[PATCH 6/7] alpha: marvel: notify environmental events

[Matt Turner <mattst88@gmail.com>]

A change in the state of a sensor arrives as a system event logout
frame. Call an atomic notifier chain on each one, so that a sensor
driver can reread its sensors and tell userspace without polling.

Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Matt Turner <mattst88@gmail.com>
---
 arch/alpha/include/asm/marvel_env.h | 5 +++++
 arch/alpha/kernel/err_marvel.c      | 9 ++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/alpha/include/asm/marvel_env.h b/arch/alpha/include/asm/marvel_env.h
index 583dca6c02d1..14b05efa6f51 100644
--- a/arch/alpha/include/asm/marvel_env.h
+++ b/arch/alpha/include/asm/marvel_env.h
@@ -2,6 +2,8 @@
 #ifndef __ALPHA_MARVEL_ENV_H
 #define __ALPHA_MARVEL_ENV_H
 
+#include <linux/notifier.h>
+
 /*
  * Ask the console to refresh the environmental readings of the GCT node at
  * @offset from the start of the GCT. Returns the console status, which is 1
@@ -9,4 +11,7 @@
  */
 long marvel_cfgtree_partial_update(unsigned long offset);
 
+/* Called from machine check context on each environmental system event. */
+extern struct atomic_notifier_head marvel_env_notifier;
+
 #endif /* __ALPHA_MARVEL_ENV_H */
diff --git a/arch/alpha/kernel/err_marvel.c b/arch/alpha/kernel/err_marvel.c
index 46c521cea9a0..6e0b0aabdaca 100644
--- a/arch/alpha/kernel/err_marvel.c
+++ b/arch/alpha/kernel/err_marvel.c
@@ -17,10 +17,14 @@
 #include <asm/smp.h>
 #include <asm/err_common.h>
 #include <asm/err_ev7.h>
+#include <asm/marvel_env.h>
 
 #include "err_impl.h"
 #include "proto.h"
 
+ATOMIC_NOTIFIER_HEAD(marvel_env_notifier);
+EXPORT_SYMBOL_GPL(marvel_env_notifier);
+
 static const char *
 marvel_env_state(u16 state)
 {
@@ -82,8 +86,11 @@ marvel_process_680_frame(struct ev7_lf_subpackets *lf_subpackets, int print)
 			status = MCHK_DISPOSITION_REPORT;
 	}
 
-	if (print)
+	/* The frame is processed twice; notify on the printing pass only. */
+	if (print) {
 		marvel_print_680_frame(lf_subpackets);
+		atomic_notifier_call_chain(&marvel_env_notifier, 0, NULL);
+	}
 
 	return status;
 }

-- 
2.56.1