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Subject[PATCH RESEND v3 1/2] tpm_tis_spi: Use DMA-safe memory for SPI transfers
Date
The buffers used as tx_buf/rx_buf in a SPI transfer need to be DMA-safe.
This cannot be guaranteed for the buffers passed to tpm_tis_spi_read_bytes
and tpm_tis_spi_write_bytes. Therefore, we need to use our own DMA-safe
buffer and copy the data to/from it.

The buffer needs to be allocated separately, to ensure that it is
cacheline-aligned and not shared with other data, so that DMA can work
correctly.

Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
Cc: stable@vger.kernel.org
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 | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index 88fe72a..05ce841 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[4];
- u8 rx_buf[4];
+ u8 *tx_buf;
+ u8 *rx_buf;
};

static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *data)
@@ -115,10 +115,9 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,

if (direction) {
spi_xfer.tx_buf = NULL;
- spi_xfer.rx_buf = buffer;
} else {
- spi_xfer.tx_buf = buffer;
spi_xfer.rx_buf = NULL;
+ memcpy(phy->tx_buf, buffer, transfer_len);
}

spi_message_init(&m);
@@ -127,6 +126,9 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
if (ret < 0)
goto exit;

+ if (direction)
+ memcpy(buffer, phy->rx_buf, transfer_len);
+
len -= transfer_len;
buffer += transfer_len;
}
@@ -194,6 +196,14 @@ 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)
+ return -ENOMEM;
+
return tpm_tis_core_init(&dev->dev, &phy->priv, -1, &tpm_spi_phy_ops,
NULL);
}
--
2.7.4
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