[PATCH] i2c-viapro: Implement I2C Block transactions

Implement the I2C block transactions on VIA chips which support them:
VT82C686B, VT8233, VT8233A, VT8235 and VT8237R. This speeds up EEPROM
accesses by a factor 10 or so.

I would like to thank Antonino A. Daplas, Hinko Kocevar, Salah Coronya
and Andreas Henriksson for their help in testing this new feature.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

 Documentation/i2c/busses/i2c-viapro |    7 +++++-
 drivers/i2c/busses/i2c-viapro.c     |   39 +++++++++++++++++++++++++++++++++---
 2 files changed, 42 insertions(+), 4 deletions(-)

Documentation/i2c/busses/i2c-viapro

@@ -14,7 +14,8 @@ Authors:
 	Frodo Looijaard <frodol@dds.nl>,
 	Philip Edelbrock <phil@netroedge.com>,
 	Kysti Mlkki <kmalkki@cc.hut.fi>,
-	Mark D. Studebaker <mdsxyz123@yahoo.com>
+	Mark D. Studebaker <mdsxyz123@yahoo.com>,
+	Jean Delvare <khali@linux-fr.org>
 
 Module Parameters
 -----------------
@@ -43,3 +44,7 @@ Your lspci -n listing must show one of these :
 
 If none of these show up, you should look in the BIOS for settings like
 enable ACPI / SMBus or even USB.
+
+Except for the oldest chips (VT82C596A/B, VT82C686A and most probably
+VT8231), this driver supports I2C block transactions. Such transactions
+are mainly useful to read from and write to EEPROMs.

drivers/i2c/busses/i2c-viapro.c

@@ -4,6 +4,7 @@
     Copyright (c) 1998 - 2002  Frodo Looijaard <frodol@dds.nl>,
     Philip Edelbrock <phil@netroedge.com>, Kysti Mlkki <kmalkki@cc.hut.fi>,
     Mark D. Studebaker <mdsxyz123@yahoo.com>
+    Copyright (C) 2005  Jean Delvare <khali@linux-fr.org>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -88,6 +89,7 @@ static unsigned short smb_cf_hstcfg = 0xD2;
 #define VT596_BYTE_DATA		0x08
 #define VT596_WORD_DATA		0x0C
 #define VT596_BLOCK_DATA	0x14
+#define VT596_I2C_BLOCK_DATA	0x34
 
 
 /* If force is set to anything different from 0, we forcibly enable the
@@ -107,6 +109,9 @@ MODULE_PARM_DESC(force_addr,
 
 static struct i2c_adapter vt596_adapter;
 
+#define FEATURE_I2CBLOCK	(1<<0)
+static unsigned int vt596_features;
+
 /* Another internally used function */
 static int vt596_transaction(void)
 {
@@ -225,6 +230,12 @@ static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
 		}
 		size = VT596_WORD_DATA;
 		break;
+	case I2C_SMBUS_I2C_BLOCK_DATA:
+		if (!(vt596_features & FEATURE_I2CBLOCK))
+			return -1;
+		if (read_write == I2C_SMBUS_READ)
+			outb_p(I2C_SMBUS_BLOCK_MAX, SMBHSTDAT0);
+		/* Fall through */
 	case I2C_SMBUS_BLOCK_DATA:
 		outb_p(((addr & 0x7f) << 1) | (read_write & 0x01),
 		       SMBHSTADD);
@@ -240,11 +251,12 @@ static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
 			for (i = 1; i <= len; i++)
 				outb_p(data->block[i], SMBBLKDAT);
 		}
-		size = VT596_BLOCK_DATA;
+		size = (size == I2C_SMBUS_I2C_BLOCK_DATA) ?
+		       VT596_I2C_BLOCK_DATA : VT596_BLOCK_DATA;
 		break;
 	}
 
-	outb_p((size & 0x1C) + (ENABLE_INT9 & 1), SMBHSTCNT);
+	outb_p((size & 0x3C) + (ENABLE_INT9 & 1), SMBHSTCNT);
 
 	if (vt596_transaction()) /* Error in transaction */
 		return -1;
@@ -266,6 +278,7 @@ static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
 	case VT596_WORD_DATA:
 		data->word = inb_p(SMBHSTDAT0) + (inb_p(SMBHSTDAT1) << 8);
 		break;
+	case VT596_I2C_BLOCK_DATA:
 	case VT596_BLOCK_DATA:
 		data->block[0] = inb_p(SMBHSTDAT0);
 		if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
@@ -280,9 +293,13 @@ static s32 vt596_access(struct i2c_adapter *adap, u16 addr,
 
 static u32 vt596_func(struct i2c_adapter *adapter)
 {
-	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
+	u32 func = I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
 	    I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
 	    I2C_FUNC_SMBUS_BLOCK_DATA;
+
+	if (vt596_features & FEATURE_I2CBLOCK)
+		func |= I2C_FUNC_SMBUS_I2C_BLOCK;
+	return func;
 }
 
 static struct i2c_algorithm smbus_algorithm = {
@@ -379,6 +396,22 @@ found:
 	dev_dbg(&pdev->dev, "SMBREV = 0x%X\n", temp);
 	dev_dbg(&pdev->dev, "VT596_smba = 0x%X\n", vt596_smba);
 
+	switch (pdev->device) {
+	case PCI_DEVICE_ID_VIA_8237:
+	case PCI_DEVICE_ID_VIA_8235:
+	case PCI_DEVICE_ID_VIA_8233A:
+	case PCI_DEVICE_ID_VIA_8233_0:
+		vt596_features |= FEATURE_I2CBLOCK;
+		break;
+	case PCI_DEVICE_ID_VIA_82C686_4:
+		/* The VT82C686B (rev 0x40) does support I2C block
+		   transactions, but the VT82C686A (rev 0x30) doesn't */
+		if (!pci_read_config_byte(pdev, PCI_REVISION_ID, &temp)
+		 && temp >= 0x40)
+			vt596_features |= FEATURE_I2CBLOCK;
+		break;
+	}
+
 	vt596_adapter.dev.parent = &pdev->dev;
 	snprintf(vt596_adapter.name, I2C_NAME_SIZE,
 		 "SMBus Via Pro adapter at %04x", vt596_smba);