mtd: omap: adding DMA mode support in nand prefetch/post-write

This patch adds DMA mode support for nand prefetch/post-write engine.

Signed-off-by: Vimal Singh <vimalsingh@ti.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

2 files changed, 193 insertions, 2 deletions

diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index 7dab79caed44..2c9a0ed4aed8 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -88,6 +88,15 @@ config MTD_NAND_OMAP_PREFETCH
          The NAND device can be accessed for Read/Write using GPMC PREFETCH engine
          to improve the performance.
 
+config MTD_NAND_OMAP_PREFETCH_DMA
+        depends on MTD_NAND_OMAP_PREFETCH
+        bool "DMA mode"
+        default n
+        help
+         The GPMC PREFETCH engine can be configured eigther in MPU interrupt mode
+         or in DMA interrupt mode.
+         Say y for DMA mode or MPU mode will be used
+
 config MTD_NAND_TS7250
         tristate "NAND Flash device on TS-7250 board"
         depends on MACH_TS72XX
diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 6736822c4751..090ab87086b5 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -18,8 +18,7 @@
 #include <linux/mtd/partitions.h>
 #include <linux/io.h>
 
-#include <asm/dma.h>
-
+#include <mach/dma.h>
 #include <mach/gpmc.h>
 #include <mach/nand.h>
 
@@ -118,8 +117,19 @@ static int use_prefetch = 1;
 /* "modprobe ... use_prefetch=0" etc */
 module_param(use_prefetch, bool, 0);
 MODULE_PARM_DESC(use_prefetch, "enable/disable use of PREFETCH");
+
+#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH_DMA
+static int use_dma = 1;
+
+/* "modprobe ... use_dma=0" etc */
+module_param(use_dma, bool, 0);
+MODULE_PARM_DESC(use_dma, "enable/disable use of DMA");
+#else
+const int use_dma;
+#endif
 #else
 const int use_prefetch;
+const int use_dma;
 #endif
 
 struct omap_nand_info {
@@ -135,6 +145,8 @@ struct omap_nand_info {
         void __iomem                    *gpmc_cs_baseaddr;
         void __iomem                    *gpmc_baseaddr;
         void __iomem                    *nand_pref_fifo_add;
+        struct completion               comp;
+        int                             dma_ch;
 };
 
 /**
@@ -355,6 +367,147 @@ static void omap_write_buf_pref(struct mtd_info *mtd,
         }
 }
 
+#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH_DMA
+/*
+ * omap_nand_dma_cb: callback on the completion of dma transfer
+ * @lch: logical channel
+ * @ch_satuts: channel status
+ * @data: pointer to completion data structure
+ */
+static void omap_nand_dma_cb(int lch, u16 ch_status, void *data)
+{
+        complete((struct completion *) data);
+}
+
+/*
+ * omap_nand_dma_transfer: configer and start dma transfer
+ * @mtd: MTD device structure
+ * @addr: virtual address in RAM of source/destination
+ * @len: number of data bytes to be transferred
+ * @is_write: flag for read/write operation
+ */
+static inline int omap_nand_dma_transfer(struct mtd_info *mtd, void *addr,
+                                        unsigned int len, int is_write)
+{
+        struct omap_nand_info *info = container_of(mtd,
+                                        struct omap_nand_info, mtd);
+        uint32_t prefetch_status = 0;
+        enum dma_data_direction dir = is_write ? DMA_TO_DEVICE :
+                                                        DMA_FROM_DEVICE;
+        dma_addr_t dma_addr;
+        int ret;
+
+        /* The fifo depth is 64 bytes. We have a sync at each frame and frame
+         * length is 64 bytes.
+         */
+        int buf_len = len >> 6;
+
+        if (addr >= high_memory) {
+                struct page *p1;
+
+                if (((size_t)addr & PAGE_MASK) !=
+                        ((size_t)(addr + len - 1) & PAGE_MASK))
+                        goto out_copy;
+                p1 = vmalloc_to_page(addr);
+                if (!p1)
+                        goto out_copy;
+                addr = page_address(p1) + ((size_t)addr & ~PAGE_MASK);
+        }
+
+        dma_addr = dma_map_single(&info->pdev->dev, addr, len, dir);
+        if (dma_mapping_error(&info->pdev->dev, dma_addr)) {
+                dev_err(&info->pdev->dev,
+                        "Couldn't DMA map a %d byte buffer\n", len);
+                goto out_copy;
+        }
+
+        if (is_write) {
+            omap_set_dma_dest_params(info->dma_ch, 0, OMAP_DMA_AMODE_CONSTANT,
+                                                info->phys_base, 0, 0);
+            omap_set_dma_src_params(info->dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
+                                                        dma_addr, 0, 0);
+            omap_set_dma_transfer_params(info->dma_ch, OMAP_DMA_DATA_TYPE_S32,
+                                        0x10, buf_len, OMAP_DMA_SYNC_FRAME,
+                                        OMAP24XX_DMA_GPMC, OMAP_DMA_DST_SYNC);
+        } else {
+            omap_set_dma_src_params(info->dma_ch, 0, OMAP_DMA_AMODE_CONSTANT,
+                                                info->phys_base, 0, 0);
+            omap_set_dma_dest_params(info->dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
+                                                        dma_addr, 0, 0);
+            omap_set_dma_transfer_params(info->dma_ch, OMAP_DMA_DATA_TYPE_S32,
+                                        0x10, buf_len, OMAP_DMA_SYNC_FRAME,
+                                        OMAP24XX_DMA_GPMC, OMAP_DMA_SRC_SYNC);
+        }
+        /*  configure and start prefetch transfer */
+        ret = gpmc_prefetch_enable(info->gpmc_cs, 0x1, len, is_write);
+        if (ret)
+                /* PFPW engine is busy, use cpu copy methode */
+                goto out_copy;
+
+        init_completion(&info->comp);
+
+        omap_start_dma(info->dma_ch);
+
+        /* setup and start DMA using dma_addr */
+        wait_for_completion(&info->comp);
+
+        while (0x3fff & (prefetch_status = gpmc_prefetch_status()))
+                ;
+        /* disable and stop the PFPW engine */
+        gpmc_prefetch_reset();
+
+        dma_unmap_single(&info->pdev->dev, dma_addr, len, dir);
+        return 0;
+
+out_copy:
+        if (info->nand.options & NAND_BUSWIDTH_16)
+                is_write == 0 ? omap_read_buf16(mtd, (u_char *) addr, len)
+                        : omap_write_buf16(mtd, (u_char *) addr, len);
+        else
+                is_write == 0 ? omap_read_buf8(mtd, (u_char *) addr, len)
+                        : omap_write_buf8(mtd, (u_char *) addr, len);
+        return 0;
+}
+#else
+static void omap_nand_dma_cb(int lch, u16 ch_status, void *data) {}
+static inline int omap_nand_dma_transfer(struct mtd_info *mtd, void *addr,
+                                        unsigned int len, int is_write)
+{
+        return 0;
+}
+#endif
+
+/**
+ * omap_read_buf_dma_pref - read data from NAND controller into buffer
+ * @mtd: MTD device structure
+ * @buf: buffer to store date
+ * @len: number of bytes to read
+ */
+static void omap_read_buf_dma_pref(struct mtd_info *mtd, u_char *buf, int len)
+{
+        if (len <= mtd->oobsize)
+                omap_read_buf_pref(mtd, buf, len);
+        else
+                /* start transfer in DMA mode */
+                omap_nand_dma_transfer(mtd, buf, len, 0x0);
+}
+
+/**
+ * omap_write_buf_dma_pref - write buffer to NAND controller
+ * @mtd: MTD device structure
+ * @buf: data buffer
+ * @len: number of bytes to write
+ */
+static void omap_write_buf_dma_pref(struct mtd_info *mtd,
+                                        const u_char *buf, int len)
+{
+        if (len <= mtd->oobsize)
+                omap_write_buf_pref(mtd, buf, len);
+        else
+                /* start transfer in DMA mode */
+                omap_nand_dma_transfer(mtd, buf, len, 0x1);
+}
+
 /**
  * omap_verify_buf - Verify chip data against buffer
  * @mtd: MTD device structure
@@ -821,6 +974,23 @@ static int __devinit omap_nand_probe(struct platform_device *pdev)
 
                 info->nand.read_buf   = omap_read_buf_pref;
                 info->nand.write_buf  = omap_write_buf_pref;
+                if (use_dma) {
+                        err = omap_request_dma(OMAP24XX_DMA_GPMC, "NAND",
+                                omap_nand_dma_cb, &info->comp, &info->dma_ch);
+                        if (err < 0) {
+                                info->dma_ch = -1;
+                                printk(KERN_WARNING "DMA request failed."
+                                        " Non-dma data transfer mode\n");
+                        } else {
+                                omap_set_dma_dest_burst_mode(info->dma_ch,
+                                                OMAP_DMA_DATA_BURST_16);
+                                omap_set_dma_src_burst_mode(info->dma_ch,
+                                                OMAP_DMA_DATA_BURST_16);
+
+                                info->nand.read_buf   = omap_read_buf_dma_pref;
+                                info->nand.write_buf  = omap_write_buf_dma_pref;
+                        }
+                }
         } else {
                 if (info->nand.options & NAND_BUSWIDTH_16) {
                         info->nand.read_buf   = omap_read_buf16;
@@ -887,6 +1057,9 @@ static int omap_nand_remove(struct platform_device *pdev)
         struct omap_nand_info *info = mtd->priv;
 
         platform_set_drvdata(pdev, NULL);
+        if (use_dma)
+                omap_free_dma(info->dma_ch);
+
         /* Release NAND device, its internal structures and partitions */
         nand_release(&info->mtd);
         iounmap(info->nand_pref_fifo_add);
@@ -906,6 +1079,15 @@ static struct platform_driver omap_nand_driver = {
 static int __init omap_nand_init(void)
 {
         printk(KERN_INFO "%s driver initializing\n", DRIVER_NAME);
+
+        /* This check is required if driver is being
+         * loaded run time as a module
+         */
+        if ((1 == use_dma) && (0 == use_prefetch)) {
+                printk(KERN_INFO"Wrong parameters: 'use_dma' can not be 1 "
+                                "without use_prefetch'. Prefetch will not be"
+                                " used in either mode (mpu or dma)\n");
+        }
         return platform_driver_register(&omap_nand_driver);
 }