tpm/tpm_crb: implement tpm crb idle state

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.

[jarkko.sakkinen@linux.intel.com: removed cmdReady debug trace on a
 success case due the heavy amount of log traffic it causes.]

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

1 files changed, 66 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index a7c870af916c..8dd0f20a839c 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -83,6 +83,72 @@ 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 */
+
+        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))
+                        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)