[media] marvell-cam: Allow selection of supported buffer modes

The Marvell camera core can support all three videobuf2 buffer modes, which
is slick, but it also requires that all three modes be built and present,
even though only one is likely to be used.  This patch allows the supported
modes to be selected at configuration time, reducing the footprint of the
driver.  Prior to this patch, the MMP camera driver looked like this:

mmp_camera             19092  0
videobuf2_core         15542  1 mmp_camera
videobuf2_dma_sg        3173  1 mmp_camera
videobuf2_dma_contig     2188  1 mmp_camera
videobuf2_vmalloc       1718  1 mmp_camera
videobuf2_memops        2100  3 videobuf2_dma_sg,videobuf2_dma_contig,videobuf2_vmalloc

Afterward, instead, with scatter/gather only configured:

mmp_camera             16021  0
videobuf2_core         15542  1 mmp_camera
videobuf2_dma_sg        3173  1 mmp_camera
videobuf2_memops        2100  1 videobuf2_dma_sg

The total goes from 43,813 bytes to 36,836.

The emphasis has been on simplicity and minimal #ifdef use rather than on
squeezing out every possible byte of code.  For configuration, the driver
simply looks at which videobuf2 modes have been configured in and supports
them all; it's simplistic but should be good enough.

The cafe driver is set to support vmalloc and dma-contig; mmp supports only
dma-sg, since that's the only mode that really makes sense to use.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 54 insertions, 5 deletions

diff --git a/drivers/media/video/marvell-ccic/mcam-core.h b/drivers/media/video/marvell-ccic/mcam-core.h
index 9a39e08b7523..aa5525537232 100644
--- a/drivers/media/video/marvell-ccic/mcam-core.h
+++ b/drivers/media/video/marvell-ccic/mcam-core.h
@@ -11,6 +11,27 @@
 #include <media/v4l2-dev.h>
 #include <media/videobuf2-core.h>
 
+/*
+ * Create our own symbols for the supported buffer modes, but, for now,
+ * base them entirely on which videobuf2 options have been selected.
+ */
+#if defined(CONFIG_VIDEOBUF2_VMALLOC) || defined(CONFIG_VIDEOBUF2_VMALLOC_MODULE)
+#define MCAM_MODE_VMALLOC 1
+#endif
+
+#if defined(CONFIG_VIDEOBUF2_DMA_CONTIG) || defined(CONFIG_VIDEOBUF2_DMA_CONTIG_MODULE)
+#define MCAM_MODE_DMA_CONTIG 1
+#endif
+
+#if defined(CONFIG_VIDEOBUF2_DMA_SG) || defined(CONFIG_VIDEOBUF2_DMA_SG_MODULE)
+#define MCAM_MODE_DMA_SG 1
+#endif
+
+#if !defined(MCAM_MODE_VMALLOC) && !defined(MCAM_MODE_DMA_CONTIG) && \
+	!defined(MCAM_MODE_DMA_SG)
+#error One of the videobuf buffer modes must be selected in the config
+#endif
+
 
 enum mcam_state {
 	S_NOTREADY,	/* Not yet initialized */
@@ -27,11 +48,33 @@ enum mcam_state {
  */
 enum mcam_buffer_mode {
 	B_vmalloc = 0,
-	B_DMA_contig,
-	B_DMA_sg
+	B_DMA_contig = 1,
+	B_DMA_sg = 2
 };
 
 /*
+ * Is a given buffer mode supported by the current kernel configuration?
+ */
+static inline int mcam_buffer_mode_supported(enum mcam_buffer_mode mode)
+{
+	switch (mode) {
+#ifdef MCAM_MODE_VMALLOC
+	case B_vmalloc:
+#endif
+#ifdef MCAM_MODE_DMA_CONTIG
+	case B_DMA_contig:
+#endif
+#ifdef MCAM_MODE_DMA_SG
+	case B_DMA_sg:
+#endif
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+
+/*
  * A description of one of our devices.
  * Locking: controlled by s_mutex.  Certain fields, however, require
  *          the dev_lock spinlock; they are marked as such by comments.
@@ -79,21 +122,27 @@ struct mcam_camera {
 	struct vb2_queue vb_queue;
 	struct list_head buffers;	/* Available frames */
 
-	/* DMA buffers - vmalloc mode */
 	unsigned int nbufs;		/* How many are alloc'd */
 	int next_buf;			/* Next to consume (dev_lock) */
+
+	/* DMA buffers - vmalloc mode */
+#ifdef MCAM_MODE_VMALLOC
 	unsigned int dma_buf_size;	/* allocated size */
 	void *dma_bufs[MAX_DMA_BUFS];	/* Internal buffer addresses */
 	dma_addr_t dma_handles[MAX_DMA_BUFS]; /* Buffer bus addresses */
+	struct tasklet_struct s_tasklet;
+#endif
 	unsigned int sequence;		/* Frame sequence number */
 	unsigned int buf_seq[MAX_DMA_BUFS]; /* Sequence for individual bufs */
 
-	/* DMA buffers - contiguous DMA mode */
+	/* DMA buffers - DMA modes */
 	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;
+	/* Mode-specific ops, set at open time */
+	void (*dma_setup)(struct mcam_camera *cam);
+	void (*frame_complete)(struct mcam_camera *cam, int frame);
 
 	/* Current operating parameters */
 	u32 sensor_type;		/* Currently ov7670 only */