[PATCH v2 2/4] mfd: bcm590xx: add support for secondary I2C slave address

[Matt Porter <mporter@linaro.org>]

BCM590xx utilizes a secondary I2C slave address to access additional
register space. Add support for the secondary address space by
instantiating a dummy I2C device with the appropriate secondary
I2C slave address. Also expose a secondary regmap register space so
that MFD drivers can access this secondary i2c slave address space.

Signed-off-by: Matt Porter <mporter@linaro.org>
---
 drivers/mfd/bcm590xx.c       | 60 +++++++++++++++++++++++++++++++++-----------
 include/linux/mfd/bcm590xx.h |  9 ++++---
 2 files changed, 52 insertions(+), 17 deletions(-)

diff --git a/drivers/mfd/bcm590xx.c b/drivers/mfd/bcm590xx.c
index e9a33c7..43cba1a 100644
--- a/drivers/mfd/bcm590xx.c
+++ b/drivers/mfd/bcm590xx.c
@@ -28,39 +28,71 @@ static const struct mfd_cell bcm590xx_devs[] = {
 	},
 };
 
-static const struct regmap_config bcm590xx_regmap_config = {
+static const struct regmap_config bcm590xx_regmap_config_pri = {
 	.reg_bits	= 8,
 	.val_bits	= 8,
-	.max_register	= BCM590XX_MAX_REGISTER,
+	.max_register	= BCM590XX_MAX_REGISTER_PRI,
 	.cache_type	= REGCACHE_RBTREE,
 };
 
-static int bcm590xx_i2c_probe(struct i2c_client *i2c,
+static const struct regmap_config bcm590xx_regmap_config_sec = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= BCM590XX_MAX_REGISTER_SEC,
+	.cache_type	= REGCACHE_RBTREE,
+};
+
+static int bcm590xx_i2c_probe(struct i2c_client *i2c_pri,
 			      const struct i2c_device_id *id)
 {
 	struct bcm590xx *bcm590xx;
 	int ret;
 
-	bcm590xx = devm_kzalloc(&i2c->dev, sizeof(*bcm590xx), GFP_KERNEL);
+	bcm590xx = devm_kzalloc(&i2c_pri->dev, sizeof(*bcm590xx), GFP_KERNEL);
 	if (!bcm590xx)
 		return -ENOMEM;
 
-	i2c_set_clientdata(i2c, bcm590xx);
-	bcm590xx->dev = &i2c->dev;
-	bcm590xx->i2c_client = i2c;
+	i2c_set_clientdata(i2c_pri, bcm590xx);
+	bcm590xx->dev = &i2c_pri->dev;
+	bcm590xx->i2c_pri = i2c_pri;
 
-	bcm590xx->regmap = devm_regmap_init_i2c(i2c, &bcm590xx_regmap_config);
-	if (IS_ERR(bcm590xx->regmap)) {
-		ret = PTR_ERR(bcm590xx->regmap);
-		dev_err(&i2c->dev, "regmap initialization failed: %d\n", ret);
+	bcm590xx->regmap_pri = devm_regmap_init_i2c(i2c_pri,
+						 &bcm590xx_regmap_config_pri);
+	if (IS_ERR(bcm590xx->regmap_pri)) {
+		ret = PTR_ERR(bcm590xx->regmap_pri);
+		dev_err(&i2c_pri->dev, "primary regmap init failed: %d\n", ret);
 		return ret;
 	}
 
-	ret = mfd_add_devices(&i2c->dev, -1, bcm590xx_devs,
+	/* Secondary I2C slave address is the base address with A(2) asserted */
+	bcm590xx->i2c_sec = i2c_new_dummy(i2c_pri->adapter,
+					  i2c_pri->addr | BIT(2));
+	if (IS_ERR_OR_NULL(bcm590xx->i2c_sec)) {
+		dev_err(&i2c_pri->dev, "failed to add secondary I2C device\n");
+		return -ENODEV;
+	}
+	i2c_set_clientdata(bcm590xx->i2c_sec, bcm590xx);
+
+	bcm590xx->regmap_sec = devm_regmap_init_i2c(bcm590xx->i2c_sec,
+						&bcm590xx_regmap_config_sec);
+	if (IS_ERR(bcm590xx->regmap_sec)) {
+		ret = PTR_ERR(bcm590xx->regmap_sec);
+		dev_err(&bcm590xx->i2c_sec->dev,
+			"secondary regmap init failed: %d\n", ret);
+		goto err;
+	}
+
+	ret = mfd_add_devices(&i2c_pri->dev, -1, bcm590xx_devs,
 			      ARRAY_SIZE(bcm590xx_devs), NULL, 0, NULL);
-	if (ret < 0)
-		dev_err(&i2c->dev, "failed to add sub-devices: %d\n", ret);
+	if (ret < 0) {
+		dev_err(&i2c_pri->dev, "failed to add sub-devices: %d\n", ret);
+		goto err;
+	}
+
+	return 0;
 
+err:
+	i2c_unregister_device(bcm590xx->i2c_sec);
 	return ret;
 }
 
diff --git a/include/linux/mfd/bcm590xx.h b/include/linux/mfd/bcm590xx.h
index 434df2d..267aede 100644
--- a/include/linux/mfd/bcm590xx.h
+++ b/include/linux/mfd/bcm590xx.h
@@ -19,12 +19,15 @@
 #include <linux/regmap.h>
 
 /* max register address */
-#define BCM590XX_MAX_REGISTER	0xe7
+#define BCM590XX_MAX_REGISTER_PRI	0xe7
+#define BCM590XX_MAX_REGISTER_SEC	0xf0
 
 struct bcm590xx {
 	struct device *dev;
-	struct i2c_client *i2c_client;
-	struct regmap *regmap;
+	struct i2c_client *i2c_pri;
+	struct i2c_client *i2c_sec;
+	struct regmap *regmap_pri;
+	struct regmap *regmap_sec;
 	unsigned int id;
 };
 
-- 
1.8.4