i2c-nforce2: Abort the transaction on error

This patch is to add an abort function that will bring back the MCP51/55
controller if it was blocked by a block-read operation, in particular.
(When a slave sends a wrong byte count on a byte read, the host gets
locked up). I've only tested it on an MCP51 and MCP55. However, I'm
almost certain it will also work on MCP65, I just did not have the board
to test it on. Thus for now the abort function will only be called
if an MCP51/55 was detected.

Signed-off-by: Oleg Ryjkov <olegr@olegr.ca>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 32 insertions, 1 deletions

diff --git a/drivers/i2c/busses/i2c-nforce2.c b/drivers/i2c/busses/i2c-nforce2.c
index 1c63c4f2e4b6..c359eabe85fb 100644
--- a/drivers/i2c/busses/i2c-nforce2.c
+++ b/drivers/i2c/busses/i2c-nforce2.c
@@ -62,6 +62,7 @@ struct nforce2_smbus {
         int base;
         int size;
         int blockops;
+        int can_abort;
 };
 
 
@@ -83,7 +84,14 @@ struct nforce2_smbus {
 #define NVIDIA_SMB_DATA         (smbus->base + 0x04)    /* 32 data registers */
 #define NVIDIA_SMB_BCNT         (smbus->base + 0x24)    /* number of data
                                                            bytes */
-
+#define NVIDIA_SMB_STATUS_ABRT  (smbus->base + 0x3c)    /* register used to
+                                                           check the status of
+                                                           the abort command */
+#define NVIDIA_SMB_CTRL         (smbus->base + 0x3e)    /* control register */
+
+#define NVIDIA_SMB_STATUS_ABRT_STS      0x01            /* Bit to notify that
+                                                           abort succeeded */
+#define NVIDIA_SMB_CTRL_ABORT   0x20
 #define NVIDIA_SMB_STS_DONE     0x80
 #define NVIDIA_SMB_STS_ALRM     0x40
 #define NVIDIA_SMB_STS_RES      0x20
@@ -103,6 +111,25 @@ struct nforce2_smbus {
 
 static struct pci_driver nforce2_driver;
 
+static void nforce2_abort(struct i2c_adapter *adap)
+{
+        struct nforce2_smbus *smbus = adap->algo_data;
+        int timeout = 0;
+        unsigned char temp;
+
+        dev_dbg(&adap->dev, "Aborting current transaction\n");
+
+        outb_p(NVIDIA_SMB_CTRL_ABORT, NVIDIA_SMB_CTRL);
+        do {
+                msleep(1);
+                temp = inb_p(NVIDIA_SMB_STATUS_ABRT);
+        } while (!(temp & NVIDIA_SMB_STATUS_ABRT_STS) &&
+                        (timeout++ < MAX_TIMEOUT));
+        if (!(temp & NVIDIA_SMB_STATUS_ABRT_STS))
+                dev_err(&adap->dev, "Can't reset the smbus\n");
+        outb_p(NVIDIA_SMB_STATUS_ABRT_STS, NVIDIA_SMB_STATUS_ABRT);
+}
+
 static int nforce2_check_status(struct i2c_adapter *adap)
 {
         struct nforce2_smbus *smbus = adap->algo_data;
@@ -116,6 +143,8 @@ static int nforce2_check_status(struct i2c_adapter *adap)
 
         if (timeout >= MAX_TIMEOUT) {
                 dev_dbg(&adap->dev, "SMBus Timeout!\n");
+                if (smbus->can_abort)
+                        nforce2_abort(adap);
                 return -1;
         }
         if (!(temp & NVIDIA_SMB_STS_DONE) || (temp & NVIDIA_SMB_STS_STATUS)) {
@@ -325,6 +354,8 @@ static int __devinit nforce2_probe(struct pci_dev *dev, const struct pci_device_
         case PCI_DEVICE_ID_NVIDIA_NFORCE_MCP55_SMBUS:
                 smbuses[0].blockops = 1;
                 smbuses[1].blockops = 1;
+                smbuses[0].can_abort = 1;
+                smbuses[1].can_abort = 1;
         }
 
         /* SMBus adapter 1 */