Re: [PATCH v5 4/4] tpm: tpm_tis_spi: Support cr50 devices

Stephen Boyd
2019-08-28T18:07:30Z

Quoting Heiko Stuebner (2019-08-28 10:36:29)
> Am Mittwoch, 28. August 2019, 10:21:50 CEST schrieb Stephen Boyd:
> > 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.
>
> While the previous version did run just fine on my mainline gru-scarlet,
> this v5 very persistently runs into a panic on every boot:
>
> [ 6.625500] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
> [ 6.632983] tpm_tis_spi spi1.0: Timeout waiting for TPM ready IRQ
> [ 6.637415] Mem abort info:
> [ 6.637417] ESR = 0x96000004
> [ 6.637419] Exception class = DABT (current EL), IL = 32 bits
> [ 6.637423] SET = 0, FnV = 0
> [ 6.644235] tpm_tis_spi spi1.0: TPM ready IRQ confirmed on attempt 1
> [ 6.647350] EA = 0, S1PTW = 0
> [ 6.647352] Data abort info:
> [ 6.647353] ISV = 0, ISS = 0x00000004
> [ 6.647354] CM = 0, WnR = 0
> [ 6.647357] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000eacc4000
> [ 6.647361] [0000000000000000] pgd=0000000000000000
> [ 6.694812] Internal error: Oops: 96000004 [#1] SMP
> [ 6.700258] Modules linked in: tpm_tis_spi_mod(+) dw_mipi_dsi industrialio_triggered_buffer panfrost(+) drm_kms_helper videobuf2_memops kfifo_buf tpm_tis_core ov2685 ov5695 cros_ec_sensors_core videobuf2_v4l2 gpu_sched tpm videobuf2_common v4l2_common v4l2_fwnode crct10dif_ce drm videodev phy_rockchip_pcie phy_rockchip_dphy dw_wdt rng_core cros_ec_dev rockchip_thermal i2c_hid elants_i2c mc drm_panel_orientation_quirks pwm_bl ipv6
> [ 6.742857] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.3.0-rc6-02924-gef15fcdb727f-dirty #1308
> [ 6.752580] Hardware name: Google Scarlet (DT)
> [ 6.757542] pstate: a0000085 (NzCv daIf -PAN -UAO)
> [ 6.762901] pc : __wake_up_common+0x58/0x170
> [ 6.767670] lr : __wake_up_locked+0x18/0x20
> [ 6.772340] sp : ffff000010003d40
> [ 6.776038] x29: ffff000010003d40 x28: 0000000000000060
> [ 6.781972] x27: 0000000000000000 x26: ffff000010e4fcef
> [ 6.787905] x25: 0000000000000001 x24: 0000000000000000
> [ 6.793838] x23: 0000000000000000 x22: 0000000000000000
> [ 6.799772] x21: 0000000000000003 x20: ffff8000f0431308
> [ 6.804944] dwmmc_rockchip fe320000.dwmmc: Unexpected data interrupt latency
> [ 6.805707] x19: ffff8000f04312f8 x18: 0000000000000000
> [ 6.819504] x17: 0000000000000000 x16: 0000000000000000
> [ 6.825437] x15: 0000000000000000 x14: 0000000000000000
> [ 6.831370] x13: 0000000000000000 x12: ffff000010dc9688
> [ 6.837304] x11: 071c71c71c71c71c x10: 0000000000000040
> [ 6.843237] x9 : ffff000010de15d8 x8 : ffff000010de15d0
> [ 6.849171] x7 : ffffffffffffffe8 x6 : 0000000000000000
> [ 6.855104] x5 : 0000000000000000 x4 : 0000000000000000
> [ 6.856947] tpm_tis_spi spi1.0: SPI transfer timed out
> [ 6.861037] x3 : 0000000000000000 x2 : 0000000000000001
> [ 6.861040] x1 : 0000000000000003 x0 : 0000000000000000
> [ 6.861045] Call trace:
> [ 6.866794] spi_master spi1: failed to transfer one message from queue
> [ 6.872724] __wake_up_common+0x58/0x170
> [ 6.872727] __wake_up_locked+0x18/0x20
> [ 6.872732] complete+0x74/0xa8
> [ 6.900836] cr50_spi_irq_handler+0x18/0x28 [tpm_tis_spi_mod]

Thanks! I forgot about pending interrupts and got a little overzealous
in consolidating that line of code. Can you try this patch?

---8<-----
diff --git a/drivers/char/tpm/cr50_spi.c b/drivers/char/tpm/cr50_spi.c
index 535674f4b02a..24b1fb514161 100644
--- a/drivers/char/tpm/cr50_spi.c
+++ b/drivers/char/tpm/cr50_spi.c
@@ -259,12 +259,12 @@ int cr50_spi_probe(struct spi_device *spi)
phy = &cr50_phy->spi_phy;
phy->flow_control = cr50_spi_flow_control;
phy->is_cr50 = true;
+ init_completion(&phy->ready);

cr50_phy->access_delay = CR50_NOIRQ_ACCESS_DELAY;
-
- mutex_init(&cr50_phy->time_track_mutex);
cr50_phy->wake_after = jiffies;
cr50_phy->last_access = jiffies;
+ mutex_init(&cr50_phy->time_track_mutex);

if (spi->irq > 0) {
ret = devm_request_irq(&spi->dev, spi->irq, cr50_spi_irq_handler,
diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index fdac842a61ed..2f120ddce2d2 100644
--- a/drivers/char/tpm/tpm_tis_spi.c
+++ b/drivers/char/tpm/tpm_tis_spi.c
@@ -201,7 +201,6 @@ int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy,
if (!phy->iobuf)
return -ENOMEM;

- init_completion(&phy->ready);
phy->spi_device = spi;

return tpm_tis_core_init(&spi->dev, &phy->priv, irq, phy_ops, NULL);
@@ -239,6 +238,7 @@ static int tpm_tis_spi_probe(struct spi_device *dev)
else
irq = -1;

+ init_completion(&phy->ready);
return tpm_tis_spi_init(dev, phy, irq, &tpm_spi_phy_ops);
}