tpm_tis: Re-enable interrupts upon (S3) resume

This patch makes sure that if the TPM TIS interface is run in interrupt mode
(rather than polling mode) that all interrupts are enabled in the TPM's
interrupt enable register after a resume from ACPI S3 suspend. The registers
may either have been cleared by the TPM loosing its state during device sleep
or by the BIOS leaving the TPM in polling mode (after sending a command to
the TPM for starting it up again)

You may want to check if your TPM runs with interrupts by doing

cat /proc/interrupts | grep -i tpm

and see whether there is an entry or otherwise for it to use interrupts:

modprobe tpm_tis interrupts=1 [add 'itpm=1' for Intel TPM ]

v2:
  - the patch was adapted to work with the pnp and platform driver
    implementations in tpm_tis.c
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>

drivers/char/tpm/tpm_tis.c

@@ -649,11 +649,36 @@ static int tpm_tis_pnp_suspend(struct pnp_dev *dev, pm_message_t msg)
 	return tpm_pm_suspend(&dev->dev, msg);
 }
 
+static void tpm_tis_reenable_interrupts(struct tpm_chip *chip)
+{
+	u32 intmask;
+
+	/* reenable interrupts that device may have lost or
+	   BIOS/firmware may have disabled */
+	iowrite8(chip->vendor.irq, chip->vendor.iobase +
+		 TPM_INT_VECTOR(chip->vendor.locality));
+
+	intmask =
+	    ioread32(chip->vendor.iobase +
+		     TPM_INT_ENABLE(chip->vendor.locality));
+
+	intmask |= TPM_INTF_CMD_READY_INT
+	    | TPM_INTF_LOCALITY_CHANGE_INT | TPM_INTF_DATA_AVAIL_INT
+	    | TPM_INTF_STS_VALID_INT | TPM_GLOBAL_INT_ENABLE;
+
+	iowrite32(intmask,
+		  chip->vendor.iobase + TPM_INT_ENABLE(chip->vendor.locality));
+}
+
+
 static int tpm_tis_pnp_resume(struct pnp_dev *dev)
 {
 	struct tpm_chip *chip = pnp_get_drvdata(dev);
 	int ret;
 
+	if (chip->vendor.irq)
+		tpm_tis_reenable_interrupts(chip);
+
 	ret = tpm_pm_resume(&dev->dev);
 	if (!ret)
 		tpm_continue_selftest(chip);
@@ -706,6 +731,11 @@ static int tpm_tis_suspend(struct platform_device *dev, pm_message_t msg)
 
 static int tpm_tis_resume(struct platform_device *dev)
 {
+	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
+
+	if (chip->vendor.irq)
+		tpm_tis_reenable_interrupts(chip);
+
 	return tpm_pm_resume(&dev->dev);
 }
 static struct platform_driver tis_drv = {