tpm: tpm_tis_spi: Support cr50 devices

Add TPM2.0 PTP FIFO compatible SPI interface for chips with Cr50
firmware. The firmware running on the currently supported H1 Secure
Microcontroller requires a special driver to handle its specifics:

 - need to ensure a certain delay between SPI transactions, or else
   the chip may miss some part of the next transaction
 - if there is no SPI activity for some time, it may go to sleep,
   and needs to be waken up before sending further commands
 - access to vendor-specific registers

Cr50 firmware has a requirement to wait for the TPM to wakeup before
sending commands over the SPI bus. Otherwise, the firmware could be in
deep sleep and not respond. The method to wait for the device to wakeup
is slightly different than the usual flow control mechanism described in
the TCG SPI spec. Add a completion to tpm_tis_spi_transfer() before we
start a SPI transfer so we can keep track of the last time the TPM
driver accessed the SPI bus to support the flow control mechanism.

Split the cr50 logic off into a different file to keep it out of the
normal code flow of the existing SPI driver while making it all part of
the same module when the code is optionally compiled into the same
module. Export a new function, tpm_tis_spi_init(), and the associated
read/write/transfer APIs so that we can do this. Make the cr50 code wrap
the tpm_tis_spi_phy struct with its own struct to override the behavior
of tpm_tis_spi_transfer() by supplying a custom flow control hook. This
shares the most code between the core driver and the cr50 support
without combining everything into the core driver or exporting module
symbols.

Signed-off-by: Andrey Pronin <apronin@chromium.org>
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>
[swboyd@chromium.org: Replace boilerplate with SPDX tag, drop
suspended bit and remove ifdef checks in cr50.h, migrate to functions
exported in tpm_tis_spi.h, combine into one module instead of two]
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>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index 9c37047f4b56..aacdeed93320 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -67,6 +67,13 @@ config TCG_TIS_SPI
 	  within Linux. To compile this driver as a module, choose  M here;
 	  the module will be called tpm_tis_spi.
 
+config TCG_TIS_SPI_CR50
+	bool "Cr50 SPI Interface"
+	depends on TCG_TIS_SPI
+	help
+	  If you have a H1 secure module running Cr50 firmware on SPI bus,
+	  say Yes and it will be accessible from within Linux.
+
 config TCG_TIS_I2C_ATMEL
 	tristate "TPM Interface Specification 1.2 Interface (I2C - Atmel)"
 	depends on I2C