linux-kernel - Re: [PATCH RFC 1/2] tpm: tpm_tis

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Message-Id: <D3Z3UFHWQ3MG.N8JU7ZHX3XHN@kernel.org>
Date: Fri, 06 Sep 2024 12:47:51 +0300
From: "Jarkko Sakkinen" <jarkko@...nel.org>
To: "Stefan Wahren" <wahrenst@....net>, "Peter Huewe" <peterhuewe@....de>,
 "Jason Gunthorpe" <jgg@...pe.ca>
Cc: <linux-integrity@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 "Stefan Berger" <stefanb@...ux.ibm.com>
Subject: Re: [PATCH RFC 1/2] tpm: tpm_tis_spi: Ensure SPI mode 0

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@....net>
> ---
>  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?

BR, Jarkko