i2c-nforce2: Add support for multiplexing on the Tyan S4985
Just like the Tyan S4882, the S4985 uses a multiplexer to give access
to all 16 memory module SPD EEPROMs. This specific i2c-nforce2-s4985
driver adds support for this. It is heavily based on the older
i2c-amd756-s4882 driver.
As more mainboards will use multiplexer chips, we will have to find a
way to support them without having to write a new specfic driver for
each. The recent changes to the i2c subsystem should help us, and the
new gpio subsystem might help, too.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/i2c/busses/i2c-nforce2.c b/drivers/i2c/busses/i2c-nforce2.c
index 43c9f8d..f95efff 100644
--- a/drivers/i2c/busses/i2c-nforce2.c
+++ b/drivers/i2c/busses/i2c-nforce2.c
@@ -124,6 +124,20 @@
static struct pci_driver nforce2_driver;
+/* For multiplexing support, we need a global reference to the 1st
+ SMBus channel */
+#if defined CONFIG_I2C_NFORCE2_S4985 || defined CONFIG_I2C_NFORCE2_S4985_MODULE
+struct i2c_adapter *nforce2_smbus;
+EXPORT_SYMBOL_GPL(nforce2_smbus);
+
+static void nforce2_set_reference(struct i2c_adapter *adap)
+{
+ nforce2_smbus = adap;
+}
+#else
+static inline void nforce2_set_reference(struct i2c_adapter *adap) { }
+#endif
+
static void nforce2_abort(struct i2c_adapter *adap)
{
struct nforce2_smbus *smbus = adap->algo_data;
@@ -398,6 +412,7 @@
return -ENODEV;
}
+ nforce2_set_reference(&smbuses[0].adapter);
return 0;
}
@@ -406,6 +421,7 @@
{
struct nforce2_smbus *smbuses = (void*) pci_get_drvdata(dev);
+ nforce2_set_reference(NULL);
if (smbuses[0].base) {
i2c_del_adapter(&smbuses[0].adapter);
release_region(smbuses[0].base, smbuses[0].size);