viafb: Add a simple VX855 DMA engine driver

This code provides a minimal amount of access to the DMA engine as
needed by the camera driver.  VX855 only; it's guaranteed not to work
on other chipsets, so it won't try.

Cc: ScottFang@viatech.com.cn
Cc: JosephChan@via.com.tw
Cc: Harald Welte <laforge@gnumonks.org>
Acked-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

1 files changed, 29 insertions, 0 deletions

diff --git a/drivers/video/via/via-core.h b/drivers/video/via/via-core.h
index ba64b36d58e3..3d03141d6074 100644
--- a/drivers/video/via/via-core.h
+++ b/drivers/video/via/via-core.h
@@ -131,4 +131,33 @@ void viafb_irq_disable(u32 mask);
 #define   VDE_I_LVDSSIEN  0x40000000  /* LVDS Sense enable */
 #define   VDE_I_ENABLE    0x80000000  /* Global interrupt enable */
 
+/*
+ * DMA management.
+ */
+int viafb_request_dma(void);
+void viafb_release_dma(void);
+/* void viafb_dma_copy_out(unsigned int offset, dma_addr_t paddr, int len); */
+int viafb_dma_copy_out_sg(unsigned int offset, struct scatterlist *sg, int nsg);
+
+/*
+ * DMA Controller registers.
+ */
+#define VDMA_MR0        0xe00           /* Mod reg 0 */
+#define   VDMA_MR_CHAIN   0x01          /* Chaining mode */
+#define   VDMA_MR_TDIE    0x02          /* Transfer done int enable */
+#define VDMA_CSR0       0xe04           /* Control/status */
+#define   VDMA_C_ENABLE   0x01            /* DMA Enable */
+#define   VDMA_C_START    0x02            /* Start a transfer */
+#define   VDMA_C_ABORT    0x04            /* Abort a transfer */
+#define   VDMA_C_DONE     0x08            /* Transfer is done */
+#define VDMA_MARL0      0xe20           /* Mem addr low */
+#define VDMA_MARH0      0xe24           /* Mem addr high */
+#define VDMA_DAR0       0xe28           /* Device address */
+#define VDMA_DQWCR0     0xe2c           /* Count (16-byte) */
+#define VDMA_TMR0       0xe30           /* Tile mode reg */
+#define VDMA_DPRL0      0xe34           /* Not sure */
+#define   VDMA_DPR_IN     0x08          /* Inbound transfer to FB */
+#define VDMA_DPRH0      0xe38
+#define VDMA_PMR0       (0xe00 + 0x134) /* Pitch mode */
+
 #endif /* __VIA_CORE_H__ */