dmaengine: add an shdma-base library

This patch extracts code from shdma.c, that does not directly deal with
hardware implementation details and can be re-used with diverse DMA
controller variants, found on SH-based SoCs.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>

include/linux/shdma-base.h

@@ -0,0 +1,123 @@
+/*
+ * Dmaengine driver base library for DMA controllers, found on SH-based SoCs
+ *
+ * extracted from shdma.c and headers
+ *
+ * Copyright (C) 2011-2012 Guennadi Liakhovetski <g.liakhovetski@gmx.de>
+ * Copyright (C) 2009 Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
+ * Copyright (C) 2009 Renesas Solutions, Inc. All rights reserved.
+ * Copyright (C) 2007 Freescale Semiconductor, Inc. All rights reserved.
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef SHDMA_BASE_H
+#define SHDMA_BASE_H
+
+#include <linux/dmaengine.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/types.h>
+
+/**
+ * shdma_pm_state - DMA channel PM state
+ * SHDMA_PM_ESTABLISHED:	either idle or during data transfer
+ * SHDMA_PM_BUSY:		during the transfer preparation, when we have to
+ *				drop the lock temporarily
+ * SHDMA_PM_PENDING:	transfers pending
+ */
+enum shdma_pm_state {
+	SHDMA_PM_ESTABLISHED,
+	SHDMA_PM_BUSY,
+	SHDMA_PM_PENDING,
+};
+
+struct device;
+
+/*
+ * Drivers, using this library are expected to embed struct shdma_dev,
+ * struct shdma_chan, struct shdma_desc, and struct shdma_slave
+ * in their respective device, channel, descriptor and slave objects.
+ */
+
+struct shdma_slave {
+	unsigned int slave_id;
+};
+
+struct shdma_desc {
+	struct list_head node;
+	struct dma_async_tx_descriptor async_tx;
+	enum dma_transfer_direction direction;
+	dma_cookie_t cookie;
+	int chunks;
+	int mark;
+};
+
+struct shdma_chan {
+	spinlock_t chan_lock;		/* Channel operation lock */
+	struct list_head ld_queue;	/* Link descriptors queue */
+	struct list_head ld_free;	/* Free link descriptors */
+	struct dma_chan dma_chan;	/* DMA channel */
+	struct device *dev;		/* Channel device */
+	void *desc;			/* buffer for descriptor array */
+	int desc_num;			/* desc count */
+	size_t max_xfer_len;		/* max transfer length */
+	int id;				/* Raw id of this channel */
+	int irq;			/* Channel IRQ */
+	enum shdma_pm_state pm_state;
+};
+
+/**
+ * struct shdma_ops - simple DMA driver operations
+ * desc_completed:	return true, if this is the descriptor, that just has
+ *			completed (atomic)
+ * halt_channel:	stop DMA channel operation (atomic)
+ * channel_busy:	return true, if the channel is busy (atomic)
+ * slave_addr:		return slave DMA address
+ * desc_setup:		set up the hardware specific descriptor portion (atomic)
+ * set_slave:		bind channel to a slave
+ * setup_xfer:		configure channel hardware for operation (atomic)
+ * start_xfer:		start the DMA transfer (atomic)
+ * embedded_desc:	return Nth struct shdma_desc pointer from the
+ *			descriptor array
+ * chan_irq:		process channel IRQ, return true if a transfer has
+ *			completed (atomic)
+ */
+struct shdma_ops {
+	bool (*desc_completed)(struct shdma_chan *, struct shdma_desc *);
+	void (*halt_channel)(struct shdma_chan *);
+	bool (*channel_busy)(struct shdma_chan *);
+	dma_addr_t (*slave_addr)(struct shdma_chan *);
+	int (*desc_setup)(struct shdma_chan *, struct shdma_desc *,
+			  dma_addr_t, dma_addr_t, size_t *);
+	int (*set_slave)(struct shdma_chan *, struct shdma_slave *);
+	void (*setup_xfer)(struct shdma_chan *, struct shdma_slave *);
+	void (*start_xfer)(struct shdma_chan *, struct shdma_desc *);
+	struct shdma_desc *(*embedded_desc)(void *, int);
+	bool (*chan_irq)(struct shdma_chan *, int);
+};
+
+struct shdma_dev {
+	struct dma_device dma_dev;
+	struct shdma_chan **schan;
+	const struct shdma_ops *ops;
+	size_t desc_size;
+};
+
+#define shdma_for_each_chan(c, d, i) for (i = 0, c = (d)->schan[0]; \
+				i < (d)->dma_dev.chancnt; c = (d)->schan[++i])
+
+int shdma_request_irq(struct shdma_chan *, int,
+			   unsigned long, const char *);
+void shdma_free_irq(struct shdma_chan *);
+bool shdma_reset(struct shdma_dev *sdev);
+void shdma_chan_probe(struct shdma_dev *sdev,
+			   struct shdma_chan *schan, int id);
+void shdma_chan_remove(struct shdma_chan *schan);
+int shdma_init(struct device *dev, struct shdma_dev *sdev,
+		    int chan_num);
+void shdma_cleanup(struct shdma_dev *sdev);
+
+#endif