linux-kernel - Applied "regmap: debugfs: Allow writes to cache state settings" to the regmap tree

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Date:	Mon, 20 Jul 2015 18:52:36 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Richard Fitzgerald <rf@...nsource.wolfsonmicro.com>,
	Mark Brown <broonie@...nel.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Applied "regmap: debugfs: Allow writes to cache state settings" to the regmap tree

The patch

   regmap: debugfs: Allow writes to cache state settings

has been applied to the regmap tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From d3dc5430d68fb91a62d971648170b34d46ab85bc Mon Sep 17 00:00:00 2001
From: Richard Fitzgerald <rf@...nsource.wolfsonmicro.com>
Date: Tue, 23 Jun 2015 14:32:55 +0100
Subject: [PATCH] regmap: debugfs: Allow writes to cache state settings

Allow the user to write the cache_only and cache_bypass settings.
This can be useful for debugging.

Since this can lead to the hardware getting out-of-sync with the
cache, at least for the period that the cache state is forced, the
kernel is tainted and the action is recorded in the kernel log.

When disabling cache_only through debugfs a cache sync will be performed.

Signed-off-by: Richard Fitzgerald <rf@...nsource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/base/regmap/regmap-debugfs.c | 90 ++++++++++++++++++++++++++++++++++--
 1 file changed, 86 insertions(+), 4 deletions(-)

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 5799a0b9e6cc..6a61e4fa73a2 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -469,6 +469,87 @@ static const struct file_operations regmap_access_fops = {
 	.llseek = default_llseek,
 };
 
+static ssize_t regmap_cache_only_write_file(struct file *file,
+					    const char __user *user_buf,
+					    size_t count, loff_t *ppos)
+{
+	struct regmap *map = container_of(file->private_data,
+					  struct regmap, cache_only);
+	ssize_t result;
+	bool was_enabled, require_sync = false;
+	int err;
+
+	map->lock(map->lock_arg);
+
+	was_enabled = map->cache_only;
+
+	result = debugfs_write_file_bool(file, user_buf, count, ppos);
+	if (result < 0) {
+		map->unlock(map->lock_arg);
+		return result;
+	}
+
+	if (map->cache_only && !was_enabled) {
+		dev_warn(map->dev, "debugfs cache_only=Y forced\n");
+		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+	} else if (!map->cache_only && was_enabled) {
+		dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
+		require_sync = true;
+	}
+
+	map->unlock(map->lock_arg);
+
+	if (require_sync) {
+		err = regcache_sync(map);
+		if (err)
+			dev_err(map->dev, "Failed to sync cache %d\n", err);
+	}
+
+	return result;
+}
+
+static const struct file_operations regmap_cache_only_fops = {
+	.open = simple_open,
+	.read = debugfs_read_file_bool,
+	.write = regmap_cache_only_write_file,
+};
+
+static ssize_t regmap_cache_bypass_write_file(struct file *file,
+					      const char __user *user_buf,
+					      size_t count, loff_t *ppos)
+{
+	struct regmap *map = container_of(file->private_data,
+					  struct regmap, cache_bypass);
+	ssize_t result;
+	bool was_enabled;
+
+	map->lock(map->lock_arg);
+
+	was_enabled = map->cache_bypass;
+
+	result = debugfs_write_file_bool(file, user_buf, count, ppos);
+	if (result < 0)
+		goto out;
+
+	if (map->cache_bypass && !was_enabled) {
+		dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
+		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+	} else if (!map->cache_bypass && was_enabled) {
+		dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
+	}
+
+out:
+	map->unlock(map->lock_arg);
+
+	return result;
+}
+
+static const struct file_operations regmap_cache_bypass_fops = {
+	.open = simple_open,
+	.read = debugfs_read_file_bool,
+	.write = regmap_cache_bypass_write_file,
+};
+
 void regmap_debugfs_init(struct regmap *map, const char *name)
 {
 	struct rb_node *next;
@@ -530,12 +611,13 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
 	}
 
 	if (map->cache_type) {
-		debugfs_create_bool("cache_only", 0400, map->debugfs,
-				    &map->cache_only);
+		debugfs_create_file("cache_only", 0600, map->debugfs,
+				    &map->cache_only, &regmap_cache_only_fops);
 		debugfs_create_bool("cache_dirty", 0400, map->debugfs,
 				    &map->cache_dirty);
-		debugfs_create_bool("cache_bypass", 0400, map->debugfs,
-				    &map->cache_bypass);
+		debugfs_create_file("cache_bypass", 0600, map->debugfs,
+				    &map->cache_bypass,
+				    &regmap_cache_bypass_fops);
 	}
 
 	next = rb_first(&map->range_tree);
-- 
2.1.4

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