diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 83acccdc1008..bdb450436cbc 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -59,6 +59,7 @@ struct regmap {
 			unsigned long raw_spinlock_flags;
 		};
 	};
+	struct lock_class_key *lock_key;
 	regmap_lock lock;
 	regmap_unlock unlock;
 	void *lock_arg; /* This is passed to lock/unlock functions */
diff --git a/drivers/base/regmap/regcache-maple.c b/drivers/base/regmap/regcache-maple.c
index 8d27d3653ea3..23da7b31d715 100644
--- a/drivers/base/regmap/regcache-maple.c
+++ b/drivers/base/regmap/regcache-maple.c
@@ -355,6 +355,9 @@ static int regcache_maple_init(struct regmap *map)
 
 	mt_init(mt);
 
+	if (!mt_external_lock(mt) && map->lock_key)
+		lockdep_set_class_and_subclass(&mt->ma_lock, map->lock_key, 1);
+
 	if (!map->num_reg_defaults)
 		return 0;
 
diff --git a/drivers/base/regmap/regmap-irq.c b/drivers/base/regmap/regmap-irq.c
index a750e48a26b8..0bcd81389a29 100644
--- a/drivers/base/regmap/regmap-irq.c
+++ b/drivers/base/regmap/regmap-irq.c
@@ -364,14 +364,11 @@ static irqreturn_t regmap_irq_thread(int irq, void *d)
 		memset32(data->status_buf, GENMASK(31, 0), chip->num_regs);
 	} else if (chip->num_main_regs) {
 		unsigned int max_main_bits;
-		unsigned long size;
-
-		size = chip->num_regs * sizeof(unsigned int);
 
 		max_main_bits = (chip->num_main_status_bits) ?
 				 chip->num_main_status_bits : chip->num_regs;
 		/* Clear the status buf as we don't read all status regs */
-		memset(data->status_buf, 0, size);
+		memset32(data->status_buf, 0, chip->num_regs);
 
 		/* We could support bulk read for main status registers
 		 * but I don't expect to see devices with really many main
@@ -514,12 +511,16 @@ exit:
 		return IRQ_NONE;
 }
 
+static struct lock_class_key regmap_irq_lock_class;
+static struct lock_class_key regmap_irq_request_class;
+
 static int regmap_irq_map(struct irq_domain *h, unsigned int virq,
 			  irq_hw_number_t hw)
 {
 	struct regmap_irq_chip_data *data = h->host_data;
 
 	irq_set_chip_data(virq, data);
+	irq_set_lockdep_class(virq, &regmap_irq_lock_class, &regmap_irq_request_class);
 	irq_set_chip(virq, &data->irq_chip);
 	irq_set_nested_thread(virq, 1);
 	irq_set_parent(virq, data->irq);
diff --git a/drivers/base/regmap/regmap-kunit.c b/drivers/base/regmap/regmap-kunit.c
index 4bf3f1e59ed7..64ea340950b6 100644
--- a/drivers/base/regmap/regmap-kunit.c
+++ b/drivers/base/regmap/regmap-kunit.c
@@ -126,7 +126,7 @@ static const struct regmap_test_param real_cache_types_list[] = {
 	{ .cache = REGCACHE_RBTREE, .from_reg = 0x2003 },
 	{ .cache = REGCACHE_RBTREE, .from_reg = 0x2004 },
 	{ .cache = REGCACHE_MAPLE,  .from_reg = 0 },
-	{ .cache = REGCACHE_RBTREE, .from_reg = 0, .fast_io = true },
+	{ .cache = REGCACHE_MAPLE,  .from_reg = 0, .fast_io = true },
 	{ .cache = REGCACHE_MAPLE,  .from_reg = 0x2001 },
 	{ .cache = REGCACHE_MAPLE,  .from_reg = 0x2002 },
 	{ .cache = REGCACHE_MAPLE,  .from_reg = 0x2003 },
@@ -1499,6 +1499,48 @@ static void cache_present(struct kunit *test)
 		KUNIT_ASSERT_TRUE(test, regcache_reg_cached(map, param->from_reg + i));
 }
 
+static void cache_write_zero(struct kunit *test)
+{
+	const struct regmap_test_param *param = test->param_value;
+	struct regmap *map;
+	struct regmap_config config;
+	struct regmap_ram_data *data;
+	unsigned int val;
+	int i;
+
+	config = test_regmap_config;
+
+	map = gen_regmap(test, &config, &data);
+	KUNIT_ASSERT_FALSE(test, IS_ERR(map));
+	if (IS_ERR(map))
+		return;
+
+	for (i = 0; i < BLOCK_TEST_SIZE; i++)
+		data->read[param->from_reg + i] = false;
+
+	/* No defaults so no registers cached. */
+	for (i = 0; i < BLOCK_TEST_SIZE; i++)
+		KUNIT_ASSERT_FALSE(test, regcache_reg_cached(map, param->from_reg + i));
+
+	/* We didn't trigger any reads */
+	for (i = 0; i < BLOCK_TEST_SIZE; i++)
+		KUNIT_ASSERT_FALSE(test, data->read[param->from_reg + i]);
+
+	/* Write a zero value */
+	KUNIT_EXPECT_EQ(test, 0, regmap_write(map, 1, 0));
+
+	/* Read that zero value back */
+	KUNIT_EXPECT_EQ(test, 0, regmap_read(map, 1, &val));
+	KUNIT_EXPECT_EQ(test, 0, val);
+
+	/* From the cache? */
+	KUNIT_ASSERT_TRUE(test, regcache_reg_cached(map, 1));
+
+	/* Try to throw it away */
+	KUNIT_EXPECT_EQ(test, 0, regcache_drop_region(map, 1, 1));
+	KUNIT_ASSERT_FALSE(test, regcache_reg_cached(map, 1));
+}
+
 /* Check that caching the window register works with sync */
 static void cache_range_window_reg(struct kunit *test)
 {
@@ -2012,6 +2054,7 @@ static struct kunit_case regmap_test_cases[] = {
 	KUNIT_CASE_PARAM(cache_drop_all_and_sync_no_defaults, sparse_cache_types_gen_params),
 	KUNIT_CASE_PARAM(cache_drop_all_and_sync_has_defaults, sparse_cache_types_gen_params),
 	KUNIT_CASE_PARAM(cache_present, sparse_cache_types_gen_params),
+	KUNIT_CASE_PARAM(cache_write_zero, sparse_cache_types_gen_params),
 	KUNIT_CASE_PARAM(cache_range_window_reg, real_cache_types_only_gen_params),
 
 	KUNIT_CASE_PARAM(raw_read_defaults_single, raw_test_types_gen_params),
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 4ded93687c1f..53131a7ede0a 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -745,6 +745,7 @@ struct regmap *__regmap_init(struct device *dev,
 						   lock_key, lock_name);
 		}
 		map->lock_arg = map;
+		map->lock_key = lock_key;
 	}
 
 	/*
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 75f162b60ba1..fd41baccbf3e 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -54,7 +54,14 @@ struct sdw_slave;
 #define REGMAP_UPSHIFT(s)	(-(s))
 #define REGMAP_DOWNSHIFT(s)	(s)
 
-/* An enum of all the supported cache types */
+/*
+ * The supported cache types, the default is no cache.  Any new caches
+ * should usually use the maple tree cache unless they specifically
+ * require that there are never any allocations at runtime and can't
+ * provide defaults in which case they should use the flat cache.  The
+ * rbtree cache *may* have some performance advantage for very low end
+ * systems that make heavy use of cache syncs but is mainly legacy.
+ */
 enum regcache_type {
 	REGCACHE_NONE,
 	REGCACHE_RBTREE,
@@ -1328,6 +1335,15 @@ static inline int regmap_clear_bits(struct regmap *map,
 	return regmap_update_bits_base(map, reg, bits, 0, NULL, false, false);
 }
 
+static inline int regmap_assign_bits(struct regmap *map, unsigned int reg,
+				     unsigned int bits, bool value)
+{
+	if (value)
+		return regmap_set_bits(map, reg, bits);
+	else
+		return regmap_clear_bits(map, reg, bits);
+}
+
 int regmap_test_bits(struct regmap *map, unsigned int reg, unsigned int bits);
 
 /**
@@ -1796,6 +1812,13 @@ static inline int regmap_clear_bits(struct regmap *map,
 	return -EINVAL;
 }
 
+static inline int regmap_assign_bits(struct regmap *map, unsigned int reg,
+				     unsigned int bits, bool value)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return -EINVAL;
+}
+
 static inline int regmap_test_bits(struct regmap *map,
 				   unsigned int reg, unsigned int bits)
 {