[PATCH V1 1/2] mfd: tps65910: use regmap for device register access.

[Laxman Dewangan <ldewangan@nvidia.com>]

Using regmap apis for accessing the device register.
using the RBTREE caching mechanims for caching registers.
Also provided apis for enabling register cache from
different sub devices of ts65910.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
---
This patch is towards the performance improvements in the 
voltage change.

 drivers/mfd/Kconfig          |    1 +
 drivers/mfd/tps65910.c       |  136 +++++++++++++++++++-----------------------
 include/linux/mfd/tps65910.h |    3 +
 3 files changed, 65 insertions(+), 75 deletions(-)

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index cd13e9f..0e066cd 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -162,6 +162,7 @@ config MFD_TPS65910
 	depends on I2C=y && GPIOLIB
 	select MFD_CORE
 	select GPIO_TPS65910
+	select REGMAP_I2C
 	help
 	  if you say yes here you get support for the TPS65910 series of
 	  Power Management chips.
diff --git a/drivers/mfd/tps65910.c b/drivers/mfd/tps65910.c
index 01cf501..1f2b004 100644
--- a/drivers/mfd/tps65910.c
+++ b/drivers/mfd/tps65910.c
@@ -16,10 +16,12 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/init.h>
+#include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/gpio.h>
 #include <linux/mfd/core.h>
+#include <linux/regmap.h>
 #include <linux/mfd/tps65910.h>
 
 static struct mfd_cell tps65910s[] = {
@@ -34,103 +36,76 @@ static struct mfd_cell tps65910s[] = {
 	},
 };
 
+static bool is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	struct tps65910 *tps65910 = dev_get_drvdata(dev);
+	return test_bit(reg, tps65910->cache_reg) ? false : true;
+}
+
+static bool regmap_volatile_range(struct tps65910 *tps65910,
+			unsigned int reg, unsigned int bytes)
+{
+	unsigned int i;
+	for (i = 0; i < bytes; i++)
+		if (!is_volatile_reg(tps65910->dev, reg + i))
+			return false;
+	return true;
+}
 
 static int tps65910_i2c_read(struct tps65910 *tps65910, u8 reg,
 				  int bytes, void *dest)
 {
-	struct i2c_client *i2c = tps65910->i2c_client;
-	struct i2c_msg xfer[2];
-	int ret;
-
-	/* Write register */
-	xfer[0].addr = i2c->addr;
-	xfer[0].flags = 0;
-	xfer[0].len = 1;
-	xfer[0].buf = &reg;
-
-	/* Read data */
-	xfer[1].addr = i2c->addr;
-	xfer[1].flags = I2C_M_RD;
-	xfer[1].len = bytes;
-	xfer[1].buf = dest;
-
-	ret = i2c_transfer(i2c->adapter, xfer, 2);
-	if (ret == 2)
-		ret = 0;
-	else if (ret >= 0)
-		ret = -EIO;
-
-	return ret;
+	return regmap_bulk_read(tps65910->regmap, reg, dest, bytes);
 }
 
 static int tps65910_i2c_write(struct tps65910 *tps65910, u8 reg,
-				   int bytes, void *src)
+				  int bytes, void *src)
 {
-	struct i2c_client *i2c = tps65910->i2c_client;
-	/* we add 1 byte for device register */
-	u8 msg[TPS65910_MAX_REGISTER + 1];
+	int i;
 	int ret;
-
-	if (bytes > TPS65910_MAX_REGISTER)
-		return -EINVAL;
-
-	msg[0] = reg;
-	memcpy(&msg[1], src, bytes);
-
-	ret = i2c_master_send(i2c, msg, bytes + 1);
-	if (ret < 0)
-		return ret;
-	if (ret != bytes + 1)
-		return -EIO;
+	unsigned char *wbuf = src;
+	unsigned int ival;
+
+	if (regmap_volatile_range(tps65910, reg, bytes))
+		return regmap_raw_write(tps65910->regmap, reg, src, bytes);
+
+	/* If any of register is non-volatile then use byte-wise transfer */
+	for (i = 0; i < bytes; ++i) {
+		ival = (unsigned int) (*wbuf++);
+		ret = regmap_write(tps65910->regmap, reg, ival);
+		if (ret < 0)
+			return ret;
+	}
 	return 0;
 }
 
 int tps65910_set_bits(struct tps65910 *tps65910, u8 reg, u8 mask)
 {
-	u8 data;
-	int err;
-
-	mutex_lock(&tps65910->io_mutex);
-	err = tps65910_i2c_read(tps65910, reg, 1, &data);
-	if (err) {
-		dev_err(tps65910->dev, "read from reg %x failed\n", reg);
-		goto out;
-	}
-
-	data |= mask;
-	err = tps65910_i2c_write(tps65910, reg, 1, &data);
-	if (err)
-		dev_err(tps65910->dev, "write to reg %x failed\n", reg);
-
-out:
-	mutex_unlock(&tps65910->io_mutex);
-	return err;
+	return regmap_update_bits(tps65910->regmap, reg, mask, mask);
 }
 EXPORT_SYMBOL_GPL(tps65910_set_bits);
 
 int tps65910_clear_bits(struct tps65910 *tps65910, u8 reg, u8 mask)
 {
-	u8 data;
-	int err;
-
-	mutex_lock(&tps65910->io_mutex);
-	err = tps65910_i2c_read(tps65910, reg, 1, &data);
-	if (err) {
-		dev_err(tps65910->dev, "read from reg %x failed\n", reg);
-		goto out;
-	}
-
-	data &= ~mask;
-	err = tps65910_i2c_write(tps65910, reg, 1, &data);
-	if (err)
-		dev_err(tps65910->dev, "write to reg %x failed\n", reg);
-
-out:
-	mutex_unlock(&tps65910->io_mutex);
-	return err;
+	return regmap_update_bits(tps65910->regmap, reg, mask, 0);
 }
 EXPORT_SYMBOL_GPL(tps65910_clear_bits);
 
+void tps65910_enable_reg_cache(struct tps65910 *tps65910, int reg)
+{
+	set_bit(reg, tps65910->cache_reg);
+}
+EXPORT_SYMBOL_GPL(tps65910_enable_reg_cache);
+
+static const struct regmap_config rc5t583_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.volatile_reg = is_volatile_reg,
+	.max_register = TPS65910_MAX_REGISTER,
+	.num_reg_defaults_raw = TPS65910_MAX_REGISTER,
+	.cache_type = REGCACHE_RBTREE,
+};
+
 static int tps65910_i2c_probe(struct i2c_client *i2c,
 			    const struct i2c_device_id *id)
 {
@@ -161,6 +136,13 @@ static int tps65910_i2c_probe(struct i2c_client *i2c,
 	tps65910->write = tps65910_i2c_write;
 	mutex_init(&tps65910->io_mutex);
 
+	tps65910->regmap = regmap_init_i2c(i2c, &rc5t583_regmap_config);
+	if (IS_ERR(tps65910->regmap)) {
+		ret = PTR_ERR(tps65910->regmap);
+		dev_err(&i2c->dev, "regmap initialization failed: %d\n", ret);
+		goto regmap_err;
+	}
+
 	ret = mfd_add_devices(tps65910->dev, -1,
 			      tps65910s, ARRAY_SIZE(tps65910s),
 			      NULL, 0);
@@ -178,6 +160,9 @@ static int tps65910_i2c_probe(struct i2c_client *i2c,
 	return ret;
 
 err:
+	mfd_remove_devices(tps65910->dev);
+	regmap_exit(tps65910->regmap);
+regmap_err:
 	kfree(tps65910);
 	kfree(init_data);
 	return ret;
@@ -189,6 +174,7 @@ static int tps65910_i2c_remove(struct i2c_client *i2c)
 
 	tps65910_irq_exit(tps65910);
 	mfd_remove_devices(tps65910->dev);
+	regmap_exit(tps65910->regmap);
 	kfree(tps65910);
 
 	return 0;
diff --git a/include/linux/mfd/tps65910.h b/include/linux/mfd/tps65910.h
index 5c76b96..6c68e2e 100644
--- a/include/linux/mfd/tps65910.h
+++ b/include/linux/mfd/tps65910.h
@@ -805,6 +805,7 @@ struct tps65910_board {
 struct tps65910 {
 	struct device *dev;
 	struct i2c_client *i2c_client;
+	struct regmap *regmap;
 	struct mutex io_mutex;
 	unsigned int id;
 	int (*read)(struct tps65910 *tps65910, u8 reg, int size, void *dest);
@@ -824,6 +825,7 @@ struct tps65910 {
 	int irq_base;
 	int irq_num;
 	u32 irq_mask;
+	unsigned long cache_reg[BITS_TO_LONGS(TPS65910_MAX_REGISTER)];
 };
 
 struct tps65910_platform_data {
@@ -837,6 +839,7 @@ void tps65910_gpio_init(struct tps65910 *tps65910, int gpio_base);
 int tps65910_irq_init(struct tps65910 *tps65910, int irq,
 		struct tps65910_platform_data *pdata);
 int tps65910_irq_exit(struct tps65910 *tps65910);
+void tps65910_enable_reg_cache(struct tps65910 *tps65910, int reg);
 
 static inline int tps65910_chip_id(struct tps65910 *tps65910)
 {
-- 
1.7.1.1