tpm_tis_spi: Use single function to transfer data

commit f848f2143ae42dc0918400039257a893835254d1 upstream.

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)

v2: u16 instead of u8 for the length.
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>
Tested-by: Benoit Houyere <benoit.houyere@st.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 24 insertions, 63 deletions

diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index dbaad9c681e3..8341d5f2792c 100644
--- a/drivers/char/tpm/tpm_tis_spi.c
+++ b/drivers/char/tpm/tpm_tis_spi.c
@@ -48,8 +48,8 @@ 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)
@@ -57,8 +57,8 @@ 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, u16 len,
+                                u8 *buffer, u8 direction)
 {
         struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
         int ret, i;
@@ -67,17 +67,17 @@ 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);
 
@@ -86,7 +86,7 @@ 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
@@ -104,7 +104,14 @@ 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);
@@ -115,62 +122,16 @@ exit:
         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)