Commit 3c5a2865 authored Feb 11, 2020 by Geert Uytterhoeven Committed by Greg Kroah-Hartman May 17, 2023

debugfs: regset32: Add Runtime PM support



commit 30332eeefec8f83afcea00c360f99ef64b87f220 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 2298b300

fs/debugfs/file.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -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>

		@@ -1119,7 +1120,14 @@ 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;
		}

include/linux/debugfs.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -35,6 +35,7 @@ struct debugfs_regset32 {
		const struct debugfs_reg32 *regs;
		int nregs;
		void __iomem *base;
		struct device dev; / Optional device for Runtime PM */
		};

		extern struct dentry *arch_debugfs_dir;