regmap: mmio: Fix regmap_mmio_write for uneven counts

Commit 93258040
"regmap: mmio: Add support for 1/2/8 bytes wide register address."
broke regmap_mmio_write for uneven counts, for example 32-bit register
addresses with no padding and 8-byte values (count = 5).
Fix this by allowing all counts large enough to include some value.
This check was BUG_ON(count < 4) before the last change.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/base/regmap/regmap-mmio.c

@@ -61,9 +61,9 @@ static int regmap_mmio_regbits_check(size_t reg_bits)
 	}
 }
 
-static inline void regmap_mmio_count_check(size_t count)
+static inline void regmap_mmio_count_check(size_t count, u32 offset)
 {
-	BUG_ON(count % 2 != 0);
+	BUG_ON(count <= offset);
 }
 
 static int regmap_mmio_gather_write(void *context,
@@ -120,7 +120,7 @@ static int regmap_mmio_write(void *context, const void *data, size_t count)
 	struct regmap_mmio_context *ctx = context;
 	u32 offset = ctx->reg_bytes + ctx->pad_bytes;
 
-	regmap_mmio_count_check(count);
+	regmap_mmio_count_check(count, offset);
 
 	return regmap_mmio_gather_write(context, data, ctx->reg_bytes,
 					data + offset, count - offset);