misc: bcm-vk: add mmap function for exposing BAR2

Add mmap function that allows host application to open up BAR2 memory
for remote spooling out messages from the VK logger.

Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-12-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/bcm-vk/bcm_vk_dev.c b/drivers/misc/bcm-vk/bcm_vk_dev.c
index e572a7b18fabd6dc37863d8f2089a6b3291e9bf4..cac07419f041fb1391ea4eb6e0c717aefdf1333a 100644 (file)
--- a/drivers/misc/bcm-vk/bcm_vk_dev.c
+++ b/drivers/misc/bcm-vk/bcm_vk_dev.c
@@ -1199,6 +1199,29 @@ err_exit:
        return ret;
 }
 
+static int bcm_vk_mmap(struct file *file, struct vm_area_struct *vma)
+{
+       struct bcm_vk_ctx *ctx = file->private_data;
+       struct bcm_vk *vk = container_of(ctx->miscdev, struct bcm_vk, miscdev);
+       unsigned long pg_size;
+
+       /* only BAR2 is mmap possible, which is bar num 4 due to 64bit */
+#define VK_MMAPABLE_BAR 4
+
+       pg_size = ((pci_resource_len(vk->pdev, VK_MMAPABLE_BAR) - 1)
+                   >> PAGE_SHIFT) + 1;
+       if (vma->vm_pgoff + vma_pages(vma) > pg_size)
+               return -EINVAL;
+
+       vma->vm_pgoff += (pci_resource_start(vk->pdev, VK_MMAPABLE_BAR)
+                         >> PAGE_SHIFT);
+       vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+       return io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
+                                 vma->vm_end - vma->vm_start,
+                                 vma->vm_page_prot);
+}
+
 static long bcm_vk_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
        long ret = -EINVAL;
@@ -1237,6 +1260,7 @@ static const struct file_operations bcm_vk_fops = {
        .write = bcm_vk_write,
        .poll = bcm_vk_poll,
        .release = bcm_vk_release,
+       .mmap = bcm_vk_mmap,
        .unlocked_ioctl = bcm_vk_ioctl,
 };