[media] marvell-cam: implement contiguous DMA operation

The core driver can now operate in either vmalloc or dma-contig modes;
obviously the latter is preferable when it is supported.  Default is
currently vmalloc on all platforms; load the module with buffer_mode=1 for
contiguous DMA mode.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/marvell-ccic/Kconfig

@@ -14,6 +14,7 @@ config VIDEO_MMP_CAMERA
 	select VIDEO_OV7670
 	select I2C_GPIO
 	select VIDEOBUF2_VMALLOC
+	select VIDEOBUF2_DMA_CONTIG
 	---help---
 	  This is a Video4Linux2 driver for the integrated camera
 	  controller found on Marvell Armada 610 application

drivers/media/video/marvell-ccic/cafe-driver.c

@@ -481,6 +481,12 @@ static int cafe_pci_probe(struct pci_dev *pdev,
 	 */
 	mcam->clock_speed = 45;
 	mcam->use_smbus = 1;
+	/*
+	 * Vmalloc mode for buffers is traditional with this driver.
+	 * We *might* be able to run DMA_contig, especially on a system
+	 * with CMA in it.
+	 */
+	mcam->buffer_mode = B_vmalloc;
 	/*
 	 * Get set up on the PCI bus.
 	 */

drivers/media/video/marvell-ccic/mcam-core.h

@@ -27,10 +27,20 @@ enum mcam_state {
 	S_NOTREADY,	/* Not yet initialized */
 	S_IDLE,		/* Just hanging around */
 	S_FLAKED,	/* Some sort of problem */
-	S_STREAMING	/* Streaming data */
+	S_STREAMING,	/* Streaming data */
+	S_BUFWAIT	/* streaming requested but no buffers yet */
 };
 #define MAX_DMA_BUFS 3
 
+/*
+ * Different platforms work best with different buffer modes, so we
+ * let the platform pick.
+ */
+enum mcam_buffer_mode {
+	B_vmalloc = 0,
+	B_DMA_contig
+};
+
 /*
  * A description of one of our devices.
  * Locking: controlled by s_mutex.  Certain fields, however, require
@@ -49,7 +59,7 @@ struct mcam_camera {
 	unsigned int chip_id;
 	short int clock_speed;	/* Sensor clock speed, default 30 */
 	short int use_smbus;	/* SMBUS or straight I2c? */
-
+	enum mcam_buffer_mode buffer_mode;
 	/*
 	 * Callbacks from the core to the platform code.
 	 */
@@ -79,7 +89,7 @@ struct mcam_camera {
 	struct vb2_queue vb_queue;
 	struct list_head buffers;	/* Available frames */
 
-	/* DMA buffers */
+	/* DMA buffers - vmalloc mode */
 	unsigned int nbufs;		/* How many are alloc'd */
 	int next_buf;			/* Next to consume (dev_lock) */
 	unsigned int dma_buf_size;	/* allocated size */
@@ -88,6 +98,11 @@ struct mcam_camera {
 	unsigned int sequence;		/* Frame sequence number */
 	unsigned int buf_seq[MAX_DMA_BUFS]; /* Sequence for individual bufs */
 
+	/* DMA buffers - contiguous DMA mode */
+	struct mcam_vb_buffer *vb_bufs[MAX_DMA_BUFS];
+	struct vb2_alloc_ctx *vb_alloc_ctx;
+	unsigned short last_delivered;
+
 	struct tasklet_struct s_tasklet;
 
 	/* Current operating parameters */

drivers/media/video/marvell-ccic/mmp-driver.c

@@ -180,6 +180,7 @@ static int mmpcam_probe(struct platform_device *pdev)
 	mcam->dev = &pdev->dev;
 	mcam->use_smbus = 0;
 	mcam->chip_id = V4L2_IDENT_ARMADA610;
+	mcam->buffer_mode = B_vmalloc;  /* Switch to dma */
 	spin_lock_init(&mcam->dev_lock);
 	/*
 	 * Get our I/O memory.