dmaengine: DW DMAC: add multi-block property to device tree

Several versions of DW DMAC have multi block transfers hardware
support. Hardware support of multi block transfers is disabled
by default if we use DT to configure DMAC and software emulation
of multi block transfers used instead.
Add multi-block property, so it is possible to enable hardware
multi block transfers (if present) via DT.

Switch from per device is_nollp variable to multi_block array
to be able enable/disable multi block transfers separately per
channel.

Acked-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Eugeniy Paltsev <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/dma/snps-dma.txt

···
   that services interrupts for this device
 - is_private: The device channels should be marked as private and not for by the
   general purpose DMA channel allocator. False if not passed.
+- multi-block: Multi block transfers supported by hardware. Array property with
+  one cell per channel. 0: not supported, 1 (default): supported.
 
 Example:
 

arch/arc/boot/dts/abilis_tb10x.dtsi

···
 			data-width = <4>;
 			clocks = <&ahb_clk>;
 			clock-names = "hclk";
+			multi-block = <1 1 1 1 1 1>;
 		};
 
 		i2c0: i2c@FF120000 {

arch/arm/boot/dts/spear13xx.dtsi

···
 			block_size = <0xfff>;
 			dma-masters = <2>;
 			data-width = <8 8>;
+			multi-block = <1 1 1 1 1 1 1 1>;
 		};
 
 		dma@eb000000 {
···
 			chan_priority = <1>;
 			block_size = <0xfff>;
 			data-width = <8 8>;
+			multi-block = <1 1 1 1 1 1 1 1>;
 		};
 
 		fsmc: flash@b0000000 {

drivers/dma/dw/core.c

···
 				(dwc_params >> DWC_PARAMS_MBLK_EN & 0x1) == 0;
 		} else {
 			dwc->block_size = pdata->block_size;
-			dwc->nollp = pdata->is_nollp;
+			dwc->nollp = !pdata->multi_block[i];
 		}
 	}
 

drivers/dma/dw/platform.c

···
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct dw_dma_platform_data *pdata;
-	u32 tmp, arr[DW_DMA_MAX_NR_MASTERS];
+	u32 tmp, arr[DW_DMA_MAX_NR_MASTERS], mb[DW_DMA_MAX_NR_CHANNELS];
 	u32 nr_masters;
 	u32 nr_channels;
 
···
 		return NULL;
 
 	if (of_property_read_u32(np, "dma-channels", &nr_channels))
+		return NULL;
+	if (nr_channels > DW_DMA_MAX_NR_CHANNELS)
 		return NULL;
 
 	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
···
 	} else if (!of_property_read_u32_array(np, "data_width", arr, nr_masters)) {
 		for (tmp = 0; tmp < nr_masters; tmp++)
 			pdata->data_width[tmp] = BIT(arr[tmp] & 0x07);
+	}
+
+	if (!of_property_read_u32_array(np, "multi-block", mb, nr_channels)) {
+		for (tmp = 0; tmp < nr_channels; tmp++)
+			pdata->multi_block[tmp] = mb[tmp];
+	} else {
+		for (tmp = 0; tmp < nr_channels; tmp++)
+			pdata->multi_block[tmp] = 1;
 	}
 
 	return pdata;

drivers/dma/dw/regs.h

···
 #include <linux/interrupt.h>
 #include <linux/dmaengine.h>
 
-#define DW_DMA_MAX_NR_CHANNELS	8
+#include "internal.h"
+
 #define DW_DMA_MAX_NR_REQUESTS	16
 
 /* flow controller */

drivers/tty/serial/8250/8250_lpss.c

···
 static const struct dw_dma_platform_data qrk_serial_dma_pdata = {
 	.nr_channels = 2,
 	.is_private = true,
-	.is_nollp = true,
 	.chan_allocation_order = CHAN_ALLOCATION_ASCENDING,
 	.chan_priority = CHAN_PRIORITY_ASCENDING,
 	.block_size = 4095,
 	.nr_masters = 1,
 	.data_width = {4},
+	.multi_block = {0},
 };
 
 static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)

include/linux/platform_data/dma-dw.h

···
 #include <linux/device.h>
 
 #define DW_DMA_MAX_NR_MASTERS	4
+#define DW_DMA_MAX_NR_CHANNELS	8
 
 /**
  * struct dw_dma_slave - Controller-specific information about a slave
···
  * @is_private: The device channels should be marked as private and not for
  *	by the general purpose DMA channel allocator.
  * @is_memcpy: The device channels do support memory-to-memory transfers.
- * @is_nollp: The device channels does not support multi block transfers.
  * @chan_allocation_order: Allocate channels starting from 0 or 7
  * @chan_priority: Set channel priority increasing from 0 to 7 or 7 to 0.
  * @block_size: Maximum block size supported by the controller
  * @nr_masters: Number of AHB masters supported by the controller
  * @data_width: Maximum data width supported by hardware per AHB master
  *		(in bytes, power of 2)
+ * @multi_block: Multi block transfers supported by hardware per channel.
  */
 struct dw_dma_platform_data {
 	unsigned int	nr_channels;
 	bool		is_private;
 	bool		is_memcpy;
-	bool		is_nollp;
 #define CHAN_ALLOCATION_ASCENDING	0	/* zero to seven */
 #define CHAN_ALLOCATION_DESCENDING	1	/* seven to zero */
 	unsigned char	chan_allocation_order;
···
 	unsigned int	block_size;
 	unsigned char	nr_masters;
 	unsigned char	data_width[DW_DMA_MAX_NR_MASTERS];
+	unsigned char	multi_block[DW_DMA_MAX_NR_CHANNELS];
 };
 
 #endif /* _PLATFORM_DATA_DMA_DW_H */