3 files changed, 82 insertions, 4 deletions

diff --git a/Documentation/i2c/busses/i2c-piix4 b/Documentation/i2c/busses/i2c-piix4
index 475bb4ae0720..1e6634f54c50 100644
--- a/Documentation/i2c/busses/i2c-piix4
+++ b/Documentation/i2c/busses/i2c-piix4
@@ -8,6 +8,11 @@ Supported adapters:
     Datasheet: Only available via NDA from ServerWorks
   * ATI IXP200, IXP300, IXP400, SB600, SB700 and SB800 southbridges
     Datasheet: Not publicly available
+    SB700 register reference available at:
+    http://support.amd.com/us/Embedded_TechDocs/43009_sb7xx_rrg_pub_1.00.pdf
+  * AMD SP5100 (SB700 derivative found on some server mainboards)
+    Datasheet: Publicly available at the AMD website
+    http://support.amd.com/us/Embedded_TechDocs/44413.pdf
   * AMD Hudson-2
     Datasheet: Not publicly available
   * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge
@@ -68,6 +73,10 @@ this driver on those mainboards.
 The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are
 identical to the PIIX4 in I2C/SMBus support.
 
+The AMD SB700 and SP5100 chipsets implement two PIIX4-compatible SMBus
+controllers. If your BIOS initializes the secondary controller, it will
+be detected by this driver as an "Auxiliary SMBus Host Controller".
+
 If you own Force CPCI735 motherboard or other OSB4 based systems you may need
 to change the SMBus Interrupt Select register so the SMBus controller uses
 the SMI mode.
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 7244c8be6063..2e7530a4e7b8 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -133,7 +133,7 @@ config I2C_PIIX4
             ATI IXP300
             ATI IXP400
             ATI SB600
-            ATI SB700
+            ATI SB700/SP5100
             ATI SB800
             AMD Hudson-2
             Serverworks OSB4
@@ -143,6 +143,10 @@ config I2C_PIIX4
             Serverworks HT-1100
             SMSC Victory66
 
+          Some AMD chipsets contain two PIIX4-compatible SMBus
+          controllers. This driver will attempt to use both controllers
+          on the SB700/SP5100, if they have been initialized by the BIOS.
+
           This driver can also be built as a module.  If so, the module
           will be called i2c-piix4.
 
diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 42ed0af10efd..ef511df2c965 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -21,11 +21,12 @@
    Supports:
         Intel PIIX4, 440MX
         Serverworks OSB4, CSB5, CSB6, HT-1000, HT-1100
-        ATI IXP200, IXP300, IXP400, SB600, SB700, SB800
+        ATI IXP200, IXP300, IXP400, SB600, SB700/SP5100, SB800
         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 more
+   SMBus interfaces.
 */
 
 #include <linux/module.h>
@@ -293,6 +294,46 @@ static int __devinit piix4_setup_sb800(struct pci_dev *PIIX4_dev,
         return piix4_smba;
 }
 
+static int __devinit piix4_setup_aux(struct pci_dev *PIIX4_dev,
+                                const struct pci_device_id *id,
+                                unsigned short base_reg_addr)
+{
+        /* Set up auxiliary SMBus controllers found on some
+         * AMD chipsets e.g. SP5100 (SB700 derivative) */
+
+        unsigned short piix4_smba;
+
+        /* Read address of auxiliary SMBus controller */
+        pci_read_config_word(PIIX4_dev, base_reg_addr, &piix4_smba);
+        if ((piix4_smba & 1) == 0) {
+                dev_dbg(&PIIX4_dev->dev,
+                        "Auxiliary SMBus controller not enabled\n");
+                return -ENODEV;
+        }
+
+        piix4_smba &= 0xfff0;
+        if (piix4_smba == 0) {
+                dev_dbg(&PIIX4_dev->dev,
+                        "Auxiliary SMBus base address uninitialized\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, "Auxiliary 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);
+
+        return piix4_smba;
+}
+
 static int piix4_transaction(struct i2c_adapter *piix4_adapter)
 {
         struct i2c_piix4_adapdata *adapdata = i2c_get_adapdata(piix4_adapter);
@@ -497,6 +538,7 @@ 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;
 
 static int __devinit piix4_add_adapter(struct pci_dev *dev,
                                         unsigned short smba,
@@ -560,10 +602,28 @@ static int __devinit piix4_probe(struct pci_dev *dev,
         else
                 retval = piix4_setup(dev, id);
 
+        /* If no main SMBus found, give up */
         if (retval < 0)
                 return retval;
 
-        return piix4_add_adapter(dev, retval, &piix4_main_adapter);
+        /* Try to register main SMBus adapter, give up if we can't */
+        retval = piix4_add_adapter(dev, retval, &piix4_main_adapter);
+        if (retval < 0)
+                return retval;
+
+        /* Check for auxiliary SMBus on some AMD chipsets */
+        if (dev->vendor == PCI_VENDOR_ID_ATI &&
+            dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
+            dev->revision < 0x40) {
+                retval = piix4_setup_aux(dev, id, 0x58);
+                if (retval > 0) {
+                        /* Try to add the aux adapter if it exists,
+                         * piix4_add_adapter will clean up if this fails */
+                        piix4_add_adapter(dev, retval, &piix4_aux_adapter);
+                }
+        }
+
+        return 0;
 }
 
 static void __devexit piix4_adap_remove(struct i2c_adapter *adap)
@@ -584,6 +644,11 @@ static void __devexit piix4_remove(struct pci_dev *dev)
                 piix4_adap_remove(piix4_main_adapter);
                 piix4_main_adapter = NULL;
         }
+
+        if (piix4_aux_adapter) {
+                piix4_adap_remove(piix4_aux_adapter);
+                piix4_aux_adapter = NULL;
+        }
 }
 
 static struct pci_driver piix4_driver = {