Re: Add restart support to i2c-pnx

[Ben Dooks <ben-i2c-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org>]

On Wed, Feb 02, 2011 at 10:23:42PM +0100, Matej Kupljen wrote:
> Kevin,
> 
> > Thanks for posting this patch. See comments below..
> > I'll be happy to test your changes once the following items
> > are clarified.
> > 
> > > The pathch is against 2.6.28.2, but it should apply to the
> > > cureent GIT version as well.
> > 
> > This patch needs to be re-based against the latest version
> > of the driver as it has changes that this patch will revert
> > or won't apply to.
> 
> I re-based it against latest version of the kernel in GIT and 
> also included your comments in the mail.
> 
> Is it O.K. now?
> 
> Regards,
> Matej
> 
> P.S.: Changed the email client. I now attached the file as 
> well as pasted it in-line.
> 
> -------------------------------------------------------------------
> Current code in i2c-pnx.c doesn't support sending messages
> with restart condition in it, for example:
> S - (address | W) - Sr - (address | R) - ... - P
> 
> This patch adds this to the current code. It has been
> tested on a custom board with LPC3152 CPU (similar to
> Embedded Artists EA313x board) with uBlox GPS receiver
> connected to I2C bus. It has been running over the night
> without errors. 
> 
> Signed-off-by: Matej Kupljen <matej.kupljen-nWYkTt+LGLL1KXRcyAk9cg@public.gmane.org>
> 
> --- i2c-pnx-orig.c	2011-02-02 21:30:19.000000000 +0100
> +++ i2c-pnx.c	2011-02-02 21:49:02.000000000 +0100
> @@ -78,7 +78,7 @@
>   * Generate a START signal in the desired mode.
>   */
>  static int i2c_pnx_start(unsigned char slave_addr,
> -	struct i2c_pnx_algo_data *alg_data)
> +	struct i2c_pnx_algo_data *alg_data, int repeated)

bool repeated.

>  {
>  	dev_dbg(&alg_data->adapter.dev, "%s(): addr 0x%x mode %d\n", __func__,
>  		slave_addr, alg_data->mif.mode);
> @@ -91,8 +91,8 @@
>  		return -EINVAL;
>  	}
>  
> -	/* First, make sure bus is idle */
> -	if (wait_timeout(I2C_PNX_TIMEOUT, alg_data)) {
> +	/* First, make sure bus is idle, if we are not doing repeated start */
> +	if ((!repeated) && (wait_timeout(I2C_PNX_TIMEOUT, alg_data))) {

no need for () around !repeated.

>  		/* Somebody else is monopolizing the bus */
>  		dev_err(&alg_data->adapter.dev,
>  			"%s: Bus busy. Slave addr = %02x, cntrl = %x, stat = %x\n",
> @@ -441,7 +441,7 @@
>  i2c_pnx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>  {
>  	struct i2c_msg *pmsg;
> -	int rc = 0, completed = 0, i;
> +	int rc = 0, completed = 0, i, repeated;

see above.

>  	struct i2c_pnx_algo_data *alg_data = adap->algo_data;
>  	u32 stat = ioread32(I2C_REG_STS(alg_data));
>  
> @@ -457,6 +457,7 @@
>  
>  		pmsg = &msgs[i];
>  		addr = pmsg->addr;
> +		repeated = 0;
>  
>  		if (pmsg->flags & I2C_M_TEN) {
>  			dev_err(&alg_data->adapter.dev,
> @@ -481,16 +482,23 @@
>  		/* initialize the completion var */
>  		init_completion(&alg_data->mif.complete);
>  
> -		/* Enable master interrupt */
> -		iowrite32(ioread32(I2C_REG_CTL(alg_data)) | mcntrl_afie |
> -				mcntrl_naie | mcntrl_drmie,
> -			  I2C_REG_CTL(alg_data));
> +		/* 
> +		 * If this is not the only message, then we need to
> +		 * send repeated start, but only if the flag allows it
> +		 */
> +		if((i > 0) && !(pmsg->flags & I2C_M_NOSTART))

no need for () around i > 0

> +			repeated = 1;
>  
>  		/* Put start-code and slave-address on the bus. */
> -		rc = i2c_pnx_start(addr, alg_data);
> +		rc = i2c_pnx_start(addr, alg_data, repeated);
>  		if (rc < 0)
>  			break;
>  
> +		/* Enable master interrupt */
> +		iowrite32(ioread32(I2C_REG_CTL(alg_data)) | mcntrl_afie |
> +				mcntrl_naie | mcntrl_drmie,
> +			  I2C_REG_CTL(alg_data));
> +
>  		/* Wait for completion */
>  		wait_for_completion(&alg_data->mif.complete);
  

-- 
Ben Dooks, ben-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org, http://www.fluff.org/ben/

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