The SB800 chipset supports a multiplexed main SMBus controller with
four ports. The multiplexed ports share the same SMBus address and
register set. The port is selected by bits 2:1 of the smb_en register
(0x2C).
Only one port can be active at any point in time therefore a mutex is
needed in order to synchronize access.
Tested on HP ProLiant MicroServer G7 N54L (where this patch adds
support to access sensor data from the w83795adg).
Cc: Thomas Brandon <tbrandonau@xxxxxxxxx>
Cc: Eddi De Pieri <eddi@xxxxxxxxxxx>
Signed-off-by: Christian Fetzer <fetzer.ch@xxxxxxxxx>
---
drivers/i2c/busses/i2c-piix4.c | 114 ++++++++++++++++++++++++++++++++++++++---
1 file changed, 107 insertions(+), 7 deletions(-)
diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 8934a32..e344abd 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -23,6 +23,9 @@
Note: we assume there can only be one device, with one or more
SMBus interfaces.
+ The device can register multiple i2c_adapters (up to PIIX4_MAX_ADAPTERS).
+ For devices supporting multiple ports the i2c_adapter should provide
+ an i2c_algorithm to access them.
*/
#include <linux/module.h>
@@ -37,6 +40,7 @@
#include <linux/dmi.h>
#include <linux/acpi.h>
#include <linux/io.h>
+#include <linux/mutex.h>
/* PIIX4 SMBus address offsets */
@@ -125,8 +129,12 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
{ },
};
+/* SB800 globals */
+DEFINE_MUTEX(piix4_mutex_sb800);
+
struct i2c_piix4_adapdata {
unsigned short smba;
+ unsigned short port;
};
static int piix4_setup(struct pci_dev *PIIX4_dev,
@@ -313,6 +321,8 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
else
dev_dbg(&PIIX4_dev->dev, "Using SMI# for SMBus\n");
+ mutex_init(&piix4_mutex_sb800);
+
dev_info(&PIIX4_dev->dev,
"SMBus Host Controller at 0x%x, revision %d\n",
piix4_smba, i2ccfg >> 4);
@@ -527,6 +537,49 @@ static s32 piix4_access(struct i2c_adapter * adap, u16 addr,
return 0;
}
+/* Handles access to multiple SMBus ports on the SB800.
+ * The port is selected by bits 2:1 of the smb_en register (0x2C).
+ * NOTE: The selected port must be returned to the initial selection to
+ * avoid problems on certain systems.
+ * Return negative errno on error.
+ */
+static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
+ unsigned short flags, char read_write,
+ u8 command, int size, union i2c_smbus_data *data)
+{
+ struct i2c_piix4_adapdata *adapdata = i2c_get_adapdata(adap);
+ unsigned short smba_idx = 0xcd6;
+ u8 smba_en_lo, smb_en = 0x2c;
+ u8 port;
+ int retval;
+
+ mutex_lock(&piix4_mutex_sb800);
+
+ if (!request_region(smba_idx, 2, "smba_idx")) {
+ dev_err(&adap->dev, "SMBus base address index region "
+ "0x%x already in use!\n", smba_idx);
+ retval = -EBUSY;
+ goto ERROR;
+ }
+ outb_p(smb_en, smba_idx);
+ smba_en_lo = inb_p(smba_idx + 1);
+
+ port = adapdata->port;
+ if ((smba_en_lo & 6) != (port << 1))
+ outb_p((smba_en_lo & ~6) | (port << 1), smba_idx + 1);
+
+ retval = piix4_access(adap, addr, flags, read_write,
+ command, size, data);
+
+ outb_p(smba_en_lo, smba_idx + 1);
+ release_region(smba_idx, 2);
+
+ERROR:
+ mutex_unlock(&piix4_mutex_sb800);
+
+ return retval;
+}
+
static u32 piix4_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
@@ -539,6 +592,11 @@ static const struct i2c_algorithm smbus_algorithm = {
.functionality = piix4_func,
};
+static const struct i2c_algorithm piix4_smbus_algorithm_sb800 = {
+ .smbus_xfer = piix4_access_sb800,
+ .functionality = piix4_func,
+};
+
static const struct pci_device_id piix4_ids[] = {
{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3) },
{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82443MX_3) },
@@ -614,6 +672,41 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
return 0;
}
+static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba)
+{
+ unsigned short port;
+ int retval;
+ struct i2c_piix4_adapdata *adapdata;
+
+ for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
+ retval = piix4_add_adapter(dev, smba, &piix4_main_adapters[port]);
+ if (retval < 0)
+ goto ERROR;
+
+ piix4_main_adapters[port]->algo = &piix4_smbus_algorithm_sb800;
+
+ adapdata = i2c_get_adapdata(piix4_main_adapters[port]);
+ adapdata->port = port;
+ }
+
+ return retval;
+
+ERROR:
+ dev_err(&dev->dev, "Error setting up SB800 adapters. "
+ "Unregistering all adapters!\n");
+ for (port--; port >= 0; port--) {
+ adapdata = i2c_get_adapdata(piix4_main_adapters[port]);
+ if (adapdata->smba) {
+ i2c_del_adapter(piix4_main_adapters[port]);
+ kfree(adapdata);
+ kfree(piix4_main_adapters[port]);
+ piix4_main_adapters[port] = NULL;
+ }
+ }
+
+ return retval;
+}
+
static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
int retval;
@@ -621,18 +714,25 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
if ((dev->vendor == PCI_VENDOR_ID_ATI &&
dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
dev->revision >= 0x40) ||
- dev->vendor == PCI_VENDOR_ID_AMD)
+ dev->vendor == PCI_VENDOR_ID_AMD) {
/* base address location etc changed in SB800 */
retval = piix4_setup_sb800(dev, id, 0);
- else
+ if (retval < 0)
+ return retval;
+
+ /* Try to register multiplexed main SMBus adapter,
+ * give up if we can't */
+ retval = piix4_add_adapters_sb800(dev, retval);
+ } else {
retval = piix4_setup(dev, id);
+ if (retval < 0)
+ return retval;
- /* If no main SMBus found, give up */
- if (retval < 0)
- return retval;
+ /* Try to register main SMBus adapter, give up if we can't */
+ retval = piix4_add_adapter(dev, retval, &piix4_main_adapters[0]);
+ }
- /* Try to register main SMBus adapter, give up if we can't */
- retval = piix4_add_adapter(dev, retval, &piix4_main_adapters[0]);
+ /* If no main SMBus found, give up */
if (retval < 0)
return retval;
--
1.9.1
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