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tpm: tpm_tis_spi: Introduce a flow control callback
Cr50 firmware has a different flow control protocol than the one used by this TPM PTP SPI driver. Introduce a flow control callback so we can override the standard sequence with the custom one that Cr50 uses. Cc: Andrey Pronin <apronin@chromium.org> Cc: Duncan Laurie <dlaurie@chromium.org> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guenter Roeck <groeck@chromium.org> Cc: Alexander Steffen <Alexander.Steffen@infineon.com> Cc: Heiko Stuebner <heiko@sntech.de> Signed-off-by: Stephen Boyd <swboyd@chromium.org> Tested-by: Heiko Stuebner <heiko@sntech.de> Reviewed-by: Heiko Stuebner <heiko@sntech.de> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
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@ -42,6 +42,8 @@
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struct tpm_tis_spi_phy {
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struct tpm_tis_data priv;
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struct spi_device *spi_device;
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int (*flow_control)(struct tpm_tis_spi_phy *phy,
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struct spi_transfer *xfer);
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u8 *iobuf;
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};
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@ -50,12 +52,46 @@ static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *da
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return container_of(data, struct tpm_tis_spi_phy, priv);
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}
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/*
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* TCG SPI flow control is documented in section 6.4 of the spec[1]. In short,
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* keep trying to read from the device until MISO goes high indicating the
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* wait state has ended.
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*
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* [1] https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
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*/
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static int tpm_tis_spi_flow_control(struct tpm_tis_spi_phy *phy,
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struct spi_transfer *spi_xfer)
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{
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struct spi_message m;
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int ret, i;
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if ((phy->iobuf[3] & 0x01) == 0) {
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// handle SPI wait states
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phy->iobuf[0] = 0;
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for (i = 0; i < TPM_RETRY; i++) {
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spi_xfer->len = 1;
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spi_message_init(&m);
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spi_message_add_tail(spi_xfer, &m);
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ret = spi_sync_locked(phy->spi_device, &m);
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if (ret < 0)
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return ret;
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if (phy->iobuf[0] & 0x01)
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break;
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}
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if (i == TPM_RETRY)
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return -ETIMEDOUT;
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}
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return 0;
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}
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static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
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u8 *in, const u8 *out)
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{
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struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
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int ret = 0;
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int i;
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struct spi_message m;
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struct spi_transfer spi_xfer;
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u8 transfer_len;
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@ -82,26 +118,9 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
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if (ret < 0)
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goto exit;
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if ((phy->iobuf[3] & 0x01) == 0) {
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// handle SPI wait states
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phy->iobuf[0] = 0;
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for (i = 0; i < TPM_RETRY; i++) {
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spi_xfer.len = 1;
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spi_message_init(&m);
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spi_message_add_tail(&spi_xfer, &m);
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ret = spi_sync_locked(phy->spi_device, &m);
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if (ret < 0)
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goto exit;
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if (phy->iobuf[0] & 0x01)
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break;
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}
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if (i == TPM_RETRY) {
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ret = -ETIMEDOUT;
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goto exit;
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}
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}
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ret = phy->flow_control(phy, &spi_xfer);
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if (ret < 0)
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goto exit;
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spi_xfer.cs_change = 0;
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spi_xfer.len = transfer_len;
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@ -207,6 +226,7 @@ static int tpm_tis_spi_probe(struct spi_device *dev)
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phy->iobuf = devm_kmalloc(&dev->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL);
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if (!phy->iobuf)
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return -ENOMEM;
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phy->flow_control = tpm_tis_spi_flow_control;
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/* If the SPI device has an IRQ then use that */
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if (dev->irq > 0)
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