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Subject[PATCH RESEND v3 2/2] tpm_tis_spi: Use a single buffer for SPI transfers
Date
A single buffer is sufficient for both tx and rx, since bytes that have
already been sent are not used anymore and can safely be overwritten with
the received bytes.

Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
drivers/char/tpm/tpm_tis_spi.c | 34 ++++++++++++++--------------------
1 file changed, 14 insertions(+), 20 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index 05ce841..5321245 100644
--- a/drivers/char/tpm/tpm_tis_spi.c
+++ b/drivers/char/tpm/tpm_tis_spi.c
@@ -46,9 +46,7 @@
struct tpm_tis_spi_phy {
struct tpm_tis_data priv;
struct spi_device *spi_device;
-
- u8 *tx_buf;
- u8 *rx_buf;
+ u8 *iobuf;
};

static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *data)
@@ -71,14 +69,14 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
while (len) {
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;
+ phy->iobuf[0] = direction | (transfer_len - 1);
+ phy->iobuf[1] = 0xd4;
+ phy->iobuf[2] = addr >> 8;
+ phy->iobuf[3] = addr;

memset(&spi_xfer, 0, sizeof(spi_xfer));
- spi_xfer.tx_buf = phy->tx_buf;
- spi_xfer.rx_buf = phy->rx_buf;
+ spi_xfer.tx_buf = phy->iobuf;
+ spi_xfer.rx_buf = phy->iobuf;
spi_xfer.len = 4;
spi_xfer.cs_change = 1;

@@ -88,9 +86,9 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
if (ret < 0)
goto exit;

- if ((phy->rx_buf[3] & 0x01) == 0) {
+ if ((phy->iobuf[3] & 0x01) == 0) {
// handle SPI wait states
- phy->tx_buf[0] = 0;
+ phy->iobuf[0] = 0;

for (i = 0; i < TPM_RETRY; i++) {
spi_xfer.len = 1;
@@ -99,7 +97,7 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
ret = spi_sync_locked(phy->spi_device, &m);
if (ret < 0)
goto exit;
- if (phy->rx_buf[0] & 0x01)
+ if (phy->iobuf[0] & 0x01)
break;
}

@@ -117,7 +115,7 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
spi_xfer.tx_buf = NULL;
} else {
spi_xfer.rx_buf = NULL;
- memcpy(phy->tx_buf, buffer, transfer_len);
+ memcpy(phy->iobuf, buffer, transfer_len);
}

spi_message_init(&m);
@@ -127,7 +125,7 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
goto exit;

if (direction)
- memcpy(buffer, phy->rx_buf, transfer_len);
+ memcpy(buffer, phy->iobuf, transfer_len);

len -= transfer_len;
buffer += transfer_len;
@@ -196,12 +194,8 @@ static int tpm_tis_spi_probe(struct spi_device *dev)

phy->spi_device = dev;

- phy->tx_buf = devm_kmalloc(&dev->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
- if (!phy->tx_buf)
- return -ENOMEM;
-
- phy->rx_buf = devm_kmalloc(&dev->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
- if (!phy->rx_buf)
+ phy->iobuf = devm_kmalloc(&dev->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
+ if (!phy->iobuf)
return -ENOMEM;

return tpm_tis_core_init(&dev->dev, &phy->priv, -1, &tpm_spi_phy_ops,
--
2.7.4
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