linux-kernel - Re: [PATCH v2] I2C Designware Core Supports SMBUS BLOCK

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Date:   Wed, 26 Oct 2016 17:52:44 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     tnhuynh@....com
Cc:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, Loc Ho <lho@....com>,
        Thang Nguyen <tqnguyen@....com>, Phong Vo <pvo@....com>,
        patches@....com
Subject: Re: [PATCH v2] I2C Designware Core Supports SMBUS BLOCK

On Wed, Oct 26, 2016 at 04:48:28PM +0700, tnhuynh@....com wrote:
> From: Tin Huynh <tnhuynh@....com>
> 
> Free and Open IPMI use SMBUS BLOCK Read/Write to support SSIF protocol.
> However, I2C Designwave Core Driver doesn't handle the case at the moment.
> The below patch supports this feature.

Looks better now but I have still couple of comments.

First, the subject line should say something like:

  i2c: designware: Implement support for SMBus block read and write

> Change from V1:
> 	-Remove empty lines
> 	-Add flags variable to make clean code
> 	-Change DW_DEFAULT_FUNCTIONALITY in i2c-designware-pcidrv.c

This changelog should be below the '---' in the patch.

> Signed-off-by: Tin Huynh <tnhuynh@....com>
> ---
>  drivers/i2c/busses/i2c-designware-core.c    |   36 ++++++++++++++++++++++++--
>  drivers/i2c/busses/i2c-designware-pcidrv.c  |    1 +
>  drivers/i2c/busses/i2c-designware-platdrv.c |    1 +
>  3 files changed, 35 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> index 1fe93c4..c77a83f 100644
> --- a/drivers/i2c/busses/i2c-designware-core.c
> +++ b/drivers/i2c/busses/i2c-designware-core.c
> @@ -543,6 +543,7 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
>  	intr_mask = DW_IC_INTR_DEFAULT_MASK;
>  
>  	for (; dev->msg_write_idx < dev->msgs_num; dev->msg_write_idx++) {
> +		u32 flags = msgs[dev->msg_write_idx].flags;
>  		/*
>  		 * if target address has changed, we need to
>  		 * reprogram the target address in the i2c
> @@ -588,8 +589,15 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
>  			 * detected from the registers so we set it always
>  			 * when writing/reading the last byte.
>  			 */
> +
> +			/*
> +			 * i2c-core.c always set the buffer length of
> +			 * I2C_FUNC_SMBUS_BLOCK_DATA to 1. The length will
> +			 * be adjusted when receiving the first byte.
> +			 * Thus we can't stop the transaction here.
> +			 */
>  			if (dev->msg_write_idx == dev->msgs_num - 1 &&
> -			    buf_len == 1)
> +			    buf_len == 1 && !(flags & I2C_M_RECV_LEN))
>  				cmd |= BIT(9);
>  
>  			if (need_restart) {
> @@ -614,7 +622,12 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
>  		dev->tx_buf = buf;
>  		dev->tx_buf_len = buf_len;
>  
> -		if (buf_len > 0) {
> +		/*
> +		 * Because we don't know the buffer length in the
> +		 * I2C_FUNC_SMBUS_BLOCK_DATA case, we can't stop
> +		 * the transaction here.
> +		 */
> +		if (buf_len > 0 || flags & I2C_M_RECV_LEN) {
>  			/* more bytes to be written */
>  			dev->status |= STATUS_WRITE_IN_PROGRESS;
>  			break;
> @@ -659,7 +672,24 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
>  		rx_valid = dw_readl(dev, DW_IC_RXFLR);
>  
>  		for (; len > 0 && rx_valid > 0; len--, rx_valid--) {
> -			*buf++ = dw_readl(dev, DW_IC_DATA_CMD);

->

> +			u32 flags = msgs[dev->msg_read_idx].flags;
> +			*buf = dw_readl(dev, DW_IC_DATA_CMD);
> +			/* ensure length byte is a valid value */
> +			if (flags & I2C_M_RECV_LEN &&
> +				*buf <= I2C_SMBUS_BLOCK_MAX && *buf > 0) {
> +				/*
> +				 * Adjust the buffer length and mask the flag
> +				 * after receiving the first byte
> +				 */
> +				len = (flags & I2C_CLIENT_PEC) ?
> +					*buf + 2 : *buf + 1;
> +				dev->tx_buf_len = len > dev->rx_outstanding ?
> +					len - dev->rx_outstanding : 0;
> +				msgs[dev->msg_read_idx].len = len;
> +				flags &= ~I2C_M_RECV_LEN;
> +				msgs[dev->msg_read_idx].flags = flags;
> +			}

<- how about moving this block to a helper function?

> +			buf++;


>  			dev->rx_outstanding--;
>  		}
>  
> diff --git a/drivers/i2c/busses/i2c-designware-pcidrv.c b/drivers/i2c/busses/i2c-designware-pcidrv.c
> index 96f8230..8ffe2da 100644
> --- a/drivers/i2c/busses/i2c-designware-pcidrv.c
> +++ b/drivers/i2c/busses/i2c-designware-pcidrv.c
> @@ -75,6 +75,7 @@ struct dw_pci_controller {
>  					I2C_FUNC_SMBUS_BYTE |		\
>  					I2C_FUNC_SMBUS_BYTE_DATA |	\
>  					I2C_FUNC_SMBUS_WORD_DATA |	\
> +					I2C_FUNC_SMBUS_BLOCK_DATA |	\
>  					I2C_FUNC_SMBUS_I2C_BLOCK)
>  
>  /* Merrifield HCNT/LCNT/SDA hold time */
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 0b42a12..886fb62 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -220,6 +220,7 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
>  		I2C_FUNC_SMBUS_BYTE |
>  		I2C_FUNC_SMBUS_BYTE_DATA |
>  		I2C_FUNC_SMBUS_WORD_DATA |
> +		I2C_FUNC_SMBUS_BLOCK_DATA |
>  		I2C_FUNC_SMBUS_I2C_BLOCK;
>  
>  	dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
> -- 
> 1.7.1