i2c: i801: Check if interrupts are disabled

There is a control bit in the PCI configuration space which disables
interrupts. If this bit is set, the driver should not try to make use
of interrupts, it won't receive any.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 20 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index a6f3bc38fbe5..3f1f30313cd7 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -109,12 +109,16 @@
 
 /* PCI Address Constants */
 #define SMBBAR          4
+#define SMBPCICTL       0x004
 #define SMBPCISTS       0x006
 #define SMBHSTCFG       0x040
 
 /* Host status bits for SMBPCISTS */
 #define SMBPCISTS_INTS          0x08
 
+/* Control bits for SMBPCICTL */
+#define SMBPCICTL_INTDIS        0x0400
+
 /* Host configuration bits for SMBHSTCFG */
 #define SMBHSTCFG_HST_EN        1
 #define SMBHSTCFG_SMB_SMI_EN    2
@@ -1232,6 +1236,22 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
         priv->adapter.timeout = HZ / 5;
 
         if (priv->features & FEATURE_IRQ) {
+                u16 pcictl, pcists;
+
+                /* Complain if an interrupt is already pending */
+                pci_read_config_word(priv->pci_dev, SMBPCISTS, &pcists);
+                if (pcists & SMBPCISTS_INTS)
+                        dev_warn(&dev->dev, "An interrupt is pending!\n");
+
+                /* Check if interrupts have been disabled */
+                pci_read_config_word(priv->pci_dev, SMBPCICTL, &pcictl);
+                if (pcictl & SMBPCICTL_INTDIS) {
+                        dev_info(&dev->dev, "Interrupts are disabled\n");
+                        priv->features &= ~FEATURE_IRQ;
+                }
+        }
+
+        if (priv->features & FEATURE_IRQ) {
                 init_waitqueue_head(&priv->waitq);
 
                 err = request_irq(dev->irq, i801_isr, IRQF_SHARED,