linux-kernel - [PATCH 6/7] media: v4l2-mem2mem: add v4l2_m2m_get_unmapped

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Message-Id: <1621508727-24486-7-git-send-email-dillon.minfei@gmail.com>
Date:   Thu, 20 May 2021 19:05:26 +0800
From:   dillon.minfei@...il.com
To:     mchehab@...nel.org, mchehab+huawei@...nel.org,
        hverkuil-cisco@...all.nl, ezequiel@...labora.com, gnurou@...il.com,
        pihsun@...omium.org, mcoquelin.stm32@...il.com,
        alexandre.torgue@...s.st.com, mturquette@...libre.com,
        sboyd@...nel.org, robh+dt@...nel.org
Cc:     patrice.chotard@...s.st.com, hugues.fruchet@...s.st.com,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, Dillon Min <dillon.minfei@...il.com>
Subject: [PATCH 6/7] media: v4l2-mem2mem: add v4l2_m2m_get_unmapped_area for no-mmu platform

From: Dillon Min <dillon.minfei@...il.com>

For platforms without MMU the m2m provides a helper method
v4l2_m2m_get_unmapped_area(), The mmap() routines will call
this to get a proposed address for the mapping.

More detailed information about get_unmapped_area can be found in
Documentation/nommu-mmap.txt

Signed-off-by: Dillon Min <dillon.minfei@...il.com>
---
 drivers/media/v4l2-core/v4l2-mem2mem.c | 20 ++++++++++++++++++++
 include/media/v4l2-mem2mem.h           |  4 ++++
 2 files changed, 24 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
index e7f4bf5bc8dd..f82a18ecab2f 100644
--- a/drivers/media/v4l2-core/v4l2-mem2mem.c
+++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
@@ -966,6 +966,26 @@ int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 }
 EXPORT_SYMBOL(v4l2_m2m_mmap);
 
+#ifndef CONFIG_MMU
+unsigned long v4l2_m2m_get_unmapped_area(struct file *file, unsigned long addr,
+		unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	struct v4l2_fh *fh = file->private_data;
+	unsigned long offset = pgoff << PAGE_SHIFT;
+	struct vb2_queue *vq;
+
+	if (offset < DST_QUEUE_OFF_BASE) {
+		vq = v4l2_m2m_get_src_vq(fh->m2m_ctx);
+	} else {
+		vq = v4l2_m2m_get_dst_vq(fh->m2m_ctx);
+		pgoff -= (DST_QUEUE_OFF_BASE >> PAGE_SHIFT);
+	}
+
+	return vb2_get_unmapped_area(vq, addr, len, pgoff, flags);
+}
+EXPORT_SYMBOL_GPL(v4l2_m2m_get_unmapped_area);
+#endif
+
 #if defined(CONFIG_MEDIA_CONTROLLER)
 void v4l2_m2m_unregister_media_controller(struct v4l2_m2m_dev *m2m_dev)
 {
diff --git a/include/media/v4l2-mem2mem.h b/include/media/v4l2-mem2mem.h
index 5a91b548ecc0..91269227c265 100644
--- a/include/media/v4l2-mem2mem.h
+++ b/include/media/v4l2-mem2mem.h
@@ -495,6 +495,10 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 int v4l2_m2m_mmap(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
 		  struct vm_area_struct *vma);
 
+#ifndef CONFIG_MMU
+unsigned long v4l2_m2m_get_unmapped_area(struct file *file, unsigned long addr,
+		unsigned long len, unsigned long pgoff, unsigned long flags);
+#endif
 /**
  * v4l2_m2m_init() - initialize per-driver m2m data
  *
-- 
2.7.4