Re: [PATCH RFC 1/2] tpm: tpm_tis_spi: Ensure SPI mode 0
From: Stefan Wahren
Date: Fri Sep 06 2024 - 10:47:25 EST
Am 06.09.24 um 11:47 schrieb Jarkko Sakkinen:
On Fri Sep 6, 2024 at 9:09 AM EEST, Stefan Wahren wrote:
According to TCG PC Client Platform TPM Profile (PTP) Specification
only SPI mode 0 is supported. In order to ensure the SPI controller
supports the necessary settings, call spi_setup() and bail out
as soon as possible in error case.
This change should affect all supported TPM SPI devices, because
tpm_tis_spi_probe is either called direct or indirectly.
Signed-off-by: Stefan Wahren <wahrenst@xxxxxxx>
---
drivers/char/tpm/tpm_tis_spi_main.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/char/tpm/tpm_tis_spi_main.c b/drivers/char/tpm/tpm_tis_spi_main.c
index 61b42c83ced8..e62d297b040e 100644
--- a/drivers/char/tpm/tpm_tis_spi_main.c
+++ b/drivers/char/tpm/tpm_tis_spi_main.c
@@ -248,6 +248,17 @@ static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr,
int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy,
int irq, const struct tpm_tis_phy_ops *phy_ops)
{
+ int ret;
+
+ spi->mode &= ~SPI_MODE_X_MASK;
+ spi->mode |= SPI_MODE_0;
+
+ ret = spi_setup(spi);
+ if (ret < 0) {
+ dev_err(&spi->dev, "SPI setup failed: %d\n", ret);
+ return ret;
+ }
+
phy->iobuf = devm_kmalloc(&spi->dev, SPI_HDRSIZE + MAX_SPI_FRAMESIZE, GFP_KERNEL);
if (!phy->iobuf)
return -ENOMEM;
--
2.34.1
Why?
SPI protocol driver usually call spi_setup to verify that the SPI
controller accept the settings (SPI mode, bit, clock rate ...). Bailing
out early is more helpful for debugging issues.
BR, Jarkko