iMX28: Add APBH DMA driver

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Detlev Zundel <dzu@denx.de>

1 files changed, 691 insertions, 0 deletions

diff --git a/drivers/dma/apbh_dma.c b/drivers/dma/apbh_dma.c
new file mode 100644
index 0000000000..69a10428ef
--- /dev/null
+++ b/drivers/dma/apbh_dma.c
@@ -0,0 +1,691 @@
+/*
+ * Freescale i.MX28 APBH DMA driver
+ *
+ * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
+ * on behalf of DENX Software Engineering GmbH
+ *
+ * Based on code from LTIB:
+ * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <linux/list.h>
+
+#include <common.h>
+#include <malloc.h>
+#include <asm/errno.h>
+#include <asm/io.h>
+#include <asm/arch/clock.h>
+#include <asm/arch/imx-regs.h>
+#include <asm/arch/sys_proto.h>
+#include <asm/arch/dma.h>
+
+static struct mxs_dma_chan mxs_dma_channels[MXS_MAX_DMA_CHANNELS];
+
+/*
+ * Test is the DMA channel is valid channel
+ */
+int mxs_dma_validate_chan(int channel)
+{
+	struct mxs_dma_chan *pchan;
+
+	if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS))
+		return -EINVAL;
+
+	pchan = mxs_dma_channels + channel;
+	if (!(pchan->flags & MXS_DMA_FLAGS_ALLOCATED))
+		return -EINVAL;
+
+	return 0;
+}
+
+/*
+ * Enable a DMA channel.
+ *
+ * If the given channel has any DMA descriptors on its active list, this
+ * function causes the DMA hardware to begin processing them.
+ *
+ * This function marks the DMA channel as "busy," whether or not there are any
+ * descriptors to process.
+ */
+int mxs_dma_enable(int channel)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	unsigned int sem;
+	struct mxs_dma_chan *pchan;
+	struct mxs_dma_desc *pdesc;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	pchan = mxs_dma_channels + channel;
+
+	if (pchan->pending_num == 0) {
+		pchan->flags |= MXS_DMA_FLAGS_BUSY;
+		return 0;
+	}
+
+	pdesc = list_first_entry(&pchan->active, struct mxs_dma_desc, node);
+	if (pdesc == NULL)
+		return -EFAULT;
+
+	if (pchan->flags & MXS_DMA_FLAGS_BUSY) {
+		if (!(pdesc->cmd.data & MXS_DMA_DESC_CHAIN))
+			return 0;
+
+		sem = mxs_dma_read_semaphore(channel);
+		if (sem == 0)
+			return 0;
+
+		if (sem == 1) {
+			pdesc = list_entry(pdesc->node.next,
+					   struct mxs_dma_desc, node);
+			writel(mxs_dma_cmd_address(pdesc),
+				&apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar);
+		}
+		writel(pchan->pending_num,
+			&apbh_regs->ch[channel].hw_apbh_ch_sema);
+		pchan->active_num += pchan->pending_num;
+		pchan->pending_num = 0;
+	} else {
+		pchan->active_num += pchan->pending_num;
+		pchan->pending_num = 0;
+		writel(mxs_dma_cmd_address(pdesc),
+			&apbh_regs->ch[channel].hw_apbh_ch_nxtcmdar);
+		writel(pchan->active_num,
+			&apbh_regs->ch[channel].hw_apbh_ch_sema);
+		writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET),
+			&apbh_regs->hw_apbh_ctrl0_clr);
+	}
+
+	pchan->flags |= MXS_DMA_FLAGS_BUSY;
+	return 0;
+}
+
+/*
+ * Disable a DMA channel.
+ *
+ * This function shuts down a DMA channel and marks it as "not busy." Any
+ * descriptors on the active list are immediately moved to the head of the
+ * "done" list, whether or not they have actually been processed by the
+ * hardware. The "ready" flags of these descriptors are NOT cleared, so they
+ * still appear to be active.
+ *
+ * This function immediately shuts down a DMA channel's hardware, aborting any
+ * I/O that may be in progress, potentially leaving I/O hardware in an undefined
+ * state. It is unwise to call this function if there is ANY chance the hardware
+ * is still processing a command.
+ */
+int mxs_dma_disable(int channel)
+{
+	struct mxs_dma_chan *pchan;
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	pchan = mxs_dma_channels + channel;
+
+	if (!(pchan->flags & MXS_DMA_FLAGS_BUSY))
+		return -EINVAL;
+
+	writel(1 << (channel + APBH_CTRL0_CLKGATE_CHANNEL_OFFSET),
+		&apbh_regs->hw_apbh_ctrl0_set);
+
+	pchan->flags &= ~MXS_DMA_FLAGS_BUSY;
+	pchan->active_num = 0;
+	pchan->pending_num = 0;
+	list_splice_init(&pchan->active, &pchan->done);
+
+	return 0;
+}
+
+/*
+ * Resets the DMA channel hardware.
+ */
+int mxs_dma_reset(int channel)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	writel(1 << (channel + APBH_CHANNEL_CTRL_RESET_CHANNEL_OFFSET),
+		&apbh_regs->hw_apbh_channel_ctrl_set);
+
+	return 0;
+}
+
+/*
+ * Freeze a DMA channel.
+ *
+ * This function causes the channel to continuously fail arbitration for bus
+ * access, which halts all forward progress without losing any state. A call to
+ * mxs_dma_unfreeze() will cause the channel to continue its current operation
+ * with no ill effect.
+ */
+int mxs_dma_freeze(int channel)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	writel(1 << (channel + APBH_CHANNEL_CTRL_FREEZE_CHANNEL_OFFSET),
+		&apbh_regs->hw_apbh_channel_ctrl_set);
+
+	return 0;
+}
+
+/*
+ * Unfreeze a DMA channel.
+ *
+ * This function reverses the effect of mxs_dma_freeze(), enabling the DMA
+ * channel to continue from where it was frozen.
+ */
+int mxs_dma_unfreeze(int channel)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	writel(1 << (channel + APBH_CHANNEL_CTRL_FREEZE_CHANNEL_OFFSET),
+		&apbh_regs->hw_apbh_channel_ctrl_clr);
+
+	return 0;
+}
+
+/*
+ * Read a DMA channel's hardware semaphore.
+ *
+ * As used by the MXS platform's DMA software, the DMA channel's hardware
+ * semaphore reflects the number of DMA commands the hardware will process, but
+ * has not yet finished. This is a volatile value read directly from hardware,
+ * so it must be be viewed as immediately stale.
+ *
+ * If the channel is not marked busy, or has finished processing all its
+ * commands, this value should be zero.
+ *
+ * See mxs_dma_append() for details on how DMA command blocks must be configured
+ * to maintain the expected behavior of the semaphore's value.
+ */
+int mxs_dma_read_semaphore(int channel)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	uint32_t tmp;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	tmp = readl(&apbh_regs->ch[channel].hw_apbh_ch_sema);
+
+	tmp &= APBH_CHn_SEMA_PHORE_MASK;
+	tmp >>= APBH_CHn_SEMA_PHORE_OFFSET;
+
+	return tmp;
+}
+
+/*
+ * Enable or disable DMA interrupt.
+ *
+ * This function enables the given DMA channel to interrupt the CPU.
+ */
+int mxs_dma_enable_irq(int channel, int enable)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	if (enable)
+		writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET),
+			&apbh_regs->hw_apbh_ctrl1_set);
+	else
+		writel(1 << (channel + APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET),
+			&apbh_regs->hw_apbh_ctrl1_clr);
+
+	return 0;
+}
+
+/*
+ * Check if a DMA interrupt is pending.
+ */
+int mxs_dma_irq_is_pending(int channel)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	uint32_t tmp;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	tmp = readl(&apbh_regs->hw_apbh_ctrl1);
+	tmp |= readl(&apbh_regs->hw_apbh_ctrl2);
+
+	return (tmp >> channel) & 1;
+}
+
+/*
+ * Clear DMA interrupt.
+ *
+ * The software that is using the DMA channel must register to receive its
+ * interrupts and, when they arrive, must call this function to clear them.
+ */
+int mxs_dma_ack_irq(int channel)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	writel(1 << channel, &apbh_regs->hw_apbh_ctrl1_clr);
+	writel(1 << channel, &apbh_regs->hw_apbh_ctrl2_clr);
+
+	return 0;
+}
+
+/*
+ * Request to reserve a DMA channel
+ */
+int mxs_dma_request(int channel)
+{
+	struct mxs_dma_chan *pchan;
+
+	if ((channel < 0) || (channel >= MXS_MAX_DMA_CHANNELS))
+		return -EINVAL;
+
+	pchan = mxs_dma_channels + channel;
+	if ((pchan->flags & MXS_DMA_FLAGS_VALID) != MXS_DMA_FLAGS_VALID)
+		return -ENODEV;
+
+	if (pchan->flags & MXS_DMA_FLAGS_ALLOCATED)
+		return -EBUSY;
+
+	pchan->flags |= MXS_DMA_FLAGS_ALLOCATED;
+	pchan->active_num = 0;
+	pchan->pending_num = 0;
+
+	INIT_LIST_HEAD(&pchan->active);
+	INIT_LIST_HEAD(&pchan->done);
+
+	return 0;
+}
+
+/*
+ * Release a DMA channel.
+ *
+ * This function releases a DMA channel from its current owner.
+ *
+ * The channel will NOT be released if it's marked "busy" (see
+ * mxs_dma_enable()).
+ */
+int mxs_dma_release(int channel)
+{
+	struct mxs_dma_chan *pchan;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	pchan = mxs_dma_channels + channel;
+
+	if (pchan->flags & MXS_DMA_FLAGS_BUSY)
+		return -EBUSY;
+
+	pchan->dev = 0;
+	pchan->active_num = 0;
+	pchan->pending_num = 0;
+	pchan->flags &= ~MXS_DMA_FLAGS_ALLOCATED;
+
+	return 0;
+}
+
+/*
+ * Allocate DMA descriptor
+ */
+struct mxs_dma_desc *mxs_dma_desc_alloc(void)
+{
+	struct mxs_dma_desc *pdesc;
+
+	pdesc = memalign(MXS_DMA_ALIGNMENT, sizeof(struct mxs_dma_desc));
+
+	if (pdesc == NULL)
+		return NULL;
+
+	memset(pdesc, 0, sizeof(*pdesc));
+	pdesc->address = (dma_addr_t)pdesc;
+
+	return pdesc;
+};
+
+/*
+ * Free DMA descriptor
+ */
+void mxs_dma_desc_free(struct mxs_dma_desc *pdesc)
+{
+	if (pdesc == NULL)
+		return;
+
+	free(pdesc);
+}
+
+/*
+ * Return the address of the command within a descriptor.
+ */
+unsigned int mxs_dma_cmd_address(struct mxs_dma_desc *desc)
+{
+	return desc->address + offsetof(struct mxs_dma_desc, cmd);
+}
+
+/*
+ * Check if descriptor is on a channel's active list.
+ *
+ * This function returns the state of a descriptor's "ready" flag. This flag is
+ * usually set only if the descriptor appears on a channel's active list. The
+ * descriptor may or may not have already been processed by the hardware.
+ *
+ * The "ready" flag is set when the descriptor is submitted to a channel by a
+ * call to mxs_dma_append() or mxs_dma_append_list(). The "ready" flag is
+ * cleared when a processed descriptor is moved off the active list by a call
+ * to mxs_dma_finish(). The "ready" flag is NOT cleared if the descriptor is
+ * aborted by a call to mxs_dma_disable().
+ */
+int mxs_dma_desc_pending(struct mxs_dma_desc *pdesc)
+{
+	return pdesc->flags & MXS_DMA_DESC_READY;
+}
+
+/*
+ * Add a DMA descriptor to a channel.
+ *
+ * If the descriptor list for this channel is not empty, this function sets the
+ * CHAIN bit and the NEXTCMD_ADDR fields in the last descriptor's DMA command so
+ * it will chain to the new descriptor's command.
+ *
+ * Then, this function marks the new descriptor as "ready," adds it to the end
+ * of the active descriptor list, and increments the count of pending
+ * descriptors.
+ *
+ * The MXS platform DMA software imposes some rules on DMA commands to maintain
+ * important invariants. These rules are NOT checked, but they must be carefully
+ * applied by software that uses MXS DMA channels.
+ *
+ * Invariant:
+ *     The DMA channel's hardware semaphore must reflect the number of DMA
+ *     commands the hardware will process, but has not yet finished.
+ *
+ * Explanation:
+ *     A DMA channel begins processing commands when its hardware semaphore is
+ *     written with a value greater than zero, and it stops processing commands
+ *     when the semaphore returns to zero.
+ *
+ *     When a channel finishes a DMA command, it will decrement its semaphore if
+ *     the DECREMENT_SEMAPHORE bit is set in that command's flags bits.
+ *
+ *     In principle, it's not necessary for the DECREMENT_SEMAPHORE to be set,
+ *     unless it suits the purposes of the software. For example, one could
+ *     construct a series of five DMA commands, with the DECREMENT_SEMAPHORE
+ *     bit set only in the last one. Then, setting the DMA channel's hardware
+ *     semaphore to one would cause the entire series of five commands to be
+ *     processed. However, this example would violate the invariant given above.
+ *
+ * Rule:
+ *    ALL DMA commands MUST have the DECREMENT_SEMAPHORE bit set so that the DMA
+ *    channel's hardware semaphore will be decremented EVERY time a command is
+ *    processed.
+ */
+int mxs_dma_desc_append(int channel, struct mxs_dma_desc *pdesc)
+{
+	struct mxs_dma_chan *pchan;
+	struct mxs_dma_desc *last;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	pchan = mxs_dma_channels + channel;
+
+	pdesc->cmd.next = mxs_dma_cmd_address(pdesc);
+	pdesc->flags |= MXS_DMA_DESC_FIRST | MXS_DMA_DESC_LAST;
+
+	if (!list_empty(&pchan->active)) {
+		last = list_entry(pchan->active.prev, struct mxs_dma_desc,
+					node);
+
+		pdesc->flags &= ~MXS_DMA_DESC_FIRST;
+		last->flags &= ~MXS_DMA_DESC_LAST;
+
+		last->cmd.next = mxs_dma_cmd_address(pdesc);
+		last->cmd.data |= MXS_DMA_DESC_CHAIN;
+	}
+	pdesc->flags |= MXS_DMA_DESC_READY;
+	if (pdesc->flags & MXS_DMA_DESC_FIRST)
+		pchan->pending_num++;
+	list_add_tail(&pdesc->node, &pchan->active);
+
+	return ret;
+}
+
+/*
+ * Retrieve processed DMA descriptors.
+ *
+ * This function moves all the descriptors from the DMA channel's "done" list to
+ * the head of the given list.
+ */
+int mxs_dma_get_finished(int channel, struct list_head *head)
+{
+	struct mxs_dma_chan *pchan;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	if (head == NULL)
+		return 0;
+
+	pchan = mxs_dma_channels + channel;
+
+	list_splice(&pchan->done, head);
+
+	return 0;
+}
+
+/*
+ * Clean up processed DMA descriptors.
+ *
+ * This function removes processed DMA descriptors from the "active" list. Pass
+ * in a non-NULL list head to get the descriptors moved to your list. Pass NULL
+ * to get the descriptors moved to the channel's "done" list. Descriptors on
+ * the "done" list can be retrieved with mxs_dma_get_finished().
+ *
+ * This function marks the DMA channel as "not busy" if no unprocessed
+ * descriptors remain on the "active" list.
+ */
+int mxs_dma_finish(int channel, struct list_head *head)
+{
+	int sem;
+	struct mxs_dma_chan *pchan;
+	struct list_head *p, *q;
+	struct mxs_dma_desc *pdesc;
+	int ret;
+
+	ret = mxs_dma_validate_chan(channel);
+	if (ret)
+		return ret;
+
+	pchan = mxs_dma_channels + channel;
+
+	sem = mxs_dma_read_semaphore(channel);
+	if (sem < 0)
+		return sem;
+
+	if (sem == pchan->active_num)
+		return 0;
+
+	list_for_each_safe(p, q, &pchan->active) {
+		if ((pchan->active_num) <= sem)
+			break;
+
+		pdesc = list_entry(p, struct mxs_dma_desc, node);
+		pdesc->flags &= ~MXS_DMA_DESC_READY;
+
+		if (head)
+			list_move_tail(p, head);
+		else
+			list_move_tail(p, &pchan->done);
+
+		if (pdesc->flags & MXS_DMA_DESC_LAST)
+			pchan->active_num--;
+	}
+
+	if (sem == 0)
+		pchan->flags &= ~MXS_DMA_FLAGS_BUSY;
+
+	return 0;
+}
+
+/*
+ * Wait for DMA channel to complete
+ */
+int mxs_dma_wait_complete(uint32_t timeout, unsigned int chan)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	int ret;
+
+	ret = mxs_dma_validate_chan(chan);
+	if (ret)
+		return ret;
+
+	if (mx28_wait_mask_set(&apbh_regs->hw_apbh_ctrl1_reg,
+				1 << chan, timeout)) {
+		ret = -ETIMEDOUT;
+		mxs_dma_reset(chan);
+	}
+
+	return 0;
+}
+
+/*
+ * Execute the DMA channel
+ */
+int mxs_dma_go(int chan)
+{
+	uint32_t timeout = 10000;
+	int ret;
+
+	LIST_HEAD(tmp_desc_list);
+
+	mxs_dma_enable_irq(chan, 1);
+	mxs_dma_enable(chan);
+
+	/* Wait for DMA to finish. */
+	ret = mxs_dma_wait_complete(timeout, chan);
+
+	/* Clear out the descriptors we just ran. */
+	mxs_dma_finish(chan, &tmp_desc_list);
+
+	/* Shut the DMA channel down. */
+	mxs_dma_ack_irq(chan);
+	mxs_dma_reset(chan);
+	mxs_dma_enable_irq(chan, 0);
+	mxs_dma_disable(chan);
+
+	return ret;
+}
+
+/*
+ * Initialize the DMA hardware
+ */
+int mxs_dma_init(void)
+{
+	struct mx28_apbh_regs *apbh_regs =
+		(struct mx28_apbh_regs *)MXS_APBH_BASE;
+	struct mxs_dma_chan *pchan;
+	int ret, channel;
+
+	mx28_reset_block(&apbh_regs->hw_apbh_ctrl0_reg);
+
+#ifdef CONFIG_APBH_DMA_BURST8
+	writel(APBH_CTRL0_AHB_BURST8_EN,
+		&apbh_regs->hw_apbh_ctrl0_set);
+#else
+	writel(APBH_CTRL0_AHB_BURST8_EN,
+		&apbh_regs->hw_apbh_ctrl0_clr);
+#endif
+
+#ifdef CONFIG_APBH_DMA_BURST
+	writel(APBH_CTRL0_APB_BURST_EN,
+		&apbh_regs->hw_apbh_ctrl0_set);
+#else
+	writel(APBH_CTRL0_APB_BURST_EN,
+		&apbh_regs->hw_apbh_ctrl0_clr);
+#endif
+
+	for (channel = 0; channel < MXS_MAX_DMA_CHANNELS; channel++) {
+		pchan = mxs_dma_channels + channel;
+		pchan->flags = MXS_DMA_FLAGS_VALID;
+
+		ret = mxs_dma_request(channel);
+
+		if (ret) {
+			printf("MXS DMA: Can't acquire DMA channel %i\n",
+				channel);
+
+			goto err;
+		}
+
+		mxs_dma_reset(channel);
+		mxs_dma_ack_irq(channel);
+	}
+
+	return 0;
+
+err:
+	while (--channel >= 0)
+		mxs_dma_release(channel);
+	return ret;
+}