[PATCH v2 4/5] tpm_tis: fix IRQ probing

[James Bottomley <James.Bottomley@HansenPartnership.com>]

There are two problems with our current interrupt probing: firstly the
TPM_CHIP_FLAG_IRQ never gets set initially, so a check for interrupts
is never done.  Fix this by setting the flag before we generate and
interrupt for probing.  Secondly our IRQ setup may be ineffective on a
TPM without legacy access cycles becuase according to the TPM
Interface Specification the interrupt registers are only writeable in
the current locality, so issue a request_locality before setting up
the interrupts.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

---

v2: improved description
---
 drivers/char/tpm/tpm_tis_core.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 0c07da8cd680..12b657ed3a39 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -809,6 +809,19 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip,
 	}
 	priv->irq = irq;
 
+	/*
+	 * note writes to the interrupt registers are only effective
+	 * when the TPM is in the active locality, so we have to
+	 * request the locality here to get the interrupt set up.
+	 * This request has no corresponding release, because the
+	 * locality will be relinquished at the end of the tpm command
+	 * that probes the interrupts
+	 */
+	if (request_locality(chip, 0) != 0) {
+		dev_err(&chip->dev, "failed to gain locality for irq probe\n");
+		return -EBUSY;
+	}
+
 	rc = tpm_tis_read8(priv, TPM_INT_VECTOR(priv->locality),
 			   &original_int_vec);
 	if (rc < 0)
@@ -836,6 +849,7 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip,
 		return rc;
 
 	priv->irq_tested = false;
+	chip->flags |= TPM_CHIP_FLAG_IRQ;
 
 	/* Generate an interrupt by having the core call through to
 	 * tpm_tis_send
-- 
2.28.0