linux-kernel - Re: [PATCH 4/5] tpm_tis_spi: Remove limitation of transfers to MAX_SPI

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Date:   Thu, 16 Feb 2017 21:11:53 -0800
From:   Christophe Ricard <christophe.ricard@...il.com>
To:     Peter Huewe <peter.huewe@...ineon.com>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        peterhuewe@....de, Christophe Ricard <christophe-h.ricard@...com>,
        stable@...r.kernel.org,
        Alexander Steffen <Alexander.Steffen@...ineon.com>
Subject: Re: [PATCH 4/5] tpm_tis_spi: Remove limitation of transfers to
 MAX_SPI_FRAMESIZE bytes

I am not sure i understand here, are you considering there could be 
burstcount > 64 with "TCG" TPM ?

Or is this because of TIS vs PTP differences ?

To be honest, this is a little behind me now :-)


On 16/02/2017 08:08, Peter Huewe wrote:
> Limiting transfers to MAX_SPI_FRAMESIZE was not expected by the upper
> layers, as tpm_tis has no such limitation. Add a loop to hide that
> limitation.
>
> Cc: <stable@...r.kernel.org>
> Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
> Signed-off-by: Alexander Steffen <Alexander.Steffen@...ineon.com>
> Signed-off-by: Peter Huewe <peter.huewe@...ineon.com>
> ---
>   drivers/char/tpm/tpm_tis_spi.c | 108 ++++++++++++++++++++++-------------------
>   1 file changed, 57 insertions(+), 51 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
> index 16938e2253d2..b50c5b072df3 100644
> --- a/drivers/char/tpm/tpm_tis_spi.c
> +++ b/drivers/char/tpm/tpm_tis_spi.c
> @@ -61,68 +61,74 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 len,
>   {
>   	struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
>   	int ret;
> -	struct spi_message m;
> -	struct spi_transfer spi_xfer = {
> -		.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] = direction | (len - 1);
> -	phy->tx_buf[1] = 0xd4;
> -	phy->tx_buf[2] = addr >> 8;
> -	phy->tx_buf[3] = addr;
> +	spi_bus_lock(phy->spi_device->master);
>   
> -	spi_message_init(&m);
> -	spi_message_add_tail(&spi_xfer, &m);
> +	while (len) {
> +		struct spi_message m;
> +		struct spi_transfer spi_xfer = {
> +			.tx_buf = phy->tx_buf,
> +			.rx_buf = phy->rx_buf,
> +			.len = 4,
> +			.cs_change = 1,
> +		};
> +		u8 transfer_len = min_t(u16, len, MAX_SPI_FRAMESIZE);
> +
> +		phy->tx_buf[0] = direction | (transfer_len - 1);
> +		phy->tx_buf[1] = 0xd4;
> +		phy->tx_buf[2] = addr >> 8;
> +		phy->tx_buf[3] = addr;
> +
> +		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_bus_lock(phy->spi_device->master);
> -	ret = spi_sync_locked(phy->spi_device, &m);
> -	if (ret < 0)
> -		goto exit;
> -
> -	if ((phy->rx_buf[3] & 0x01) == 0) {
> -		// handle SPI wait states
> -		int i;
> -
> -		phy->tx_buf[0] = 0;
> -
> -		for (i = 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)
> +		if ((phy->rx_buf[3] & 0x01) == 0) {
> +			// handle SPI wait states
> +			int i;
> +
> +			phy->tx_buf[0] = 0;
> +
> +			for (i = 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;
> +				if (phy->rx_buf[0] & 0x01)
> +					break;
> +			}
> +
> +			if (i == TPM_RETRY) {
> +				ret = -ETIMEDOUT;
>   				goto exit;
> -			if (phy->rx_buf[0] & 0x01)
> -				break;
> +			}
>   		}
>   
> -		if (i == TPM_RETRY) {
> -			ret = -ETIMEDOUT;
> -			goto exit;
> +		spi_xfer.cs_change = 0;
> +		spi_xfer.len = transfer_len;
> +
> +		if (direction) {
> +			spi_xfer.tx_buf = NULL;
> +			spi_xfer.rx_buf = buffer;
> +		} else {
> +			spi_xfer.tx_buf = buffer;
> +			spi_xfer.rx_buf = NULL;
>   		}
> -	}
>   
> -	spi_xfer.cs_change = 0;
> -	spi_xfer.len = len;
> +		spi_message_init(&m);
> +		spi_message_add_tail(&spi_xfer, &m);
> +		ret = spi_sync_locked(phy->spi_device, &m);
> +		if (ret < 0)
> +			goto exit;
>   
> -	if (direction) {
> -		spi_xfer.tx_buf = NULL;
> -		spi_xfer.rx_buf = buffer;
> -	} else {
> -		spi_xfer.tx_buf = buffer;
> -		spi_xfer.rx_buf = NULL;
> +		len -= transfer_len;
> +		buffer += transfer_len;
>   	}
>   
> -	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;