[PATCH v22 3/7] remoteproc: core: Introduce rproc_pa_to_va helper

[Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>]

When a resource table is loaded by an external entity such as U-boot or
OP-TEE, we do not necessarily get the device address(da) but the physical
address(pa).
This helper performs similar translation than the rproc_da_to_va()
but based on a physical address.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
---
V22 updates:
-  use size_t for offset and remove its comparaison with 0
---
 drivers/remoteproc/remoteproc_core.c | 50 ++++++++++++++++++++++++++++
 include/linux/remoteproc.h           |  1 +
 2 files changed, 51 insertions(+)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index b087ed21858a..ec1860e1cfa9 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -225,6 +225,56 @@ void *rproc_da_to_va(struct rproc *rproc, u64 da, size_t len, bool *is_iomem)
 }
 EXPORT_SYMBOL(rproc_da_to_va);
 
+/**
+ * rproc_pa_to_va() - lookup the kernel virtual address for a physical address of a remoteproc
+ * memory
+ *
+ * @rproc: handle of a remote processor
+ * @pa: remoteproc physical address
+ * @len: length of the memory region @pa is pointing to
+ * @is_iomem: optional pointer filled in to indicate if @pa is iomapped memory
+ *
+ * This function is a helper function similar to rproc_da_to_va() but it deals with physical
+ * addresses instead of device addresses.
+ *
+ * Return: a valid kernel address on success or NULL on failure
+ */
+void *rproc_pa_to_va(struct rproc *rproc, phys_addr_t pa, size_t len, bool *is_iomem)
+{
+	struct rproc_mem_entry *carveout;
+	void *ptr = NULL;
+	size_t offset;
+
+	list_for_each_entry(carveout, &rproc->carveouts, node) {
+		/* Verify that carveout is allocated */
+		if (!carveout->va)
+			continue;
+
+		/* try next carveout if pa is too small */
+		if (pa < carveout->dma)
+			continue;
+
+		offset = pa - carveout->dma;
+
+		/* try next carveout if pa is too large */
+		if (offset > carveout->len)
+			continue;
+
+		if (len > carveout->len - offset)
+			continue;
+
+		ptr = carveout->va + offset;
+
+		if (is_iomem)
+			*is_iomem = carveout->is_iomem;
+
+		break;
+	}
+
+	return ptr;
+}
+EXPORT_SYMBOL(rproc_pa_to_va);
+
 /**
  * rproc_find_carveout_by_name() - lookup the carveout region by a name
  * @rproc: handle of a remote processor
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index b4795698d8c2..8fd0d7f63c8e 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -690,6 +690,7 @@ int rproc_detach(struct rproc *rproc);
 int rproc_set_firmware(struct rproc *rproc, const char *fw_name);
 void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type);
 void *rproc_da_to_va(struct rproc *rproc, u64 da, size_t len, bool *is_iomem);
+void *rproc_pa_to_va(struct rproc *rproc, phys_addr_t pa, size_t len, bool *is_iomem);
 
 /* from remoteproc_coredump.c */
 void rproc_coredump_cleanup(struct rproc *rproc);
-- 
2.43.0