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

Jarkko Sakkinen
2017-02-24T12:54:32Z

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@vger.kernel.org>
> [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@infineon.com>
> Signed-off-by: Peter Huewe <peter.huewe@infineon.com>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

/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
>