ARM: sa1111: register sa1111 devices with dmabounce in bus notifier

Use the bus notifier to register sa1111 devices with dmabounce, rather
than after the device has been registered, potentially racing with
driver binding.
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/common/sa1111.c

@@ -603,36 +603,6 @@ sa1111_configure_smc(struct sa1111 *sachip, int sdram, unsigned int drac,
 }
 #endif
 
-#ifdef CONFIG_DMABOUNCE
-/*
- * According to the "Intel StrongARM SA-1111 Microprocessor Companion
- * Chip Specification Update" (June 2000), erratum #7, there is a
- * significant bug in the SA1111 SDRAM shared memory controller.  If
- * an access to a region of memory above 1MB relative to the bank base,
- * it is important that address bit 10 _NOT_ be asserted. Depending
- * on the configuration of the RAM, bit 10 may correspond to one
- * of several different (processor-relative) address bits.
- *
- * This routine only identifies whether or not a given DMA address
- * is susceptible to the bug.
- *
- * This should only get called for sa1111_device types due to the
- * way we configure our device dma_masks.
- */
-static int sa1111_needs_bounce(struct device *dev, dma_addr_t addr, size_t size)
-{
-	/*
-	 * Section 4.6 of the "Intel StrongARM SA-1111 Development Module
-	 * User's Guide" mentions that jumpers R51 and R52 control the
-	 * target of SA-1111 DMA (either SDRAM bank 0 on Assabet, or
-	 * SDRAM bank 1 on Neponset). The default configuration selects
-	 * Assabet, so any address in bank 1 is necessarily invalid.
-	 */
-	return (machine_is_assabet() || machine_is_pfs168()) &&
-		(addr >= 0xc8000000 || (addr + size) >= 0xc8000000);
-}
-#endif
-
 static void sa1111_dev_release(struct device *_dev)
 {
 	struct sa1111_dev *dev = SA1111_DEV(_dev);
@@ -660,7 +630,6 @@ sa1111_init_one_child(struct sa1111 *sachip, struct resource *parent,
 	dev->dev.parent  = sachip->dev;
 	dev->dev.bus     = &sa1111_bus_type;
 	dev->dev.release = sa1111_dev_release;
-	dev->dev.coherent_dma_mask = sachip->dev->coherent_dma_mask;
 	dev->res.start   = sachip->phys + info->offset;
 	dev->res.end     = dev->res.start + 511;
 	dev->res.name    = dev_name(&dev->dev);
@@ -671,6 +640,16 @@ sa1111_init_one_child(struct sa1111 *sachip, struct resource *parent,
 	for (i = 0; i < ARRAY_SIZE(info->irq); i++)
 		dev->irq[i] = sachip->irq_base + info->irq[i];
 
+	/*
+	 * If the parent device has a DMA mask associated with it,
+	 * propagate it down to the children.
+	 */
+	if (sachip->dev->dma_mask) {
+		dev->dma_mask = *sachip->dev->dma_mask;
+		dev->dev.dma_mask = &dev->dma_mask;
+		dev->dev.coherent_dma_mask = sachip->dev->coherent_dma_mask;
+	}
+
 	ret = request_resource(parent, &dev->res);
 	if (ret) {
 		printk("SA1111: failed to allocate resource for %s\n",
@@ -680,36 +659,12 @@ sa1111_init_one_child(struct sa1111 *sachip, struct resource *parent,
 		goto out;
 	}
 
-
 	ret = device_register(&dev->dev);
 	if (ret) {
 		release_resource(&dev->res);
 		kfree(dev);
-		goto out;
 	}
 
-#ifdef CONFIG_DMABOUNCE
-	/*
-	 * If the parent device has a DMA mask associated with it,
-	 * propagate it down to the children.
-	 */
-	if (sachip->dev->dma_mask) {
-		dev->dma_mask = *sachip->dev->dma_mask;
-		dev->dev.dma_mask = &dev->dma_mask;
-
-		if (dev->dma_mask != 0xffffffffUL) {
-			ret = dmabounce_register_dev(&dev->dev, 1024, 4096,
-					sa1111_needs_bounce);
-			if (ret) {
-				dev_err(&dev->dev, "SA1111: Failed to register"
-					" with dmabounce\n");
-				device_unregister(&dev->dev);
-			}
-		}
-	}
-#endif
-
-out:
 	return ret;
 }
 
@@ -1411,9 +1366,70 @@ void sa1111_driver_unregister(struct sa1111_driver *driver)
 }
 EXPORT_SYMBOL(sa1111_driver_unregister);
 
+#ifdef CONFIG_DMABOUNCE
+/*
+ * According to the "Intel StrongARM SA-1111 Microprocessor Companion
+ * Chip Specification Update" (June 2000), erratum #7, there is a
+ * significant bug in the SA1111 SDRAM shared memory controller.  If
+ * an access to a region of memory above 1MB relative to the bank base,
+ * it is important that address bit 10 _NOT_ be asserted. Depending
+ * on the configuration of the RAM, bit 10 may correspond to one
+ * of several different (processor-relative) address bits.
+ *
+ * This routine only identifies whether or not a given DMA address
+ * is susceptible to the bug.
+ *
+ * This should only get called for sa1111_device types due to the
+ * way we configure our device dma_masks.
+ */
+static int sa1111_needs_bounce(struct device *dev, dma_addr_t addr, size_t size)
+{
+	/*
+	 * Section 4.6 of the "Intel StrongARM SA-1111 Development Module
+	 * User's Guide" mentions that jumpers R51 and R52 control the
+	 * target of SA-1111 DMA (either SDRAM bank 0 on Assabet, or
+	 * SDRAM bank 1 on Neponset). The default configuration selects
+	 * Assabet, so any address in bank 1 is necessarily invalid.
+	 */
+	return (machine_is_assabet() || machine_is_pfs168()) &&
+		(addr >= 0xc8000000 || (addr + size) >= 0xc8000000);
+}
+
+static int sa1111_notifier_call(struct notifier_block *n, unsigned long action,
+	void *data)
+{
+	struct sa1111_dev *dev = SA1111_DEV(data);
+
+	switch (action) {
+	case BUS_NOTIFY_ADD_DEVICE:
+		if (dev->dev.dma_mask && dev->dma_mask < 0xffffffffUL) {
+			int ret = dmabounce_register_dev(&dev->dev, 1024, 4096,
+					sa1111_needs_bounce);
+			if (ret)
+				dev_err(&dev->dev, "failed to register with dmabounce: %d\n", ret);
+		}
+		break;
+
+	case BUS_NOTIFY_DEL_DEVICE:
+		if (dev->dev.dma_mask && dev->dma_mask < 0xffffffffUL)
+			dmabounce_unregister_dev(&dev->dev);
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block sa1111_bus_notifier = {
+	.notifier_call = sa1111_notifier_call,
+};
+#endif
+
 static int __init sa1111_init(void)
 {
 	int ret = bus_register(&sa1111_bus_type);
+#ifdef CONFIG_DMABOUNCE
+	if (ret == 0)
+		bus_register_notifier(&sa1111_bus_type, &sa1111_bus_notifier);
+#endif
 	if (ret == 0)
 		platform_driver_register(&sa1111_device_driver);
 	return ret;
@@ -1422,6 +1438,9 @@ static int __init sa1111_init(void)
 static void __exit sa1111_exit(void)
 {
 	platform_driver_unregister(&sa1111_device_driver);
+#ifdef CONFIG_DMABOUNCE
+	bus_unregister_notifier(&sa1111_bus_type, &sa1111_bus_notifier);
+#endif
 	bus_unregister(&sa1111_bus_type);
 }