From 30332eeefec8f83afcea00c360f99ef64b87f220 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Tue, 11 Feb 2020 19:18:55 +0100
Subject: debugfs: regset32: Add Runtime PM support
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Hardware registers of devices under control of power management cannot
be accessed at all times.  If such a device is suspended, register
accesses may lead to undefined behavior, like reading bogus values, or
causing exceptions or system lock-ups.

Extend struct debugfs_regset32 with an optional field to let device
drivers specify the device the registers in the set belong to.  This
allows debugfs_show_regset32() to make sure the device is resumed while
its registers are being read.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 fs/debugfs/file.c | 8 ++++++++
 1 file changed, 8 insertions(+)

(limited to 'fs')

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 634b09d18b77..204734f8d1c6 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -18,6 +18,7 @@
 #include <linux/slab.h>
 #include <linux/atomic.h>
 #include <linux/device.h>
+#include <linux/pm_runtime.h>
 #include <linux/poll.h>
 #include <linux/security.h>
 
@@ -1060,7 +1061,14 @@ static int debugfs_show_regset32(struct seq_file *s, void *data)
 {
 	struct debugfs_regset32 *regset = s->private;
 
+	if (regset->dev)
+		pm_runtime_get_sync(regset->dev);
+
 	debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, "");
+
+	if (regset->dev)
+		pm_runtime_put(regset->dev);
+
 	return 0;
 }
 
-- 
cgit