1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index c2268cdf38e8..e34d82e79b98 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -585,10 +585,29 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
                  u8 command, int size, union i2c_smbus_data *data)
 {
         struct i2c_piix4_adapdata *adapdata = i2c_get_adapdata(adap);
+        unsigned short piix4_smba = adapdata->smba;
+        int retries = MAX_TIMEOUT;
+        int smbslvcnt;
         u8 smba_en_lo;
         u8 port;
         int retval;
 
+        /* Request the SMBUS semaphore, avoid conflicts with the IMC */
+        smbslvcnt  = inb_p(SMBSLVCNT);
+        do {
+                outb_p(smbslvcnt | 0x10, SMBSLVCNT);
+
+                /* Check the semaphore status */
+                smbslvcnt  = inb_p(SMBSLVCNT);
+                if (smbslvcnt & 0x10)
+                        break;
+
+                usleep_range(1000, 2000);
+        } while (--retries);
+        /* SMBus is still owned by the IMC, we give up */
+        if (!retries)
+                return -EBUSY;
+
         mutex_lock(&piix4_mutex_sb800);
 
         outb_p(piix4_port_sel_sb800, SB800_PIIX4_SMB_IDX);
@@ -606,6 +625,9 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
 
         mutex_unlock(&piix4_mutex_sb800);
 
+        /* Release the semaphore */
+        outb_p(smbslvcnt | 0x20, SMBSLVCNT);
+
         return retval;
 }