linux-kernel - Re: [PATCH] i2c/busses: (mpc) Add support for SMBUS_READ_BLOCK

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Date:	Mon, 12 Dec 2011 01:28:06 -0800
From:	Guenter Roeck <guenter.roeck@...csson.com>
To:	"Yuantian.tang@...escale.com" <Yuantian.tang@...escale.com>
CC:	"ben-linux@...ff.org" <ben-linux@...ff.org>,
	"khali@...ux-fr.org" <khali@...ux-fr.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Tang Yuantian <B29983@...escale.com>
Subject: Re: [PATCH] i2c/busses: (mpc) Add support for SMBUS_READ_BLOCK_DATA

On Sun, Dec 11, 2011 at 11:10:10PM -0500, Yuantian.tang@...escale.com wrote:
> From: Tang Yuantian <B29983@...escale.com>
> 
> Add support for SMBUS_READ_BLOCK_DATA to the i2c-mpc bus driver.
> 
> Signed-off-by: Tang Yuantian <Yuantian.Tang@...escale.com>
> Signed-off-by: Guenter Roeck <guenter.roeck@...csson.com>

You can not do this. While I may have written this patch originally,
I abandoned it, and you can not use my signature.

Guenter

> ---
> tested on p1022ds
> 
>  drivers/i2c/busses/i2c-mpc.c |   63 ++++++++++++++++++++++++++++++++---------
>  1 files changed, 49 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
> index 107397a..bba9a07 100644
> --- a/drivers/i2c/busses/i2c-mpc.c
> +++ b/drivers/i2c/busses/i2c-mpc.c
> @@ -454,7 +454,7 @@ static int mpc_write(struct mpc_i2c *i2c, int target,
>  }
>  
>  static int mpc_read(struct mpc_i2c *i2c, int target,
> -		    u8 *data, int length, int restart)
> +		    u8 *data, int length, int restart, bool recv_len)
>  {
>  	unsigned timeout = i2c->adap.timeout;
>  	int i, result;
> @@ -470,7 +470,7 @@ static int mpc_read(struct mpc_i2c *i2c, int target,
>  		return result;
>  
>  	if (length) {
> -		if (length == 1)
> +		if (length == 1 && !recv_len)
>  			writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_TXAK);
>  		else
>  			writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA);
> @@ -479,17 +479,46 @@ static int mpc_read(struct mpc_i2c *i2c, int target,
>  	}
>  
>  	for (i = 0; i < length; i++) {
> +		u8 byte;
> +
>  		result = i2c_wait(i2c, timeout, 0);
>  		if (result < 0)
>  			return result;
>  
> -		/* Generate txack on next to last byte */
> -		if (i == length - 2)
> -			writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_TXAK);
> -		/* Do not generate stop on last byte */
> -		if (i == length - 1)
> -			writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_MTX);
> -		data[i] = readb(i2c->base + MPC_I2C_DR);
> +		/*
> +		 * For block reads, we have to know the total length (1st byte)
> +		 * before we can determine if we are done.
> +		 */
> +		if (i || !recv_len) {
> +			/* Generate txack on next to last byte */
> +			if (i == length - 2)
> +				writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA
> +					 | CCR_TXAK);
> +			/* Do not generate stop on last byte */
> +			if (i == length - 1)
> +				writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA
> +					 | CCR_MTX);
> +		}
> +
> +		byte = readb(i2c->base + MPC_I2C_DR);
> +
> +		/*
> +		 * Adjust length if first received byte is length.
> +		 * The length is 1 length byte plus actually data length
> +		 */
> +		if (i == 0 && recv_len) {
> +			if (byte == 0 || byte > I2C_SMBUS_BLOCK_MAX)
> +				return -EPROTO;
> +			length += byte;
> +			/*
> +			 * For block reads, generate txack here if data length
> +			 * is 1 byte (total length is 2 bytes).
> +			 */
> +			if (length == 2)
> +				writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA
> +					 | CCR_TXAK);
> +		}
> +		data[i] = byte;
>  	}
>  
>  	return length;
> @@ -532,12 +561,17 @@ static int mpc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>  			"Doing %s %d bytes to 0x%02x - %d of %d messages\n",
>  			pmsg->flags & I2C_M_RD ? "read" : "write",
>  			pmsg->len, pmsg->addr, i + 1, num);
> -		if (pmsg->flags & I2C_M_RD)
> -			ret =
> -			    mpc_read(i2c, pmsg->addr, pmsg->buf, pmsg->len, i);
> -		else
> +		if (pmsg->flags & I2C_M_RD) {
> +			bool recv_len = pmsg->flags & I2C_M_RECV_LEN;
> +
> +			ret = mpc_read(i2c, pmsg->addr, pmsg->buf, pmsg->len, i,
> +				       recv_len);
> +			if (recv_len && ret > 0)
> +				pmsg->len = ret;
> +		} else {
>  			ret =
>  			    mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, i);
> +		}
>  	}
>  	mpc_i2c_stop(i2c);
>  	return (ret < 0) ? ret : num;
> @@ -545,7 +579,8 @@ static int mpc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>  
>  static u32 mpc_functionality(struct i2c_adapter *adap)
>  {
> -	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
> +	  | I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL;
>  }
>  
>  static const struct i2c_algorithm mpc_algo = {
> -- 
> 1.6.4
> 
> 
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