[U-Boot] [PATCH 08/15] iMX28: Add APBH DMA driver

[Marek Vasut <marek.vasut@gmail.com>]

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>
---
 arch/arm/include/asm/arch-mx28/dma.h       |  170 +++++++
 arch/arm/include/asm/arch-mx28/imx-regs.h  |    1 +
 arch/arm/include/asm/arch-mx28/regs-apbh.h |  466 +++++++++++++++++++
 drivers/dma/Makefile                       |    1 +
 drivers/dma/apbh_dma.c                     |  691 ++++++++++++++++++++++++++++
 5 files changed, 1329 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/include/asm/arch-mx28/dma.h
 create mode 100644 arch/arm/include/asm/arch-mx28/regs-apbh.h
 create mode 100644 drivers/dma/apbh_dma.c

diff --git a/arch/arm/include/asm/arch-mx28/dma.h b/arch/arm/include/asm/arch-mx28/dma.h
new file mode 100644
index 0000000..7061e7c
--- /dev/null
+++ b/arch/arm/include/asm/arch-mx28/dma.h
@@ -0,0 +1,170 @@
+/*
+ * Freescale i.MX28 APBH DMA
+ *
+ * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
+ * on behalf of DENX Software Engineering GmbH
+ *
+ * Based on code from LTIB:
+ * Copyright 2008-2010 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ */
+
+#ifndef __DMA_H__
+#define __DMA_H__
+
+#include <linux/list.h>
+
+#ifndef	CONFIG_ARCH_DMA_PIO_WORDS
+#define	DMA_PIO_WORDS		15
+#else
+#define	DMA_PIO_WORDS		CONFIG_ARCH_DMA_PIO_WORDS
+#endif
+
+#define MXS_DMA_ALIGNMENT	32
+
+/*
+ * MXS DMA channels
+ */
+enum {
+	MXS_DMA_CHANNEL_AHB_APBH_SSP0 = 0,
+	MXS_DMA_CHANNEL_AHB_APBH_SSP1,
+	MXS_DMA_CHANNEL_AHB_APBH_SSP2,
+	MXS_DMA_CHANNEL_AHB_APBH_SSP3,
+	MXS_DMA_CHANNEL_AHB_APBH_GPMI0,
+	MXS_DMA_CHANNEL_AHB_APBH_GPMI1,
+	MXS_DMA_CHANNEL_AHB_APBH_GPMI2,
+	MXS_DMA_CHANNEL_AHB_APBH_GPMI3,
+	MXS_DMA_CHANNEL_AHB_APBH_GPMI4,
+	MXS_DMA_CHANNEL_AHB_APBH_GPMI5,
+	MXS_DMA_CHANNEL_AHB_APBH_GPMI6,
+	MXS_DMA_CHANNEL_AHB_APBH_GPMI7,
+	MXS_DMA_CHANNEL_AHB_APBH_SSP,
+	MXS_MAX_DMA_CHANNELS,
+};
+
+/*
+ * MXS DMA hardware command.
+ *
+ * This structure describes the in-memory layout of an entire DMA command,
+ * including space for the maximum number of PIO accesses. See the appropriate
+ * reference manual for a detailed description of what these fields mean to the
+ * DMA hardware.
+ */
+#define	MXS_DMA_DESC_COMMAND_MASK	0x3
+#define	MXS_DMA_DESC_COMMAND_OFFSET	0
+#define	MXS_DMA_DESC_COMMAND_NO_DMAXFER	0x0
+#define	MXS_DMA_DESC_COMMAND_DMA_WRITE	0x1
+#define	MXS_DMA_DESC_COMMAND_DMA_READ	0x2
+#define	MXS_DMA_DESC_COMMAND_DMA_SENSE	0x3
+#define	MXS_DMA_DESC_CHAIN		(1 << 2)
+#define	MXS_DMA_DESC_IRQ		(1 << 3)
+#define	MXS_DMA_DESC_NAND_LOCK		(1 << 4)
+#define	MXS_DMA_DESC_NAND_WAIT_4_READY	(1 << 5)
+#define	MXS_DMA_DESC_DEC_SEM		(1 << 6)
+#define	MXS_DMA_DESC_WAIT4END		(1 << 7)
+#define	MXS_DMA_DESC_HALT_ON_TERMINATE	(1 << 8)
+#define	MXS_DMA_DESC_TERMINATE_FLUSH	(1 << 9)
+#define	MXS_DMA_DESC_PIO_WORDS_MASK	(0xf << 12)
+#define	MXS_DMA_DESC_PIO_WORDS_OFFSET	12
+#define	MXS_DMA_DESC_BYTES_MASK		(0xffff << 16)
+#define	MXS_DMA_DESC_BYTES_OFFSET	16
+
+struct mxs_dma_cmd {
+	unsigned long		next;
+	unsigned long		data;
+	union {
+		dma_addr_t	address;
+		unsigned long	alternate;
+	};
+	unsigned long		pio_words[DMA_PIO_WORDS];
+};
+
+/*
+ * MXS DMA command descriptor.
+ *
+ * This structure incorporates an MXS DMA hardware command structure, along
+ * with metadata.
+ */
+#define	MXS_DMA_DESC_FIRST	(1 << 0)
+#define	MXS_DMA_DESC_LAST	(1 << 1)
+#define	MXS_DMA_DESC_READY	(1 << 31)
+
+struct mxs_dma_desc {
+	struct mxs_dma_cmd	cmd;
+	unsigned int		flags;
+	dma_addr_t		address;
+	void			*buffer;
+	struct list_head	node;
+};
+
+/**
+ * MXS DMA channel
+ *
+ * This structure represents a single DMA channel. The MXS platform code
+ * maintains an array of these structures to represent every DMA channel in the
+ * system (see mxs_dma_channels).
+ */
+#define	MXS_DMA_FLAGS_IDLE	0
+#define	MXS_DMA_FLAGS_BUSY	(1 << 0)
+#define	MXS_DMA_FLAGS_FREE	0
+#define	MXS_DMA_FLAGS_ALLOCATED	(1 << 16)
+#define	MXS_DMA_FLAGS_VALID	(1 << 31)
+
+struct mxs_dma_chan {
+	const char *name;
+	unsigned long dev;
+	struct mxs_dma_device *dma;
+	unsigned int flags;
+	unsigned int active_num;
+	unsigned int pending_num;
+	struct list_head active;
+	struct list_head done;
+};
+
+/* Hardware management ops */
+int mxs_dma_enable(int channel);
+int mxs_dma_disable(int channel);
+int mxs_dma_reset(int channel);
+int mxs_dma_freeze(int channel);
+int mxs_dma_unfreeze(int channel);
+int mxs_dma_read_semaphore(int channel);
+int mxs_dma_enable_irq(int channel, int enable);
+int mxs_dma_irq_is_pending(int channel);
+int mxs_dma_ack_irq(int channel);
+
+/* Channel management ops */
+int mxs_dma_request(int channel);
+int mxs_dma_release(int channel);
+
+/* Descriptor management ops */
+struct mxs_dma_desc *mxs_dma_desc_alloc(void);
+void mxs_dma_desc_free(struct mxs_dma_desc *);
+
+unsigned int mxs_dma_cmd_address(struct mxs_dma_desc *desc);
+int mxs_dma_desc_pending(struct mxs_dma_desc *pdesc);
+
+int mxs_dma_desc_append(int channel, struct mxs_dma_desc *pdesc);
+
+int mxs_dma_get_finished(int channel, struct list_head *head);
+int mxs_dma_finish(int channel, struct list_head *head);
+
+int mxs_dma_wait_complete(uint32_t timeout, unsigned int chan);
+int mxs_dma_go(int chan);
+
+int mxs_dma_init(void);
+
+#endif	/* __DMA_H__ */
diff --git a/arch/arm/include/asm/arch-mx28/imx-regs.h b/arch/arm/include/asm/arch-mx28/imx-regs.h
index 32bfd7e..9561b5e 100644
--- a/arch/arm/include/asm/arch-mx28/imx-regs.h
+++ b/arch/arm/include/asm/arch-mx28/imx-regs.h
@@ -23,6 +23,7 @@
 #ifndef __IMX_REGS_H__
 #define __IMX_REGS_H__
 
+#include <asm/arch/regs-apbh.h>
 #include <asm/arch/regs-base.h>
 #include <asm/arch/regs-bch.h>
 #include <asm/arch/regs-clkctrl.h>
diff --git a/arch/arm/include/asm/arch-mx28/regs-apbh.h b/arch/arm/include/asm/arch-mx28/regs-apbh.h
new file mode 100644
index 0000000..a7fa1ec
--- /dev/null
+++ b/arch/arm/include/asm/arch-mx28/regs-apbh.h
@@ -0,0 +1,466 @@
+/*
+ * Freescale i.MX28 APBH Register Definitions
+ *
+ * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
+ * on behalf of DENX Software Engineering GmbH
+ *
+ * Based on code from LTIB:
+ * Copyright 2008-2010 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ */
+
+#ifndef __REGS_APBH_H__
+#define __REGS_APBH_H__
+
+#include <asm/arch/regs-common.h>
+
+#ifndef	__ASSEMBLY__
+struct mx28_apbh_regs {
+	mx28_reg(hw_apbh_ctrl0)
+	mx28_reg(hw_apbh_ctrl1)
+	mx28_reg(hw_apbh_ctrl2)
+	mx28_reg(hw_apbh_channel_ctrl)
+	mx28_reg(hw_apbh_devsel)
+	mx28_reg(hw_apbh_dma_burst_size)
+	mx28_reg(hw_apbh_debug)
+
+	uint32_t	reserved[36];
+
+	union {
+	struct {
+		mx28_reg(hw_apbh_ch_curcmdar)
+		mx28_reg(hw_apbh_ch_nxtcmdar)
+		mx28_reg(hw_apbh_ch_cmd)
+		mx28_reg(hw_apbh_ch_bar)
+		mx28_reg(hw_apbh_ch_sema)
+		mx28_reg(hw_apbh_ch_debug1)
+		mx28_reg(hw_apbh_ch_debug2)
+	} ch[16];
+	struct {
+		mx28_reg(hw_apbh_ch0_curcmdar)
+		mx28_reg(hw_apbh_ch0_nxtcmdar)
+		mx28_reg(hw_apbh_ch0_cmd)
+		mx28_reg(hw_apbh_ch0_bar)
+		mx28_reg(hw_apbh_ch0_sema)
+		mx28_reg(hw_apbh_ch0_debug1)
+		mx28_reg(hw_apbh_ch0_debug2)
+		mx28_reg(hw_apbh_ch1_curcmdar)
+		mx28_reg(hw_apbh_ch1_nxtcmdar)
+		mx28_reg(hw_apbh_ch1_cmd)
+		mx28_reg(hw_apbh_ch1_bar)
+		mx28_reg(hw_apbh_ch1_sema)
+		mx28_reg(hw_apbh_ch1_debug1)
+		mx28_reg(hw_apbh_ch1_debug2)
+		mx28_reg(hw_apbh_ch2_curcmdar)
+		mx28_reg(hw_apbh_ch2_nxtcmdar)
+		mx28_reg(hw_apbh_ch2_cmd)
+		mx28_reg(hw_apbh_ch2_bar)
+		mx28_reg(hw_apbh_ch2_sema)
+		mx28_reg(hw_apbh_ch2_debug1)
+		mx28_reg(hw_apbh_ch2_debug2)
+		mx28_reg(hw_apbh_ch3_curcmdar)
+		mx28_reg(hw_apbh_ch3_nxtcmdar)
+		mx28_reg(hw_apbh_ch3_cmd)
+		mx28_reg(hw_apbh_ch3_bar)
+		mx28_reg(hw_apbh_ch3_sema)
+		mx28_reg(hw_apbh_ch3_debug1)
+		mx28_reg(hw_apbh_ch3_debug2)
+		mx28_reg(hw_apbh_ch4_curcmdar)
+		mx28_reg(hw_apbh_ch4_nxtcmdar)
+		mx28_reg(hw_apbh_ch4_cmd)
+		mx28_reg(hw_apbh_ch4_bar)
+		mx28_reg(hw_apbh_ch4_sema)
+		mx28_reg(hw_apbh_ch4_debug1)
+		mx28_reg(hw_apbh_ch4_debug2)
+		mx28_reg(hw_apbh_ch5_curcmdar)
+		mx28_reg(hw_apbh_ch5_nxtcmdar)
+		mx28_reg(hw_apbh_ch5_cmd)
+		mx28_reg(hw_apbh_ch5_bar)
+		mx28_reg(hw_apbh_ch5_sema)
+		mx28_reg(hw_apbh_ch5_debug1)
+		mx28_reg(hw_apbh_ch5_debug2)
+		mx28_reg(hw_apbh_ch6_curcmdar)
+		mx28_reg(hw_apbh_ch6_nxtcmdar)
+		mx28_reg(hw_apbh_ch6_cmd)
+		mx28_reg(hw_apbh_ch6_bar)
+		mx28_reg(hw_apbh_ch6_sema)
+		mx28_reg(hw_apbh_ch6_debug1)
+		mx28_reg(hw_apbh_ch6_debug2)
+		mx28_reg(hw_apbh_ch7_curcmdar)
+		mx28_reg(hw_apbh_ch7_nxtcmdar)
+		mx28_reg(hw_apbh_ch7_cmd)
+		mx28_reg(hw_apbh_ch7_bar)
+		mx28_reg(hw_apbh_ch7_sema)
+		mx28_reg(hw_apbh_ch7_debug1)
+		mx28_reg(hw_apbh_ch7_debug2)
+		mx28_reg(hw_apbh_ch8_curcmdar)
+		mx28_reg(hw_apbh_ch8_nxtcmdar)
+		mx28_reg(hw_apbh_ch8_cmd)
+		mx28_reg(hw_apbh_ch8_bar)
+		mx28_reg(hw_apbh_ch8_sema)
+		mx28_reg(hw_apbh_ch8_debug1)
+		mx28_reg(hw_apbh_ch8_debug2)
+		mx28_reg(hw_apbh_ch9_curcmdar)
+		mx28_reg(hw_apbh_ch9_nxtcmdar)
+		mx28_reg(hw_apbh_ch9_cmd)
+		mx28_reg(hw_apbh_ch9_bar)
+		mx28_reg(hw_apbh_ch9_sema)
+		mx28_reg(hw_apbh_ch9_debug1)
+		mx28_reg(hw_apbh_ch9_debug2)
+		mx28_reg(hw_apbh_ch10_curcmdar)
+		mx28_reg(hw_apbh_ch10_nxtcmdar)
+		mx28_reg(hw_apbh_ch10_cmd)
+		mx28_reg(hw_apbh_ch10_bar)
+		mx28_reg(hw_apbh_ch10_sema)
+		mx28_reg(hw_apbh_ch10_debug1)
+		mx28_reg(hw_apbh_ch10_debug2)
+		mx28_reg(hw_apbh_ch11_curcmdar)
+		mx28_reg(hw_apbh_ch11_nxtcmdar)
+		mx28_reg(hw_apbh_ch11_cmd)
+		mx28_reg(hw_apbh_ch11_bar)
+		mx28_reg(hw_apbh_ch11_sema)
+		mx28_reg(hw_apbh_ch11_debug1)
+		mx28_reg(hw_apbh_ch11_debug2)
+		mx28_reg(hw_apbh_ch12_curcmdar)
+		mx28_reg(hw_apbh_ch12_nxtcmdar)
+		mx28_reg(hw_apbh_ch12_cmd)
+		mx28_reg(hw_apbh_ch12_bar)
+		mx28_reg(hw_apbh_ch12_sema)
+		mx28_reg(hw_apbh_ch12_debug1)
+		mx28_reg(hw_apbh_ch12_debug2)
+		mx28_reg(hw_apbh_ch13_curcmdar)
+		mx28_reg(hw_apbh_ch13_nxtcmdar)
+		mx28_reg(hw_apbh_ch13_cmd)
+		mx28_reg(hw_apbh_ch13_bar)
+		mx28_reg(hw_apbh_ch13_sema)
+		mx28_reg(hw_apbh_ch13_debug1)
+		mx28_reg(hw_apbh_ch13_debug2)
+		mx28_reg(hw_apbh_ch14_curcmdar)
+		mx28_reg(hw_apbh_ch14_nxtcmdar)
+		mx28_reg(hw_apbh_ch14_cmd)
+		mx28_reg(hw_apbh_ch14_bar)
+		mx28_reg(hw_apbh_ch14_sema)
+		mx28_reg(hw_apbh_ch14_debug1)
+		mx28_reg(hw_apbh_ch14_debug2)
+		mx28_reg(hw_apbh_ch15_curcmdar)
+		mx28_reg(hw_apbh_ch15_nxtcmdar)
+		mx28_reg(hw_apbh_ch15_cmd)
+		mx28_reg(hw_apbh_ch15_bar)
+		mx28_reg(hw_apbh_ch15_sema)
+		mx28_reg(hw_apbh_ch15_debug1)
+		mx28_reg(hw_apbh_ch15_debug2)
+	};
+	};
+	mx28_reg(hw_apbh_version)
+};
+#endif
+
+#define	APBH_CTRL0_SFTRST				(1 << 31)
+#define	APBH_CTRL0_CLKGATE				(1 << 30)
+#define	APBH_CTRL0_AHB_BURST8_EN			(1 << 29)
+#define	APBH_CTRL0_APB_BURST_EN				(1 << 28)
+#define	APBH_CTRL0_RSVD0_MASK				(0xfff << 16)
+#define	APBH_CTRL0_RSVD0_OFFSET				16
+#define	APBH_CTRL0_CLKGATE_CHANNEL_MASK			0xffff
+#define	APBH_CTRL0_CLKGATE_CHANNEL_OFFSET		0
+#define	APBH_CTRL0_CLKGATE_CHANNEL_SSP0			0x0001
+#define	APBH_CTRL0_CLKGATE_CHANNEL_SSP1			0x0002
+#define	APBH_CTRL0_CLKGATE_CHANNEL_SSP2			0x0004
+#define	APBH_CTRL0_CLKGATE_CHANNEL_SSP3			0x0008
+#define	APBH_CTRL0_CLKGATE_CHANNEL_NAND0		0x0010
+#define	APBH_CTRL0_CLKGATE_CHANNEL_NAND1		0x0020
+#define	APBH_CTRL0_CLKGATE_CHANNEL_NAND2		0x0040
+#define	APBH_CTRL0_CLKGATE_CHANNEL_NAND3		0x0080
+#define	APBH_CTRL0_CLKGATE_CHANNEL_NAND4		0x0100
+#define	APBH_CTRL0_CLKGATE_CHANNEL_NAND5		0x0200
+#define	APBH_CTRL0_CLKGATE_CHANNEL_NAND6		0x0400
+#define	APBH_CTRL0_CLKGATE_CHANNEL_NAND7		0x0800
+#define	APBH_CTRL0_CLKGATE_CHANNEL_HSADC		0x1000
+#define	APBH_CTRL0_CLKGATE_CHANNEL_LCDIF		0x2000
+
+#define	APBH_CTRL1_CH15_CMDCMPLT_IRQ_EN			(1 << 31)
+#define	APBH_CTRL1_CH14_CMDCMPLT_IRQ_EN			(1 << 30)
+#define	APBH_CTRL1_CH13_CMDCMPLT_IRQ_EN			(1 << 29)
+#define	APBH_CTRL1_CH12_CMDCMPLT_IRQ_EN			(1 << 28)
+#define	APBH_CTRL1_CH11_CMDCMPLT_IRQ_EN			(1 << 27)
+#define	APBH_CTRL1_CH10_CMDCMPLT_IRQ_EN			(1 << 26)
+#define	APBH_CTRL1_CH9_CMDCMPLT_IRQ_EN			(1 << 25)
+#define	APBH_CTRL1_CH8_CMDCMPLT_IRQ_EN			(1 << 24)
+#define	APBH_CTRL1_CH7_CMDCMPLT_IRQ_EN			(1 << 23)
+#define	APBH_CTRL1_CH6_CMDCMPLT_IRQ_EN			(1 << 22)
+#define	APBH_CTRL1_CH5_CMDCMPLT_IRQ_EN			(1 << 21)
+#define	APBH_CTRL1_CH4_CMDCMPLT_IRQ_EN			(1 << 20)
+#define	APBH_CTRL1_CH3_CMDCMPLT_IRQ_EN			(1 << 19)
+#define	APBH_CTRL1_CH2_CMDCMPLT_IRQ_EN			(1 << 18)
+#define	APBH_CTRL1_CH1_CMDCMPLT_IRQ_EN			(1 << 17)
+#define	APBH_CTRL1_CH0_CMDCMPLT_IRQ_EN			(1 << 16)
+#define	APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_OFFSET		16
+#define	APBH_CTRL1_CH_CMDCMPLT_IRQ_EN_MASK		(0xffff << 16)
+#define	APBH_CTRL1_CH15_CMDCMPLT_IRQ			(1 << 15)
+#define	APBH_CTRL1_CH14_CMDCMPLT_IRQ			(1 << 14)
+#define	APBH_CTRL1_CH13_CMDCMPLT_IRQ			(1 << 13)
+#define	APBH_CTRL1_CH12_CMDCMPLT_IRQ			(1 << 12)
+#define	APBH_CTRL1_CH11_CMDCMPLT_IRQ			(1 << 11)
+#define	APBH_CTRL1_CH10_CMDCMPLT_IRQ			(1 << 10)
+#define	APBH_CTRL1_CH9_CMDCMPLT_IRQ			(1 << 9)
+#define	APBH_CTRL1_CH8_CMDCMPLT_IRQ			(1 << 8)
+#define	APBH_CTRL1_CH7_CMDCMPLT_IRQ			(1 << 7)
+#define	APBH_CTRL1_CH6_CMDCMPLT_IRQ			(1 << 6)
+#define	APBH_CTRL1_CH5_CMDCMPLT_IRQ			(1 << 5)
+#define	APBH_CTRL1_CH4_CMDCMPLT_IRQ			(1 << 4)
+#define	APBH_CTRL1_CH3_CMDCMPLT_IRQ			(1 << 3)
+#define	APBH_CTRL1_CH2_CMDCMPLT_IRQ			(1 << 2)
+#define	APBH_CTRL1_CH1_CMDCMPLT_IRQ			(1 << 1)
+#define	APBH_CTRL1_CH0_CMDCMPLT_IRQ			(1 << 0)
+
+#define	APBH_CTRL2_CH15_ERROR_STATUS			(1 << 31)
+#define	APBH_CTRL2_CH14_ERROR_STATUS			(1 << 30)
+#define	APBH_CTRL2_CH13_ERROR_STATUS			(1 << 29)
+#define	APBH_CTRL2_CH12_ERROR_STATUS			(1 << 28)
+#define	APBH_CTRL2_CH11_ERROR_STATUS			(1 << 27)
+#define	APBH_CTRL2_CH10_ERROR_STATUS			(1 << 26)
+#define	APBH_CTRL2_CH9_ERROR_STATUS			(1 << 25)
+#define	APBH_CTRL2_CH8_ERROR_STATUS			(1 << 24)
+#define	APBH_CTRL2_CH7_ERROR_STATUS			(1 << 23)
+#define	APBH_CTRL2_CH6_ERROR_STATUS			(1 << 22)
+#define	APBH_CTRL2_CH5_ERROR_STATUS			(1 << 21)
+#define	APBH_CTRL2_CH4_ERROR_STATUS			(1 << 20)
+#define	APBH_CTRL2_CH3_ERROR_STATUS			(1 << 19)
+#define	APBH_CTRL2_CH2_ERROR_STATUS			(1 << 18)
+#define	APBH_CTRL2_CH1_ERROR_STATUS			(1 << 17)
+#define	APBH_CTRL2_CH0_ERROR_STATUS			(1 << 16)
+#define	APBH_CTRL2_CH15_ERROR_IRQ			(1 << 15)
+#define	APBH_CTRL2_CH14_ERROR_IRQ			(1 << 14)
+#define	APBH_CTRL2_CH13_ERROR_IRQ			(1 << 13)
+#define	APBH_CTRL2_CH12_ERROR_IRQ			(1 << 12)
+#define	APBH_CTRL2_CH11_ERROR_IRQ			(1 << 11)
+#define	APBH_CTRL2_CH10_ERROR_IRQ			(1 << 10)
+#define	APBH_CTRL2_CH9_ERROR_IRQ			(1 << 9)
+#define	APBH_CTRL2_CH8_ERROR_IRQ			(1 << 8)
+#define	APBH_CTRL2_CH7_ERROR_IRQ			(1 << 7)
+#define	APBH_CTRL2_CH6_ERROR_IRQ			(1 << 6)
+#define	APBH_CTRL2_CH5_ERROR_IRQ			(1 << 5)
+#define	APBH_CTRL2_CH4_ERROR_IRQ			(1 << 4)
+#define	APBH_CTRL2_CH3_ERROR_IRQ			(1 << 3)
+#define	APBH_CTRL2_CH2_ERROR_IRQ			(1 << 2)
+#define	APBH_CTRL2_CH1_ERROR_IRQ			(1 << 1)
+#define	APBH_CTRL2_CH0_ERROR_IRQ			(1 << 0)
+
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_MASK		(0xffff << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_OFFSET		16
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_SSP0		(0x0001 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_SSP1		(0x0002 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_SSP2		(0x0004 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_SSP3		(0x0008 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_NAND0		(0x0010 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_NAND1		(0x0020 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_NAND2		(0x0040 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_NAND3		(0x0080 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_NAND4		(0x0100 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_NAND5		(0x0200 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_NAND6		(0x0400 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_NAND7		(0x0800 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_HSADC		(0x1000 << 16)
+#define	APBH_CHANNEL_CTRL_RESET_CHANNEL_LCDIF		(0x2000 << 16)
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_MASK		0xffff
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_OFFSET		0
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_SSP0		0x0001
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_SSP1		0x0002
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_SSP2		0x0004
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_SSP3		0x0008
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_NAND0		0x0010
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_NAND1		0x0020
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_NAND2		0x0040
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_NAND3		0x0080
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_NAND4		0x0100
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_NAND5		0x0200
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_NAND6		0x0400
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_NAND7		0x0800
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_HSADC		0x1000
+#define	APBH_CHANNEL_CTRL_FREEZE_CHANNEL_LCDIF		0x2000
+
+#define	APBH_DEVSEL_CH15_MASK				(0x3 << 30)
+#define	APBH_DEVSEL_CH15_OFFSET				30
+#define	APBH_DEVSEL_CH14_MASK				(0x3 << 28)
+#define	APBH_DEVSEL_CH14_OFFSET				28
+#define	APBH_DEVSEL_CH13_MASK				(0x3 << 26)
+#define	APBH_DEVSEL_CH13_OFFSET				26
+#define	APBH_DEVSEL_CH12_MASK				(0x3 << 24)
+#define	APBH_DEVSEL_CH12_OFFSET				24
+#define	APBH_DEVSEL_CH11_MASK				(0x3 << 22)
+#define	APBH_DEVSEL_CH11_OFFSET				22
+#define	APBH_DEVSEL_CH10_MASK				(0x3 << 20)
+#define	APBH_DEVSEL_CH10_OFFSET				20
+#define	APBH_DEVSEL_CH9_MASK				(0x3 << 18)
+#define	APBH_DEVSEL_CH9_OFFSET				18
+#define	APBH_DEVSEL_CH8_MASK				(0x3 << 16)
+#define	APBH_DEVSEL_CH8_OFFSET				16
+#define	APBH_DEVSEL_CH7_MASK				(0x3 << 14)
+#define	APBH_DEVSEL_CH7_OFFSET				14
+#define	APBH_DEVSEL_CH6_MASK				(0x3 << 12)
+#define	APBH_DEVSEL_CH6_OFFSET				12
+#define	APBH_DEVSEL_CH5_MASK				(0x3 << 10)
+#define	APBH_DEVSEL_CH5_OFFSET				10
+#define	APBH_DEVSEL_CH4_MASK				(0x3 << 8)
+#define	APBH_DEVSEL_CH4_OFFSET				8
+#define	APBH_DEVSEL_CH3_MASK				(0x3 << 6)
+#define	APBH_DEVSEL_CH3_OFFSET				6
+#define	APBH_DEVSEL_CH2_MASK				(0x3 << 4)
+#define	APBH_DEVSEL_CH2_OFFSET				4
+#define	APBH_DEVSEL_CH1_MASK				(0x3 << 2)
+#define	APBH_DEVSEL_CH1_OFFSET				2
+#define	APBH_DEVSEL_CH0_MASK				(0x3 << 0)
+#define	APBH_DEVSEL_CH0_OFFSET				0
+
+#define	APBH_DMA_BURST_SIZE_CH15_MASK			(0x3 << 30)
+#define	APBH_DMA_BURST_SIZE_CH15_OFFSET			30
+#define	APBH_DMA_BURST_SIZE_CH14_MASK			(0x3 << 28)
+#define	APBH_DMA_BURST_SIZE_CH14_OFFSET			28
+#define	APBH_DMA_BURST_SIZE_CH13_MASK			(0x3 << 26)
+#define	APBH_DMA_BURST_SIZE_CH13_OFFSET			26
+#define	APBH_DMA_BURST_SIZE_CH12_MASK			(0x3 << 24)
+#define	APBH_DMA_BURST_SIZE_CH12_OFFSET			24
+#define	APBH_DMA_BURST_SIZE_CH11_MASK			(0x3 << 22)
+#define	APBH_DMA_BURST_SIZE_CH11_OFFSET			22
+#define	APBH_DMA_BURST_SIZE_CH10_MASK			(0x3 << 20)
+#define	APBH_DMA_BURST_SIZE_CH10_OFFSET			20
+#define	APBH_DMA_BURST_SIZE_CH9_MASK			(0x3 << 18)
+#define	APBH_DMA_BURST_SIZE_CH9_OFFSET			18
+#define	APBH_DMA_BURST_SIZE_CH8_MASK			(0x3 << 16)
+#define	APBH_DMA_BURST_SIZE_CH8_OFFSET			16
+#define	APBH_DMA_BURST_SIZE_CH8_BURST0			(0x0 << 16)
+#define	APBH_DMA_BURST_SIZE_CH8_BURST4			(0x1 << 16)
+#define	APBH_DMA_BURST_SIZE_CH8_BURST8			(0x2 << 16)
+#define	APBH_DMA_BURST_SIZE_CH7_MASK			(0x3 << 14)
+#define	APBH_DMA_BURST_SIZE_CH7_OFFSET			14
+#define	APBH_DMA_BURST_SIZE_CH6_MASK			(0x3 << 12)
+#define	APBH_DMA_BURST_SIZE_CH6_OFFSET			12
+#define	APBH_DMA_BURST_SIZE_CH5_MASK			(0x3 << 10)
+#define	APBH_DMA_BURST_SIZE_CH5_OFFSET			10
+#define	APBH_DMA_BURST_SIZE_CH4_MASK			(0x3 << 8)
+#define	APBH_DMA_BURST_SIZE_CH4_OFFSET			8
+#define	APBH_DMA_BURST_SIZE_CH3_MASK			(0x3 << 6)
+#define	APBH_DMA_BURST_SIZE_CH3_OFFSET			6
+#define	APBH_DMA_BURST_SIZE_CH3_BURST0			(0x0 << 6)
+#define	APBH_DMA_BURST_SIZE_CH3_BURST4			(0x1 << 6)
+#define	APBH_DMA_BURST_SIZE_CH3_BURST8			(0x2 << 6)
+
+#define	APBH_DMA_BURST_SIZE_CH2_MASK			(0x3 << 4)
+#define	APBH_DMA_BURST_SIZE_CH2_OFFSET			4
+#define	APBH_DMA_BURST_SIZE_CH2_BURST0			(0x0 << 4)
+#define	APBH_DMA_BURST_SIZE_CH2_BURST4			(0x1 << 4)
+#define	APBH_DMA_BURST_SIZE_CH2_BURST8			(0x2 << 4)
+#define	APBH_DMA_BURST_SIZE_CH1_MASK			(0x3 << 2)
+#define	APBH_DMA_BURST_SIZE_CH1_OFFSET			2
+#define	APBH_DMA_BURST_SIZE_CH1_BURST0			(0x0 << 2)
+#define	APBH_DMA_BURST_SIZE_CH1_BURST4			(0x1 << 2)
+#define	APBH_DMA_BURST_SIZE_CH1_BURST8			(0x2 << 2)
+
+#define	APBH_DMA_BURST_SIZE_CH0_MASK			0x3
+#define	APBH_DMA_BURST_SIZE_CH0_OFFSET			0
+#define	APBH_DMA_BURST_SIZE_CH0_BURST0			0x0
+#define	APBH_DMA_BURST_SIZE_CH0_BURST4			0x1
+#define	APBH_DMA_BURST_SIZE_CH0_BURST8			0x2
+
+#define	APBH_DEBUG_GPMI_ONE_FIFO			(1 << 0)
+
+#define	APBH_CHn_CURCMDAR_CMD_ADDR_MASK			0xffffffff
+#define	APBH_CHn_CURCMDAR_CMD_ADDR_OFFSET		0
+
+#define	APBH_CHn_NXTCMDAR_CMD_ADDR_MASK			0xffffffff
+#define	APBH_CHn_NXTCMDAR_CMD_ADDR_OFFSET		0
+
+#define	APBH_CHn_CMD_XFER_COUNT_MASK			(0xffff << 16)
+#define	APBH_CHn_CMD_XFER_COUNT_OFFSET			16
+#define	APBH_CHn_CMD_CMDWORDS_MASK			(0xf << 12)
+#define	APBH_CHn_CMD_CMDWORDS_OFFSET			12
+#define	APBH_CHn_CMD_HALTONTERMINATE			(1 << 8)
+#define	APBH_CHn_CMD_WAIT4ENDCMD			(1 << 7)
+#define	APBH_CHn_CMD_SEMAPHORE				(1 << 6)
+#define	APBH_CHn_CMD_NANDWAIT4READY			(1 << 5)
+#define	APBH_CHn_CMD_NANDLOCK				(1 << 4)
+#define	APBH_CHn_CMD_IRQONCMPLT				(1 << 3)
+#define	APBH_CHn_CMD_CHAIN				(1 << 2)
+#define	APBH_CHn_CMD_COMMAND_MASK			0x3
+#define	APBH_CHn_CMD_COMMAND_OFFSET			0
+#define	APBH_CHn_CMD_COMMAND_NO_DMA_XFER		0x0
+#define	APBH_CHn_CMD_COMMAND_DMA_WRITE			0x1
+#define	APBH_CHn_CMD_COMMAND_DMA_READ			0x2
+#define	APBH_CHn_CMD_COMMAND_DMA_SENSE			0x3
+
+#define	APBH_CHn_BAR_ADDRESS_MASK			0xffffffff
+#define	APBH_CHn_BAR_ADDRESS_OFFSET			0
+
+#define	APBH_CHn_SEMA_RSVD2_MASK			(0xff << 24)
+#define	APBH_CHn_SEMA_RSVD2_OFFSET			24
+#define	APBH_CHn_SEMA_PHORE_MASK			(0xff << 16)
+#define	APBH_CHn_SEMA_PHORE_OFFSET			16
+#define	APBH_CHn_SEMA_RSVD1_MASK			(0xff << 8)
+#define	APBH_CHn_SEMA_RSVD1_OFFSET			8
+#define	APBH_CHn_SEMA_INCREMENT_SEMA_MASK		(0xff << 0)
+#define	APBH_CHn_SEMA_INCREMENT_SEMA_OFFSET		0
+
+#define	APBH_CHn_DEBUG1_REQ				(1 << 31)
+#define	APBH_CHn_DEBUG1_BURST				(1 << 30)
+#define	APBH_CHn_DEBUG1_KICK				(1 << 29)
+#define	APBH_CHn_DEBUG1_END				(1 << 28)
+#define	APBH_CHn_DEBUG1_SENSE				(1 << 27)
+#define	APBH_CHn_DEBUG1_READY				(1 << 26)
+#define	APBH_CHn_DEBUG1_LOCK				(1 << 25)
+#define	APBH_CHn_DEBUG1_NEXTCMDADDRVALID		(1 << 24)
+#define	APBH_CHn_DEBUG1_RD_FIFO_EMPTY			(1 << 23)
+#define	APBH_CHn_DEBUG1_RD_FIFO_FULL			(1 << 22)
+#define	APBH_CHn_DEBUG1_WR_FIFO_EMPTY			(1 << 21)
+#define	APBH_CHn_DEBUG1_WR_FIFO_FULL			(1 << 20)
+#define	APBH_CHn_DEBUG1_RSVD1_MASK			(0x7fff << 5)
+#define	APBH_CHn_DEBUG1_RSVD1_OFFSET			5
+#define	APBH_CHn_DEBUG1_STATEMACHINE_MASK		0x1f
+#define	APBH_CHn_DEBUG1_STATEMACHINE_OFFSET		0
+#define	APBH_CHn_DEBUG1_STATEMACHINE_IDLE		0x00
+#define	APBH_CHn_DEBUG1_STATEMACHINE_REQ_CMD1		0x01
+#define	APBH_CHn_DEBUG1_STATEMACHINE_REQ_CMD3		0x02
+#define	APBH_CHn_DEBUG1_STATEMACHINE_REQ_CMD2		0x03
+#define	APBH_CHn_DEBUG1_STATEMACHINE_XFER_DECODE	0x04
+#define	APBH_CHn_DEBUG1_STATEMACHINE_REQ_WAIT		0x05
+#define	APBH_CHn_DEBUG1_STATEMACHINE_REQ_CMD4		0x06
+#define	APBH_CHn_DEBUG1_STATEMACHINE_PIO_REQ		0x07
+#define	APBH_CHn_DEBUG1_STATEMACHINE_READ_FLUSH		0x08
+#define	APBH_CHn_DEBUG1_STATEMACHINE_READ_WAIT		0x09
+#define	APBH_CHn_DEBUG1_STATEMACHINE_WRITE		0x0c
+#define	APBH_CHn_DEBUG1_STATEMACHINE_READ_REQ		0x0d
+#define	APBH_CHn_DEBUG1_STATEMACHINE_CHECK_CHAIN	0x0e
+#define	APBH_CHn_DEBUG1_STATEMACHINE_XFER_COMPLETE	0x0f
+#define	APBH_CHn_DEBUG1_STATEMACHINE_TERMINATE		0x14
+#define	APBH_CHn_DEBUG1_STATEMACHINE_WAIT_END		0x15
+#define	APBH_CHn_DEBUG1_STATEMACHINE_WRITE_WAIT		0x1c
+#define	APBH_CHn_DEBUG1_STATEMACHINE_HALT_AFTER_TERM	0x1d
+#define	APBH_CHn_DEBUG1_STATEMACHINE_CHECK_WAIT		0x1e
+#define	APBH_CHn_DEBUG1_STATEMACHINE_WAIT_READY		0x1f
+
+#define	APBH_CHn_DEBUG2_APB_BYTES_MASK			(0xffff << 16)
+#define	APBH_CHn_DEBUG2_APB_BYTES_OFFSET		16
+#define	APBH_CHn_DEBUG2_AHB_BYTES_MASK			0xffff
+#define	APBH_CHn_DEBUG2_AHB_BYTES_OFFSET		0
+
+#define	APBH_VERSION_MAJOR_MASK				(0xff << 24)
+#define	APBH_VERSION_MAJOR_OFFSET			24
+#define	APBH_VERSION_MINOR_MASK				(0xff << 16)
+#define	APBH_VERSION_MINOR_OFFSET			16
+#define	APBH_VERSION_STEP_MASK				0xffff
+#define	APBH_VERSION_STEP_OFFSET			0
+
+#endif	/* __REGS_APBH_H__ */
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index 9d945a0..514828b 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -26,6 +26,7 @@ include $(TOPDIR)/config.mk
 LIB	:= $(obj)libdma.o
 
 COBJS-$(CONFIG_FSLDMAFEC) += MCD_tasksInit.o MCD_dmaApi.o MCD_tasks.o
+COBJS-$(CONFIG_APBH_DMA) += apbh_dma.o
 COBJS-$(CONFIG_FSL_DMA) += fsl_dma.o
 
 COBJS	:= $(COBJS-y)
diff --git a/drivers/dma/apbh_dma.c b/drivers/dma/apbh_dma.c
new file mode 100644
index 0000000..69a1042
--- /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;
+}
-- 
1.7.5.4