1 files changed, 47 insertions, 15 deletions

diff --git a/drivers/base/regmap/regmap-spi.c b/drivers/base/regmap/regmap-spi.c
index c7150dd264d5..14b1d88997cb 100644
--- a/drivers/base/regmap/regmap-spi.c
+++ b/drivers/base/regmap/regmap-spi.c
@@ -1,14 +1,10 @@
-/*
- * Register map access API - SPI support
- *
- * Copyright 2011 Wolfson Microelectronics plc
- *
- * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
+// SPDX-License-Identifier: GPL-2.0
+//
+// Register map access API - SPI support
+//
+// Copyright 2011 Wolfson Microelectronics plc
+//
+// Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
 
 #include <linux/regmap.h>
 #include <linux/spi/spi.h>
@@ -113,13 +109,44 @@ static const struct regmap_bus regmap_spi = {
 	.val_format_endian_default = REGMAP_ENDIAN_BIG,
 };
 
+static const struct regmap_bus *regmap_get_spi_bus(struct spi_device *spi,
+						   const struct regmap_config *config)
+{
+	size_t max_size = spi_max_transfer_size(spi);
+	size_t max_msg_size, reg_reserve_size;
+	struct regmap_bus *bus;
+
+	if (max_size != SIZE_MAX) {
+		bus = kmemdup(&regmap_spi, sizeof(*bus), GFP_KERNEL);
+		if (!bus)
+			return ERR_PTR(-ENOMEM);
+
+		max_msg_size = spi_max_message_size(spi);
+		reg_reserve_size = (config->reg_bits + config->pad_bits) / BITS_PER_BYTE;
+		if (max_size + reg_reserve_size > max_msg_size)
+			max_size -= reg_reserve_size;
+
+		bus->free_on_exit = true;
+		bus->max_raw_read = max_size;
+		bus->max_raw_write = max_size;
+
+		return bus;
+	}
+
+	return &regmap_spi;
+}
+
 struct regmap *__regmap_init_spi(struct spi_device *spi,
 				 const struct regmap_config *config,
 				 struct lock_class_key *lock_key,
 				 const char *lock_name)
 {
-	return __regmap_init(&spi->dev, &regmap_spi, &spi->dev, config,
-			     lock_key, lock_name);
+	const struct regmap_bus *bus = regmap_get_spi_bus(spi, config);
+
+	if (IS_ERR(bus))
+		return ERR_CAST(bus);
+
+	return __regmap_init(&spi->dev, bus, &spi->dev, config, lock_key, lock_name);
 }
 EXPORT_SYMBOL_GPL(__regmap_init_spi);
 
@@ -128,9 +155,14 @@ struct regmap *__devm_regmap_init_spi(struct spi_device *spi,
 				      struct lock_class_key *lock_key,
 				      const char *lock_name)
 {
-	return __devm_regmap_init(&spi->dev, &regmap_spi, &spi->dev, config,
-				  lock_key, lock_name);
+	const struct regmap_bus *bus = regmap_get_spi_bus(spi, config);
+
+	if (IS_ERR(bus))
+		return ERR_CAST(bus);
+
+	return __devm_regmap_init(&spi->dev, bus, &spi->dev, config, lock_key, lock_name);
 }
 EXPORT_SYMBOL_GPL(__devm_regmap_init_spi);
 
+MODULE_DESCRIPTION("regmap SPI Module");
 MODULE_LICENSE("GPL");