SMBUS_BLOCK_DATA transactions might fail due to a race condition with
the IMC (Integrated Micro Controller), even when the IMC semaphore
is used.
This bug has been reported and confirmed by AMD, who suggested as a
solution an IMC firmware upgrade (obtained via BIOS update) and
disabling the IMC during SMBUS_BLOCK_DATA transactions.
Even without the IMC upgrade, the SMBUS is much more stable with this
patch.
Tested on a Bettong-alike board.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx>
---
v3: Suggestions by Jean Delvare <jdelvare@xxxxxxx>
-Group booleans in struct i2c_piix4_adaptada
(Sorry about that, I thought your concern was the space between the
new field and the rest)
-Rename port regions
-Rename definitions
-Unify comment style
v2: Suggestions by Jean Delvare <jdelvare@xxxxxxx>
-Fix function definitions (static)
-Add register definition
-Use muxed_io interface
-Improve comments
-Keep old timeout
-Rebase
drivers/i2c/busses/i2c-piix4.c | 132 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 126 insertions(+), 6 deletions(-)
diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 8f1c5f24c1df..9643b277e0a4 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -85,6 +85,9 @@
/* SB800 constants */
#define SB800_PIIX4_SMB_IDX 0xcd6
+#define KERNCZ_IMC_IDX 0x3e
+#define KERNCZ_IMC_DATA 0x3f
+
/*
* SB800 port is selected by bits 2:1 of the smb_en register (0x2c)
* or the smb_sel register (0x2e), depending on bit 0 of register 0x2f.
@@ -167,6 +170,7 @@ struct i2c_piix4_adapdata {
/* SB800 */
bool sb800_main;
+ bool notify_imc;
u8 port; /* Port number, shifted */
};
@@ -594,6 +598,67 @@ static s32 piix4_access(struct i2c_adapter * adap, u16 addr,
return 0;
}
+static uint8_t piix4_imc_read(uint8_t idx)
+{
+ outb_p(idx, KERNCZ_IMC_IDX);
+ return inb_p(KERNCZ_IMC_DATA);
+}
+
+static void piix4_imc_write(uint8_t idx, uint8_t value)
+{
+ outb_p(idx, KERNCZ_IMC_IDX);
+ outb_p(value, KERNCZ_IMC_DATA);
+}
+
+static int piix4_imc_sleep(void)
+{
+ int timeout = MAX_TIMEOUT;
+
+ if (!request_muxed_region(KERNCZ_IMC_IDX, 2, "smbus_kerncz_imc"))
+ return -EBUSY;
+
+ /* clear response register */
+ piix4_imc_write(0x82, 0x00);
+ /* request ownership flag */
+ piix4_imc_write(0x83, 0xB4);
+ /* kick off IMC Mailbox command 96 */
+ piix4_imc_write(0x80, 0x96);
+
+ while (timeout--) {
+ if (piix4_imc_read(0x82) == 0xfa) {
+ release_region(KERNCZ_IMC_IDX, 2);
+ return 0;
+ }
+ usleep_range(1000, 2000);
+ }
+
+ release_region(KERNCZ_IMC_IDX, 2);
+ return -ETIMEDOUT;
+}
+
+static void piix4_imc_wakeup(void)
+{
+ int timeout = MAX_TIMEOUT;
+
+ if (!request_muxed_region(KERNCZ_IMC_IDX, 2, "smbus_kerncz_imc"))
+ return;
+
+ /* clear response register */
+ piix4_imc_write(0x82, 0x00);
+ /* release ownership flag */
+ piix4_imc_write(0x83, 0xB5);
+ /* kick off IMC Mailbox command 96 */
+ piix4_imc_write(0x80, 0x96);
+
+ while (timeout--) {
+ if (piix4_imc_read(0x82) == 0xfa)
+ break;
+ usleep_range(1000, 2000);
+ }
+
+ release_region(KERNCZ_IMC_IDX, 2);
+}
+
/*
* Handles access to multiple SMBus ports on the SB800.
* The port is selected by bits 2:1 of the smb_en register (0x2c).
@@ -634,6 +699,41 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
return -EBUSY;
}
+ /*
+ * Notify the IMC (Integrated Micro Controller) if required.
+ * Among other responsibilities, the IMC is in charge of monitoring
+ * the System fans and temperature sensors, and act accordingly.
+ * All this is done through SMBus and can/will collide
+ * with our transactions if they are long (BLOCK_DATA).
+ * Therefore we need to request the ownership flag during those
+ * transactions.
+ */
+ if ((size == I2C_SMBUS_BLOCK_DATA) && adapdata->notify_imc) {
+ int ret;
+
+ ret = piix4_imc_sleep();
+ switch (ret) {
+ case -EBUSY:
+ dev_warn(&adap->dev,
+ "IMC base address index region 0x%x already in use.\n",
+ KERNCZ_IMC_IDX);
+ break;
+ case -ETIMEDOUT:
+ dev_warn(&adap->dev,
+ "Failed to communicate with the IMC.\n");
+ break;
+ default:
+ break;
+ }
+
+ /* If IMC communication fails do not retry */
+ if (ret) {
+ dev_warn(&adap->dev,
+ "Continuing without IMC notification.\n");
+ adapdata->notify_imc = false;
+ }
+ }
+
outb_p(piix4_port_sel_sb800, SB800_PIIX4_SMB_IDX);
smba_en_lo = inb_p(SB800_PIIX4_SMB_IDX + 1);
@@ -650,6 +750,9 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
/* Release the semaphore */
outb_p(smbslvcnt | 0x20, SMBSLVCNT);
+ if ((size == I2C_SMBUS_BLOCK_DATA) && adapdata->notify_imc)
+ piix4_imc_wakeup();
+
mutex_unlock(&piix4_mutex_sb800);
return retval;
@@ -701,7 +804,7 @@ static struct i2c_adapter *piix4_main_adapters[PIIX4_MAX_ADAPTERS];
static struct i2c_adapter *piix4_aux_adapter;
static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
- bool sb800_main, u8 port,
+ bool sb800_main, u8 port, bool notify_imc,
const char *name, struct i2c_adapter **padap)
{
struct i2c_adapter *adap;
@@ -729,6 +832,7 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
adapdata->smba = smba;
adapdata->sb800_main = sb800_main;
adapdata->port = port << piix4_port_shift_sb800;
+ adapdata->notify_imc = notify_imc;
/* set up the sysfs linkage to our parent device */
adap->dev.parent = &dev->dev;
@@ -750,14 +854,15 @@ 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)
+static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba,
+ bool notify_imc)
{
struct i2c_piix4_adapdata *adapdata;
int port;
int retval;
for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
- retval = piix4_add_adapter(dev, smba, true, port,
+ retval = piix4_add_adapter(dev, smba, true, port, notify_imc,
piix4_main_port_names_sb800[port],
&piix4_main_adapters[port]);
if (retval < 0)
@@ -791,6 +896,7 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
dev->revision >= 0x40) ||
dev->vendor == PCI_VENDOR_ID_AMD) {
+ bool notify_imc = false;
is_sb800 = true;
if (!request_region(SB800_PIIX4_SMB_IDX, 2, "smba_idx")) {
@@ -800,6 +906,20 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
return -EBUSY;
}
+ if (dev->vendor == PCI_VENDOR_ID_AMD &&
+ dev->device == PCI_DEVICE_ID_AMD_KERNCZ_SMBUS) {
+ u8 imc;
+
+ /*
+ * Detect if IMC is active or not, this method is
+ * described on coreboot's AMD IMC notes
+ */
+ pci_bus_read_config_byte(dev->bus, PCI_DEVFN(0x14, 3),
+ 0x40, &imc);
+ if (imc & 0x80)
+ notify_imc = true;
+ }
+
/* base address location etc changed in SB800 */
retval = piix4_setup_sb800(dev, id, 0);
if (retval < 0) {
@@ -811,7 +931,7 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
* Try to register multiplexed main SMBus adapter,
* give up if we can't
*/
- retval = piix4_add_adapters_sb800(dev, retval);
+ retval = piix4_add_adapters_sb800(dev, retval, notify_imc);
if (retval < 0) {
release_region(SB800_PIIX4_SMB_IDX, 2);
return retval;
@@ -822,7 +942,7 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
return retval;
/* Try to register main SMBus adapter, give up if we can't */
- retval = piix4_add_adapter(dev, retval, false, 0, "",
+ retval = piix4_add_adapter(dev, retval, false, 0, false, "",
&piix4_main_adapters[0]);
if (retval < 0)
return retval;
@@ -849,7 +969,7 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
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, false, 0,
+ piix4_add_adapter(dev, retval, false, 0, false,
is_sb800 ? piix4_aux_port_name_sb800 : "",
&piix4_aux_adapter);
}
--
2.13.2
