Re: [PATCH 1/5] tpm_tis_spi: Use single function to transfer data

[Jarkko Sakkinen]

On Thu, Feb 16, 2017 at 04:08:22PM +0000, Peter Huewe wrote:
> The algorithm for sending data to the TPM is mostly identical to the
> algorithm for receiving data from the TPM, so a single function is
> sufficient to handle both cases.
> 
> This is a prequisite for all the other fixes, so we don't have to fix
> everything twice (send/receive)
> 
> Cc: <stable@xxxxxxxxxxxxxxx>
> [prerequisite for other fixes in this series]
> Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
> Signed-off-by: Alexander Steffen <Alexander.Steffen@xxxxxxxxxxxx>
> Signed-off-by: Peter Huewe <peter.huewe@xxxxxxxxxxxx>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>

/Jarkko

> ---
>  drivers/char/tpm/tpm_tis_spi.c | 87 ++++++++++++------------------------------
>  1 file changed, 24 insertions(+), 63 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
> index 5292e5768a7e..6e1a3c43f621 100644
> --- a/drivers/char/tpm/tpm_tis_spi.c
> +++ b/drivers/char/tpm/tpm_tis_spi.c
> @@ -47,8 +47,8 @@ struct tpm_tis_spi_phy {
>  	struct tpm_tis_data priv;
>  	struct spi_device *spi_device;
>  
> -	u8 tx_buf[MAX_SPI_FRAMESIZE + 4];
> -	u8 rx_buf[MAX_SPI_FRAMESIZE + 4];
> +	u8 tx_buf[4];
> +	u8 rx_buf[4];
>  };
>  
>  static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *data)
> @@ -56,8 +56,8 @@ static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *da
>  	return container_of(data, struct tpm_tis_spi_phy, priv);
>  }
>  
> -static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
> -				  u16 len, u8 *result)
> +static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 len,
> +				u8 *buffer, u8 direction)
>  {
>  	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
>  	int ret, i;
> @@ -66,17 +66,17 @@ static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
>  		.tx_buf = phy->tx_buf,
>  		.rx_buf = phy->rx_buf,
>  		.len = 4,
> +		.cs_change = 1,
>  	};
>  
>  	if (len > MAX_SPI_FRAMESIZE)
>  		return -ENOMEM;
>  
> -	phy->tx_buf[0] = 0x80 | (len - 1);
> +	phy->tx_buf[0] = direction | (len - 1);
>  	phy->tx_buf[1] = 0xd4;
> -	phy->tx_buf[2] = (addr >> 8)  & 0xFF;
> -	phy->tx_buf[3] = addr	      & 0xFF;
> +	phy->tx_buf[2] = addr >> 8;
> +	phy->tx_buf[3] = addr;
>  
> -	spi_xfer.cs_change = 1;
>  	spi_message_init(&m);
>  	spi_message_add_tail(&spi_xfer, &m);
>  
> @@ -85,7 +85,7 @@ static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
>  	if (ret < 0)
>  		goto exit;
>  
> -	memset(phy->tx_buf, 0, len);
> +	phy->tx_buf[0] = 0;
>  
>  	/* According to TCG PTP specification, if there is no TPM present at
>  	 * all, then the design has a weak pull-up on MISO. If a TPM is not
> @@ -103,7 +103,14 @@ static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
>  
>  	spi_xfer.cs_change = 0;
>  	spi_xfer.len = len;
> -	spi_xfer.rx_buf = result;
> +
> +	if (direction) {
> +		spi_xfer.tx_buf = NULL;
> +		spi_xfer.rx_buf = buffer;
> +	} else {
> +		spi_xfer.tx_buf = buffer;
> +		spi_xfer.rx_buf = NULL;
> +	}
>  
>  	spi_message_init(&m);
>  	spi_message_add_tail(&spi_xfer, &m);
> @@ -114,62 +121,16 @@ static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
>  	return ret;
>  }
>  
> +static int tpm_tis_spi_read_bytes(struct tpm_tis_data *data, u32 addr,
> +				  u16 len, u8 *result)
> +{
> +	return tpm_tis_spi_transfer(data, addr, len, result, 0x80);
> +}
> +
>  static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
>  				   u16 len, u8 *value)
>  {
> -	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
> -	int ret, i;
> -	struct spi_message m;
> -	struct spi_transfer spi_xfer = {
> -		.tx_buf = phy->tx_buf,
> -		.rx_buf = phy->rx_buf,
> -		.len = 4,
> -	};
> -
> -	if (len > MAX_SPI_FRAMESIZE)
> -		return -ENOMEM;
> -
> -	phy->tx_buf[0] = len - 1;
> -	phy->tx_buf[1] = 0xd4;
> -	phy->tx_buf[2] = (addr >> 8)  & 0xFF;
> -	phy->tx_buf[3] = addr         & 0xFF;
> -
> -	spi_xfer.cs_change = 1;
> -	spi_message_init(&m);
> -	spi_message_add_tail(&spi_xfer, &m);
> -
> -	spi_bus_lock(phy->spi_device->master);
> -	ret = spi_sync_locked(phy->spi_device, &m);
> -	if (ret < 0)
> -		goto exit;
> -
> -	memset(phy->tx_buf, 0, len);
> -
> -	/* According to TCG PTP specification, if there is no TPM present at
> -	 * all, then the design has a weak pull-up on MISO. If a TPM is not
> -	 * present, a pull-up on MISO means that the SB controller sees a 1,
> -	 * and will latch in 0xFF on the read.
> -	 */
> -	for (i = 0; (phy->rx_buf[0] & 0x01) == 0 && i < TPM_RETRY; i++) {
> -		spi_xfer.len = 1;
> -		spi_message_init(&m);
> -		spi_message_add_tail(&spi_xfer, &m);
> -		ret = spi_sync_locked(phy->spi_device, &m);
> -		if (ret < 0)
> -			goto exit;
> -	}
> -
> -	spi_xfer.len = len;
> -	spi_xfer.tx_buf = value;
> -	spi_xfer.cs_change = 0;
> -	spi_xfer.tx_buf = value;
> -	spi_message_init(&m);
> -	spi_message_add_tail(&spi_xfer, &m);
> -	ret = spi_sync_locked(phy->spi_device, &m);
> -
> -exit:
> -	spi_bus_unlock(phy->spi_device->master);
> -	return ret;
> +	return tpm_tis_spi_transfer(data, addr, len, value, 0);
>  }
>  
>  static int tpm_tis_spi_read16(struct tpm_tis_data *data, u32 addr, u16 *result)
> -- 
> 2.7.4
>