * qcom_scm_pas_metadata_release() by the caller.
  */
-int qcom_scm_pas_init_image(u32 peripheral, const void *metadata, size_t size)
+int qcom_scm_pas_init_image(u32 peripheral, const void *metadata, size_t size,
+			    struct qcom_scm_pas_metadata *ctx)
 {
 	dma_addr_t mdata_phys;
 	void *mdata_buf;
@@ -464,7 +470,7 @@ int qcom_scm_pas_init_image(u32 peripheral, const void *metadata, size_t size)
 
 	ret = qcom_scm_clk_enable();
 	if (ret)
-		goto free_metadata;
+		goto out;
 
 	desc.args[1] = mdata_phys;
 
@@ -472,13 +478,36 @@ int qcom_scm_pas_init_image(u32 peripheral, const void *metadata, size_t size)
 
 	qcom_scm_clk_disable();
 
-free_metadata:
-	dma_free_coherent(__scm->dev, size, mdata_buf, mdata_phys);
+out:
+	if (ret < 0 || !ctx) {
+		dma_free_coherent(__scm->dev, size, mdata_buf, mdata_phys);
+	} else if (ctx) {
+		ctx->ptr = mdata_buf;
+		ctx->phys = mdata_phys;
+		ctx->size = size;
+	}
 
 	return ret ? : res.result[0];
 }
 EXPORT_SYMBOL(qcom_scm_pas_init_image);
 
+/**
+ * qcom_scm_pas_metadata_release() - release metadata context
+ * @ctx:	metadata context
+ */
+void qcom_scm_pas_metadata_release(struct qcom_scm_pas_metadata *ctx)
+{
+	if (!ctx->ptr)
+		return;
+
+	dma_free_coherent(__scm->dev, ctx->size, ctx->ptr, ctx->phys);
+
+	ctx->ptr = NULL;
+	ctx->phys = 0;
+	ctx->size = 0;
+}
+EXPORT_SYMBOL(qcom_scm_pas_metadata_release);
+
 /**
  * qcom_scm_pas_mem_setup() - Prepare the memory related to a given peripheral
  *			      for firmware loading

drivers/soc/qcom/mdt_loader.c

@@ -171,7 +171,7 @@ static int __qcom_mdt_load(struct device *dev, const struct firmware *fw,
 			goto out;
 		}
 
-		ret = qcom_scm_pas_init_image(pas_id, metadata, metadata_len);
+		ret = qcom_scm_pas_init_image(pas_id, metadata, metadata_len, NULL);
 
 		kfree(metadata);
 		if (ret) {

include/linux/qcom_scm.h

@@ -68,8 +68,16 @@ extern int qcom_scm_set_warm_boot_addr(void *entry, const cpumask_t *cpus);
 extern void qcom_scm_cpu_power_down(u32 flags);
 extern int qcom_scm_set_remote_state(u32 state, u32 id);
 
+struct qcom_scm_pas_metadata {
+	void *ptr;
+	dma_addr_t phys;
+	ssize_t size;
+};
+
 extern int qcom_scm_pas_init_image(u32 peripheral, const void *metadata,
-				   size_t size);
+				   size_t size,
+				   struct qcom_scm_pas_metadata *ctx);
+void qcom_scm_pas_metadata_release(struct qcom_scm_pas_metadata *ctx);
 extern int qcom_scm_pas_mem_setup(u32 peripheral, phys_addr_t addr,
 				  phys_addr_t size);
 extern int qcom_scm_pas_auth_and_reset(u32 peripheral);