[PATCH v4 3/6] tpm: tpm_tis_spi: Add a pre-transfer callback

[Stephen Boyd]

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. Add a hook 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.

Cc: Andrey Pronin <apro...@chromium.org>
Cc: Duncan Laurie <dlau...@chromium.org>
Cc: Jason Gunthorpe <j...@ziepe.ca>
Cc: Arnd Bergmann <a...@arndb.de>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Guenter Roeck <gro...@chromium.org>
Cc: Alexander Steffen <alexander.stef...@infineon.com>
Signed-off-by: Stephen Boyd <swb...@chromium.org>
---
 drivers/char/tpm/tpm_tis_spi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index 819602e85b34..93f49b1941f0 100644
--- a/drivers/char/tpm/tpm_tis_spi.c
+++ b/drivers/char/tpm/tpm_tis_spi.c
@@ -44,6 +44,7 @@ struct tpm_tis_spi_phy {
        struct spi_device *spi_device;
        int (*flow_control)(struct tpm_tis_spi_phy *phy,
                            struct spi_transfer *xfer);
+       void (*pre_transfer)(struct tpm_tis_spi_phy *phy);
        u8 *iobuf;
 };
 
@@ -129,6 +130,8 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, 
u32 addr, u16 len,
 
                spi_message_init(&m);
                spi_message_add_tail(&spi_xfer, &m);
+               if (phy->pre_transfer)
+                       phy->pre_transfer(phy);
                ret = spi_sync_locked(phy->spi_device, &m);
                if (ret < 0)
                        goto exit;
-- 
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