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

Peter Huewe
2017-02-16T16:10:08Z

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>
---
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