Patchwork [RFC] imx-i2c: Add smbus block read support to imx i2c bus

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Submitter Kaushal Butala
Date March 25, 2014, 3:06 p.m.
Message ID <1395759982-18559-1-git-send-email-kaushalkernelmailinglist@gmail.com>
Download mbox | patch
Permalink /patch/333501/
State Superseded
Headers show

Comments

Kaushal Butala - March 25, 2014, 3:06 p.m.
From: Kaushal Butala <kaushal.butala@gmail.com>

The smbus block read is not currently supported for imx i2c devices.
This patchset adds the support to imx i2c bus so that blocks of data
can be read using SMbus block reads.(using i2c_smbus_read_block_data()
function from the i2c_core.c.). Tested with 3.10.9 kernel.

Signed-off-by: Kaushal Butala <kaushalkernelmailinglist@gmail.com>
---
 drivers/i2c/busses/i2c-imx.c |   31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)
Shawn Guo - April 2, 2014, 8:30 a.m.
On Tue, Mar 25, 2014 at 04:06:22PM +0100, Kaushal Butala wrote:
> From: Kaushal Butala <kaushal.butala@gmail.com>
> 
> The smbus block read is not currently supported for imx i2c devices.
> This patchset adds the support to imx i2c bus so that blocks of data
> can be read using SMbus block reads.(using i2c_smbus_read_block_data()
> function from the i2c_core.c.). Tested with 3.10.9 kernel.
> 
> Signed-off-by: Kaushal Butala <kaushalkernelmailinglist@gmail.com>

The patch should be sent to I2C subsystem maintainer - Wolfram (copied)
rather than me.

The patch looks good to me except a few unnecessary parentheses.

> ---
>  drivers/i2c/busses/i2c-imx.c |   31 ++++++++++++++++++++++++++++---
>  1 file changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index db895fb..b6c2c3c 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -462,6 +462,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
>  {
>  	int i, result;
>  	unsigned int temp;
> +	int block_data = msgs->flags & I2C_M_RECV_LEN;
>  
>  	dev_dbg(&i2c_imx->adapter.dev,
>  		"<%s> write slave address: addr=0x%x\n",
> @@ -481,7 +482,12 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
>  	/* setup bus to read data */
>  	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
>  	temp &= ~I2CR_MTX;
> -	if (msgs->len - 1)
> +
> +	/*
> +	 * Reset the I2CR_TXAK flag initially for SMbus block read since the
> +	 * length is unknown
> +	 */
> +	if ((msgs->len - 1) || (block_data))

Unnecessary parentheses around block_data.

>  		temp &= ~I2CR_TXAK;
>  	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
>  	imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */
> @@ -490,9 +496,24 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
>  
>  	/* read data */
>  	for (i = 0; i < msgs->len; i++) {
> +		u8 len = 0;
>  		result = i2c_imx_trx_complete(i2c_imx);
>  		if (result)
>  			return result;
> +		/*
> +		 * First byte is the length of remaining packet
> +		 * in the SMBus block data read. Add it to
> +		 * msgs->len.
> +		 */
> +		if ((!i) && (block_data)) {

if (!i && block_data)

> +			len = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
> +			if ((len == 0) || (len > I2C_SMBUS_BLOCK_MAX))
> +				return -EPROTO;
> +			dev_dbg(&i2c_imx->adapter.dev,
> +				"<%s> read length: 0x%X\n",
> +				__func__, len);
> +			msgs->len += len;
> +		}
>  		if (i == (msgs->len - 1)) {
>  			/* It must generate STOP before read I2DR to prevent
>  			   controller from generating another clock cycle */
> @@ -510,7 +531,10 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
>  			temp |= I2CR_TXAK;
>  			imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
>  		}
> -		msgs->buf[i] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
> +		if ((!i) && (block_data))

Ditto

Shawn

> +			msgs->buf[0] = len;
> +		else
> +			msgs->buf[i] =  imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
>  		dev_dbg(&i2c_imx->adapter.dev,
>  			"<%s> read byte: B%d=0x%X\n",
>  			__func__, i, msgs->buf[i]);
> @@ -583,7 +607,8 @@ fail0:
>  
>  static u32 i2c_imx_func(struct i2c_adapter *adapter)
>  {
> -	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
> +		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
>  }
>  
>  static struct i2c_algorithm i2c_imx_algo = {
> -- 
> 1.7.9.5
> 
> 
> 

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Patch

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index db895fb..b6c2c3c 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -462,6 +462,7 @@  static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
 {
 	int i, result;
 	unsigned int temp;
+	int block_data = msgs->flags & I2C_M_RECV_LEN;
 
 	dev_dbg(&i2c_imx->adapter.dev,
 		"<%s> write slave address: addr=0x%x\n",
@@ -481,7 +482,12 @@  static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
 	/* setup bus to read data */
 	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
 	temp &= ~I2CR_MTX;
-	if (msgs->len - 1)
+
+	/*
+	 * Reset the I2CR_TXAK flag initially for SMbus block read since the
+	 * length is unknown
+	 */
+	if ((msgs->len - 1) || (block_data))
 		temp &= ~I2CR_TXAK;
 	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
 	imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); /* dummy read */
@@ -490,9 +496,24 @@  static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
 
 	/* read data */
 	for (i = 0; i < msgs->len; i++) {
+		u8 len = 0;
 		result = i2c_imx_trx_complete(i2c_imx);
 		if (result)
 			return result;
+		/*
+		 * First byte is the length of remaining packet
+		 * in the SMBus block data read. Add it to
+		 * msgs->len.
+		 */
+		if ((!i) && (block_data)) {
+			len = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
+			if ((len == 0) || (len > I2C_SMBUS_BLOCK_MAX))
+				return -EPROTO;
+			dev_dbg(&i2c_imx->adapter.dev,
+				"<%s> read length: 0x%X\n",
+				__func__, len);
+			msgs->len += len;
+		}
 		if (i == (msgs->len - 1)) {
 			/* It must generate STOP before read I2DR to prevent
 			   controller from generating another clock cycle */
@@ -510,7 +531,10 @@  static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
 			temp |= I2CR_TXAK;
 			imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
 		}
-		msgs->buf[i] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
+		if ((!i) && (block_data))
+			msgs->buf[0] = len;
+		else
+			msgs->buf[i] =  imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
 		dev_dbg(&i2c_imx->adapter.dev,
 			"<%s> read byte: B%d=0x%X\n",
 			__func__, i, msgs->buf[i]);
@@ -583,7 +607,8 @@  fail0:
 
 static u32 i2c_imx_func(struct i2c_adapter *adapter)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
+		| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
 }
 
 static struct i2c_algorithm i2c_imx_algo = {