[PATCH] [MTD] [NAND] Add prefetch and dma support for omap2/3 NAND driver

From: vimal singh
Date: Tue Jun 02 2009 - 08:38:23 EST

This patch adds prefetch support to access nand flash in both mpu and dma mode.
This patch also adds 8-bit nand support (omap_read/write_buf8).
Prefetch can be used for both 8- and 16-bit devices.

Signed-off-by: Vimal Singh <vimalsingh@xxxxxx>
---
I prepared this patch on top of "OMAP2 / OMAP3 NAND driver" patch:
http://lists.infradead.org/pipermail/linux-mtd/2009-May/025562.html

---
arch/arm/mach-omap2/gpmc.c | 102 ++++++++++
arch/arm/plat-omap/include/mach/gpmc.h | 4
drivers/mtd/nand/Kconfig | 17 +
drivers/mtd/nand/omap2.c | 308 ++++++++++++++++++++++++++++++++-
4 files changed, 422 insertions(+), 9 deletions(-)

Index: mtd-2.6/arch/arm/mach-omap2/gpmc.c
===================================================================
--- mtd-2.6.orig/arch/arm/mach-omap2/gpmc.c
+++ mtd-2.6/arch/arm/mach-omap2/gpmc.c
@@ -54,6 +54,12 @@
#define GPMC_CHUNK_SHIFT 24 /* 16 MB */
#define GPMC_SECTION_SHIFT 28 /* 128 MB */

+#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH
+#define CS_NUM_SHIFT 24
+#define ENABLE_PREFETCH 7
+#define DMA_MPU_MODE 2
+#endif
+
static struct resource gpmc_mem_root;
static struct resource gpmc_cs_mem[GPMC_CS_NUM];
static DEFINE_SPINLOCK(gpmc_mem_lock);
@@ -383,6 +389,99 @@ void gpmc_cs_free(int cs)
}
EXPORT_SYMBOL(gpmc_cs_free);

+#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH
+/**
+ * gpmc_prefetch_init - configures default configuration for prefetch engine
+ */
+static void gpmc_prefetch_init(void)
+{
+ /* Setting the default threshold to 64 */
+ gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x0);
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG1, 0x40 << 8);
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG2, 0x0);
+}
+
+/**
+ * gpmc_prefetch_start - configures and starts prefetch transfer
+ * @cs: nand cs (chip select) number
+ * @dma_mode: dma mode enable (1) or disable (0)
+ * @u32_count: number of bytes to be transferred
+ * @is_write: prefetch read(0) or write post(1) mode
+ */
+void gpmc_prefetch_start(int cs, int dma_mode,
+ unsigned int u32_count, int is_write)
+{
+ uint32_t prefetch_config1;
+ if (is_write) {
+ /* Set the amount of bytes to be prefetched */
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG2, u32_count);
+
+ /* Set dma/mpu mode, the post write and enable the engine
+ * Set which cs is using the post write
+ */
+ prefetch_config1 = gpmc_read_reg(GPMC_PREFETCH_CONFIG1);
+ prefetch_config1 |= ((cs << CS_NUM_SHIFT) |
+ (dma_mode << DMA_MPU_MODE) |
+ (1 << ENABLE_PREFETCH) | 0x1);
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG1, prefetch_config1);
+ } else {
+ /* Set the amount of bytes to be prefetched */
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG2, u32_count);
+
+ /* Set dma/mpu mode, the prefech read and enable the engine
+ * Set which cs is using the prefetch
+ */
+ prefetch_config1 = gpmc_read_reg(GPMC_PREFETCH_CONFIG1);
+ prefetch_config1 |= (((cs << CS_NUM_SHIFT) |
+ (dma_mode << DMA_MPU_MODE) |
+ (1 << ENABLE_PREFETCH)) & ~0x1);
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG1, prefetch_config1);
+ }
+ /* Start the prefetch engine */
+ gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x1);
+}
+EXPORT_SYMBOL(gpmc_prefetch_start);
+
+/**
+ * gpmc_prefetch_stop - disables and stops the prefetch engine
+ */
+void gpmc_prefetch_stop(void)
+{
+ uint32_t prefetch_config1;
+ /* stop the PFPW engine */
+ gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x0);
+
+ /* Disable the PFPW engine */
+ prefetch_config1 = gpmc_read_reg(GPMC_PREFETCH_CONFIG1);
+ prefetch_config1 &= ~((0x07 << CS_NUM_SHIFT) |
+ (1 << ENABLE_PREFETCH) |
+ (1 << DMA_MPU_MODE) | 0x1);
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG1, prefetch_config1);
+}
+EXPORT_SYMBOL(gpmc_prefetch_stop);
+
+/**
+ * gpmc_prefetch_status - reads prefetch status of engine
+ */
+int gpmc_prefetch_status(void)
+{
+ return gpmc_read_reg(GPMC_PREFETCH_STATUS);
+}
+EXPORT_SYMBOL(gpmc_prefetch_status);
+#else
+int gpmc_prefetch_status(void)
+{
+ return 0;
+}
+void gpmc_prefetch_stop(void)
+{
+}
+void gpmc_prefetch_start(int cs, int dma_mode,
+ unsigned int u32_count, int is_write)
+{
+}
+#endif
+
static void __init gpmc_mem_init(void)
{
int cs;
@@ -447,5 +546,8 @@ void __init gpmc_init(void)
l |= (0x02 << 3) | (1 << 0);
gpmc_write_reg(GPMC_SYSCONFIG, l);

+#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH
+ gpmc_prefetch_init();
+#endif
gpmc_mem_init();
}
Index: mtd-2.6/arch/arm/plat-omap/include/mach/gpmc.h
===================================================================
--- mtd-2.6.orig/arch/arm/plat-omap/include/mach/gpmc.h
+++ mtd-2.6/arch/arm/plat-omap/include/mach/gpmc.h
@@ -103,6 +103,10 @@ extern int gpmc_cs_request(int cs, unsig
extern void gpmc_cs_free(int cs);
extern int gpmc_cs_set_reserved(int cs, int reserved);
extern int gpmc_cs_reserved(int cs);
+extern void gpmc_prefetch_start(int cs, int dma_mode,
+ unsigned int u32_count, int is_write);
+extern void gpmc_prefetch_stop(void);
+extern int gpmc_prefetch_status(void);
extern void __init gpmc_init(void);

#endif
Index: mtd-2.6/drivers/mtd/nand/Kconfig
===================================================================
--- mtd-2.6.orig/drivers/mtd/nand/Kconfig
+++ mtd-2.6/drivers/mtd/nand/Kconfig
@@ -80,6 +80,23 @@ config MTD_NAND_OMAP2
help
Support for NAND flash on Texas Instruments OMAP2 and OMAP3 platforms.

+config MTD_NAND_OMAP_PREFETCH
+ bool "GPMC prefetch support for NAND Flash device"
+ depends on MTD_NAND && MTD_NAND_OMAP2
+ default y
+ help
+ 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
Index: mtd-2.6/drivers/mtd/nand/omap2.c
===================================================================
--- mtd-2.6.orig/drivers/mtd/nand/omap2.c
+++ mtd-2.6/drivers/mtd/nand/omap2.c
@@ -16,8 +16,7 @@
#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>

@@ -110,6 +109,27 @@
static const char *part_probes[] = { "cmdlinepart", NULL };
#endif

+#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH
+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 {
struct nand_hw_control controller;
struct omap_nand_platform_data *pdata;
@@ -122,6 +142,9 @@ struct omap_nand_info {
unsigned long phys_base;
void __iomem *gpmc_cs_baseaddr;
void __iomem *gpmc_baseaddr;
+ void __iomem *nand_pref_fifo_add;
+ struct completion comp;
+ int dma_ch;
};

/**
@@ -187,6 +210,40 @@ static void omap_hwcontrol(struct mtd_in
}

/**
+ * omap_read_buf8 - 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_buf8(struct mtd_info *mtd, u_char *buf, int len)
+{
+ struct nand_chip *nand = mtd->priv;
+ u_char *p = (u_char *)buf;
+
+ while (len--)
+ *p++ = __raw_readb(nand->IO_ADDR_R);
+}
+
+/**
+ * omap_write_buf8 - write buffer to NAND controller
+ * @mtd: MTD device structure
+ * @buf: data buffer
+ * @len: number of bytes to write
+ */
+static void omap_write_buf8(struct mtd_info *mtd, const u_char *buf, int len)
+{
+ struct omap_nand_info *info = container_of(mtd,
+ struct omap_nand_info, mtd);
+ u_char *p = (u_char *)buf;
+
+ while (len--) {
+ writeb(*p++, info->nand.IO_ADDR_W);
+ while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
+ GPMC_STATUS) & GPMC_BUF_FULL));
+ }
+}
+
+/**
* omap_read_buf16 - read data from NAND controller into buffer
* @mtd: MTD device structure
* @buf: buffer to store date
@@ -222,6 +279,205 @@ static void omap_write_buf16(struct 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;
+
+ /* The fifo depth is 64 bytes. We have a sync at each frame and frame
+ * length is 64 bytes.
+ */
+ int buf_len = len/64;
+
+ 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_dest_burst_mode(info->dma_ch, OMAP_DMA_DATA_BURST_16);
+ omap_set_dma_src_params(info->dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
+ dma_addr, 0, 0);
+ omap_set_dma_src_burst_mode(info->dma_ch, OMAP_DMA_DATA_BURST_16);
+ 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_src_burst_mode(info->dma_ch, OMAP_DMA_DATA_BURST_16);
+ omap_set_dma_dest_params(info->dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
+ dma_addr, 0, 0);
+ omap_set_dma_dest_burst_mode(info->dma_ch, OMAP_DMA_DATA_BURST_16);
+ 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 */
+ gpmc_prefetch_start(info->gpmc_cs, 0x1, len, is_write);
+ 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_stop();
+
+ 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_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_pref(struct mtd_info *mtd, u_char *buf, int len)
+{
+ struct omap_nand_info *info = container_of(mtd,
+ struct omap_nand_info, mtd);
+ uint32_t prefetch_status = 0, read_count = 0;
+ u32 *p = (u32 *)buf;
+
+ if ((use_dma && len <= mtd->oobsize) || (!use_dma)) {
+
+ /* take care of subpage reads */
+ for (; len % 4 != 0; ) {
+ *buf++ = __raw_readb(info->nand.IO_ADDR_R);
+ len--;
+ }
+ p = (u32 *) buf;
+
+ /* configure and start prefetch transfer */
+ gpmc_prefetch_start(info->gpmc_cs, 0x0, len, 0x0);
+
+ do {
+ prefetch_status = gpmc_prefetch_status();
+ read_count = ((prefetch_status >> 24) & 0x7F) >> 2;
+ __raw_readsl(info->nand_pref_fifo_add, p,
+ read_count);
+ p += read_count;
+ len -= read_count << 2;
+ } while (len);
+
+ /* disable and stop the PFPW engine */
+ gpmc_prefetch_stop();
+ } else if (use_dma) {
+ if (info->dma_ch >= 0)
+ /* start transfer in DMA mode */
+ omap_nand_dma_transfer(mtd, p, len, 0x0);
+ }
+}
+
+/**
+ * omap_write_buf_pref - write buffer to NAND controller
+ * @mtd: MTD device structure
+ * @buf: data buffer
+ * @len: number of bytes to write
+ */
+static void omap_write_buf_pref(struct mtd_info *mtd,
+ const u_char *buf, int len)
+{
+ struct omap_nand_info *info = container_of(mtd,
+ struct omap_nand_info, mtd);
+ uint32_t prefetch_status = 0, write_count = 0;
+ int i = 0;
+ u16 *p = (u16 *) buf;
+
+ if ((use_dma && len <= mtd->oobsize) || (!use_dma)) {
+
+ /* take care of subpage writes */
+ if (len % 2 != 0) {
+ writeb(*buf, info->nand.IO_ADDR_R);
+ p = (u16 *)(buf + 1);
+ len--;
+ }
+
+ /* configure and start prefetch transfer */
+ gpmc_prefetch_start(info->gpmc_cs, 0x0, len, 0x1);
+
+ prefetch_status = gpmc_prefetch_status();
+ while (prefetch_status & 0x3FFF) {
+ write_count = ((prefetch_status >> 24) & 0x7F) >> 1;
+ for (i = 0; (i < write_count) && len; i++, len -= 2)
+ __raw_writew(*p++, info->nand_pref_fifo_add);
+ prefetch_status = gpmc_prefetch_status();
+ }
+
+ /* disable and stop the PFPW engine */
+ gpmc_prefetch_stop();
+ } else if (use_dma) {
+ if (info->dma_ch >= 0)
+ /* start transfer in DMA mode */
+ omap_nand_dma_transfer(mtd, p, len, 0x1);
+ }
+}
+
/**
* omap_verify_buf - Verify chip data against buffer
* @mtd: MTD device structure
@@ -655,17 +911,25 @@ static int __devinit omap_nand_probe(str
err = -ENOMEM;
goto out_release_mem_region;
}
+
+ if (use_prefetch) {
+ /* copy the virtual address of nand base for fifo access */
+ info->nand_pref_fifo_add = info->nand.IO_ADDR_R;
+ 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");
+ }
+ }
+ }
info->nand.controller = &info->controller;

info->nand.IO_ADDR_W = info->nand.IO_ADDR_R;
info->nand.cmd_ctrl = omap_hwcontrol;

- /* REVISIT: only supports 16-bit NAND flash */
-
- info->nand.read_buf = omap_read_buf16;
- info->nand.write_buf = omap_write_buf16;
- info->nand.verify_buf = omap_verify_buf;
-
/*
* If RDY/BSY line is connected to OMAP then use the omap ready
* funcrtion and the generic nand_wait function which reads the status
@@ -686,6 +950,20 @@ static int __devinit omap_nand_probe(str
== 0x1000)
info->nand.options |= NAND_BUSWIDTH_16;

+ if (use_prefetch) {
+ info->nand.read_buf = omap_read_buf_pref;
+ info->nand.write_buf = omap_write_buf_pref;
+ } else {
+ if (info->nand.options & NAND_BUSWIDTH_16) {
+ info->nand.read_buf = omap_read_buf16;
+ info->nand.write_buf = omap_write_buf16;
+ } else {
+ info->nand.read_buf = omap_read_buf8;
+ info->nand.write_buf = omap_write_buf8;
+ }
+ }
+ info->nand.verify_buf = omap_verify_buf;
+
#ifdef CONFIG_MTD_NAND_OMAP_HWECC
info->nand.ecc.bytes = 3;
info->nand.ecc.size = 512;
@@ -741,9 +1019,12 @@ static int omap_nand_remove(struct platf
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.IO_ADDR_R);
+ iounmap(info->nand_pref_fifo_add);
kfree(&info->mtd);
return 0;
}
@@ -760,6 +1041,15 @@ static struct platform_driver omap_nand_
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);
}



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