[i2c] [PATCH 1 of 2] Clean up of i2c-nforce2

[Oleg Ryjkov]

Hi Jean, hi list

This is the first part of the patch that adds a function to reset the
nvidia MCP51/55 i2c controller, if something bad happens to it (i.e.
a slave sends a wrong byte count during a block transaction).

This patch just adds nforce2_check_status function. It was originally
written by Hans-Frieder Vogt <hfvogt at gmx.net>, and was posted on this
list around October 2006 (see
http://lists.lm-sensors.org/pipermail/i2c/2006-October/000380.html).
However, unfortunately, he never got around to submitting it to the
kernel.
The reason that I'm the one sending it is is:
- I relied on it for the second part of the patch,
- It makes the driver code cleaner/better.

Signed-off-by: Oleg Ryjkov <olegr at google.com>

--- linux-2.6-untouched/drivers/i2c/busses/i2c-nforce2.c	2007-08-13 18:28:26.000000000 -0700
+++ linux-2.6/drivers/i2c/busses/i2c-nforce2.c	2007-08-30 19:38:13.000000000 -0700
@@ -98,15 +98,39 @@
 #define NVIDIA_SMB_PRTCL_BLOCK_DATA		0x0a
 #define NVIDIA_SMB_PRTCL_PEC			0x80
 
+/* Misc definitions */
+#define MAX_TIMEOUT	100
+
 static struct pci_driver nforce2_driver;
 
+static int nforce2_check_status(struct i2c_adapter * adap) {
+	struct nforce2_smbus *smbus = adap->algo_data;
+	int timeout = 0;
+	unsigned char temp;
+
+	do {
+		msleep(1);
+		temp = inb_p(NVIDIA_SMB_STS);
+	} while ((!temp) && (timeout++ < MAX_TIMEOUT));
+
+	if ((~temp & NVIDIA_SMB_STS_DONE) && (timeout >= MAX_TIMEOUT)) {
+		dev_dbg(&adap->dev, "SMBus Timeout (0x%02x)!\n", temp);
+		return -1;
+	}
+	if ((~temp & NVIDIA_SMB_STS_DONE) || (temp & NVIDIA_SMB_STS_STATUS)) {
+		dev_dbg(&adap->dev, "Transaction failed (0x%02x)!\n", temp);
+		return -1;
+	}
+	return 0;
+}
+
 /* Return -1 on error */
 static s32 nforce2_access(struct i2c_adapter * adap, u16 addr,
 		unsigned short flags, char read_write,
 		u8 command, int size, union i2c_smbus_data * data)
 {
 	struct nforce2_smbus *smbus = adap->algo_data;
-	unsigned char protocol, pec, temp;
+	unsigned char protocol, pec;
 	u8 len;
 	int i;
 
@@ -170,22 +194,9 @@
 	outb_p((addr & 0x7f) << 1, NVIDIA_SMB_ADDR);
 	outb_p(protocol, NVIDIA_SMB_PRTCL);
 
-	temp = inb_p(NVIDIA_SMB_STS);
-
-	if (~temp & NVIDIA_SMB_STS_DONE) {
-		udelay(500);
-		temp = inb_p(NVIDIA_SMB_STS);
-	}
-	if (~temp & NVIDIA_SMB_STS_DONE) {
-		msleep(10);
-		temp = inb_p(NVIDIA_SMB_STS);
-	}
-
-	if ((~temp & NVIDIA_SMB_STS_DONE) || (temp & NVIDIA_SMB_STS_STATUS)) {
-		dev_dbg(&adap->dev, "SMBus Timeout! (0x%02x)\n", temp);
+	if (nforce2_check_status(adap))
 		return -1;
-	}
-
+        
 	if (read_write == I2C_SMBUS_WRITE)
 		return 0;
 
@@ -202,7 +213,12 @@
 
 		case I2C_SMBUS_BLOCK_DATA:
 			len = inb_p(NVIDIA_SMB_BCNT);
-			len = min_t(u8, len, I2C_SMBUS_BLOCK_MAX);
+			if ((len <= 0) || (len > I2C_SMBUS_BLOCK_MAX)) {
+				dev_err(&adap->dev, "Transaction failed"
+					"(requested block size: 0x%02x)"
+					"\n", len);
+				return -1;
+			}
 			for (i = 0; i < len; i++)
 				data->block[i+1] = inb_p(NVIDIA_SMB_DATA + i);
 			data->block[0] = len;