regmap: Add soundwire bus support

Add soundwire bus support to regmap. This change enables
codec drivers using soundwire hardware interface to use
regmap interface for register read/write functionality.

Signed-off-by: Sudheer Papothi <spapothi@codeaurora.org>

drivers/base/regmap/Kconfig

@@ -3,7 +3,7 @@
 # subsystems should select the appropriate symbols.
 
 config REGMAP
-	default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ)
+	default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ || REGMAP_SWR)
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
 	select IRQ_DOMAIN if REGMAP_IRQ
@@ -29,3 +29,6 @@ config REGMAP_MMIO
 
 config REGMAP_IRQ
 	bool
+
+config REGMAP_SWR
+	tristate

drivers/base/regmap/Makefile

@@ -10,3 +10,4 @@ obj-$(CONFIG_REGMAP_SPI) += regmap-spi.o
 obj-$(CONFIG_REGMAP_SPMI) += regmap-spmi.o
 obj-$(CONFIG_REGMAP_MMIO) += regmap-mmio.o
 obj-$(CONFIG_REGMAP_IRQ) += regmap-irq.o
+obj-$(CONFIG_REGMAP_SWR) += regmap-swr.o

drivers/base/regmap/regmap-swr.c

@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2015, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/regmap.h>
+#include <linux/soundwire/soundwire.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+#include "internal.h"
+
+static int regmap_swr_gather_write(void *context,
+				const void *reg, size_t reg_size,
+				const void *val, size_t val_size)
+{
+	struct device *dev = context;
+	struct swr_device *swr = to_swr_device(dev);
+	struct regmap *map = dev_get_regmap(dev, NULL);
+	size_t addr_bytes = map->format.reg_bytes;
+	int ret = 0;
+	int i;
+	u32 reg_addr = 0;
+
+	if (swr == NULL) {
+		dev_err(dev, "%s: swr device is NULL\n", __func__);
+		return -EINVAL;
+	}
+	if (reg_size != addr_bytes) {
+		dev_err(dev, "%s: reg size %zd bytes not supported\n",
+			__func__, reg_size);
+		return -EINVAL;
+	}
+	reg_addr = *(u16 *)reg;
+	for (i = 0; i < val_size; i++) {
+		ret = swr_write(swr, swr->dev_num, (reg_addr+i),
+				(u32 *)(val+i));
+		if (ret < 0) {
+			dev_err(dev, "%s: write reg 0x%x failed, err %d\n",
+				__func__, (reg_addr+i), ret);
+			break;
+		}
+	}
+	return ret;
+}
+
+static int regmap_swr_write(void *context, const void *data, size_t count)
+{
+	struct device *dev = context;
+	struct regmap *map = dev_get_regmap(dev, NULL);
+	size_t addr_bytes = map->format.reg_bytes;
+
+	WARN_ON(count < addr_bytes);
+
+	return regmap_swr_gather_write(context, data, addr_bytes,
+					(data + addr_bytes),
+					(count - addr_bytes));
+}
+
+static int regmap_swr_read(void *context,
+			const void *reg, size_t reg_size,
+			void *val, size_t val_size)
+{
+	struct device *dev = context;
+	struct swr_device *swr = to_swr_device(dev);
+	struct regmap *map = dev_get_regmap(dev, NULL);
+	size_t addr_bytes = map->format.reg_bytes;
+	int ret = 0;
+	u32 reg_addr = 0;
+
+	if (swr == NULL) {
+		dev_err(dev, "%s: swr is NULL\n", __func__);
+		return -EINVAL;
+	}
+	if (reg_size != addr_bytes) {
+		dev_err(dev, "%s: register size %zd bytes not supported\n",
+			__func__, reg_size);
+		return -EINVAL;
+	}
+	reg_addr = *(u32 *)reg;
+	ret = swr_read(swr, swr->dev_num, reg_addr, val, val_size);
+	if (ret < 0)
+		dev_err(dev, "%s: codec reg 0x%x read failed %d\n",
+			__func__, reg_addr, ret);
+	return ret;
+}
+
+static struct regmap_bus regmap_swr = {
+	.write = regmap_swr_write,
+	.gather_write = regmap_swr_gather_write,
+	.read = regmap_swr_read,
+	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
+	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
+};
+
+struct regmap *__regmap_init_swr(struct swr_device *swr,
+				 const struct regmap_config *config,
+				 struct lock_class_key *lock_key,
+				 const char *lock_name)
+{
+	return __regmap_init(&swr->dev, &regmap_swr, &swr->dev, config,
+			   lock_key, lock_name);
+}
+EXPORT_SYMBOL(__regmap_init_swr);
+
+struct regmap *__devm_regmap_init_swr(struct swr_device *swr,
+				      const struct regmap_config *config,
+				      struct lock_class_key *lock_key,
+				      const char *lock_name)
+{
+	return __devm_regmap_init(&swr->dev, &regmap_swr, &swr->dev, config,
+				lock_key, lock_name);
+}
+EXPORT_SYMBOL(__devm_regmap_init_swr);
+
+MODULE_LICENSE("GPL v2");

include/linux/regmap.h

@@ -29,6 +29,7 @@ struct regmap;
 struct regmap_range_cfg;
 struct regmap_field;
 struct snd_ac97;
+struct swr_device;
 
 /* An enum of all the supported cache types */
 enum regcache_type {
@@ -387,7 +388,10 @@ struct regmap *__regmap_init_ac97(struct snd_ac97 *ac97,
 				  const struct regmap_config *config,
 				  struct lock_class_key *lock_key,
 				  const char *lock_name);
-
+struct regmap *__regmap_init_swr(struct swr_device *dev,
+				 const struct regmap_config *config,
+				 struct lock_class_key *lock_key,
+				 const char *lock_name);
 struct regmap *__devm_regmap_init(struct device *dev,
 				  const struct regmap_bus *bus,
 				  void *bus_context,
@@ -420,6 +424,10 @@ struct regmap *__devm_regmap_init_ac97(struct snd_ac97 *ac97,
 				       const struct regmap_config *config,
 				       struct lock_class_key *lock_key,
 				       const char *lock_name);
+struct regmap *__devm_regmap_init_swr(struct swr_device *dev,
+				      const struct regmap_config *config,
+				      struct lock_class_key *lock_key,
+				      const char *lock_name);
 
 /*
  * Wrapper for regmap_init macros to include a unique lockdep key and name
@@ -553,6 +561,18 @@ int regmap_attach_dev(struct device *dev, struct regmap *map,
 				ac97, config)
 bool regmap_ac97_default_volatile(struct device *dev, unsigned int reg);
 
+/**
+ * regmap_init_swr(): Initialise register map
+ *
+ * @swr: Device that will be interacted with
+ * @config: Configuration for register map
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer to
+ * a struct regmap.
+ */
+#define regmap_init_swr(swr, config)					\
+	__regmap_lockdep_wrapper(__regmap_init_swr, #config,		\
+				swr, config)
 /**
  * devm_regmap_init(): Initialise managed register map
  *
@@ -668,6 +688,20 @@ bool regmap_ac97_default_volatile(struct device *dev, unsigned int reg);
 	__regmap_lockdep_wrapper(__devm_regmap_init_ac97, #config,	\
 				ac97, config)
 
+/**
+ * devm_regmap_init_swr(): Initialise managed register map
+ *
+ * @swr: Device that will be interacted with
+ * @config: Configuration for register map
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer
+ * to a struct regmap.  The regmap will be automatically freed by the
+ * device management code.
+ */
+#define devm_regmap_init_swr(swr, config)				\
+	__regmap_lockdep_wrapper(__devm_regmap_init_swr, #config,	\
+				swr, config)
+
 void regmap_exit(struct regmap *map);
 int regmap_reinit_cache(struct regmap *map,
 			const struct regmap_config *config);