The 2.6.31 kernel has threaded IRQ support and b43 is the first
wireless driver that makes use of it. To support threaded IRSs
on older kernels we built our own struct compat_threaded_irq
to queue_work() onto it as the kernel thread be running the
thread in process context as well.

--- a/drivers/net/wireless/b43/main.c
+++ b/drivers/net/wireless/b43/main.c
@@ -4207,8 +4207,13 @@ redo:
 	if (b43_bus_host_is_sdio(dev->dev)) {
 		b43_sdio_free_irq(dev);
 	} else {
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,31)
+		compat_synchronize_threaded_irq(&dev->irq_compat);
+		compat_free_threaded_irq(&dev->irq_compat);
+#else
 		synchronize_irq(dev->dev->irq);
 		free_irq(dev->dev->irq, dev);
+#endif
 	}
 	mutex_lock(&wl->mutex);
 	dev = wl->current_dev;
@@ -4250,9 +4255,17 @@ static int b43_wireless_core_start(struc
 			goto out;
 		}
 	} else {
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,31)
+		err = compat_request_threaded_irq(&dev->irq_compat,
+						  dev->dev->irq,
+						  b43_interrupt_handler,
+						  b43_interrupt_thread_handler,
+						  IRQF_SHARED, KBUILD_MODNAME, dev);
+#else
 		err = request_threaded_irq(dev->dev->irq, b43_interrupt_handler,
 					   b43_interrupt_thread_handler,
 					   IRQF_SHARED, KBUILD_MODNAME, dev);
+#endif
 		if (err) {
 			b43err(dev->wl, "Cannot request IRQ-%d\n",
 			       dev->dev->irq);
@@ -5046,6 +5059,10 @@ static int b43_setup_bands(struct b43_wl
 
 static void b43_wireless_core_detach(struct b43_wldev *dev)
 {
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,31)
+	if (dev->dev->sdev->bus->bustype != SSB_BUSTYPE_SDIO)
+		compat_destroy_threaded_irq(&dev->irq_compat);
+#endif
 	/* We release firmware that late to not be required to re-request
 	 * is all the time when we reinit the core. */
 	b43_release_firmware(dev);
--- a/drivers/net/wireless/b43/b43.h
+++ b/drivers/net/wireless/b43/b43.h
@@ -855,6 +855,9 @@ struct b43_wldev {
 	unsigned int tx_count;
 	unsigned int rx_count;
 #endif
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,31)
+	struct compat_threaded_irq irq_compat;
+#endif
 };
 
 /* Data structure for the WLAN parts (802.11 cores) of the b43 chip. */
--- a/drivers/net/wireless/ti/wlcore/main.c
+++ b/drivers/net/wireless/ti/wlcore/main.c
@@ -4986,14 +4986,25 @@ int __devinit wlcore_probe(struct wl1271
 
 	platform_set_drvdata(pdev, wl);
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,32)
+	irqflags = IRQF_TRIGGER_RISING;
+#else
 	if (wl->platform_quirks & WL12XX_PLATFORM_QUIRK_EDGE_IRQ)
 		irqflags = IRQF_TRIGGER_RISING;
 	else
 		irqflags = IRQF_TRIGGER_HIGH | IRQF_ONESHOT;
+#endif
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,31)
+	ret = compat_request_threaded_irq(&wl->irq_compat, wl->irq,
+					  wl12xx_hardirq, wl1271_irq,
+					  irqflags,
+					  pdev->name, wl);
+#else
 	ret = request_threaded_irq(wl->irq, wl12xx_hardirq, wl1271_irq,
 				   irqflags,
 				   pdev->name, wl);
+#endif
 	if (ret < 0) {
 		wl1271_error("request_irq() failed: %d", ret);
 		goto out_free_hw;
@@ -5047,7 +5058,11 @@ out_bt_coex_state:
 	device_remove_file(wl->dev, &dev_attr_bt_coex_state);
 
 out_irq:
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,31)
+	compat_free_threaded_irq(&wl->irq_compat);
+#else
 	free_irq(wl->irq, wl);
+#endif
 
 out_free_hw:
 	wlcore_free_hw(wl);
@@ -5066,7 +5081,12 @@ int __devexit wlcore_remove(struct platf
 		disable_irq_wake(wl->irq);
 	}
 	wl1271_unregister_hw(wl);
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,31)
+	compat_free_threaded_irq(&wl->irq_compat);
+	compat_destroy_threaded_irq(&wl->irq_compat);
+#else
 	free_irq(wl->irq, wl);
+#endif
 	wlcore_free_hw(wl);
 
 	return 0;
--- a/drivers/net/wireless/ti/wlcore/wlcore.h
+++ b/drivers/net/wireless/ti/wlcore/wlcore.h
@@ -349,6 +349,10 @@ struct wl1271 {
 
 	/* size of the private FW status data */
 	size_t fw_status_priv_len;
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,31)
+	struct compat_threaded_irq irq_compat;
+#endif
 };
 
 int __devinit wlcore_probe(struct wl1271 *wl, struct platform_device *pdev);