1 files changed, 408 insertions, 0 deletions
diff --git a/arch/arm/mach-ep93xx/dma-m2p.c b/arch/arm/mach-ep93xx/dma-m2p.c
new file mode 100644
index 00000000000..a2df5bb7dff
--- /dev/null
+++ b/arch/arm/mach-ep93xx/dma-m2p.c
@@ -0,0 +1,408 @@
+/*
+ * arch/arm/mach-ep93xx/dma-m2p.c
+ * M2P DMA handling for Cirrus EP93xx chips.
+ *
+ * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
+ * Copyright (C) 2006 Applied Data Systems
+ *
+ * Copyright (C) 2009 Ryan Mallon <ryan@bluewatersys.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ */
+
+/*
+ * On the EP93xx chip the following peripherals my be allocated to the 10
+ * Memory to Internal Peripheral (M2P) channels (5 transmit + 5 receive).
+ *
+ *	I2S	contains 3 Tx and 3 Rx DMA Channels
+ *	AAC	contains 3 Tx and 3 Rx DMA Channels
+ *	UART1	contains 1 Tx and 1 Rx DMA Channels
+ *	UART2	contains 1 Tx and 1 Rx DMA Channels
+ *	UART3	contains 1 Tx and 1 Rx DMA Channels
+ *	IrDA	contains 1 Tx and 1 Rx DMA Channels
+ *
+ * SSP and IDE use the Memory to Memory (M2M) channels and are not covered
+ * with this implementation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+
+#include <mach/dma.h>
+#include <mach/hardware.h>
+
+#define M2P_CONTROL			0x00
+#define  M2P_CONTROL_STALL_IRQ_EN	(1 << 0)
+#define  M2P_CONTROL_NFB_IRQ_EN		(1 << 1)
+#define  M2P_CONTROL_ERROR_IRQ_EN	(1 << 3)
+#define  M2P_CONTROL_ENABLE		(1 << 4)
+#define M2P_INTERRUPT			0x04
+#define  M2P_INTERRUPT_STALL		(1 << 0)
+#define  M2P_INTERRUPT_NFB		(1 << 1)
+#define  M2P_INTERRUPT_ERROR		(1 << 3)
+#define M2P_PPALLOC			0x08
+#define M2P_STATUS			0x0c
+#define M2P_REMAIN			0x14
+#define M2P_MAXCNT0			0x20
+#define M2P_BASE0			0x24
+#define M2P_MAXCNT1			0x30
+#define M2P_BASE1			0x34
+
+#define STATE_IDLE	0	/* Channel is inactive.  */
+#define STATE_STALL	1	/* Channel is active, no buffers pending.  */
+#define STATE_ON	2	/* Channel is active, one buffer pending.  */
+#define STATE_NEXT	3	/* Channel is active, two buffers pending.  */
+
+struct m2p_channel {
+	char				*name;
+	void __iomem			*base;
+	int				irq;
+
+	struct clk			*clk;
+	spinlock_t			lock;
+
+	void				*client;
+	unsigned			next_slot:1;
+	struct ep93xx_dma_buffer	*buffer_xfer;
+	struct ep93xx_dma_buffer	*buffer_next;
+	struct list_head		buffers_pending;
+};
+
+static struct m2p_channel m2p_rx[] = {
+	{"m2p1", EP93XX_DMA_BASE + 0x0040, IRQ_EP93XX_DMAM2P1},
+	{"m2p3", EP93XX_DMA_BASE + 0x00c0, IRQ_EP93XX_DMAM2P3},
+	{"m2p5", EP93XX_DMA_BASE + 0x0200, IRQ_EP93XX_DMAM2P5},
+	{"m2p7", EP93XX_DMA_BASE + 0x0280, IRQ_EP93XX_DMAM2P7},
+	{"m2p9", EP93XX_DMA_BASE + 0x0300, IRQ_EP93XX_DMAM2P9},
+	{NULL},
+};
+
+static struct m2p_channel m2p_tx[] = {
+	{"m2p0", EP93XX_DMA_BASE + 0x0000, IRQ_EP93XX_DMAM2P0},
+	{"m2p2", EP93XX_DMA_BASE + 0x0080, IRQ_EP93XX_DMAM2P2},
+	{"m2p4", EP93XX_DMA_BASE + 0x0240, IRQ_EP93XX_DMAM2P4},
+	{"m2p6", EP93XX_DMA_BASE + 0x02c0, IRQ_EP93XX_DMAM2P6},
+	{"m2p8", EP93XX_DMA_BASE + 0x0340, IRQ_EP93XX_DMAM2P8},
+	{NULL},
+};
+
+static void feed_buf(struct m2p_channel *ch, struct ep93xx_dma_buffer *buf)
+{
+	if (ch->next_slot == 0) {
+		writel(buf->size, ch->base + M2P_MAXCNT0);
+		writel(buf->bus_addr, ch->base + M2P_BASE0);
+	} else {
+		writel(buf->size, ch->base + M2P_MAXCNT1);
+		writel(buf->bus_addr, ch->base + M2P_BASE1);
+	}
+	ch->next_slot ^= 1;
+}
+
+static void choose_buffer_xfer(struct m2p_channel *ch)
+{
+	struct ep93xx_dma_buffer *buf;
+
+	ch->buffer_xfer = NULL;
+	if (!list_empty(&ch->buffers_pending)) {
+		buf = list_entry(ch->buffers_pending.next,
+				 struct ep93xx_dma_buffer, list);
+		list_del(&buf->list);
+		feed_buf(ch, buf);
+		ch->buffer_xfer = buf;
+	}
+}
+
+static void choose_buffer_next(struct m2p_channel *ch)
+{
+	struct ep93xx_dma_buffer *buf;
+
+	ch->buffer_next = NULL;
+	if (!list_empty(&ch->buffers_pending)) {
+		buf = list_entry(ch->buffers_pending.next,
+				 struct ep93xx_dma_buffer, list);
+		list_del(&buf->list);
+		feed_buf(ch, buf);
+		ch->buffer_next = buf;
+	}
+}
+
+static inline void m2p_set_control(struct m2p_channel *ch, u32 v)
+{
+	/*
+	 * The control register must be read immediately after being written so
+	 * that the internal state machine is correctly updated. See the ep93xx
+	 * users' guide for details.
+	 */
+	writel(v, ch->base + M2P_CONTROL);
+	readl(ch->base + M2P_CONTROL);
+}
+
+static inline int m2p_channel_state(struct m2p_channel *ch)
+{
+	return (readl(ch->base + M2P_STATUS) >> 4) & 0x3;
+}
+
+static irqreturn_t m2p_irq(int irq, void *dev_id)
+{
+	struct m2p_channel *ch = dev_id;
+	struct ep93xx_dma_m2p_client *cl;
+	u32 irq_status, v;
+	int error = 0;
+
+	cl = ch->client;
+
+	spin_lock(&ch->lock);
+	irq_status = readl(ch->base + M2P_INTERRUPT);
+
+	if (irq_status & M2P_INTERRUPT_ERROR) {
+		writel(M2P_INTERRUPT_ERROR, ch->base + M2P_INTERRUPT);
+		error = 1;
+	}
+
+	if ((irq_status & (M2P_INTERRUPT_STALL | M2P_INTERRUPT_NFB)) == 0) {
+		spin_unlock(&ch->lock);
+		return IRQ_NONE;
+	}
+
+	switch (m2p_channel_state(ch)) {
+	case STATE_IDLE:
+		pr_crit("m2p_irq: dma interrupt without a dma buffer\n");
+		BUG();
+		break;
+
+	case STATE_STALL:
+		cl->buffer_finished(cl->cookie, ch->buffer_xfer, 0, error);
+		if (ch->buffer_next != NULL) {
+			cl->buffer_finished(cl->cookie, ch->buffer_next,
+					    0, error);
+		}
+		choose_buffer_xfer(ch);
+		choose_buffer_next(ch);
+		if (ch->buffer_xfer != NULL)
+			cl->buffer_started(cl->cookie, ch->buffer_xfer);
+		break;
+
+	case STATE_ON:
+		cl->buffer_finished(cl->cookie, ch->buffer_xfer, 0, error);
+		ch->buffer_xfer = ch->buffer_next;
+		choose_buffer_next(ch);
+		cl->buffer_started(cl->cookie, ch->buffer_xfer);
+		break;
+
+	case STATE_NEXT:
+		pr_crit("m2p_irq: dma interrupt while next\n");
+		BUG();
+		break;
+	}
+
+	v = readl(ch->base + M2P_CONTROL) & ~(M2P_CONTROL_STALL_IRQ_EN |
+					      M2P_CONTROL_NFB_IRQ_EN);
+	if (ch->buffer_xfer != NULL)
+		v |= M2P_CONTROL_STALL_IRQ_EN;
+	if (ch->buffer_next != NULL)
+		v |= M2P_CONTROL_NFB_IRQ_EN;
+	m2p_set_control(ch, v);
+
+	spin_unlock(&ch->lock);
+	return IRQ_HANDLED;
+}
+
+static struct m2p_channel *find_free_channel(struct ep93xx_dma_m2p_client *cl)
+{
+	struct m2p_channel *ch;
+	int i;
+
+	if (cl->flags & EP93XX_DMA_M2P_RX)
+		ch = m2p_rx;
+	else
+		ch = m2p_tx;
+
+	for (i = 0; ch[i].base; i++) {
+		struct ep93xx_dma_m2p_client *client;
+
+		client = ch[i].client;
+		if (client != NULL) {
+			int port;
+
+			port = cl->flags & EP93XX_DMA_M2P_PORT_MASK;
+			if (port == (client->flags &
+				     EP93XX_DMA_M2P_PORT_MASK)) {
+				pr_warning("DMA channel already used by %s\n",
+					   cl->name ? : "unknown client");
+				return ERR_PTR(-EBUSY);
+			}
+		}
+	}
+
+	for (i = 0; ch[i].base; i++) {
+		if (ch[i].client == NULL)
+			return ch + i;
+	}
+
+	pr_warning("No free DMA channel for %s\n",
+		   cl->name ? : "unknown client");
+	return ERR_PTR(-ENODEV);
+}
+
+static void channel_enable(struct m2p_channel *ch)
+{
+	struct ep93xx_dma_m2p_client *cl = ch->client;
+	u32 v;
+
+	clk_enable(ch->clk);
+
+	v = cl->flags & EP93XX_DMA_M2P_PORT_MASK;
+	writel(v, ch->base + M2P_PPALLOC);
+
+	v = cl->flags & EP93XX_DMA_M2P_ERROR_MASK;
+	v |= M2P_CONTROL_ENABLE | M2P_CONTROL_ERROR_IRQ_EN;
+	m2p_set_control(ch, v);
+}
+
+static void channel_disable(struct m2p_channel *ch)
+{
+	u32 v;
+
+	v = readl(ch->base + M2P_CONTROL);
+	v &= ~(M2P_CONTROL_STALL_IRQ_EN | M2P_CONTROL_NFB_IRQ_EN);
+	m2p_set_control(ch, v);
+
+	while (m2p_channel_state(ch) == STATE_ON)
+		cpu_relax();
+
+	m2p_set_control(ch, 0x0);
+
+	while (m2p_channel_state(ch) == STATE_STALL)
+		cpu_relax();
+
+	clk_disable(ch->clk);
+}
+
+int ep93xx_dma_m2p_client_register(struct ep93xx_dma_m2p_client *cl)
+{
+	struct m2p_channel *ch;
+	int err;
+
+	ch = find_free_channel(cl);
+	if (IS_ERR(ch))
+		return PTR_ERR(ch);
+
+	err = request_irq(ch->irq, m2p_irq, 0, cl->name ? : "dma-m2p", ch);
+	if (err)
+		return err;
+
+	ch->client = cl;
+	ch->next_slot = 0;
+	ch->buffer_xfer = NULL;
+	ch->buffer_next = NULL;
+	INIT_LIST_HEAD(&ch->buffers_pending);
+
+	cl->channel = ch;
+
+	channel_enable(ch);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ep93xx_dma_m2p_client_register);
+
+void ep93xx_dma_m2p_client_unregister(struct ep93xx_dma_m2p_client *cl)
+{
+	struct m2p_channel *ch = cl->channel;
+
+	channel_disable(ch);
+	free_irq(ch->irq, ch);
+	ch->client = NULL;
+}
+EXPORT_SYMBOL_GPL(ep93xx_dma_m2p_client_unregister);
+
+void ep93xx_dma_m2p_submit(struct ep93xx_dma_m2p_client *cl,
+			   struct ep93xx_dma_buffer *buf)
+{
+	struct m2p_channel *ch = cl->channel;
+	unsigned long flags;
+	u32 v;
+
+	spin_lock_irqsave(&ch->lock, flags);
+	v = readl(ch->base + M2P_CONTROL);
+	if (ch->buffer_xfer == NULL) {
+		ch->buffer_xfer = buf;
+		feed_buf(ch, buf);
+		cl->buffer_started(cl->cookie, buf);
+
+		v |= M2P_CONTROL_STALL_IRQ_EN;
+		m2p_set_control(ch, v);
+
+	} else if (ch->buffer_next == NULL) {
+		ch->buffer_next = buf;
+		feed_buf(ch, buf);
+
+		v |= M2P_CONTROL_NFB_IRQ_EN;
+		m2p_set_control(ch, v);
+	} else {
+		list_add_tail(&buf->list, &ch->buffers_pending);
+	}
+	spin_unlock_irqrestore(&ch->lock, flags);
+}
+EXPORT_SYMBOL_GPL(ep93xx_dma_m2p_submit);
+
+void ep93xx_dma_m2p_submit_recursive(struct ep93xx_dma_m2p_client *cl,
+				     struct ep93xx_dma_buffer *buf)
+{
+	struct m2p_channel *ch = cl->channel;
+
+	list_add_tail(&buf->list, &ch->buffers_pending);
+}
+EXPORT_SYMBOL_GPL(ep93xx_dma_m2p_submit_recursive);
+
+void ep93xx_dma_m2p_flush(struct ep93xx_dma_m2p_client *cl)
+{
+	struct m2p_channel *ch = cl->channel;
+
+	channel_disable(ch);
+	ch->next_slot = 0;
+	ch->buffer_xfer = NULL;
+	ch->buffer_next = NULL;
+	INIT_LIST_HEAD(&ch->buffers_pending);
+	channel_enable(ch);
+}
+EXPORT_SYMBOL_GPL(ep93xx_dma_m2p_flush);
+
+static int init_channel(struct m2p_channel *ch)
+{
+	ch->clk = clk_get(NULL, ch->name);
+	if (IS_ERR(ch->clk))
+		return PTR_ERR(ch->clk);
+
+	spin_lock_init(&ch->lock);
+	ch->client = NULL;
+
+	return 0;
+}
+
+static int __init ep93xx_dma_m2p_init(void)
+{
+	int i;
+	int ret;
+
+	for (i = 0; m2p_rx[i].base; i++) {
+		ret = init_channel(m2p_rx + i);
+		if (ret)
+			return ret;
+	}
+
+	for (i = 0; m2p_tx[i].base; i++) {
+		ret = init_channel(m2p_tx + i);
+		if (ret)
+			return ret;
+	}
+
+	pr_info("M2P DMA subsystem initialized\n");
+	return 0;
+}
+arch_initcall(ep93xx_dma_m2p_init);