[SERIAL] 8250_hcdp needs irq sharing

Patch from Alex Williamson

Here's a trivial patch that makes 8250_hcdp setup the correct flags
when IRQ sharing is enabled for serial ports.

The HCDP table tells us if the device is a PCI UART.  We can use this
to set the shared interrupt flag as well as program the interrupt with
the correct polarity/trigger (should get rid of "changing vector <x>
from IO-SAPIC-edge to IO-SAPIC-level" messages at bootup).  This also
allows non-PCI UARTs to be left un-shareable, which is likely much
more safe (edge triggered).

The bit that I'm keying on is still part of the older 1.0a HCDP spec,
so should be implemented (it was on all the boxes I tested).  If
there's firmware out there that doesn't set this bit or the interrupt
supported flag, the HCDP UART may run in polling mode, but should
still be functional.

drivers/serial/8250_hcdp.c

@@ -147,7 +147,7 @@ setup_serial_hcdp(void *tablep)
 		printk("  gsi = %d, baud rate = %lu, bits = %d, clock = %d\n",
 		       gsi, (unsigned long) hcdp_dev->baud, hcdp_dev->bits,
 		       hcdp_dev->clock_rate);
-		if (hcdp_dev->base_addr.space_id == ACPI_PCICONF_SPACE)
+		if (HCDP_PCI_UART(hcdp_dev))
 			printk(" PCI id: %02x:%02x:%02x, vendor ID=0x%x, "
 				"dev ID=0x%x\n", hcdp_dev->pci_seg,
 				hcdp_dev->pci_bus, hcdp_dev->pci_dev,
@@ -179,16 +179,26 @@ setup_serial_hcdp(void *tablep)
 			printk(KERN_WARNING"warning: No support for PCI serial console\n");
 			return;
 		}
+
+		if (HCDP_IRQ_SUPPORTED(hcdp_dev)) {
 #ifdef CONFIG_IA64
-		port.irq = acpi_register_irq(gsi, ACPI_ACTIVE_HIGH,
-				ACPI_EDGE_SENSITIVE);
+			if (HCDP_PCI_UART(hcdp_dev))
+				port.irq = acpi_register_irq(gsi,
+					ACPI_ACTIVE_LOW, ACPI_LEVEL_SENSITIVE);
+			else
+				port.irq = acpi_register_irq(gsi,
+					ACPI_ACTIVE_HIGH, ACPI_EDGE_SENSITIVE);
 #else
-		port.irq = gsi;
+			port.irq = gsi;
 #endif
-		port.flags = UPF_SKIP_TEST | UPF_BOOT_AUTOCONF | UPF_RESOURCES;
-		if (gsi)
 			port.flags |= UPF_AUTO_IRQ;
 
+			if (HCDP_PCI_UART(hcdp_dev))
+				port.flags |= UPF_SHARE_IRQ;
+		}
+
+		port.flags |= UPF_SKIP_TEST | UPF_BOOT_AUTOCONF | UPF_RESOURCES;
+
 		/*
 		 * Note: the above memset() initializes port.line to 0,
 		 * so we register this port as ttyS0.
@@ -197,6 +207,7 @@ setup_serial_hcdp(void *tablep)
 			printk("setup_serial_hcdp(): early_serial_setup() "
 				"for HCDP serial console port failed. "
 				"Will try any additional consoles in HCDP.\n");
+			memset(&port, 0, sizeof(port));
 			continue;
 		}
 		break;

drivers/serial/8250_hcdp.h

@@ -77,3 +77,6 @@ typedef struct {
 	u32	num_entries;
 	hcdp_dev_t	hcdp_dev[MAX_HCDP_DEVICES];
 } hcdp_t;
+
+#define HCDP_PCI_UART(x) (x->pci_func & 1UL<<7)
+#define HCDP_IRQ_SUPPORTED(x) (x->pci_func & 1UL<<6)