PCI: dwc: Use the DMA-API to get the MSI address

Use the DMA-API to get the MSI address. This address will be written to
our PCI config space and to the register which determines which AXI
address the DWC IP will spoof for incoming MSI irqs.

Since it is a PCIe endpoint device, rather than the CPU, that is supposed
to write to the MSI address, the proper way to get the MSI address is by
using the DMA API, not by using virt_to_phys().

Using virt_to_phys() might work on some systems, but using the DMA API
should work on all systems.

This is essentially the same thing as allocating a buffer in a driver
to which the endpoint will write to. To do this, we use the DMA API.

Tested-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Signed-off-by: Niklas Cassel <niklas.cassel@axis.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Joao Pinto <jpinto@synopsys.com>

diff --git a/drivers/pci/dwc/pcie-designware-host.c b/drivers/pci/dwc/pcie-designware-host.c
index 81e2157..bf558df 100644 (file)
--- a/drivers/pci/dwc/pcie-designware-host.c
+++ b/drivers/pci/dwc/pcie-designware-host.c
@@ -83,10 +83,19 @@ irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
 
 void dw_pcie_msi_init(struct pcie_port *pp)
 {
+       struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+       struct device *dev = pci->dev;
+       struct page *page;
        u64 msi_target;
 
-       pp->msi_data = __get_free_pages(GFP_KERNEL, 0);
-       msi_target = virt_to_phys((void *)pp->msi_data);
+       page = alloc_page(GFP_KERNEL);
+       pp->msi_data = dma_map_page(dev, page, 0, PAGE_SIZE, DMA_FROM_DEVICE);
+       if (dma_mapping_error(dev, pp->msi_data)) {
+               dev_err(dev, "failed to map MSI data\n");
+               __free_page(page);
+               return;
+       }
+       msi_target = (u64)pp->msi_data;
 
        /* program the msi_data */
        dw_pcie_wr_own_conf(pp, PCIE_MSI_ADDR_LO, 4,
@@ -187,7 +196,7 @@ static void dw_msi_setup_msg(struct pcie_port *pp, unsigned int irq, u32 pos)
        if (pp->ops->get_msi_addr)
                msi_target = pp->ops->get_msi_addr(pp);
        else
-               msi_target = virt_to_phys((void *)pp->msi_data);
+               msi_target = (u64)pp->msi_data;
 
        msg.address_lo = (u32)(msi_target & 0xffffffff);
        msg.address_hi = (u32)(msi_target >> 32 & 0xffffffff);

diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie-designware.h
index e5d9d77..ecdede6 100644 (file)
--- a/drivers/pci/dwc/pcie-designware.h
+++ b/drivers/pci/dwc/pcie-designware.h
@@ -14,6 +14,7 @@
 #ifndef _PCIE_DESIGNWARE_H
 #define _PCIE_DESIGNWARE_H
 
+#include <linux/dma-mapping.h>
 #include <linux/irq.h>
 #include <linux/msi.h>
 #include <linux/pci.h>
@@ -168,7 +169,7 @@ struct pcie_port {
        const struct dw_pcie_host_ops *ops;
        int                     msi_irq;
        struct irq_domain       *irq_domain;
-       unsigned long           msi_data;
+       dma_addr_t              msi_data;
        DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
 };