x86/platform/intel-mid: Make IRQ allocation a bit more flexible

In the future we would use dynamic allocation for IRQ which brings
non-1:1 mapping for IOAPIC domain. Thus, we need to respect return value
of mp_map_gsi_to_irq() and assign it back to the device structure.

Besides that we need to read GSI from interrupt pin register to avoid
cases when some drivers will try to initialize PCI device twice in a row
which will call pcibios_enable_irq() twice as well.

	serial 0000:00:04.1: Mapped GSI28 to IRQ5
	serial 0000:00:04.2: Mapped GSI29 to IRQ5
	serial 0000:00:04.3: Mapped GSI54 to IRQ5
	8250_mid 0000:00:04.1: Mapped GSI28 to IRQ5
	8250_mid 0000:00:04.2: Mapped GSI29 to IRQ6
	8250_mid 0000:00:04.3: Mapped GSI54 to IRQ7

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-pci@vger.kernel.org
Link: http://lkml.kernel.org/r/20170724173402.12939-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/pci/intel_mid_pci.c

@@ -215,16 +215,23 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev)
 	struct irq_alloc_info info;
 	int polarity;
 	int ret;
+	u8 gsi;
 
 	if (dev->irq_managed && dev->irq > 0)
 		return 0;
 
+	ret = pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &gsi);
+	if (ret < 0) {
+		dev_warn(&dev->dev, "Failed to read interrupt line: %d\n", ret);
+		return ret;
+	}
+
 	switch (intel_mid_identify_cpu()) {
 	case INTEL_MID_CPU_CHIP_TANGIER:
 		polarity = IOAPIC_POL_HIGH;
 
 		/* Special treatment for IRQ0 */
-		if (dev->irq == 0) {
+		if (gsi == 0) {
 			/*
 			 * Skip HS UART common registers device since it has
 			 * IRQ0 assigned and not used by the kernel.
@@ -253,10 +260,11 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev)
 	 * MRST only have IOAPIC, the PCI irq lines are 1:1 mapped to
 	 * IOAPIC RTE entries, so we just enable RTE for the device.
 	 */
-	ret = mp_map_gsi_to_irq(dev->irq, IOAPIC_MAP_ALLOC, &info);
+	ret = mp_map_gsi_to_irq(gsi, IOAPIC_MAP_ALLOC, &info);
 	if (ret < 0)
 		return ret;
 
+	dev->irq = ret;
 	dev->irq_managed = 1;
 
 	return 0;

arch/x86/platform/intel-mid/device_libs/platform_mrfld_wdt.c

@@ -30,13 +30,13 @@ static int tangier_probe(struct platform_device *pdev)
 {
 	struct irq_alloc_info info;
 	struct intel_mid_wdt_pdata *pdata = pdev->dev.platform_data;
-	int gsi, irq;
+	int gsi = TANGIER_EXT_TIMER0_MSI;
+	int irq;
 
 	if (!pdata)
 		return -EINVAL;
 
 	/* IOAPIC builds identity mapping between GSI and IRQ on MID */
-	gsi = pdata->irq;
 	ioapic_set_alloc_attr(&info, cpu_to_node(0), 1, 0);
 	irq = mp_map_gsi_to_irq(gsi, IOAPIC_MAP_ALLOC, &info);
 	if (irq < 0) {
@@ -44,11 +44,11 @@ static int tangier_probe(struct platform_device *pdev)
 		return irq;
 	}
 
+	pdata->irq = irq;
 	return 0;
 }
 
 static struct intel_mid_wdt_pdata tangier_pdata = {
-	.irq = TANGIER_EXT_TIMER0_MSI,
 	.probe = tangier_probe,
 };