iMX28: Add GPMI NAND driver
authorMarek Vasut <marek.vasut@gmail.com>
Tue, 8 Nov 2011 23:18:16 +0000 (23:18 +0000)
committerStefano Babic <sbabic@denx.de>
Fri, 11 Nov 2011 10:36:57 +0000 (11:36 +0100)
Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Detlev Zundel <dzu@denx.de>
drivers/mtd/nand/Makefile
drivers/mtd/nand/mxs_nand.c [new file with mode: 0644]

index 28bd3507dc996caf5f03d8f1895df0522d34da52..36ee454304351358dcddd36b756f4d87654c3dc1 100644 (file)
@@ -54,6 +54,7 @@ COBJS-$(CONFIG_NAND_KIRKWOOD) += kirkwood_nand.o
 COBJS-$(CONFIG_NAND_KMETER1) += kmeter1_nand.o
 COBJS-$(CONFIG_NAND_MPC5121_NFC) += mpc5121_nfc.o
 COBJS-$(CONFIG_NAND_MXC) += mxc_nand.o
+COBJS-$(CONFIG_NAND_MXS) += mxs_nand.o
 COBJS-$(CONFIG_NAND_NDFC) += ndfc.o
 COBJS-$(CONFIG_NAND_NOMADIK) += nomadik.o
 COBJS-$(CONFIG_NAND_S3C2410) += s3c2410_nand.o
diff --git a/drivers/mtd/nand/mxs_nand.c b/drivers/mtd/nand/mxs_nand.c
new file mode 100644 (file)
index 0000000..ce2a326
--- /dev/null
@@ -0,0 +1,1118 @@
+/*
+ * Freescale i.MX28 NAND flash driver
+ *
+ * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
+ * on behalf of DENX Software Engineering GmbH
+ *
+ * Based on code from LTIB:
+ * Freescale GPMI NFC NAND Flash Driver
+ *
+ * Copyright (C) 2010 Freescale Semiconductor, Inc.
+ * Copyright (C) 2008 Embedded Alley Solutions, Inc.
+ *
+ * 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/mtd/mtd.h>
+#include <linux/mtd/nand.h>
+#include <linux/types.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>
+
+#define        MXS_NAND_DMA_DESCRIPTOR_COUNT           4
+
+#define        MXS_NAND_CHUNK_DATA_CHUNK_SIZE          512
+#define        MXS_NAND_METADATA_SIZE                  10
+
+#define        MXS_NAND_COMMAND_BUFFER_SIZE            32
+
+#define        MXS_NAND_BCH_TIMEOUT                    10000
+
+struct mxs_nand_info {
+       int             cur_chip;
+
+       uint32_t        cmd_queue_len;
+
+       uint8_t         *cmd_buf;
+       uint8_t         *data_buf;
+       uint8_t         *oob_buf;
+
+       uint8_t         marking_block_bad;
+       uint8_t         raw_oob_mode;
+
+       /* Functions with altered behaviour */
+       int             (*hooked_read_oob)(struct mtd_info *mtd,
+                               loff_t from, struct mtd_oob_ops *ops);
+       int             (*hooked_write_oob)(struct mtd_info *mtd,
+                               loff_t to, struct mtd_oob_ops *ops);
+       int             (*hooked_block_markbad)(struct mtd_info *mtd,
+                               loff_t ofs);
+
+       /* DMA descriptors */
+       struct mxs_dma_desc     **desc;
+       uint32_t                desc_index;
+};
+
+struct nand_ecclayout fake_ecc_layout;
+
+static struct mxs_dma_desc *mxs_nand_get_dma_desc(struct mxs_nand_info *info)
+{
+       struct mxs_dma_desc *desc;
+
+       if (info->desc_index >= MXS_NAND_DMA_DESCRIPTOR_COUNT) {
+               printf("MXS NAND: Too many DMA descriptors requested\n");
+               return NULL;
+       }
+
+       desc = info->desc[info->desc_index];
+       info->desc_index++;
+
+       return desc;
+}
+
+static void mxs_nand_return_dma_descs(struct mxs_nand_info *info)
+{
+       int i;
+       struct mxs_dma_desc *desc;
+
+       for (i = 0; i < info->desc_index; i++) {
+               desc = info->desc[i];
+               memset(desc, 0, sizeof(struct mxs_dma_desc));
+               desc->address = (dma_addr_t)desc;
+       }
+
+       info->desc_index = 0;
+}
+
+static uint32_t mxs_nand_ecc_chunk_cnt(uint32_t page_data_size)
+{
+       return page_data_size / MXS_NAND_CHUNK_DATA_CHUNK_SIZE;
+}
+
+static uint32_t mxs_nand_ecc_size_in_bits(uint32_t ecc_strength)
+{
+       return ecc_strength * 13;
+}
+
+static uint32_t mxs_nand_aux_status_offset(void)
+{
+       return (MXS_NAND_METADATA_SIZE + 0x3) & ~0x3;
+}
+
+static inline uint32_t mxs_nand_get_ecc_strength(uint32_t page_data_size,
+                                               uint32_t page_oob_size)
+{
+       if (page_data_size == 2048)
+               return 8;
+
+       if (page_data_size == 4096) {
+               if (page_oob_size == 128)
+                       return 8;
+
+               if (page_oob_size == 218)
+                       return 16;
+       }
+
+       return 0;
+}
+
+static inline uint32_t mxs_nand_get_mark_offset(uint32_t page_data_size,
+                                               uint32_t ecc_strength)
+{
+       uint32_t chunk_data_size_in_bits;
+       uint32_t chunk_ecc_size_in_bits;
+       uint32_t chunk_total_size_in_bits;
+       uint32_t block_mark_chunk_number;
+       uint32_t block_mark_chunk_bit_offset;
+       uint32_t block_mark_bit_offset;
+
+       chunk_data_size_in_bits = MXS_NAND_CHUNK_DATA_CHUNK_SIZE * 8;
+       chunk_ecc_size_in_bits  = mxs_nand_ecc_size_in_bits(ecc_strength);
+
+       chunk_total_size_in_bits =
+                       chunk_data_size_in_bits + chunk_ecc_size_in_bits;
+
+       /* Compute the bit offset of the block mark within the physical page. */
+       block_mark_bit_offset = page_data_size * 8;
+
+       /* Subtract the metadata bits. */
+       block_mark_bit_offset -= MXS_NAND_METADATA_SIZE * 8;
+
+       /*
+        * Compute the chunk number (starting at zero) in which the block mark
+        * appears.
+        */
+       block_mark_chunk_number =
+                       block_mark_bit_offset / chunk_total_size_in_bits;
+
+       /*
+        * Compute the bit offset of the block mark within its chunk, and
+        * validate it.
+        */
+       block_mark_chunk_bit_offset = block_mark_bit_offset -
+                       (block_mark_chunk_number * chunk_total_size_in_bits);
+
+       if (block_mark_chunk_bit_offset > chunk_data_size_in_bits)
+               return 1;
+
+       /*
+        * Now that we know the chunk number in which the block mark appears,
+        * we can subtract all the ECC bits that appear before it.
+        */
+       block_mark_bit_offset -=
+               block_mark_chunk_number * chunk_ecc_size_in_bits;
+
+       return block_mark_bit_offset;
+}
+
+static uint32_t mxs_nand_mark_byte_offset(struct mtd_info *mtd)
+{
+       uint32_t ecc_strength;
+       ecc_strength = mxs_nand_get_ecc_strength(mtd->writesize, mtd->oobsize);
+       return mxs_nand_get_mark_offset(mtd->writesize, ecc_strength) >> 3;
+}
+
+static uint32_t mxs_nand_mark_bit_offset(struct mtd_info *mtd)
+{
+       uint32_t ecc_strength;
+       ecc_strength = mxs_nand_get_ecc_strength(mtd->writesize, mtd->oobsize);
+       return mxs_nand_get_mark_offset(mtd->writesize, ecc_strength) & 0x7;
+}
+
+/*
+ * Wait for BCH complete IRQ and clear the IRQ
+ */
+static int mxs_nand_wait_for_bch_complete(void)
+{
+       struct mx28_bch_regs *bch_regs = (struct mx28_bch_regs *)MXS_BCH_BASE;
+       int timeout = MXS_NAND_BCH_TIMEOUT;
+       int ret;
+
+       ret = mx28_wait_mask_set(&bch_regs->hw_bch_ctrl_reg,
+               BCH_CTRL_COMPLETE_IRQ, timeout);
+
+       writel(BCH_CTRL_COMPLETE_IRQ, &bch_regs->hw_bch_ctrl_clr);
+
+       return ret;
+}
+
+/*
+ * This is the function that we install in the cmd_ctrl function pointer of the
+ * owning struct nand_chip. The only functions in the reference implementation
+ * that use these functions pointers are cmdfunc and select_chip.
+ *
+ * In this driver, we implement our own select_chip, so this function will only
+ * be called by the reference implementation's cmdfunc. For this reason, we can
+ * ignore the chip enable bit and concentrate only on sending bytes to the NAND
+ * Flash.
+ */
+static void mxs_nand_cmd_ctrl(struct mtd_info *mtd, int data, unsigned int ctrl)
+{
+       struct nand_chip *nand = mtd->priv;
+       struct mxs_nand_info *nand_info = nand->priv;
+       struct mxs_dma_desc *d;
+       uint32_t channel = MXS_DMA_CHANNEL_AHB_APBH_GPMI0 + nand_info->cur_chip;
+       int ret;
+
+       /*
+        * If this condition is true, something is _VERY_ wrong in MTD
+        * subsystem!
+        */
+       if (nand_info->cmd_queue_len == MXS_NAND_COMMAND_BUFFER_SIZE) {
+               printf("MXS NAND: Command queue too long\n");
+               return;
+       }
+
+       /*
+        * Every operation begins with a command byte and a series of zero or
+        * more address bytes. These are distinguished by either the Address
+        * Latch Enable (ALE) or Command Latch Enable (CLE) signals being
+        * asserted. When MTD is ready to execute the command, it will
+        * deasert both latch enables.
+        *
+        * Rather than run a separate DMA operation for every single byte, we
+        * queue them up and run a single DMA operation for the entire series
+        * of command and data bytes.
+        */
+       if (ctrl & (NAND_ALE | NAND_CLE)) {
+               if (data != NAND_CMD_NONE)
+                       nand_info->cmd_buf[nand_info->cmd_queue_len++] = data;
+               return;
+       }
+
+       /*
+        * If control arrives here, MTD has deasserted both the ALE and CLE,
+        * which means it's ready to run an operation. Check if we have any
+        * bytes to send.
+        */
+       if (nand_info->cmd_queue_len == 0)
+               return;
+
+       /* Compile the DMA descriptor -- a descriptor that sends command. */
+       d = mxs_nand_get_dma_desc(nand_info);
+       d->cmd.data =
+               MXS_DMA_DESC_COMMAND_DMA_READ | MXS_DMA_DESC_IRQ |
+               MXS_DMA_DESC_CHAIN | MXS_DMA_DESC_DEC_SEM |
+               MXS_DMA_DESC_WAIT4END | (3 << MXS_DMA_DESC_PIO_WORDS_OFFSET) |
+               (nand_info->cmd_queue_len << MXS_DMA_DESC_BYTES_OFFSET);
+
+       d->cmd.address = (dma_addr_t)nand_info->cmd_buf;
+
+       d->cmd.pio_words[0] =
+               GPMI_CTRL0_COMMAND_MODE_WRITE |
+               GPMI_CTRL0_WORD_LENGTH |
+               (nand_info->cur_chip << GPMI_CTRL0_CS_OFFSET) |
+               GPMI_CTRL0_ADDRESS_NAND_CLE |
+               GPMI_CTRL0_ADDRESS_INCREMENT |
+               nand_info->cmd_queue_len;
+
+       mxs_dma_desc_append(channel, d);
+
+       /* Execute the DMA chain. */
+       ret = mxs_dma_go(channel);
+       if (ret)
+               printf("MXS NAND: Error sending command\n");
+
+       mxs_nand_return_dma_descs(nand_info);
+
+       /* Reset the command queue. */
+       nand_info->cmd_queue_len = 0;
+}
+
+/*
+ * Test if the NAND flash is ready.
+ */
+static int mxs_nand_device_ready(struct mtd_info *mtd)
+{
+       struct nand_chip *chip = mtd->priv;
+       struct mxs_nand_info *nand_info = chip->priv;
+       struct mx28_gpmi_regs *gpmi_regs =
+               (struct mx28_gpmi_regs *)MXS_GPMI_BASE;
+       uint32_t tmp;
+
+       tmp = readl(&gpmi_regs->hw_gpmi_stat);
+       tmp >>= (GPMI_STAT_READY_BUSY_OFFSET + nand_info->cur_chip);
+
+       return tmp & 1;
+}
+
+/*
+ * Select the NAND chip.
+ */
+static void mxs_nand_select_chip(struct mtd_info *mtd, int chip)
+{
+       struct nand_chip *nand = mtd->priv;
+       struct mxs_nand_info *nand_info = nand->priv;
+
+       nand_info->cur_chip = chip;
+}
+
+/*
+ * Handle block mark swapping.
+ *
+ * Note that, when this function is called, it doesn't know whether it's
+ * swapping the block mark, or swapping it *back* -- but it doesn't matter
+ * because the the operation is the same.
+ */
+static void mxs_nand_swap_block_mark(struct mtd_info *mtd,
+                                       uint8_t *data_buf, uint8_t *oob_buf)
+{
+       uint32_t bit_offset;
+       uint32_t buf_offset;
+
+       uint32_t src;
+       uint32_t dst;
+
+       bit_offset = mxs_nand_mark_bit_offset(mtd);
+       buf_offset = mxs_nand_mark_byte_offset(mtd);
+
+       /*
+        * Get the byte from the data area that overlays the block mark. Since
+        * the ECC engine applies its own view to the bits in the page, the
+        * physical block mark won't (in general) appear on a byte boundary in
+        * the data.
+        */
+       src = data_buf[buf_offset] >> bit_offset;
+       src |= data_buf[buf_offset + 1] << (8 - bit_offset);
+
+       dst = oob_buf[0];
+
+       oob_buf[0] = src;
+
+       data_buf[buf_offset] &= ~(0xff << bit_offset);
+       data_buf[buf_offset + 1] &= 0xff << bit_offset;
+
+       data_buf[buf_offset] |= dst << bit_offset;
+       data_buf[buf_offset + 1] |= dst >> (8 - bit_offset);
+}
+
+/*
+ * Read data from NAND.
+ */
+static void mxs_nand_read_buf(struct mtd_info *mtd, uint8_t *buf, int length)
+{
+       struct nand_chip *nand = mtd->priv;
+       struct mxs_nand_info *nand_info = nand->priv;
+       struct mxs_dma_desc *d;
+       uint32_t channel = MXS_DMA_CHANNEL_AHB_APBH_GPMI0 + nand_info->cur_chip;
+       int ret;
+
+       if (length > NAND_MAX_PAGESIZE) {
+               printf("MXS NAND: DMA buffer too big\n");
+               return;
+       }
+
+       if (!buf) {
+               printf("MXS NAND: DMA buffer is NULL\n");
+               return;
+       }
+
+       /* Compile the DMA descriptor - a descriptor that reads data. */
+       d = mxs_nand_get_dma_desc(nand_info);
+       d->cmd.data =
+               MXS_DMA_DESC_COMMAND_DMA_WRITE | MXS_DMA_DESC_IRQ |
+               MXS_DMA_DESC_DEC_SEM | MXS_DMA_DESC_WAIT4END |
+               (1 << MXS_DMA_DESC_PIO_WORDS_OFFSET) |
+               (length << MXS_DMA_DESC_BYTES_OFFSET);
+
+       d->cmd.address = (dma_addr_t)nand_info->data_buf;
+
+       d->cmd.pio_words[0] =
+               GPMI_CTRL0_COMMAND_MODE_READ |
+               GPMI_CTRL0_WORD_LENGTH |
+               (nand_info->cur_chip << GPMI_CTRL0_CS_OFFSET) |
+               GPMI_CTRL0_ADDRESS_NAND_DATA |
+               length;
+
+       mxs_dma_desc_append(channel, d);
+
+       /*
+        * A DMA descriptor that waits for the command to end and the chip to
+        * become ready.
+        *
+        * I think we actually should *not* be waiting for the chip to become
+        * ready because, after all, we don't care. I think the original code
+        * did that and no one has re-thought it yet.
+        */
+       d = mxs_nand_get_dma_desc(nand_info);
+       d->cmd.data =
+               MXS_DMA_DESC_COMMAND_NO_DMAXFER | MXS_DMA_DESC_IRQ |
+               MXS_DMA_DESC_NAND_WAIT_4_READY | MXS_DMA_DESC_DEC_SEM |
+               MXS_DMA_DESC_WAIT4END | (4 << MXS_DMA_DESC_PIO_WORDS_OFFSET);
+
+       d->cmd.address = 0;
+
+       d->cmd.pio_words[0] =
+               GPMI_CTRL0_COMMAND_MODE_WAIT_FOR_READY |
+               GPMI_CTRL0_WORD_LENGTH |
+               (nand_info->cur_chip << GPMI_CTRL0_CS_OFFSET) |
+               GPMI_CTRL0_ADDRESS_NAND_DATA;
+
+       mxs_dma_desc_append(channel, d);
+
+       /* Execute the DMA chain. */
+       ret = mxs_dma_go(channel);
+       if (ret) {
+               printf("MXS NAND: DMA read error\n");
+               goto rtn;
+       }
+
+       memcpy(buf, nand_info->data_buf, length);
+
+rtn:
+       mxs_nand_return_dma_descs(nand_info);
+}
+
+/*
+ * Write data to NAND.
+ */
+static void mxs_nand_write_buf(struct mtd_info *mtd, const uint8_t *buf,
+                               int length)
+{
+       struct nand_chip *nand = mtd->priv;
+       struct mxs_nand_info *nand_info = nand->priv;
+       struct mxs_dma_desc *d;
+       uint32_t channel = MXS_DMA_CHANNEL_AHB_APBH_GPMI0 + nand_info->cur_chip;
+       int ret;
+
+       if (length > NAND_MAX_PAGESIZE) {
+               printf("MXS NAND: DMA buffer too big\n");
+               return;
+       }
+
+       if (!buf) {
+               printf("MXS NAND: DMA buffer is NULL\n");
+               return;
+       }
+
+       memcpy(nand_info->data_buf, buf, length);
+
+       /* Compile the DMA descriptor - a descriptor that writes data. */
+       d = mxs_nand_get_dma_desc(nand_info);
+       d->cmd.data =
+               MXS_DMA_DESC_COMMAND_DMA_READ | MXS_DMA_DESC_IRQ |
+               MXS_DMA_DESC_DEC_SEM | MXS_DMA_DESC_WAIT4END |
+               (4 << MXS_DMA_DESC_PIO_WORDS_OFFSET) |
+               (length << MXS_DMA_DESC_BYTES_OFFSET);
+
+       d->cmd.address = (dma_addr_t)nand_info->data_buf;
+
+       d->cmd.pio_words[0] =
+               GPMI_CTRL0_COMMAND_MODE_WRITE |
+               GPMI_CTRL0_WORD_LENGTH |
+               (nand_info->cur_chip << GPMI_CTRL0_CS_OFFSET) |
+               GPMI_CTRL0_ADDRESS_NAND_DATA |
+               length;
+
+       mxs_dma_desc_append(channel, d);
+
+       /* Execute the DMA chain. */
+       ret = mxs_dma_go(channel);
+       if (ret)
+               printf("MXS NAND: DMA write error\n");
+
+       mxs_nand_return_dma_descs(nand_info);
+}
+
+/*
+ * Read a single byte from NAND.
+ */
+static uint8_t mxs_nand_read_byte(struct mtd_info *mtd)
+{
+       uint8_t buf;
+       mxs_nand_read_buf(mtd, &buf, 1);
+       return buf;
+}
+
+/*
+ * Read a page from NAND.
+ */
+static int mxs_nand_ecc_read_page(struct mtd_info *mtd, struct nand_chip *nand,
+                                       uint8_t *buf, int page)
+{
+       struct mxs_nand_info *nand_info = nand->priv;
+       struct mxs_dma_desc *d;
+       uint32_t channel = MXS_DMA_CHANNEL_AHB_APBH_GPMI0 + nand_info->cur_chip;
+       uint32_t corrected = 0, failed = 0;
+       uint8_t *status;
+       int i, ret;
+
+       /* Compile the DMA descriptor - wait for ready. */
+       d = mxs_nand_get_dma_desc(nand_info);
+       d->cmd.data =
+               MXS_DMA_DESC_COMMAND_NO_DMAXFER | MXS_DMA_DESC_CHAIN |
+               MXS_DMA_DESC_NAND_WAIT_4_READY | MXS_DMA_DESC_WAIT4END |
+               (1 << MXS_DMA_DESC_PIO_WORDS_OFFSET);
+
+       d->cmd.address = 0;
+
+       d->cmd.pio_words[0] =
+               GPMI_CTRL0_COMMAND_MODE_WAIT_FOR_READY |
+               GPMI_CTRL0_WORD_LENGTH |
+               (nand_info->cur_chip << GPMI_CTRL0_CS_OFFSET) |
+               GPMI_CTRL0_ADDRESS_NAND_DATA;
+
+       mxs_dma_desc_append(channel, d);
+
+       /* Compile the DMA descriptor - enable the BCH block and read. */
+       d = mxs_nand_get_dma_desc(nand_info);
+       d->cmd.data =
+               MXS_DMA_DESC_COMMAND_NO_DMAXFER | MXS_DMA_DESC_CHAIN |
+               MXS_DMA_DESC_WAIT4END | (6 << MXS_DMA_DESC_PIO_WORDS_OFFSET);
+
+       d->cmd.address = 0;
+
+       d->cmd.pio_words[0] =
+               GPMI_CTRL0_COMMAND_MODE_READ |
+               GPMI_CTRL0_WORD_LENGTH |
+               (nand_info->cur_chip << GPMI_CTRL0_CS_OFFSET) |
+               GPMI_CTRL0_ADDRESS_NAND_DATA |
+               (mtd->writesize + mtd->oobsize);
+       d->cmd.pio_words[1] = 0;
+       d->cmd.pio_words[2] =
+               GPMI_ECCCTRL_ENABLE_ECC |
+               GPMI_ECCCTRL_ECC_CMD_DECODE |
+               GPMI_ECCCTRL_BUFFER_MASK_BCH_PAGE;
+       d->cmd.pio_words[3] = mtd->writesize + mtd->oobsize;
+       d->cmd.pio_words[4] = (dma_addr_t)nand_info->data_buf;
+       d->cmd.pio_words[5] = (dma_addr_t)nand_info->oob_buf;
+
+       mxs_dma_desc_append(channel, d);
+
+       /* Compile the DMA descriptor - disable the BCH block. */
+       d = mxs_nand_get_dma_desc(nand_info);
+       d->cmd.data =
+               MXS_DMA_DESC_COMMAND_NO_DMAXFER | MXS_DMA_DESC_CHAIN |
+               MXS_DMA_DESC_NAND_WAIT_4_READY | MXS_DMA_DESC_WAIT4END |
+               (3 << MXS_DMA_DESC_PIO_WORDS_OFFSET);
+
+       d->cmd.address = 0;
+
+       d->cmd.pio_words[0] =
+               GPMI_CTRL0_COMMAND_MODE_WAIT_FOR_READY |
+               GPMI_CTRL0_WORD_LENGTH |
+               (nand_info->cur_chip << GPMI_CTRL0_CS_OFFSET) |
+               GPMI_CTRL0_ADDRESS_NAND_DATA |
+               (mtd->writesize + mtd->oobsize);
+       d->cmd.pio_words[1] = 0;
+       d->cmd.pio_words[2] = 0;
+
+       mxs_dma_desc_append(channel, d);
+
+       /* Compile the DMA descriptor - deassert the NAND lock and interrupt. */
+       d = mxs_nand_get_dma_desc(nand_info);
+       d->cmd.data =
+               MXS_DMA_DESC_COMMAND_NO_DMAXFER | MXS_DMA_DESC_IRQ |
+               MXS_DMA_DESC_DEC_SEM;
+
+       d->cmd.address = 0;
+
+       mxs_dma_desc_append(channel, d);
+
+       /* Execute the DMA chain. */
+       ret = mxs_dma_go(channel);
+       if (ret) {
+               printf("MXS NAND: DMA read error\n");
+               goto rtn;
+       }
+
+       ret = mxs_nand_wait_for_bch_complete();
+       if (ret) {
+               printf("MXS NAND: BCH read timeout\n");
+               goto rtn;
+       }
+
+       /* Read DMA completed, now do the mark swapping. */
+       mxs_nand_swap_block_mark(mtd, nand_info->data_buf, nand_info->oob_buf);
+
+       /* Loop over status bytes, accumulating ECC status. */
+       status = nand_info->oob_buf + mxs_nand_aux_status_offset();
+       for (i = 0; i < mxs_nand_ecc_chunk_cnt(mtd->writesize); i++) {
+               if (status[i] == 0x00)
+                       continue;
+
+               if (status[i] == 0xff)
+                       continue;
+
+               if (status[i] == 0xfe) {
+                       failed++;
+                       continue;
+               }
+
+               corrected += status[i];
+       }
+
+       /* Propagate ECC status to the owning MTD. */
+       mtd->ecc_stats.failed += failed;
+       mtd->ecc_stats.corrected += corrected;
+
+       /*
+        * It's time to deliver the OOB bytes. See mxs_nand_ecc_read_oob() for
+        * details about our policy for delivering the OOB.
+        *
+        * We fill the caller's buffer with set bits, and then copy the block
+        * mark to the caller's buffer. Note that, if block mark swapping was
+        * necessary, it has already been done, so we can rely on the first
+        * byte of the auxiliary buffer to contain the block mark.
+        */
+       memset(nand->oob_poi, 0xff, mtd->oobsize);
+
+       nand->oob_poi[0] = nand_info->oob_buf[0];
+
+       memcpy(buf, nand_info->data_buf, mtd->writesize);
+
+rtn:
+       mxs_nand_return_dma_descs(nand_info);
+
+       return ret;
+}
+
+/*
+ * Write a page to NAND.
+ */
+static void mxs_nand_ecc_write_page(struct mtd_info *mtd,
+                               struct nand_chip *nand, const uint8_t *buf)
+{
+       struct mxs_nand_info *nand_info = nand->priv;
+       struct mxs_dma_desc *d;
+       uint32_t channel = MXS_DMA_CHANNEL_AHB_APBH_GPMI0 + nand_info->cur_chip;
+       int ret;
+
+       memcpy(nand_info->data_buf, buf, mtd->writesize);
+       memcpy(nand_info->oob_buf, nand->oob_poi, mtd->oobsize);
+
+       /* Handle block mark swapping. */
+       mxs_nand_swap_block_mark(mtd, nand_info->data_buf, nand_info->oob_buf);
+
+       /* Compile the DMA descriptor - write data. */
+       d = mxs_nand_get_dma_desc(nand_info);
+       d->cmd.data =
+               MXS_DMA_DESC_COMMAND_NO_DMAXFER | MXS_DMA_DESC_IRQ |
+               MXS_DMA_DESC_DEC_SEM | MXS_DMA_DESC_WAIT4END |
+               (6 << MXS_DMA_DESC_PIO_WORDS_OFFSET);
+
+       d->cmd.address = 0;
+
+       d->cmd.pio_words[0] =
+               GPMI_CTRL0_COMMAND_MODE_WRITE |
+               GPMI_CTRL0_WORD_LENGTH |
+               (nand_info->cur_chip << GPMI_CTRL0_CS_OFFSET) |
+               GPMI_CTRL0_ADDRESS_NAND_DATA;
+       d->cmd.pio_words[1] = 0;
+       d->cmd.pio_words[2] =
+               GPMI_ECCCTRL_ENABLE_ECC |
+               GPMI_ECCCTRL_ECC_CMD_ENCODE |
+               GPMI_ECCCTRL_BUFFER_MASK_BCH_PAGE;
+       d->cmd.pio_words[3] = (mtd->writesize + mtd->oobsize);
+       d->cmd.pio_words[4] = (dma_addr_t)nand_info->data_buf;
+       d->cmd.pio_words[5] = (dma_addr_t)nand_info->oob_buf;
+
+       mxs_dma_desc_append(channel, d);
+
+       /* Execute the DMA chain. */
+       ret = mxs_dma_go(channel);
+       if (ret) {
+               printf("MXS NAND: DMA write error\n");
+               goto rtn;
+       }
+
+       ret = mxs_nand_wait_for_bch_complete();
+       if (ret) {
+               printf("MXS NAND: BCH write timeout\n");
+               goto rtn;
+       }
+
+rtn:
+       mxs_nand_return_dma_descs(nand_info);
+}
+
+/*
+ * Read OOB from NAND.
+ *
+ * This function is a veneer that replaces the function originally installed by
+ * the NAND Flash MTD code.
+ */
+static int mxs_nand_hook_read_oob(struct mtd_info *mtd, loff_t from,
+                                       struct mtd_oob_ops *ops)
+{
+       struct nand_chip *chip = mtd->priv;
+       struct mxs_nand_info *nand_info = chip->priv;
+       int ret;
+
+       if (ops->mode == MTD_OOB_RAW)
+               nand_info->raw_oob_mode = 1;
+       else
+               nand_info->raw_oob_mode = 0;
+
+       ret = nand_info->hooked_read_oob(mtd, from, ops);
+
+       nand_info->raw_oob_mode = 0;
+
+       return ret;
+}
+
+/*
+ * Write OOB to NAND.
+ *
+ * This function is a veneer that replaces the function originally installed by
+ * the NAND Flash MTD code.
+ */
+static int mxs_nand_hook_write_oob(struct mtd_info *mtd, loff_t to,
+                                       struct mtd_oob_ops *ops)
+{
+       struct nand_chip *chip = mtd->priv;
+       struct mxs_nand_info *nand_info = chip->priv;
+       int ret;
+
+       if (ops->mode == MTD_OOB_RAW)
+               nand_info->raw_oob_mode = 1;
+       else
+               nand_info->raw_oob_mode = 0;
+
+       ret = nand_info->hooked_write_oob(mtd, to, ops);
+
+       nand_info->raw_oob_mode = 0;
+
+       return ret;
+}
+
+/*
+ * Mark a block bad in NAND.
+ *
+ * This function is a veneer that replaces the function originally installed by
+ * the NAND Flash MTD code.
+ */
+static int mxs_nand_hook_block_markbad(struct mtd_info *mtd, loff_t ofs)
+{
+       struct nand_chip *chip = mtd->priv;
+       struct mxs_nand_info *nand_info = chip->priv;
+       int ret;
+
+       nand_info->marking_block_bad = 1;
+
+       ret = nand_info->hooked_block_markbad(mtd, ofs);
+
+       nand_info->marking_block_bad = 0;
+
+       return ret;
+}
+
+/*
+ * There are several places in this driver where we have to handle the OOB and
+ * block marks. This is the function where things are the most complicated, so
+ * this is where we try to explain it all. All the other places refer back to
+ * here.
+ *
+ * These are the rules, in order of decreasing importance:
+ *
+ * 1) Nothing the caller does can be allowed to imperil the block mark, so all
+ *    write operations take measures to protect it.
+ *
+ * 2) In read operations, the first byte of the OOB we return must reflect the
+ *    true state of the block mark, no matter where that block mark appears in
+ *    the physical page.
+ *
+ * 3) ECC-based read operations return an OOB full of set bits (since we never
+ *    allow ECC-based writes to the OOB, it doesn't matter what ECC-based reads
+ *    return).
+ *
+ * 4) "Raw" read operations return a direct view of the physical bytes in the
+ *    page, using the conventional definition of which bytes are data and which
+ *    are OOB. This gives the caller a way to see the actual, physical bytes
+ *    in the page, without the distortions applied by our ECC engine.
+ *
+ * What we do for this specific read operation depends on whether we're doing
+ * "raw" read, or an ECC-based read.
+ *
+ * It turns out that knowing whether we want an "ECC-based" or "raw" read is not
+ * easy. When reading a page, for example, the NAND Flash MTD code calls our
+ * ecc.read_page or ecc.read_page_raw function. Thus, the fact that MTD wants an
+ * ECC-based or raw view of the page is implicit in which function it calls
+ * (there is a similar pair of ECC-based/raw functions for writing).
+ *
+ * Since MTD assumes the OOB is not covered by ECC, there is no pair of
+ * ECC-based/raw functions for reading or or writing the OOB. The fact that the
+ * caller wants an ECC-based or raw view of the page is not propagated down to
+ * this driver.
+ *
+ * Since our OOB *is* covered by ECC, we need this information. So, we hook the
+ * ecc.read_oob and ecc.write_oob function pointers in the owning
+ * struct mtd_info with our own functions. These hook functions set the
+ * raw_oob_mode field so that, when control finally arrives here, we'll know
+ * what to do.
+ */
+static int mxs_nand_ecc_read_oob(struct mtd_info *mtd, struct nand_chip *nand,
+                               int page, int cmd)
+{
+       struct mxs_nand_info *nand_info = nand->priv;
+
+       /*
+        * First, fill in the OOB buffer. If we're doing a raw read, we need to
+        * get the bytes from the physical page. If we're not doing a raw read,
+        * we need to fill the buffer with set bits.
+        */
+       if (nand_info->raw_oob_mode) {
+               /*
+                * If control arrives here, we're doing a "raw" read. Send the
+                * command to read the conventional OOB and read it.
+                */
+               nand->cmdfunc(mtd, NAND_CMD_READ0, mtd->writesize, page);
+               nand->read_buf(mtd, nand->oob_poi, mtd->oobsize);
+       } else {
+               /*
+                * If control arrives here, we're not doing a "raw" read. Fill
+                * the OOB buffer with set bits and correct the block mark.
+                */
+               memset(nand->oob_poi, 0xff, mtd->oobsize);
+
+               nand->cmdfunc(mtd, NAND_CMD_READ0, mtd->writesize, page);
+               mxs_nand_read_buf(mtd, nand->oob_poi, 1);
+       }
+
+       return 0;
+
+}
+
+/*
+ * Write OOB data to NAND.
+ */
+static int mxs_nand_ecc_write_oob(struct mtd_info *mtd, struct nand_chip *nand,
+                                       int page)
+{
+       struct mxs_nand_info *nand_info = nand->priv;
+       uint8_t block_mark = 0;
+
+       /*
+        * There are fundamental incompatibilities between the i.MX GPMI NFC and
+        * the NAND Flash MTD model that make it essentially impossible to write
+        * the out-of-band bytes.
+        *
+        * We permit *ONE* exception. If the *intent* of writing the OOB is to
+        * mark a block bad, we can do that.
+        */
+
+       if (!nand_info->marking_block_bad) {
+               printf("NXS NAND: Writing OOB isn't supported\n");
+               return -EIO;
+       }
+
+       /* Write the block mark. */
+       nand->cmdfunc(mtd, NAND_CMD_SEQIN, mtd->writesize, page);
+       nand->write_buf(mtd, &block_mark, 1);
+       nand->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
+
+       /* Check if it worked. */
+       if (nand->waitfunc(mtd, nand) & NAND_STATUS_FAIL)
+               return -EIO;
+
+       return 0;
+}
+
+/*
+ * Claims all blocks are good.
+ *
+ * In principle, this function is *only* called when the NAND Flash MTD system
+ * isn't allowed to keep an in-memory bad block table, so it is forced to ask
+ * the driver for bad block information.
+ *
+ * In fact, we permit the NAND Flash MTD system to have an in-memory BBT, so
+ * this function is *only* called when we take it away.
+ *
+ * Thus, this function is only called when we want *all* blocks to look good,
+ * so it *always* return success.
+ */
+static int mxs_nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip)
+{
+       return 0;
+}
+
+/*
+ * Nominally, the purpose of this function is to look for or create the bad
+ * block table. In fact, since the we call this function at the very end of
+ * the initialization process started by nand_scan(), and we doesn't have a
+ * more formal mechanism, we "hook" this function to continue init process.
+ *
+ * At this point, the physical NAND Flash chips have been identified and
+ * counted, so we know the physical geometry. This enables us to make some
+ * important configuration decisions.
+ *
+ * The return value of this function propogates directly back to this driver's
+ * call to nand_scan(). Anything other than zero will cause this driver to
+ * tear everything down and declare failure.
+ */
+static int mxs_nand_scan_bbt(struct mtd_info *mtd)
+{
+       struct nand_chip *nand = mtd->priv;
+       struct mxs_nand_info *nand_info = nand->priv;
+       struct mx28_bch_regs *bch_regs = (struct mx28_bch_regs *)MXS_BCH_BASE;
+       uint32_t tmp;
+
+       /* Configure BCH and set NFC geometry */
+       mx28_reset_block(&bch_regs->hw_bch_ctrl_reg);
+
+       /* Configure layout 0 */
+       tmp = (mxs_nand_ecc_chunk_cnt(mtd->writesize) - 1)
+               << BCH_FLASHLAYOUT0_NBLOCKS_OFFSET;
+       tmp |= MXS_NAND_METADATA_SIZE << BCH_FLASHLAYOUT0_META_SIZE_OFFSET;
+       tmp |= (mxs_nand_get_ecc_strength(mtd->writesize, mtd->oobsize) >> 1)
+               << BCH_FLASHLAYOUT0_ECC0_OFFSET;
+       tmp |= MXS_NAND_CHUNK_DATA_CHUNK_SIZE;
+       writel(tmp, &bch_regs->hw_bch_flash0layout0);
+
+       tmp = (mtd->writesize + mtd->oobsize)
+               << BCH_FLASHLAYOUT1_PAGE_SIZE_OFFSET;
+       tmp |= (mxs_nand_get_ecc_strength(mtd->writesize, mtd->oobsize) >> 1)
+               << BCH_FLASHLAYOUT1_ECCN_OFFSET;
+       tmp |= MXS_NAND_CHUNK_DATA_CHUNK_SIZE;
+       writel(tmp, &bch_regs->hw_bch_flash0layout1);
+
+       /* Set *all* chip selects to use layout 0 */
+       writel(0, &bch_regs->hw_bch_layoutselect);
+
+       /* Enable BCH complete interrupt */
+       writel(BCH_CTRL_COMPLETE_IRQ_EN, &bch_regs->hw_bch_ctrl_set);
+
+       /* Hook some operations at the MTD level. */
+       if (mtd->read_oob != mxs_nand_hook_read_oob) {
+               nand_info->hooked_read_oob = mtd->read_oob;
+               mtd->read_oob = mxs_nand_hook_read_oob;
+       }
+
+       if (mtd->write_oob != mxs_nand_hook_write_oob) {
+               nand_info->hooked_write_oob = mtd->write_oob;
+               mtd->write_oob = mxs_nand_hook_write_oob;
+       }
+
+       if (mtd->block_markbad != mxs_nand_hook_block_markbad) {
+               nand_info->hooked_block_markbad = mtd->block_markbad;
+               mtd->block_markbad = mxs_nand_hook_block_markbad;
+       }
+
+       /* We use the reference implementation for bad block management. */
+       return nand_default_bbt(mtd);
+}
+
+/*
+ * Allocate DMA buffers
+ */
+int mxs_nand_alloc_buffers(struct mxs_nand_info *nand_info)
+{
+       uint8_t *buf;
+       const int size = NAND_MAX_PAGESIZE + NAND_MAX_OOBSIZE;
+
+       /* DMA buffers */
+       buf = memalign(MXS_DMA_ALIGNMENT, size);
+       if (!buf) {
+               printf("MXS NAND: Error allocating DMA buffers\n");
+               return -ENOMEM;
+       }
+
+       memset(buf, 0, size);
+
+       nand_info->data_buf = buf;
+       nand_info->oob_buf = buf + NAND_MAX_PAGESIZE;
+
+       /* Command buffers */
+       nand_info->cmd_buf = memalign(MXS_DMA_ALIGNMENT,
+                               MXS_NAND_COMMAND_BUFFER_SIZE);
+       if (!nand_info->cmd_buf) {
+               free(buf);
+               printf("MXS NAND: Error allocating command buffers\n");
+               return -ENOMEM;
+       }
+       memset(nand_info->cmd_buf, 0, MXS_NAND_COMMAND_BUFFER_SIZE);
+       nand_info->cmd_queue_len = 0;
+
+       return 0;
+}
+
+/*
+ * Initializes the NFC hardware.
+ */
+int mxs_nand_init(struct mxs_nand_info *info)
+{
+       struct mx28_gpmi_regs *gpmi_regs =
+               (struct mx28_gpmi_regs *)MXS_GPMI_BASE;
+       int i = 0;
+
+       info->desc = malloc(sizeof(struct mxs_dma_desc *) *
+                               MXS_NAND_DMA_DESCRIPTOR_COUNT);
+       if (!info->desc)
+               goto err1;
+
+       /* Allocate the DMA descriptors. */
+       for (i = 0; i < MXS_NAND_DMA_DESCRIPTOR_COUNT; i++) {
+               info->desc[i] = mxs_dma_desc_alloc();
+               if (!info->desc[i])
+                       goto err2;
+       }
+
+       /* Init the DMA controller. */
+       mxs_dma_init();
+
+       /* Reset the GPMI block. */
+       mx28_reset_block(&gpmi_regs->hw_gpmi_ctrl0_reg);
+
+       /*
+        * Choose NAND mode, set IRQ polarity, disable write protection and
+        * select BCH ECC.
+        */
+       clrsetbits_le32(&gpmi_regs->hw_gpmi_ctrl1,
+                       GPMI_CTRL1_GPMI_MODE,
+                       GPMI_CTRL1_ATA_IRQRDY_POLARITY | GPMI_CTRL1_DEV_RESET |
+                       GPMI_CTRL1_BCH_MODE);
+
+       return 0;
+
+err2:
+       free(info->desc);
+err1:
+       for (--i; i >= 0; i--)
+               mxs_dma_desc_free(info->desc[i]);
+       printf("MXS NAND: Unable to allocate DMA descriptors\n");
+       return -ENOMEM;
+}
+
+/*!
+ * This function is called during the driver binding process.
+ *
+ * @param   pdev  the device structure used to store device specific
+ *                information that is used by the suspend, resume and
+ *                remove functions
+ *
+ * @return  The function always returns 0.
+ */
+int board_nand_init(struct nand_chip *nand)
+{
+       struct mxs_nand_info *nand_info;
+       int err;
+
+       nand_info = malloc(sizeof(struct mxs_nand_info));
+       if (!nand_info) {
+               printf("MXS NAND: Failed to allocate private data\n");
+               return -ENOMEM;
+       }
+       memset(nand_info, 0, sizeof(struct mxs_nand_info));
+
+       err = mxs_nand_alloc_buffers(nand_info);
+       if (err)
+               goto err1;
+
+       err = mxs_nand_init(nand_info);
+       if (err)
+               goto err2;
+
+       memset(&fake_ecc_layout, 0, sizeof(fake_ecc_layout));
+
+       nand->priv = nand_info;
+       nand->options |= NAND_NO_SUBPAGE_WRITE;
+
+       nand->cmd_ctrl          = mxs_nand_cmd_ctrl;
+
+       nand->dev_ready         = mxs_nand_device_ready;
+       nand->select_chip       = mxs_nand_select_chip;
+       nand->block_bad         = mxs_nand_block_bad;
+       nand->scan_bbt          = mxs_nand_scan_bbt;
+
+       nand->read_byte         = mxs_nand_read_byte;
+
+       nand->read_buf          = mxs_nand_read_buf;
+       nand->write_buf         = mxs_nand_write_buf;
+
+       nand->ecc.read_page     = mxs_nand_ecc_read_page;
+       nand->ecc.write_page    = mxs_nand_ecc_write_page;
+       nand->ecc.read_oob      = mxs_nand_ecc_read_oob;
+       nand->ecc.write_oob     = mxs_nand_ecc_write_oob;
+
+       nand->ecc.layout        = &fake_ecc_layout;
+       nand->ecc.mode          = NAND_ECC_HW;
+       nand->ecc.bytes         = 9;
+       nand->ecc.size          = 512;
+
+       return 0;
+
+err2:
+       free(nand_info->data_buf);
+       free(nand_info->cmd_buf);
+err1:
+       free(nand_info);
+       return err;
+}