[PATCH v2 2/4] i2c: mux: add basic support for calling i2c_register_spd on muxed bus segments

[Heiner Kallweit <hkallweit1@gmail.com>]

This extension allows mux drivers to instruct i2c_mux_add_adapter to
call i2c_register_spd. First user of this feature will be gpio mux.

Note: In order to avoid a link error we have to ensure that I2C_SMBUS=y
if I2C_MUX=y.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- Select I2C_SMBUS to avoid a link error if I2C_MUX=y and I2C_SMBUS=m
---
 drivers/i2c/Kconfig     | 1 +
 drivers/i2c/i2c-mux.c   | 4 ++++
 include/linux/i2c-mux.h | 1 +
 3 files changed, 6 insertions(+)

diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 9388823bb..f57a4d3fe 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -61,6 +61,7 @@ config I2C_CHARDEV
 
 config I2C_MUX
 	tristate "I2C bus multiplexing support"
+	select I2C_SMBUS
 	help
 	  Say Y here if you want the I2C core to support the ability to
 	  handle multiplexed I2C bus topologies, by presenting each
diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 57ff09f18..ada9c764f 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -22,6 +22,7 @@
 #include <linux/acpi.h>
 #include <linux/i2c.h>
 #include <linux/i2c-mux.h>
+#include <linux/i2c-smbus.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -429,6 +430,9 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
 	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
 		 i2c_adapter_id(&priv->adap));
 
+	if (muxc->register_spd)
+		i2c_register_spd(&priv->adap);
+
 	muxc->adapter[muxc->num_adapters++] = &priv->adap;
 	return 0;
 
diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
index 98ef73b7c..ec51d9bc4 100644
--- a/include/linux/i2c-mux.h
+++ b/include/linux/i2c-mux.h
@@ -21,6 +21,7 @@ struct i2c_mux_core {
 	unsigned int mux_locked:1;
 	unsigned int arbitrator:1;
 	unsigned int gate:1;
+	unsigned int register_spd:1;
 
 	void *priv;
 
-- 
2.43.0