[PATCH v2 1/1] remoteproc: add support for co-processor booted before kernel

[Loic Pallardy <loic.pallardy@xxxxxx>]

Remote processor could boot independently or be started before Linux
kernel by bootloader or any firmware.
This patch introduces a new property in rproc core, named preloaded,
to be able to allocate resources and sub-devices like vdev and to
synchronize with current state without loading firmware from file system.
It is platform driver responsibility to implement the right firmware
load ops according to HW specificities.

Signed-off-by: Loic Pallardy <loic.pallardy@xxxxxx>

---
Change from v1:
- Keep bool in struct rproc
---
 drivers/remoteproc/remoteproc_core.c | 37 +++++++++++++++++++++++++++---------
 include/linux/remoteproc.h           |  2 ++
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 3c5fbbbfb0f1..7eaf0f949afa 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -1372,7 +1372,11 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
 	if (ret)
 		return ret;
 
-	dev_info(dev, "Booting fw image %s, size %zd\n", name, fw->size);
+	if (fw)
+		dev_info(dev, "Booting fw image %s, size %zd\n", name,
+			 fw->size);
+	else
+		dev_info(dev, "Synchronizing with preloaded co-processor\n");
 
 	/*
 	 * if enabling an IOMMU isn't relevant for this rproc, this is
@@ -1728,7 +1732,7 @@ static void rproc_crash_handler_work(struct work_struct *work)
  */
 int rproc_boot(struct rproc *rproc)
 {
-	const struct firmware *firmware_p;
+	const struct firmware *firmware_p = NULL;
 	struct device *dev;
 	int ret;
 
@@ -1759,11 +1763,17 @@ int rproc_boot(struct rproc *rproc)
 
 	dev_info(dev, "powering up %s\n", rproc->name);
 
-	/* load firmware */
-	ret = request_firmware(&firmware_p, rproc->firmware, dev);
-	if (ret < 0) {
-		dev_err(dev, "request_firmware failed: %d\n", ret);
-		goto downref_rproc;
+	if (!rproc->preloaded) {
+		/* load firmware */
+		ret = request_firmware(&firmware_p, rproc->firmware, dev);
+		if (ret < 0) {
+			dev_err(dev, "request_firmware failed: %d\n", ret);
+			goto downref_rproc;
+		}
+	} else {
+		/* set firmware name to null as unknown */
+		kfree(rproc->firmware);
+		rproc->firmware = NULL;
 	}
 
 	ret = rproc_fw_boot(rproc, firmware_p);
@@ -1917,8 +1927,17 @@ int rproc_add(struct rproc *rproc)
 	/* create debugfs entries */
 	rproc_create_debug_dir(rproc);
 
-	/* if rproc is marked always-on, request it to boot */
-	if (rproc->auto_boot) {
+	if (rproc->preloaded) {
+		/*
+		 * If rproc is marked already booted, no need to wait
+		 * for firmware.
+		 * Just handle associated resources and start sub devices
+		 */
+		ret = rproc_boot(rproc);
+		if (ret < 0)
+			return ret;
+	} else if (rproc->auto_boot) {
+		/* if rproc is marked always-on, request it to boot */
 		ret = rproc_trigger_auto_boot(rproc);
 		if (ret < 0)
 			return ret;
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index 16ad66683ad0..b68fbd576a77 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -479,6 +479,7 @@ struct rproc_dump_segment {
  * @table_sz: size of @cached_table
  * @has_iommu: flag to indicate if remote processor is behind an MMU
  * @auto_boot: flag to indicate if remote processor should be auto-started
+ * @preloaded: remote processor has been preloaded before start sequence
  * @dump_segments: list of segments in the firmware
  * @nb_vdev: number of vdev currently handled by rproc
  */
@@ -512,6 +513,7 @@ struct rproc {
 	size_t table_sz;
 	bool has_iommu;
 	bool auto_boot;
+	bool preloaded;
 	struct list_head dump_segments;
 	int nb_vdev;
 };
-- 
2.7.4