[PATCH v4 2/3] i2c: piix4: fix probing of reserved ports on AMD

[Andrew Cooks]

Prevent bus timeouts and resets on Family 16h Model 30h), by not
probing reserved Ports 3 and 4.

According to the AMD BIOS and Kernel Developer's Guides (BKDG), Port 3
and Port 4 are reserved on the following devices:
 - Family 15h Model 60h-6Fh,
 - Family 15h Model 70h-7Fh,
 - Family 16h Model 30h-3Fh,

Signed-off-by: Andrew Cooks <andrew.co...@opengear.com>
---
 drivers/i2c/busses/i2c-piix4.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 5c90a44..01f1610 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -80,7 +80,8 @@
 #define PIIX4_BLOCK_DATA       0x14
 
 /* Multi-port constants */
-#define PIIX4_MAX_ADAPTERS 4
+#define PIIX4_MAX_ADAPTERS     4
+#define HUDSON2_MAIN_PORTS     2 /* HUDSON2, KERNCZ reserves ports 3, 4 */
 
 /* SB800 constants */
 #define SB800_PIIX4_SMB_IDX            0xcd6
@@ -800,6 +801,7 @@ MODULE_DEVICE_TABLE (pci, piix4_ids);
 
 static struct i2c_adapter *piix4_main_adapters[PIIX4_MAX_ADAPTERS];
 static struct i2c_adapter *piix4_aux_adapter;
+static int piix4_adapter_count;
 
 static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
                             bool sb800_main, u8 port, bool notify_imc,
@@ -849,6 +851,7 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned 
short smba,
        }
 
        *padap = adap;
+       piix4_adapter_count++;
        return 0;
 }
 
@@ -856,10 +859,17 @@ static int piix4_add_adapters_sb800(struct pci_dev *dev, 
unsigned short smba,
                                    bool notify_imc)
 {
        struct i2c_piix4_adapdata *adapdata;
-       int port;
+       int port, port_count;
        int retval;
 
-       for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
+       if (dev->device == PCI_DEVICE_ID_AMD_HUDSON2_SMBUS ||
+           dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) {
+               port_count = HUDSON2_MAIN_PORTS;
+       } else {
+               port_count = PIIX4_MAX_ADAPTERS;
+       }
+
+       for (port = 0; port < port_count; port++) {
                retval = piix4_add_adapter(dev, smba, true, port, notify_imc,
                                           piix4_main_port_names_sb800[port],
                                           &piix4_main_adapters[port]);
@@ -889,6 +899,7 @@ static int piix4_probe(struct pci_dev *dev, const struct 
pci_device_id *id)
 {
        int retval;
        bool is_sb800 = false;
+       piix4_adapter_count = 0;
 
        if ((dev->vendor == PCI_VENDOR_ID_ATI &&
             dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
@@ -993,7 +1004,7 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
 
 static void piix4_remove(struct pci_dev *dev)
 {
-       int port = PIIX4_MAX_ADAPTERS;
+       int port = piix4_adapter_count;
 
        while (--port >= 0) {
                if (piix4_main_adapters[port]) {
-- 
2.7.4