| Message ID | 20230302041804.24718-2-kyarlagadda@nvidia.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Tegra TPM driver with HW flow control | expand |
On Thu, Mar 02, 2023 at 09:48:02AM +0530, Krishna Yarlagadda wrote: > TPM specification [1] defines flow control over SPI. Client device can > insert a wait state on MISO when address is transmitted by controller > on MOSI. Detecting the wait state in software is only possible for > full duplex controllers. For controllers that support only half- > duplex, the wait state detection needs to be implemented in hardware. > > Add a flag SPI_TPM_HW_FLOW for TPM device to set when software flow > control is not possible and hardware flow control is expected from > SPI controller. > > Reference: > [1] https://trustedcomputinggroup.org/resource/pc-client-work-group- > pc-client-specific-tpm-interface-specification-tis/ > Minor thing, but should this reference the newer specification [1]? [1] https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/ Regards, Jerry > Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com> > --- > include/linux/spi/spi.h | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h > index 4fa26b9a3572..b9e49ed42955 100644 > --- a/include/linux/spi/spi.h > +++ b/include/linux/spi/spi.h > @@ -184,8 +184,18 @@ struct spi_device { > u8 chip_select; > u8 bits_per_word; > bool rt; > -#define SPI_NO_TX BIT(31) /* No transmit wire */ > -#define SPI_NO_RX BIT(30) /* No receive wire */ > +#define SPI_NO_TX BIT(31) /* No transmit wire */ > +#define SPI_NO_RX BIT(30) /* No receive wire */ > + /* > + * TPM specification defines flow control over SPI. Client device > + * can insert a wait state on MISO when address is transmitted by > + * controller on MOSI. Detecting the wait state in software is only > + * possible for full duplex controllers. For controllers that support > + * only half-duplex, the wait state detection needs to be implemented > + * in hardware. TPM devices would set this flag when hardware flow > + * control is expected from SPI controller. > + */ > +#define SPI_TPM_HW_FLOW BIT(29) /* TPM HW flow control */ > /* > * All bits defined above should be covered by SPI_MODE_KERNEL_MASK. > * The SPI_MODE_KERNEL_MASK has the SPI_MODE_USER_MASK counterpart, > @@ -195,7 +205,7 @@ struct spi_device { > * These bits must not overlap. A static assert check should make sure of that. > * If adding extra bits, make sure to decrease the bit index below as well. > */ > -#define SPI_MODE_KERNEL_MASK (~(BIT(30) - 1)) > +#define SPI_MODE_KERNEL_MASK (~(BIT(29) - 1)) > u32 mode; > int irq; > void *controller_state; > -- > 2.17.1 >
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 4fa26b9a3572..b9e49ed42955 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -184,8 +184,18 @@ struct spi_device { u8 chip_select; u8 bits_per_word; bool rt; -#define SPI_NO_TX BIT(31) /* No transmit wire */ -#define SPI_NO_RX BIT(30) /* No receive wire */ +#define SPI_NO_TX BIT(31) /* No transmit wire */ +#define SPI_NO_RX BIT(30) /* No receive wire */ + /* + * TPM specification defines flow control over SPI. Client device + * can insert a wait state on MISO when address is transmitted by + * controller on MOSI. Detecting the wait state in software is only + * possible for full duplex controllers. For controllers that support + * only half-duplex, the wait state detection needs to be implemented + * in hardware. TPM devices would set this flag when hardware flow + * control is expected from SPI controller. + */ +#define SPI_TPM_HW_FLOW BIT(29) /* TPM HW flow control */ /* * All bits defined above should be covered by SPI_MODE_KERNEL_MASK. * The SPI_MODE_KERNEL_MASK has the SPI_MODE_USER_MASK counterpart, @@ -195,7 +205,7 @@ struct spi_device { * These bits must not overlap. A static assert check should make sure of that. * If adding extra bits, make sure to decrease the bit index below as well. */ -#define SPI_MODE_KERNEL_MASK (~(BIT(30) - 1)) +#define SPI_MODE_KERNEL_MASK (~(BIT(29) - 1)) u32 mode; int irq; void *controller_state;
TPM specification [1] defines flow control over SPI. Client device can insert a wait state on MISO when address is transmitted by controller on MOSI. Detecting the wait state in software is only possible for full duplex controllers. For controllers that support only half- duplex, the wait state detection needs to be implemented in hardware. Add a flag SPI_TPM_HW_FLOW for TPM device to set when software flow control is not possible and hardware flow control is expected from SPI controller. Reference: [1] https://trustedcomputinggroup.org/resource/pc-client-work-group- pc-client-specific-tpm-interface-specification-tis/ Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com> --- include/linux/spi/spi.h | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)