From f0873adea6ba910896f282c5d91729a931107d2e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Erik=20Agsj=C3=B6?= <erik.agsjo@gmail.com>
Date: Mon, 27 Feb 2017 20:53:01 +0100
Subject: [PATCH] Removed smbus block operations
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Signed-off-by: Erik Agsjö <erik.agsjo@gmail.com>
---
 drivers/i2c/i2c.go      |  8 ------
 drivers/i2c/i2c_test.go | 10 ++------
 sysfs/i2c_device.go     | 55 ++++++++++++++++-------------------------
 3 files changed, 23 insertions(+), 50 deletions(-)

diff --git a/drivers/i2c/i2c.go b/drivers/i2c/i2c.go
index 75cf9211..7a1521c1 100644
--- a/drivers/i2c/i2c.go
+++ b/drivers/i2c/i2c.go
@@ -103,14 +103,6 @@ func (c *i2cConnection) ReadWordData(reg uint8) (val uint16, err error) {
 	return c.bus.ReadWordData(reg)
 }
 
-// ReadBlockData reads a block of bytes for a register on the i2c device.
-func (c *i2cConnection) ReadBlockData(reg uint8, b []byte) (n int, err error) {
-	if err := c.bus.SetAddress(c.address); err != nil {
-		return 0, err
-	}
-	return c.bus.ReadBlockData(reg, b)
-}
-
 // WriteByte writes a single byte to the i2c device.
 func (c *i2cConnection) WriteByte(val byte) (err error) {
 	if err := c.bus.SetAddress(c.address); err != nil {
diff --git a/drivers/i2c/i2c_test.go b/drivers/i2c/i2c_test.go
index b8067373..7a54da2e 100644
--- a/drivers/i2c/i2c_test.go
+++ b/drivers/i2c/i2c_test.go
@@ -53,12 +53,6 @@ func TestI2CReadWordData(t *testing.T) {
 	gobottest.Assert(t, v, uint16(0))
 }
 
-func TestI2CReadBlockData(t *testing.T) {
-	c := NewConnection(initI2CDevice(), 0x06)
-	i, _ := c.ReadBlockData(0x01, []byte{})
-	gobottest.Assert(t, i, 0)
-}
-
 func TestI2CWriteByte(t *testing.T) {
 	c := NewConnection(initI2CDevice(), 0x06)
 	err := c.WriteByte(0x01)
@@ -77,8 +71,8 @@ func TestI2CWriteWordData(t *testing.T) {
 	gobottest.Assert(t, err, nil)
 }
 
-func TestI2CWriteBlockDataErrNotSupported(t *testing.T) {
+func TestI2CWriteBlockData(t *testing.T) {
 	c := NewConnection(initI2CDevice(), 0x06)
 	err := c.WriteBlockData(0x01, []byte{0x01, 0x02})
-	gobottest.Refute(t, err, nil)
+	gobottest.Assert(t, err, nil)
 }
diff --git a/sysfs/i2c_device.go b/sysfs/i2c_device.go
index a133d9f7..bcf3ed84 100644
--- a/sysfs/i2c_device.go
+++ b/sysfs/i2c_device.go
@@ -20,17 +20,14 @@ const (
 	I2C_FUNC_SMBUS_READ_BLOCK_DATA  = 0x01000000
 	I2C_FUNC_SMBUS_WRITE_BLOCK_DATA = 0x02000000
 	// Transaction types
-	I2C_SMBUS_BYTE                = 1
-	I2C_SMBUS_BYTE_DATA           = 2
-	I2C_SMBUS_WORD_DATA           = 3
-	I2C_SMBUS_PROC_CALL           = 4
-	I2C_SMBUS_BLOCK_DATA          = 5
-	I2C_SMBUS_I2C_BLOCK_DATA      = 6
-	I2C_SMBUS_BLOCK_PROC_CALL     = 7  /* SMBus 2.0 */
-	I2C_SMBUS_BLOCK_DATA_PEC      = 8  /* SMBus 2.0 */
-	I2C_SMBUS_PROC_CALL_PEC       = 9  /* SMBus 2.0 */
-	I2C_SMBUS_BLOCK_PROC_CALL_PEC = 10 /* SMBus 2.0 */
-	I2C_SMBUS_WORD_DATA_PEC       = 11 /* SMBus 2.0 */
+	I2C_SMBUS_BYTE             = 1
+	I2C_SMBUS_BYTE_DATA        = 2
+	I2C_SMBUS_WORD_DATA        = 3
+	I2C_SMBUS_PROC_CALL        = 4
+	I2C_SMBUS_BLOCK_DATA       = 5
+	I2C_SMBUS_I2C_BLOCK_BROKEN = 6
+	I2C_SMBUS_BLOCK_PROC_CALL  = 7 /* SMBus 2.0 */
+	I2C_SMBUS_I2C_BLOCK_DATA   = 8 /* SMBus 2.0 */
 )
 
 type i2cSmbusIoctlData struct {
@@ -45,7 +42,6 @@ type I2cOperations interface {
 	ReadByte() (val uint8, err error)
 	ReadByteData(reg uint8) (val uint8, err error)
 	ReadWordData(reg uint8) (val uint16, err error)
-	ReadBlockData(reg uint8, b []byte) (n int, err error)
 	WriteByte(val uint8) (err error)
 	WriteByteData(reg uint8, val uint8) (err error)
 	WriteWordData(reg uint8, val uint16) (err error)
@@ -129,19 +125,6 @@ func (d *i2cDevice) ReadWordData(reg uint8) (val uint16, err error) {
 	return data, err
 }
 
-func (d *i2cDevice) ReadBlockData(reg uint8, buf []byte) (n int, err error) {
-	if d.funcs&I2C_FUNC_SMBUS_READ_BLOCK_DATA == 0 {
-		return 0, fmt.Errorf("SMBus block data reading not supported")
-	}
-
-	data := make([]byte, 32+1) // Max message + size as defined by SMBus standard
-
-	err = d.smbusAccess(I2C_SMBUS_READ, reg, I2C_SMBUS_I2C_BLOCK_DATA, uintptr(unsafe.Pointer(&data[0])))
-
-	copy(buf, data[1:])
-	return int(data[0]), err
-}
-
 func (d *i2cDevice) WriteByte(val uint8) (err error) {
 	err = d.smbusAccess(I2C_SMBUS_WRITE, val, I2C_SMBUS_BYTE, uintptr(0))
 	return err
@@ -160,21 +143,25 @@ func (d *i2cDevice) WriteWordData(reg uint8, val uint16) (err error) {
 }
 
 func (d *i2cDevice) WriteBlockData(reg uint8, data []byte) (err error) {
-	if d.funcs&I2C_FUNC_SMBUS_WRITE_BLOCK_DATA == 0 {
-		return fmt.Errorf("SMBus block data writing not supported")
-	}
-
 	if len(data) > 32 {
-		data = data[:32]
+		return fmt.Errorf("Writing blocks larger than 32 bytes (%v) not supported", len(data))
 	}
 
 	buf := make([]byte, len(data)+1)
-	copy(buf[:1], data)
-	buf[0] = uint8(len(data))
+	copy(buf[1:], data)
+	buf[0] = reg
 
-	err = d.smbusAccess(I2C_SMBUS_WRITE, reg, I2C_SMBUS_I2C_BLOCK_DATA, uintptr(unsafe.Pointer(&buf[0])))
+	n, err := d.file.Write(buf)
 
-	return err
+	if err != nil {
+		return err
+	}
+
+	if n != len(buf) {
+		return fmt.Errorf("Write to device truncated, %v of %v written", n, len(buf))
+	}
+
+	return nil
 }
 
 // Read implements the io.ReadWriteCloser method by direct I2C read operations.