[PATCH v4 15/16] misc: bcm-vk: add mmap function for exposing BAR2

Scott Branden
2020-09-29T00:13:38Z

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>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
---
drivers/misc/bcm-vk/bcm_vk_dev.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/drivers/misc/bcm-vk/bcm_vk_dev.c b/drivers/misc/bcm-vk/bcm_vk_dev.c
index 000febe967c1..e83c0e48fdeb 100644
--- a/drivers/misc/bcm-vk/bcm_vk_dev.c
+++ b/drivers/misc/bcm-vk/bcm_vk_dev.c
@@ -1178,6 +1178,29 @@ static long bcm_vk_reset(struct bcm_vk *vk, struct vk_reset __user *arg)
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;
@@ -1216,6 +1239,7 @@ 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,
};

--
2.17.1