dmaengine: dw-axi-dmac: Add Intel KeemBay DMA register fields

Add support for Intel KeemBay DMA registers. These registers are required
to run data transfer between device to memory and memory to device on Intel
KeemBay SoC.

Signed-off-by: Sia Jee Heng <[e-mail]>
Tested-by: Eugeniy Paltsev <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Eugeniy Paltsev <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/dw-axi-dmac/dw-axi-dmac.h

···
 	struct device		*dev;
 	int			irq;
 	void __iomem		*regs;
+	void __iomem		*apb_regs;
 	struct clk		*core_clk;
 	struct clk		*cfgr_clk;
 	struct dw_axi_dma	*dw;
···
 #define CH_INTSIGNAL_ENA	0x090 /* R/W Chan Interrupt Signal Enable */
 #define CH_INTCLEAR		0x098 /* W Chan Interrupt Clear */
 
+/* These Apb registers are used by Intel KeemBay SoC */
+#define DMAC_APB_CFG		0x000 /* DMAC Apb Configuration Register */
+#define DMAC_APB_STAT		0x004 /* DMAC Apb Status Register */
+#define DMAC_APB_DEBUG_STAT_0	0x008 /* DMAC Apb Debug Status Register 0 */
+#define DMAC_APB_DEBUG_STAT_1	0x00C /* DMAC Apb Debug Status Register 1 */
+#define DMAC_APB_HW_HS_SEL_0	0x010 /* DMAC Apb HW HS register 0 */
+#define DMAC_APB_HW_HS_SEL_1	0x014 /* DMAC Apb HW HS register 1 */
+#define DMAC_APB_LPI		0x018 /* DMAC Apb Low Power Interface Reg */
+#define DMAC_APB_BYTE_WR_CH_EN	0x01C /* DMAC Apb Byte Write Enable */
+#define DMAC_APB_HALFWORD_WR_CH_EN	0x020 /* DMAC Halfword write enables */
+
+#define UNUSED_CHANNEL		0x3F /* Set unused DMA channel to 0x3F */
+#define MAX_BLOCK_SIZE		0x1000 /* 1024 blocks * 4 bytes data width */
 
 /* DMAC_CFG */
 #define DMAC_EN_POS			0