Merge tag 'regmap-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap

Pull regmap updates from Mark Brown:
 "The main change here is a fix for an issue where we were letting the
  selector for windowed register ranges get out of sync with the
  hardware during a cache sync plus associated KUnit tests. This was
  reported just at the end of the release cycle and only in -next for a
  day prior to the merge window so it seemed better to hold off for now,
  the bug had been present for more than a decade so wasn't causing too
  many practical problems hopefully.

  There's also a fix for error handling in the debugfs output from
  Christope Jaillet"

* tag 'regmap-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
  regmap: Ensure range selector registers are updated after cache sync
  regmap: kunit: Add test for cache sync interaction with ranges
  regmap: kunit: Fix marking of the range window as volatile
  regmap: debugfs: Fix a erroneous check after snprintf()

drivers/base/regmap/regcache.c

@@ -334,6 +334,11 @@ static int regcache_default_sync(struct regmap *map, unsigned int min,
 	return 0;
 }
 
+static int rbtree_all(const void *key, const struct rb_node *node)
+{
+	return 0;
+}
+
 /**
  * regcache_sync - Sync the register cache with the hardware.
  *
@@ -351,6 +356,7 @@ int regcache_sync(struct regmap *map)
 	unsigned int i;
 	const char *name;
 	bool bypass;
+	struct rb_node *node;
 
 	if (WARN_ON(map->cache_type == REGCACHE_NONE))
 		return -EINVAL;
@@ -392,6 +398,30 @@ int regcache_sync(struct regmap *map)
 	/* Restore the bypass state */
 	map->cache_bypass = bypass;
 	map->no_sync_defaults = false;
+
+	/*
+	 * If we did any paging with cache bypassed and a cached
+	 * paging register then the register and cache state might
+	 * have gone out of sync, force writes of all the paging
+	 * registers.
+	 */
+	rb_for_each(node, 0, &map->range_tree, rbtree_all) {
+		struct regmap_range_node *this =
+			rb_entry(node, struct regmap_range_node, node);
+
+		/* If there's nothing in the cache there's nothing to sync */
+		ret = regcache_read(map, this->selector_reg, &i);
+		if (ret != 0)
+			continue;
+
+		ret = _regmap_write(map, this->selector_reg, i);
+		if (ret != 0) {
+			dev_err(map->dev, "Failed to write %x = %x: %d\n",
+				this->selector_reg, i, ret);
+			break;
+		}
+	}
+
 	map->unlock(map->lock_arg);
 
 	regmap_async_complete(map);

drivers/base/regmap/regmap-debugfs.c

@@ -48,7 +48,7 @@ static ssize_t regmap_name_read_file(struct file *file,
 		name = map->dev->driver->name;
 
 	ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
-	if (ret < 0) {
+	if (ret >= PAGE_SIZE) {
 		kfree(buf);
 		return ret;
 	}

drivers/base/regmap/regmap-kunit.c

@@ -442,10 +442,18 @@ static struct regmap_range_cfg test_range = {
 	.range_max = 40,
 };
 
-static bool test_range_volatile(struct device *dev, unsigned int reg)
+static bool test_range_window_volatile(struct device *dev, unsigned int reg)
 {
 	if (reg >= test_range.window_start &&
-	    reg <= test_range.selector_reg + test_range.window_len)
+	    reg <= test_range.window_start + test_range.window_len)
+		return true;
+
+	return false;
+}
+
+static bool test_range_all_volatile(struct device *dev, unsigned int reg)
+{
+	if (test_range_window_volatile(dev, reg))
 		return true;
 
 	if (reg >= test_range.range_min && reg <= test_range.range_max)
@@ -465,7 +473,7 @@ static void basic_ranges(struct kunit *test)
 
 	config = test_regmap_config;
 	config.cache_type = t->type;
-	config.volatile_reg = test_range_volatile;
+	config.volatile_reg = test_range_all_volatile;
 	config.ranges = &test_range;
 	config.num_ranges = 1;
 	config.max_register = test_range.range_max;
@@ -875,6 +883,59 @@ static void cache_present(struct kunit *test)
 	regmap_exit(map);
 }
 
+/* Check that caching the window register works with sync */
+static void cache_range_window_reg(struct kunit *test)
+{
+	struct regcache_types *t = (struct regcache_types *)test->param_value;
+	struct regmap *map;
+	struct regmap_config config;
+	struct regmap_ram_data *data;
+	unsigned int val;
+	int i;
+
+	config = test_regmap_config;
+	config.cache_type = t->type;
+	config.volatile_reg = test_range_window_volatile;
+	config.ranges = &test_range;
+	config.num_ranges = 1;
+	config.max_register = test_range.range_max;
+
+	map = gen_regmap(&config, &data);
+	KUNIT_ASSERT_FALSE(test, IS_ERR(map));
+	if (IS_ERR(map))
+		return;
+
+	/* Write new values to the entire range */
+	for (i = test_range.range_min; i <= test_range.range_max; i++)
+		KUNIT_ASSERT_EQ(test, 0, regmap_write(map, i, 0));
+
+	val = data->vals[test_range.selector_reg] & test_range.selector_mask;
+	KUNIT_ASSERT_EQ(test, val, 2);
+
+	/* Write to the first register in the range to reset the page */
+	KUNIT_ASSERT_EQ(test, 0, regmap_write(map, test_range.range_min, 0));
+	val = data->vals[test_range.selector_reg] & test_range.selector_mask;
+	KUNIT_ASSERT_EQ(test, val, 0);
+
+	/* Trigger a cache sync */
+	regcache_mark_dirty(map);
+	KUNIT_ASSERT_EQ(test, 0, regcache_sync(map));
+
+	/* Write to the first register again, the page should be reset */
+	KUNIT_ASSERT_EQ(test, 0, regmap_write(map, test_range.range_min, 0));
+	val = data->vals[test_range.selector_reg] & test_range.selector_mask;
+	KUNIT_ASSERT_EQ(test, val, 0);
+
+	/* Trigger another cache sync */
+	regcache_mark_dirty(map);
+	KUNIT_ASSERT_EQ(test, 0, regcache_sync(map));
+
+	/* Write to the last register again, the page should be reset */
+	KUNIT_ASSERT_EQ(test, 0, regmap_write(map, test_range.range_max, 0));
+	val = data->vals[test_range.selector_reg] & test_range.selector_mask;
+	KUNIT_ASSERT_EQ(test, val, 2);
+}
+
 struct raw_test_types {
 	const char *name;
 
@@ -1217,6 +1278,7 @@ static struct kunit_case regmap_test_cases[] = {
 	KUNIT_CASE_PARAM(cache_sync_patch, real_cache_types_gen_params),
 	KUNIT_CASE_PARAM(cache_drop, sparse_cache_types_gen_params),
 	KUNIT_CASE_PARAM(cache_present, sparse_cache_types_gen_params),
+	KUNIT_CASE_PARAM(cache_range_window_reg, real_cache_types_gen_params),
 
 	KUNIT_CASE_PARAM(raw_read_defaults_single, raw_test_types_gen_params),
 	KUNIT_CASE_PARAM(raw_read_defaults, raw_test_types_gen_params),