tpm_tis: Fix the probing for interrupts
Stefan Berger [Wed, 30 Mar 2011 16:13:32 +0000 (12:13 -0400)]
This patch fixes several aspects of the probing for interrupts.

This patch reads the TPM's timeouts before probing for the interrupts. The
tpm_get_timeouts() function is invoked in polling mode and gets the proper
timeouts from the TPM so that we don't need to fall back to 2 minutes timeouts
for short duration commands while the interrupt probing is happening.

This patch introduces a variable probed_irq into the vendor structure that gets
the irq number if an interrupt is received while the the tpm_gen_interrupt()
function is run in polling mode during interrupt probing. Previously some
parts of tpm_gen_interrupt() were run in polling mode, then the irq variable
was set in the interrupt handler when an interrupt was received and execution
of tpm_gen_interrupt() ended up switching over to interrupt mode.
tpm_gen_interrupt() execution ended up on an event queue where it eventually
timed out since the probing handler doesn't wake any queues.

Before calling into free_irq() clear all interrupt flags that may have
been set by the TPM. The reason is that free_irq() will call into the probing
interrupt handler and may otherwise fool us into thinking that a real interrupt
happened (because we see the flags as being set) while the TPM's interrupt line
is not even connected to anything on the motherboard. This solves a problem
on one machine I did testing on (Thinkpad T60).

If a TPM claims to use a specifc interrupt, the probing is done as well
to verify that the interrupt is actually working. If a TPM indicates
that it does not use a specific interrupt (returns '0'), probe all interrupts
from 3 to 15.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>

drivers/char/tpm/tpm.h
drivers/char/tpm/tpm_tis.c

index c5e01c5..9c4163c 100644 (file)
@@ -71,6 +71,7 @@ struct tpm_vendor_specific {
        unsigned long base;             /* TPM base address */
 
        int irq;
+       int probed_irq;
 
        int region_size;
        int have_region;
index b97ce2b..47517e4 100644 (file)
@@ -438,7 +438,7 @@ static irqreturn_t tis_int_probe(int irq, void *dev_id)
        if (interrupt == 0)
                return IRQ_NONE;
 
-       chip->vendor.irq = irq;
+       chip->vendor.probed_irq = irq;
 
        /* Clear interrupts handled with TPM_EOI */
        iowrite32(interrupt,
@@ -486,7 +486,7 @@ static int tpm_tis_init(struct device *dev, resource_size_t start,
                        resource_size_t len, unsigned int irq)
 {
        u32 vendor, intfcaps, intmask;
-       int rc, i;
+       int rc, i, irq_s, irq_e;
        struct tpm_chip *chip;
 
        if (!(chip = tpm_register_hardware(dev, &tpm_tis)))
@@ -544,6 +544,9 @@ static int tpm_tis_init(struct device *dev, resource_size_t start,
        if (intfcaps & TPM_INTF_DATA_AVAIL_INT)
                dev_dbg(dev, "\tData Avail Int Support\n");
 
+       /* get the timeouts before testing for irqs */
+       tpm_get_timeouts(chip);
+
        /* INTERRUPT Setup */
        init_waitqueue_head(&chip->vendor.read_queue);
        init_waitqueue_head(&chip->vendor.int_queue);
@@ -562,13 +565,19 @@ static int tpm_tis_init(struct device *dev, resource_size_t start,
        if (interrupts)
                chip->vendor.irq = irq;
        if (interrupts && !chip->vendor.irq) {
-               chip->vendor.irq =
+               irq_s =
                    ioread8(chip->vendor.iobase +
                            TPM_INT_VECTOR(chip->vendor.locality));
+               if (irq_s) {
+                       irq_e = irq_s;
+               } else {
+                       irq_s = 3;
+                       irq_e = 15;
+               }
 
-               for (i = 3; i < 16 && chip->vendor.irq == 0; i++) {
+               for (i = irq_s; i <= irq_e && chip->vendor.irq == 0; i++) {
                        iowrite8(i, chip->vendor.iobase +
-                                   TPM_INT_VECTOR(chip->vendor.locality));
+                                TPM_INT_VECTOR(chip->vendor.locality));
                        if (request_irq
                            (i, tis_int_probe, IRQF_SHARED,
                             chip->vendor.miscdev.name, chip) != 0) {
@@ -590,9 +599,22 @@ static int tpm_tis_init(struct device *dev, resource_size_t start,
                                  chip->vendor.iobase +
                                  TPM_INT_ENABLE(chip->vendor.locality));
 
+                       chip->vendor.probed_irq = 0;
+
                        /* Generate Interrupts */
                        tpm_gen_interrupt(chip);
 
+                       chip->vendor.irq = chip->vendor.probed_irq;
+
+                       /* free_irq will call into tis_int_probe;
+                          clear all irqs we haven't seen while doing
+                          tpm_gen_interrupt */
+                       iowrite32(ioread32
+                                 (chip->vendor.iobase +
+                                  TPM_INT_STATUS(chip->vendor.locality)),
+                                 chip->vendor.iobase +
+                                 TPM_INT_STATUS(chip->vendor.locality));
+
                        /* Turn off */
                        iowrite32(intmask,
                                  chip->vendor.iobase +
@@ -631,7 +653,6 @@ static int tpm_tis_init(struct device *dev, resource_size_t start,
        list_add(&chip->vendor.list, &tis_chips);
        spin_unlock(&tis_lock);
 
-       tpm_get_timeouts(chip);
        tpm_continue_selftest(chip);
 
        return 0;