dmaengine: at_hdmac: add DMA slave transfers

This patch for at_hdmac adds the slave transfers capability to the Atmel DMA
controller available on some AT91 SOCs. This allow peripheral to memory and
memory to peripheral transfers with hardware handshaking.

Slave structure for controller specific information is passed through channel
private data. This at_dma_slave structure is defined in at_hdmac.h header file
and relative hardware definition are moved to this file from at_hdmac_regs.h.
Doing this we allow the channel configuration from platform definition code.

This work is intensively based on dw_dmac and several slave implementations.
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

arch/arm/mach-at91/include/mach/at_hdmac.h

@@ -23,4 +23,80 @@ struct at_dma_platform_data {
 	dma_cap_mask_t  cap_mask;
 };
 
+/**
+ * enum at_dma_slave_width - DMA slave register access width.
+ * @AT_DMA_SLAVE_WIDTH_8BIT: Do 8-bit slave register accesses
+ * @AT_DMA_SLAVE_WIDTH_16BIT: Do 16-bit slave register accesses
+ * @AT_DMA_SLAVE_WIDTH_32BIT: Do 32-bit slave register accesses
+ */
+enum at_dma_slave_width {
+	AT_DMA_SLAVE_WIDTH_8BIT = 0,
+	AT_DMA_SLAVE_WIDTH_16BIT,
+	AT_DMA_SLAVE_WIDTH_32BIT,
+};
+
+/**
+ * struct at_dma_slave - Controller-specific information about a slave
+ * @dma_dev: required DMA master device
+ * @tx_reg: physical address of data register used for
+ *	memory-to-peripheral transfers
+ * @rx_reg: physical address of data register used for
+ *	peripheral-to-memory transfers
+ * @reg_width: peripheral register width
+ * @cfg: Platform-specific initializer for the CFG register
+ * @ctrla: Platform-specific initializer for the CTRLA register
+ */
+struct at_dma_slave {
+	struct device		*dma_dev;
+	dma_addr_t		tx_reg;
+	dma_addr_t		rx_reg;
+	enum at_dma_slave_width	reg_width;
+	u32			cfg;
+	u32			ctrla;
+};
+
+
+/* Platform-configurable bits in CFG */
+#define	ATC_SRC_PER(h)		(0xFU & (h))	/* Channel src rq associated with periph handshaking ifc h */
+#define	ATC_DST_PER(h)		((0xFU & (h)) <<  4)	/* Channel dst rq associated with periph handshaking ifc h */
+#define	ATC_SRC_REP		(0x1 <<  8)	/* Source Replay Mod */
+#define	ATC_SRC_H2SEL		(0x1 <<  9)	/* Source Handshaking Mod */
+#define		ATC_SRC_H2SEL_SW	(0x0 <<  9)
+#define		ATC_SRC_H2SEL_HW	(0x1 <<  9)
+#define	ATC_DST_REP		(0x1 << 12)	/* Destination Replay Mod */
+#define	ATC_DST_H2SEL		(0x1 << 13)	/* Destination Handshaking Mod */
+#define		ATC_DST_H2SEL_SW	(0x0 << 13)
+#define		ATC_DST_H2SEL_HW	(0x1 << 13)
+#define	ATC_SOD			(0x1 << 16)	/* Stop On Done */
+#define	ATC_LOCK_IF		(0x1 << 20)	/* Interface Lock */
+#define	ATC_LOCK_B		(0x1 << 21)	/* AHB Bus Lock */
+#define	ATC_LOCK_IF_L		(0x1 << 22)	/* Master Interface Arbiter Lock */
+#define		ATC_LOCK_IF_L_CHUNK	(0x0 << 22)
+#define		ATC_LOCK_IF_L_BUFFER	(0x1 << 22)
+#define	ATC_AHB_PROT_MASK	(0x7 << 24)	/* AHB Protection */
+#define	ATC_FIFOCFG_MASK	(0x3 << 28)	/* FIFO Request Configuration */
+#define		ATC_FIFOCFG_LARGESTBURST	(0x0 << 28)
+#define		ATC_FIFOCFG_HALFFIFO		(0x1 << 28)
+#define		ATC_FIFOCFG_ENOUGHSPACE		(0x2 << 28)
+
+/* Platform-configurable bits in CTRLA */
+#define	ATC_SCSIZE_MASK		(0x7 << 16)	/* Source Chunk Transfer Size */
+#define		ATC_SCSIZE_1		(0x0 << 16)
+#define		ATC_SCSIZE_4		(0x1 << 16)
+#define		ATC_SCSIZE_8		(0x2 << 16)
+#define		ATC_SCSIZE_16		(0x3 << 16)
+#define		ATC_SCSIZE_32		(0x4 << 16)
+#define		ATC_SCSIZE_64		(0x5 << 16)
+#define		ATC_SCSIZE_128		(0x6 << 16)
+#define		ATC_SCSIZE_256		(0x7 << 16)
+#define	ATC_DCSIZE_MASK		(0x7 << 20)	/* Destination Chunk Transfer Size */
+#define		ATC_DCSIZE_1		(0x0 << 20)
+#define		ATC_DCSIZE_4		(0x1 << 20)
+#define		ATC_DCSIZE_8		(0x2 << 20)
+#define		ATC_DCSIZE_16		(0x3 << 20)
+#define		ATC_DCSIZE_32		(0x4 << 20)
+#define		ATC_DCSIZE_64		(0x5 << 20)
+#define		ATC_DCSIZE_128		(0x6 << 20)
+#define		ATC_DCSIZE_256		(0x7 << 20)
+
 #endif /* AT_HDMAC_H */

drivers/dma/at_hdmac.c

@@ -608,6 +608,187 @@ atc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
 	return NULL;
 }
 
+
+/**
+ * atc_prep_slave_sg - prepare descriptors for a DMA_SLAVE transaction
+ * @chan: DMA channel
+ * @sgl: scatterlist to transfer to/from
+ * @sg_len: number of entries in @scatterlist
+ * @direction: DMA direction
+ * @flags: tx descriptor status flags
+ */
+static struct dma_async_tx_descriptor *
+atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
+		unsigned int sg_len, enum dma_data_direction direction,
+		unsigned long flags)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma_slave	*atslave = chan->private;
+	struct at_desc		*first = NULL;
+	struct at_desc		*prev = NULL;
+	u32			ctrla;
+	u32			ctrlb;
+	dma_addr_t		reg;
+	unsigned int		reg_width;
+	unsigned int		mem_width;
+	unsigned int		i;
+	struct scatterlist	*sg;
+	size_t			total_len = 0;
+
+	dev_vdbg(chan2dev(chan), "prep_slave_sg: %s f0x%lx\n",
+			direction == DMA_TO_DEVICE ? "TO DEVICE" : "FROM DEVICE",
+			flags);
+
+	if (unlikely(!atslave || !sg_len)) {
+		dev_dbg(chan2dev(chan), "prep_dma_memcpy: length is zero!\n");
+		return NULL;
+	}
+
+	reg_width = atslave->reg_width;
+
+	sg_len = dma_map_sg(chan2parent(chan), sgl, sg_len, direction);
+
+	ctrla = ATC_DEFAULT_CTRLA | atslave->ctrla;
+	ctrlb = ATC_DEFAULT_CTRLB | ATC_IEN;
+
+	switch (direction) {
+	case DMA_TO_DEVICE:
+		ctrla |=  ATC_DST_WIDTH(reg_width);
+		ctrlb |=  ATC_DST_ADDR_MODE_FIXED
+			| ATC_SRC_ADDR_MODE_INCR
+			| ATC_FC_MEM2PER;
+		reg = atslave->tx_reg;
+		for_each_sg(sgl, sg, sg_len, i) {
+			struct at_desc	*desc;
+			u32		len;
+			u32		mem;
+
+			desc = atc_desc_get(atchan);
+			if (!desc)
+				goto err_desc_get;
+
+			mem = sg_phys(sg);
+			len = sg_dma_len(sg);
+			mem_width = 2;
+			if (unlikely(mem & 3 || len & 3))
+				mem_width = 0;
+
+			desc->lli.saddr = mem;
+			desc->lli.daddr = reg;
+			desc->lli.ctrla = ctrla
+					| ATC_SRC_WIDTH(mem_width)
+					| len >> mem_width;
+			desc->lli.ctrlb = ctrlb;
+
+			if (!first) {
+				first = desc;
+			} else {
+				/* inform the HW lli about chaining */
+				prev->lli.dscr = desc->txd.phys;
+				/* insert the link descriptor to the LD ring */
+				list_add_tail(&desc->desc_node,
+						&first->txd.tx_list);
+			}
+			prev = desc;
+			total_len += len;
+		}
+		break;
+	case DMA_FROM_DEVICE:
+		ctrla |=  ATC_SRC_WIDTH(reg_width);
+		ctrlb |=  ATC_DST_ADDR_MODE_INCR
+			| ATC_SRC_ADDR_MODE_FIXED
+			| ATC_FC_PER2MEM;
+
+		reg = atslave->rx_reg;
+		for_each_sg(sgl, sg, sg_len, i) {
+			struct at_desc	*desc;
+			u32		len;
+			u32		mem;
+
+			desc = atc_desc_get(atchan);
+			if (!desc)
+				goto err_desc_get;
+
+			mem = sg_phys(sg);
+			len = sg_dma_len(sg);
+			mem_width = 2;
+			if (unlikely(mem & 3 || len & 3))
+				mem_width = 0;
+
+			desc->lli.saddr = reg;
+			desc->lli.daddr = mem;
+			desc->lli.ctrla = ctrla
+					| ATC_DST_WIDTH(mem_width)
+					| len >> mem_width;
+			desc->lli.ctrlb = ctrlb;
+
+			if (!first) {
+				first = desc;
+			} else {
+				/* inform the HW lli about chaining */
+				prev->lli.dscr = desc->txd.phys;
+				/* insert the link descriptor to the LD ring */
+				list_add_tail(&desc->desc_node,
+						&first->txd.tx_list);
+			}
+			prev = desc;
+			total_len += len;
+		}
+		break;
+	default:
+		return NULL;
+	}
+
+	/* set end-of-link to the last link descriptor of list*/
+	set_desc_eol(prev);
+
+	/* First descriptor of the chain embedds additional information */
+	first->txd.cookie = -EBUSY;
+	first->len = total_len;
+
+	/* last link descriptor of list is responsible of flags */
+	prev->txd.flags = flags; /* client is in control of this ack */
+
+	return &first->txd;
+
+err_desc_get:
+	dev_err(chan2dev(chan), "not enough descriptors available\n");
+	atc_desc_put(atchan, first);
+	return NULL;
+}
+
+static void atc_terminate_all(struct dma_chan *chan)
+{
+	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
+	struct at_dma		*atdma = to_at_dma(chan->device);
+	struct at_desc		*desc, *_desc;
+	LIST_HEAD(list);
+
+	/*
+	 * This is only called when something went wrong elsewhere, so
+	 * we don't really care about the data. Just disable the
+	 * channel. We still have to poll the channel enable bit due
+	 * to AHB/HSB limitations.
+	 */
+	spin_lock_bh(&atchan->lock);
+
+	dma_writel(atdma, CHDR, atchan->mask);
+
+	/* confirm that this channel is disabled */
+	while (dma_readl(atdma, CHSR) & atchan->mask)
+		cpu_relax();
+
+	/* active_list entries will end up before queued entries */
+	list_splice_init(&atchan->queue, &list);
+	list_splice_init(&atchan->active_list, &list);
+
+	spin_unlock_bh(&atchan->lock);
+
+	/* Flush all pending and queued descriptors */
+	list_for_each_entry_safe(desc, _desc, &list, desc_node)
+		atc_chain_complete(atchan, desc);
+}
+
 /**
  * atc_is_tx_complete - poll for transaction completion
  * @chan: DMA channel
@@ -686,7 +867,9 @@ static int atc_alloc_chan_resources(struct dma_chan *chan)
 	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
 	struct at_dma		*atdma = to_at_dma(chan->device);
 	struct at_desc		*desc;
+	struct at_dma_slave	*atslave;
 	int			i;
+	u32			cfg;
 	LIST_HEAD(tmp_list);
 
 	dev_vdbg(chan2dev(chan), "alloc_chan_resources\n");
@@ -697,7 +880,23 @@ static int atc_alloc_chan_resources(struct dma_chan *chan)
 		return -EIO;
 	}
 
-	/* have we already been set up? */
+	cfg = ATC_DEFAULT_CFG;
+
+	atslave = chan->private;
+	if (atslave) {
+		/*
+		 * We need controller-specific data to set up slave
+		 * transfers.
+		 */
+		BUG_ON(!atslave->dma_dev || atslave->dma_dev != atdma->dma_common.dev);
+
+		/* if cfg configuration specified take it instad of default */
+		if (atslave->cfg)
+			cfg = atslave->cfg;
+	}
+
+	/* have we already been set up?
+	 * reconfigure channel but no need to reallocate descriptors */
 	if (!list_empty(&atchan->free_list))
 		return atchan->descs_allocated;
 
@@ -719,7 +918,7 @@ static int atc_alloc_chan_resources(struct dma_chan *chan)
 	spin_unlock_bh(&atchan->lock);
 
 	/* channel parameters */
-	channel_writel(atchan, CFG, ATC_DEFAULT_CFG);
+	channel_writel(atchan, CFG, cfg);
 
 	dev_dbg(chan2dev(chan),
 		"alloc_chan_resources: allocated %d descriptors\n",
@@ -888,6 +1087,11 @@ static int __init at_dma_probe(struct platform_device *pdev)
 	if (dma_has_cap(DMA_MEMCPY, atdma->dma_common.cap_mask))
 		atdma->dma_common.device_prep_dma_memcpy = atc_prep_dma_memcpy;
 
+	if (dma_has_cap(DMA_SLAVE, atdma->dma_common.cap_mask)) {
+		atdma->dma_common.device_prep_slave_sg = atc_prep_slave_sg;
+		atdma->dma_common.device_terminate_all = atc_terminate_all;
+	}
+
 	dma_writel(atdma, EN, AT_DMA_ENABLE);
 
 	dev_info(&pdev->dev, "Atmel AHB DMA Controller ( %s%s), %d channels\n",

drivers/dma/at_hdmac_regs.h

@@ -87,29 +87,14 @@
 /* Bitfields in CTRLA */
 #define	ATC_BTSIZE_MAX		0xFFFFUL	/* Maximum Buffer Transfer Size */
 #define	ATC_BTSIZE(x)		(ATC_BTSIZE_MAX & (x)) /* Buffer Transfer Size */
-#define	ATC_SCSIZE_MASK		(0x7 << 16)	/* Source Chunk Transfer Size */
-#define		ATC_SCSIZE_1		(0x0 << 16)
-#define		ATC_SCSIZE_4		(0x1 << 16)
-#define		ATC_SCSIZE_8		(0x2 << 16)
-#define		ATC_SCSIZE_16		(0x3 << 16)
-#define		ATC_SCSIZE_32		(0x4 << 16)
-#define		ATC_SCSIZE_64		(0x5 << 16)
-#define		ATC_SCSIZE_128		(0x6 << 16)
-#define		ATC_SCSIZE_256		(0x7 << 16)
-#define	ATC_DCSIZE_MASK		(0x7 << 20)	/* Destination Chunk Transfer Size */
-#define		ATC_DCSIZE_1		(0x0 << 20)
-#define		ATC_DCSIZE_4		(0x1 << 20)
-#define		ATC_DCSIZE_8		(0x2 << 20)
-#define		ATC_DCSIZE_16		(0x3 << 20)
-#define		ATC_DCSIZE_32		(0x4 << 20)
-#define		ATC_DCSIZE_64		(0x5 << 20)
-#define		ATC_DCSIZE_128		(0x6 << 20)
-#define		ATC_DCSIZE_256		(0x7 << 20)
+/* Chunck Tranfer size definitions are in at_hdmac.h */
 #define	ATC_SRC_WIDTH_MASK	(0x3 << 24)	/* Source Single Transfer Size */
+#define		ATC_SRC_WIDTH(x)	((x) << 24)
 #define		ATC_SRC_WIDTH_BYTE	(0x0 << 24)
 #define		ATC_SRC_WIDTH_HALFWORD	(0x1 << 24)
 #define		ATC_SRC_WIDTH_WORD	(0x2 << 24)
 #define	ATC_DST_WIDTH_MASK	(0x3 << 28)	/* Destination Single Transfer Size */
+#define		ATC_DST_WIDTH(x)	((x) << 28)
 #define		ATC_DST_WIDTH_BYTE	(0x0 << 28)
 #define		ATC_DST_WIDTH_HALFWORD	(0x1 << 28)
 #define		ATC_DST_WIDTH_WORD	(0x2 << 28)
@@ -129,7 +114,8 @@
 #define		ATC_FC_PER2PER		(0x3 << 21)	/* Periph-to-Periph (DMA) */
 #define		ATC_FC_PER2MEM_PER	(0x4 << 21)	/* Periph-to-Mem (Peripheral) */
 #define		ATC_FC_MEM2PER_PER	(0x5 << 21)	/* Mem-to-Periph (Peripheral) */
-#define		ATC_FC_PER2PER_PER	(0x6 << 21)	/* Periph-to-Periph (Src Peripheral) */
+#define		ATC_FC_PER2PER_SRCPER	(0x6 << 21)	/* Periph-to-Periph (Src Peripheral) */
+#define		ATC_FC_PER2PER_DSTPER	(0x7 << 21)	/* Periph-to-Periph (Dst Peripheral) */
 #define	ATC_SRC_ADDR_MODE_MASK	(0x3 << 24)
 #define		ATC_SRC_ADDR_MODE_INCR	(0x0 << 24)	/* Incrementing Mode */
 #define		ATC_SRC_ADDR_MODE_DECR	(0x1 << 24)	/* Decrementing Mode */
@@ -142,27 +128,7 @@
 #define	ATC_AUTO		(0x1 << 31)	/* Auto multiple buffer tx enable */
 
 /* Bitfields in CFG */
-#define	ATC_SRC_PER(h)		(0xFU & (h))	/* Channel src rq associated with periph handshaking ifc h */
-#define	ATC_DST_PER(h)		((0xFU & (h)) <<  4)	/* Channel dst rq associated with periph handshaking ifc h */
-#define	ATC_SRC_REP		(0x1 <<  8)	/* Source Replay Mod */
-#define	ATC_SRC_H2SEL		(0x1 <<  9)	/* Source Handshaking Mod */
-#define		ATC_SRC_H2SEL_SW	(0x0 <<  9)
-#define		ATC_SRC_H2SEL_HW	(0x1 <<  9)
-#define	ATC_DST_REP		(0x1 << 12)	/* Destination Replay Mod */
-#define	ATC_DST_H2SEL		(0x1 << 13)	/* Destination Handshaking Mod */
-#define		ATC_DST_H2SEL_SW	(0x0 << 13)
-#define		ATC_DST_H2SEL_HW	(0x1 << 13)
-#define	ATC_SOD			(0x1 << 16)	/* Stop On Done */
-#define	ATC_LOCK_IF		(0x1 << 20)	/* Interface Lock */
-#define	ATC_LOCK_B		(0x1 << 21)	/* AHB Bus Lock */
-#define	ATC_LOCK_IF_L		(0x1 << 22)	/* Master Interface Arbiter Lock */
-#define		ATC_LOCK_IF_L_CHUNK	(0x0 << 22)
-#define		ATC_LOCK_IF_L_BUFFER	(0x1 << 22)
-#define	ATC_AHB_PROT_MASK	(0x7 << 24)	/* AHB Protection */
-#define	ATC_FIFOCFG_MASK	(0x3 << 28)	/* FIFO Request Configuration */
-#define		ATC_FIFOCFG_LARGESTBURST	(0x0 << 28)
-#define		ATC_FIFOCFG_HALFFIFO		(0x1 << 28)
-#define		ATC_FIFOCFG_ENOUGHSPACE		(0x2 << 28)
+/* are in at_hdmac.h */
 
 /* Bitfields in SPIP */
 #define	ATC_SPIP_HOLE(x)	(0xFFFFU & (x))
@@ -316,11 +282,12 @@ static void vdbg_dump_regs(struct at_dma_chan *atchan)
 		dma_readl(atdma, CHSR));
 
 	dev_err(chan2dev(&atchan->chan_common),
-		"  channel: s0x%x d0x%x ctrl0x%x:0x%x l0x%x\n",
+		"  channel: s0x%x d0x%x ctrl0x%x:0x%x cfg0x%x l0x%x\n",
 		channel_readl(atchan, SADDR),
 		channel_readl(atchan, DADDR),
 		channel_readl(atchan, CTRLA),
 		channel_readl(atchan, CTRLB),
+		channel_readl(atchan, CFG),
 		channel_readl(atchan, DSCR));
 }
 #else