From: Michael Ellerman Date: Fri, 25 Jan 2008 05:59:14 +0000 (+1100) Subject: [POWERPC] Avoid DMA exception when using axon_msi with IOMMU X-Git-Tag: v2.6.25-rc1~303^2~35 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=de4c928b843063b7079c35c950c1d38c559fa0cb;p=linux-2.6 [POWERPC] Avoid DMA exception when using axon_msi with IOMMU There's a brown-paper-bag bug in axon_msi, we pass the address of our FIFO directly to the hardware, without DMA mapping it. This leads to DMA exceptions if you enable MSI & the IOMMU. The fix is to correctly DMA map the fifo, dma_alloc_coherent() does what we want - and we need to track the virt & phys addresses. Signed-off-by: Michael Ellerman Acked-by: Benjamin Herrenschmidt Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/platforms/cell/axon_msi.c b/arch/powerpc/platforms/cell/axon_msi.c index ea3dc8c64a..b9a97c4ae1 100644 --- a/arch/powerpc/platforms/cell/axon_msi.c +++ b/arch/powerpc/platforms/cell/axon_msi.c @@ -65,7 +65,8 @@ struct axon_msic { struct irq_host *irq_host; - __le32 *fifo; + __le32 *fifo_virt; + dma_addr_t fifo_phys; dcr_host_t dcr_host; u32 read_offset; }; @@ -91,7 +92,7 @@ static void axon_msi_cascade(unsigned int irq, struct irq_desc *desc) while (msic->read_offset != write_offset) { idx = msic->read_offset / sizeof(__le32); - msi = le32_to_cpu(msic->fifo[idx]); + msi = le32_to_cpu(msic->fifo_virt[idx]); msi &= 0xFFFF; pr_debug("axon_msi: woff %x roff %x msi %x\n", @@ -306,7 +307,6 @@ static int axon_msi_shutdown(struct of_device *device) static int axon_msi_probe(struct of_device *device, const struct of_device_id *device_id) { - struct page *page; struct device_node *dn = device->node; struct axon_msic *msic; unsigned int virq; @@ -338,16 +338,14 @@ static int axon_msi_probe(struct of_device *device, goto out_free_msic; } - page = alloc_pages_node(of_node_to_nid(dn), GFP_KERNEL, - get_order(MSIC_FIFO_SIZE_BYTES)); - if (!page) { + msic->fifo_virt = dma_alloc_coherent(&device->dev, MSIC_FIFO_SIZE_BYTES, + &msic->fifo_phys, GFP_KERNEL); + if (!msic->fifo_virt) { printk(KERN_ERR "axon_msi: couldn't allocate fifo for %s\n", dn->full_name); goto out_free_msic; } - msic->fifo = page_address(page); - msic->irq_host = irq_alloc_host(of_node_get(dn), IRQ_HOST_MAP_NOMAP, NR_IRQS, &msic_host_ops, 0); if (!msic->irq_host) { @@ -370,9 +368,9 @@ static int axon_msi_probe(struct of_device *device, pr_debug("axon_msi: irq 0x%x setup for axon_msi\n", virq); /* Enable the MSIC hardware */ - msic_dcr_write(msic, MSIC_BASE_ADDR_HI_REG, (u64)msic->fifo >> 32); + msic_dcr_write(msic, MSIC_BASE_ADDR_HI_REG, msic->fifo_phys >> 32); msic_dcr_write(msic, MSIC_BASE_ADDR_LO_REG, - (u64)msic->fifo & 0xFFFFFFFF); + msic->fifo_phys & 0xFFFFFFFF); msic_dcr_write(msic, MSIC_CTRL_REG, MSIC_CTRL_IRQ_ENABLE | MSIC_CTRL_ENABLE | MSIC_CTRL_FIFO_SIZE); @@ -390,7 +388,8 @@ static int axon_msi_probe(struct of_device *device, out_free_host: kfree(msic->irq_host); out_free_fifo: - __free_pages(virt_to_page(msic->fifo), get_order(MSIC_FIFO_SIZE_BYTES)); + dma_free_coherent(&device->dev, MSIC_FIFO_SIZE_BYTES, msic->fifo_virt, + msic->fifo_phys); out_free_msic: kfree(msic); out: