[PATCH v2 6/8] 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>
---

Changes since v1:
- None

 drivers/remoteproc/remoteproc_core.c | 17 +++++++++++++++++
 include/linux/remoteproc.h           |  4 ++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 307df98347ba..779f19d6d8e7 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -1832,6 +1832,17 @@ 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);
+
+	if (rproc->state == RPROC_RUNNING)
+		rproc->ops->panic(rproc);
+
+	return NOTIFY_DONE;
+}
+
 /**
  * rproc_get_by_phandle() - find a remote processor by phandle
  * @phandle: phandle to the rproc
@@ -2057,6 +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..7836c528d309 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -369,6 +369,7 @@ enum rsc_handling_status {
  *			expects to find it
  * @sanity_check:	sanity check the fw image
  * @get_boot_addr:	get boot address to entry point specified in firmware
+ * @panic:	optional callback to react to system panic
  */
 struct rproc_ops {
 	int (*start)(struct rproc *rproc);
@@ -383,6 +384,7 @@ 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 +483,7 @@ 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 +517,7 @@ struct rproc {
 	bool auto_boot;
 	struct list_head dump_segments;
 	int nb_vdev;
+	struct notifier_block panic_nb;
 };
 
 /**
-- 
2.24.0