diff mbox

[v4,1/4] tpm/tpm_crb: implement tpm crb idle state

Message ID 1475927979-23484-2-git-send-email-tomas.winkler@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Winkler, Tomas Oct. 8, 2016, 11:59 a.m. UTC 
From: "Winkler, Tomas" <tomas.winkler@intel.com>

The register TPM_CRB_CTRL_REQ_x contains bits goIdle and cmdReady for
SW to indicate that the device can enter or should exit the idle state.

The legacy ACPI-start (SMI + DMA) based devices do not support these
bits and the idle state management is not exposed to the host SW.
Thus, this functionality only is enabled only for a CRB start (MMIO)
based devices.

Based on Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
original patch:
'tpm_crb: implement power tpm crb power management'

To keep the implementation local to the hw we don't use wait_for_tpm_stat
for polling the TPM_CRB_CTRL_REQ.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
V2: do not export the functions via tpm ops
V3: fix lower case corruption; adjust function documentation
V4: resend

 drivers/char/tpm/tpm_crb.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

Comments

Jarkko Sakkinen Oct. 8, 2016, 4:30 p.m. UTC | #1 
On Sat, Oct 08, 2016 at 02:59:36PM +0300, Tomas Winkler wrote:
> From: "Winkler, Tomas" <tomas.winkler@intel.com>
> 
> The register TPM_CRB_CTRL_REQ_x contains bits goIdle and cmdReady for
> SW to indicate that the device can enter or should exit the idle state.
> 
> The legacy ACPI-start (SMI + DMA) based devices do not support these
> bits and the idle state management is not exposed to the host SW.
> Thus, this functionality only is enabled only for a CRB start (MMIO)
> based devices.
> 
> Based on Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> original patch:
> 'tpm_crb: implement power tpm crb power management'
> 
> To keep the implementation local to the hw we don't use wait_for_tpm_stat
> for polling the TPM_CRB_CTRL_REQ.

I just realized that the HW specific argument does not hold at all.  The
tpm_tis_core heavily uses wait_for_tpm_stat and return value of status
is synthetized.

It's upper layer for FIFO implemetations but still the arguement still
holds.

Lets keep it the way it is for now because this is fairly well test but
I might consider sending patch  that migrates to wait_for_tpm_stat unless
there is no real reason not to do so.

/Jarkko

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most 
engaging tech sites, SlashDot.org! http://sdm.link/slashdot
diff mbox

Patch

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index a7c870af916c..0f3b3f3d12d3 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -83,6 +83,76 @@  struct crb_priv {
 	u32 cmd_size;
 };
 
+/**
+ * crb_go_idle - request tpm crb device to go the idle state
+ *
+ * @dev:  crb device
+ * @priv: crb private data
+ *
+ * Write CRB_CTRL_REQ_GO_IDLE to TPM_CRB_CTRL_REQ
+ * The device should respond within TIMEOUT_C by clearing the bit.
+ * Anyhow, we do not wait here as a consequent CMD_READY request
+ * will be handled correctly even if idle was not completed.
+ *
+ * The function does nothing for devices with ACPI-start method.
+ *
+ * Return: 0 always
+ */
+static int __maybe_unused crb_go_idle(struct device *dev, struct crb_priv *priv)
+{
+	if (priv->flags & CRB_FL_ACPI_START)
+		return 0;
+
+	iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->cca->req);
+	/* we don't really care when this settles */
+	dev_dbg(dev, "goIdle\n");
+
+	return 0;
+}
+
+/**
+ * crb_cmd_ready - request tpm crb device to enter ready state
+ *
+ * @dev:  crb device
+ * @priv: crb private data
+ *
+ * Write CRB_CTRL_REQ_CMD_READY to TPM_CRB_CTRL_REQ
+ * and poll till the device acknowledge it by clearing the bit.
+ * The device should respond within TIMEOUT_C.
+ *
+ * The function does nothing for devices with ACPI-start method
+ *
+ * Return: 0 on success -ETIME on timeout;
+ */
+static int __maybe_unused crb_cmd_ready(struct device *dev,
+					struct crb_priv *priv)
+{
+	ktime_t stop, start;
+
+	if (priv->flags & CRB_FL_ACPI_START)
+		return 0;
+
+	iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->cca->req);
+
+	start = ktime_get();
+	stop = ktime_add(start, ms_to_ktime(TPM2_TIMEOUT_C));
+	do {
+		if (!(ioread32(&priv->cca->req) & CRB_CTRL_REQ_CMD_READY)) {
+			dev_dbg(dev, "cmdReady in %lld usecs\n",
+				ktime_to_us(ktime_sub(ktime_get(), start)));
+			return 0;
+		}
+		usleep_range(50, 100);
+	} while (ktime_before(ktime_get(), stop));
+
+	if (ioread32(&priv->cca->req) & CRB_CTRL_REQ_CMD_READY) {
+		dev_warn(dev, "cmdReady timed out\n");
+		return -ETIME;
+	}
+
+	return 0;
+}
+
 static SIMPLE_DEV_PM_OPS(crb_pm, tpm_pm_suspend, tpm_pm_resume);
 
 static u8 crb_status(struct tpm_chip *chip)