[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 <michael@ellerman.id.au> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
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@ -65,7 +65,8 @@
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struct axon_msic {
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struct irq_host *irq_host;
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__le32 *fifo;
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__le32 *fifo_virt;
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dma_addr_t fifo_phys;
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dcr_host_t dcr_host;
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u32 read_offset;
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};
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@ -91,7 +92,7 @@ static void axon_msi_cascade(unsigned int irq, struct irq_desc *desc)
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while (msic->read_offset != write_offset) {
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idx = msic->read_offset / sizeof(__le32);
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msi = le32_to_cpu(msic->fifo[idx]);
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msi = le32_to_cpu(msic->fifo_virt[idx]);
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msi &= 0xFFFF;
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pr_debug("axon_msi: woff %x roff %x msi %x\n",
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@ -306,7 +307,6 @@ static int axon_msi_shutdown(struct of_device *device)
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static int axon_msi_probe(struct of_device *device,
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const struct of_device_id *device_id)
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{
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struct page *page;
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struct device_node *dn = device->node;
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struct axon_msic *msic;
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unsigned int virq;
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@ -338,16 +338,14 @@ static int axon_msi_probe(struct of_device *device,
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goto out_free_msic;
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}
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page = alloc_pages_node(of_node_to_nid(dn), GFP_KERNEL,
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get_order(MSIC_FIFO_SIZE_BYTES));
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if (!page) {
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msic->fifo_virt = dma_alloc_coherent(&device->dev, MSIC_FIFO_SIZE_BYTES,
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&msic->fifo_phys, GFP_KERNEL);
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if (!msic->fifo_virt) {
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printk(KERN_ERR "axon_msi: couldn't allocate fifo for %s\n",
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dn->full_name);
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goto out_free_msic;
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}
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msic->fifo = page_address(page);
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msic->irq_host = irq_alloc_host(of_node_get(dn), IRQ_HOST_MAP_NOMAP,
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NR_IRQS, &msic_host_ops, 0);
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if (!msic->irq_host) {
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@ -370,9 +368,9 @@ static int axon_msi_probe(struct of_device *device,
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pr_debug("axon_msi: irq 0x%x setup for axon_msi\n", virq);
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/* Enable the MSIC hardware */
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msic_dcr_write(msic, MSIC_BASE_ADDR_HI_REG, (u64)msic->fifo >> 32);
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msic_dcr_write(msic, MSIC_BASE_ADDR_HI_REG, msic->fifo_phys >> 32);
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msic_dcr_write(msic, MSIC_BASE_ADDR_LO_REG,
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(u64)msic->fifo & 0xFFFFFFFF);
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msic->fifo_phys & 0xFFFFFFFF);
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msic_dcr_write(msic, MSIC_CTRL_REG,
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MSIC_CTRL_IRQ_ENABLE | MSIC_CTRL_ENABLE |
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MSIC_CTRL_FIFO_SIZE);
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@ -390,7 +388,8 @@ static int axon_msi_probe(struct of_device *device,
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out_free_host:
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kfree(msic->irq_host);
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out_free_fifo:
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__free_pages(virt_to_page(msic->fifo), get_order(MSIC_FIFO_SIZE_BYTES));
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dma_free_coherent(&device->dev, MSIC_FIFO_SIZE_BYTES, msic->fifo_virt,
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msic->fifo_phys);
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out_free_msic:
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kfree(msic);
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out:
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