[PATCH 7/9] remoteproc: Introduce "panic" callback in ops

[Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>]

Introduce a "panic" function in the remoteproc ops table, to allow
remoteproc instances to perform operations needed in order to aid in
post mortem system debugging, such as flushing caches etc, when the
kernel panics.

Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
---
 drivers/remoteproc/remoteproc_core.c | 16 ++++++++++++++++
 include/linux/remoteproc.h           |  3 +++
 2 files changed, 19 insertions(+)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 3c5fbbbfb0f1..cc47797c6496 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -1833,6 +1833,16 @@ void rproc_shutdown(struct rproc *rproc)
 }
 EXPORT_SYMBOL(rproc_shutdown);
 
+static int rproc_panic_handler(struct notifier_block *nb, unsigned long event,
+			       void *ptr)
+{
+	struct rproc *rproc = container_of(nb, struct rproc, panic_nb);
+
+	rproc->ops->panic(rproc);
+
+	return NOTIFY_DONE;
+}
+
 /**
  * rproc_get_by_phandle() - find a remote processor by phandle
  * @phandle: phandle to the rproc
@@ -2058,6 +2068,12 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
 		rproc->ops->get_boot_addr = rproc_elf_get_boot_addr;
 	}
 
+	/* Register panic notifier for remoteprocs with "panic" callback */
+	if (rproc->ops->panic) {
+		rproc->panic_nb.notifier_call = rproc_panic_handler;
+		atomic_notifier_chain_register(&panic_notifier_list, &rproc->panic_nb);
+	}
+
 	mutex_init(&rproc->lock);
 
 	idr_init(&rproc->notifyids);
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index 16ad66683ad0..33553f6d8ff0 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -383,6 +383,7 @@ struct rproc_ops {
 	int (*load)(struct rproc *rproc, const struct firmware *fw);
 	int (*sanity_check)(struct rproc *rproc, const struct firmware *fw);
 	u32 (*get_boot_addr)(struct rproc *rproc, const struct firmware *fw);
+	void (*panic)(struct rproc *rproc);
 };
 
 /**
@@ -481,6 +482,7 @@ struct rproc_dump_segment {
  * @auto_boot: flag to indicate if remote processor should be auto-started
  * @dump_segments: list of segments in the firmware
  * @nb_vdev: number of vdev currently handled by rproc
+ * @panic_nb: notifier_block for remoteproc's panic handler
  */
 struct rproc {
 	struct list_head node;
@@ -514,6 +516,7 @@ struct rproc {
 	bool auto_boot;
 	struct list_head dump_segments;
 	int nb_vdev;
+	struct notifier_block panic_nb;
 };
 
 /**
-- 
2.18.0