From 21e2079fe4938e84c0c5c0996cc03d63d5f9cacc Mon Sep 17 00:00:00 2001 From: Vidya Sagar Date: Tue, 16 Apr 2019 16:21:44 +0530 Subject: [PATCH] PCI: tegra: Use the DMA-API to get the MSI address Since the upstream MSI memory writes are generated by downstream devices, it is logically correct to have MSI target memory coming from the DMA pool reserved for PCIe than from the general memory pool reserved for CPU access to avoid PCIe DMA addresses coinciding with MSI target address thereby raising unwanted MSI interrupts. Enforce this behaviour by retrieving the MSI address through the DMA API. Limit the MSI target address to 32-bits to make it work for PCIe endpoints that support only 32-bit MSI target address; endpoints that support 64-bit MSI target address work with 32-bit MSI target address too. Signed-off-by: Vidya Sagar [lorenzo.pieralisi@arm.com: updated commit log] Signed-off-by: Lorenzo Pieralisi Reviewed-by: Robin Murphy Reviewed-by: Thierry Reding Acked-by: Thierry Reding --- drivers/pci/controller/pci-tegra.c | 37 ++++++++++++++++++++++-------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c index f4f53d092e00..464ba2538d52 100644 --- a/drivers/pci/controller/pci-tegra.c +++ b/drivers/pci/controller/pci-tegra.c @@ -231,9 +231,9 @@ struct tegra_msi { struct msi_controller chip; DECLARE_BITMAP(used, INT_PCI_MSI_NR); struct irq_domain *domain; - unsigned long pages; struct mutex lock; - u64 phys; + void *virt; + dma_addr_t phys; int irq; }; @@ -1536,7 +1536,7 @@ static int tegra_pcie_msi_setup(struct tegra_pcie *pcie) err = platform_get_irq_byname(pdev, "msi"); if (err < 0) { dev_err(dev, "failed to get IRQ: %d\n", err); - goto err; + goto free_irq_domain; } msi->irq = err; @@ -1545,17 +1545,35 @@ static int tegra_pcie_msi_setup(struct tegra_pcie *pcie) tegra_msi_irq_chip.name, pcie); if (err < 0) { dev_err(dev, "failed to request IRQ: %d\n", err); - goto err; + goto free_irq_domain; + } + + /* Though the PCIe controller can address >32-bit address space, to + * facilitate endpoints that support only 32-bit MSI target address, + * the mask is set to 32-bit to make sure that MSI target address is + * always a 32-bit address + */ + err = dma_set_coherent_mask(dev, DMA_BIT_MASK(32)); + if (err < 0) { + dev_err(dev, "failed to set DMA coherent mask: %d\n", err); + goto free_irq; + } + + msi->virt = dma_alloc_attrs(dev, PAGE_SIZE, &msi->phys, GFP_KERNEL, + DMA_ATTR_NO_KERNEL_MAPPING); + if (!msi->virt) { + dev_err(dev, "failed to allocate DMA memory for MSI\n"); + err = -ENOMEM; + goto free_irq; } - /* setup AFI/FPCI range */ - msi->pages = __get_free_pages(GFP_KERNEL, 0); - msi->phys = virt_to_phys((void *)msi->pages); host->msi = &msi->chip; return 0; -err: +free_irq: + free_irq(msi->irq, pcie); +free_irq_domain: irq_domain_remove(msi->domain); return err; } @@ -1592,7 +1610,8 @@ static void tegra_pcie_msi_teardown(struct tegra_pcie *pcie) struct tegra_msi *msi = &pcie->msi; unsigned int i, irq; - free_pages(msi->pages, 0); + dma_free_attrs(pcie->dev, PAGE_SIZE, msi->virt, msi->phys, + DMA_ATTR_NO_KERNEL_MAPPING); if (msi->irq > 0) free_irq(msi->irq, pcie);