[PATCH 3/3] i2c-piix4: support aux SMBus on AMD chipsets

[Andrew Armenia <andrew@asquaredlabs.com>]

Some AMD chipsets, such as the SP5100, have an auxiliary SMBus with a second
set of registers. This patch adds support for the SP5100 and should work on
similar chipsets. Tested on ASUS KCMA-D8 motherboard.

Signed-off-by: Andrew Armenia <andrew@asquaredlabs.com>
---
 drivers/i2c/busses/i2c-piix4.c |   83 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 76 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 8a87b3f..972b604 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -25,7 +25,8 @@
 	AMD Hudson-2
 	SMSC Victory66
 
-   Note: we assume there can only be one device, with one SMBus interface.
+   Note: we assume there can only be one device, with one or two SMBus
+   interfaces.
 */
 
 #include <linux/module.h>
@@ -66,6 +67,7 @@
 #define SMBSHDW1	0x0D4
 #define SMBSHDW2	0x0D5
 #define SMBREV		0x0D6
+#define SMBAUXBA	0x058
 
 /* Other settings */
 #define MAX_TIMEOUT	500
@@ -130,6 +132,8 @@ struct i2c_piix4_adapdata {
 	unsigned short smba;
 };
 
+static void piix4_adap_remove(struct i2c_adapter *adap);
+
 static int __devinit piix4_setup(struct pci_dev *PIIX4_dev,
 				const struct pci_device_id *id,
 				unsigned short *smba)
@@ -300,6 +304,45 @@ static int __devinit piix4_setup_sb800(struct pci_dev *PIIX4_dev,
 	return 0;
 }
 
+static int __devinit piix4_setup_aux(struct pci_dev *PIIX4_dev,
+				const struct pci_device_id *id,
+				unsigned short base_reg_addr,
+				unsigned short *smba)
+{
+	/* Set up auxiliary SMBus controllers found on some AMD
+	 * chipsets e.g. SP5100 */
+	unsigned short piix4_smba;
+
+	/* Read address of auxiliary SMBus controller */
+	pci_read_config_word(PIIX4_dev, base_reg_addr, &piix4_smba);
+	piix4_smba &= 0xffe0;
+
+	if (piix4_smba == 0) {
+		dev_err(&PIIX4_dev->dev, "Aux SMBus base address "
+			"uninitialized - upgrade BIOS\n");
+		return -ENODEV;
+	}
+
+	if (acpi_check_region(piix4_smba, SMBIOSIZE, piix4_driver.name))
+		return -ENODEV;
+
+	if (!request_region(piix4_smba, SMBIOSIZE, piix4_driver.name)) {
+		dev_err(&PIIX4_dev->dev, "Aux SMBus region 0x%x already"
+			" in use!\n", piix4_smba);
+		return -EBUSY;
+	}
+
+	dev_info(&PIIX4_dev->dev,
+		"Auxiliary SMBus Host Controller at 0x%x\n",
+		piix4_smba
+	);
+
+	*smba = piix4_smba;
+
+	return 0;
+}
+
+
 static int piix4_transaction(unsigned short piix4_smba)
 {
 	int temp;
@@ -505,6 +548,7 @@ static DEFINE_PCI_DEVICE_TABLE(piix4_ids) = {
 MODULE_DEVICE_TABLE (pci, piix4_ids);
 
 static struct i2c_adapter *piix4_main_adapter;
+static struct i2c_adapter *piix4_aux_adapter;
 
 /* register piix4 I2C adapter at the given base address */
 static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
@@ -562,9 +606,33 @@ static int __devinit piix4_probe(struct pci_dev *dev,
 		retval = piix4_setup(dev, id, &smba);
 
 	if (retval)
-		return retval;
+		goto error;
+
+	retval = piix4_add_adapter(dev, smba, &piix4_main_adapter);
+	if (retval)
+		goto error;
 
-	return piix4_add_adapter(dev, smba, &piix4_main_adapter);
+	/* check for AMD SP5100 (maybe others) with aux SMBus port */
+	if (dev->vendor == PCI_VENDOR_ID_ATI &&
+	    dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
+		dev->revision == 0x3d) {
+
+		retval = piix4_setup_aux(dev, id, SMBAUXBA, &smba);
+		if (retval)
+			goto error;
+
+		retval = piix4_add_adapter(dev, smba, &piix4_aux_adapter);
+		if (retval)
+			goto error;
+	}
+
+	return 0;
+
+error:
+	/* clean up any adapters that were already added */
+	piix4_adap_remove(piix4_main_adapter);
+	piix4_adap_remove(piix4_aux_adapter);
+	return retval;
 }
 
 /* Remove the adapter and its associated IO region */
@@ -572,6 +640,9 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
 {
 	struct i2c_piix4_adapdata *adapdata;
 
+	if (adap == NULL)
+		return;
+
 	adapdata = (struct i2c_piix4_adapdata *)i2c_get_adapdata(adap);
 	if (adapdata->smba) {
 		i2c_del_adapter(adap);
@@ -585,10 +656,8 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
 
 static void __devexit piix4_remove(struct pci_dev *dev)
 {
-	if (piix4_main_adapter) {
-		piix4_adap_remove(piix4_main_adapter);
-		piix4_main_adapter = NULL;
-	}
+	piix4_adap_remove(piix4_main_adapter);
+	piix4_adap_remove(piix4_aux_adapter);
 }
 
 static struct pci_driver piix4_driver = {
-- 
1.7.10