[PATCH-v2 1:2] [MTD][NAND]omap: Adding support for nand prefetch-read and post-write, in MPU mode.

vimal singh
2009-07-10T13:32:15Z

Please ignore previous patch, it had some problem.
Fixing and re-submitting the patch this time.

-vimal

This patch adds prefetch support to access nand flash in mpu 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@ti.com>
---

arch/arm/mach-omap2/gpmc.c | 63 ++++++++++++-
arch/arm/plat-omap/include/mach/gpmc.h | 4
drivers/mtd/nand/Kconfig | 8 +
drivers/mtd/nand/omap2.c | 159 +++++++++++++++++++++++++++++++--
4 files changed, 226 insertions(+), 8 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
@@ -57,6 +57,11 @@
#define GPMC_CHUNK_SHIFT 24 /* 16 MB */
#define GPMC_SECTION_SHIFT 28 /* 128 MB */

+#define PREFETCH_FIFOTHRESHOLD (0x40 << 8)
+#define CS_NUM_SHIFT 24
+#define ENABLE_PREFETCH (0x1 << 7)
+#define DMA_MPU_MODE 2
+
static struct resource gpmc_mem_root;
static struct resource gpmc_cs_mem[GPMC_CS_NUM];
static DEFINE_SPINLOCK(gpmc_mem_lock);
@@ -386,6 +391,63 @@ void gpmc_cs_free(int cs)
}
EXPORT_SYMBOL(gpmc_cs_free);

+/**
+ * gpmc_prefetch_enable - 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
+ */
+int gpmc_prefetch_enable(int cs, int dma_mode,
+ unsigned int u32_count, int is_write)
+{
+ uint32_t prefetch_config1;
+
+ if (!(gpmc_read_reg(GPMC_PREFETCH_CONTROL))) {
+ /* Set the amount of bytes to be prefetched */
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG2, u32_count);
+
+ /* Set dma/mpu mode, the prefetch read / post write and
+ * enable the engine. Set which cs is has requested for.
+ */
+ prefetch_config1 = ((cs << CS_NUM_SHIFT) |
+ PREFETCH_FIFOTHRESHOLD |
+ ENABLE_PREFETCH |
+ (dma_mode << DMA_MPU_MODE) |
+ (0x1 & is_write));
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG1, prefetch_config1);
+ } else {
+ return -EBUSY;
+ }
+ /* Start the prefetch engine */
+ gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x1);
+
+ return 0;
+}
+EXPORT_SYMBOL(gpmc_prefetch_enable);
+
+/**
+ * gpmc_prefetch_reset - disables and stops the prefetch engine
+ */
+void gpmc_prefetch_reset(void)
+{
+ /* Stop the PFPW engine */
+ gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x0);
+
+ /* Reset/disable the PFPW engine */
+ gpmc_write_reg(GPMC_PREFETCH_CONFIG1, 0x0);
+}
+EXPORT_SYMBOL(gpmc_prefetch_reset);
+
+/**
+ * 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);
+
static void __init gpmc_mem_init(void)
{
int cs;
@@ -452,6 +514,5 @@ void __init gpmc_init(void)
l &= 0x03 << 3;
l |= (0x02 << 3) | (1 << 0);
gpmc_write_reg(GPMC_SYSCONFIG, l);
-
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 int gpmc_prefetch_enable(int cs, int dma_mode,
+ unsigned int u32_count, int is_write);
+extern void gpmc_prefetch_reset(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 +80,14 @@ 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_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
@@ -112,6 +112,16 @@
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");
+#else
+const int use_prefetch;
+#endif
+
struct omap_nand_info {
struct nand_hw_control controller;
struct omap_nand_platform_data *pdata;
@@ -124,6 +134,7 @@ struct omap_nand_info {
unsigned long phys_base;
void __iomem *gpmc_cs_baseaddr;
void __iomem *gpmc_baseaddr;
+ void __iomem *nand_pref_fifo_add;
};

/**
@@ -189,6 +200,40 @@ 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
@@ -224,6 +269,94 @@ static void omap_write_buf16(struct mtd_
;
}
}
+
+/**
+ * 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 pfpw_status = 0, r_count = 0;
+ int ret = 0;
+ u32 *p = (u32 *)buf;
+
+ /* 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 */
+ ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);
+ if (ret) {
+ /* PFPW engine is busy, use cpu copy methode */
+ if (info->nand.options & NAND_BUSWIDTH_16)
+ omap_read_buf16(mtd, buf, len);
+ else
+ omap_read_buf8(mtd, buf, len);
+ } else {
+ do {
+ pfpw_status = gpmc_prefetch_status();
+ r_count = ((pfpw_status >> 24) & 0x7F) >> 2;
+ __raw_readsl(info->nand_pref_fifo_add, p, r_count);
+ p += r_count;
+ len -= r_count << 2;
+ } while (len);
+
+ /* disable and stop the PFPW engine */
+ gpmc_prefetch_reset();
+ }
+}
+
+/**
+ * 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 pfpw_status = 0, w_count = 0;
+ int i = 0, ret = 0;
+ u16 *p = (u16 *) buf;
+
+ /* 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 */
+ ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x1);
+ if (ret) {
+ /* PFPW engine is busy, use cpu copy methode */
+ if (info->nand.options & NAND_BUSWIDTH_16)
+ omap_write_buf16(mtd, buf, len);
+ else
+ omap_write_buf8(mtd, buf, len);
+ } else {
+ pfpw_status = gpmc_prefetch_status();
+ while (pfpw_status & 0x3FFF) {
+ w_count = ((pfpw_status >> 24) & 0x7F) >> 1;
+ for (i = 0; (i < w_count) && len; i++, len -= 2)
+ __raw_writew(*p++, info->nand_pref_fifo_add);
+ pfpw_status = gpmc_prefetch_status();
+ }
+
+ /* disable and stop the PFPW engine */
+ gpmc_prefetch_reset();
+ }
+}
+
/**
* omap_verify_buf - Verify chip data against buffer
* @mtd: MTD device structure
@@ -658,17 +791,12 @@ static int __devinit omap_nand_probe(str
err = -ENOMEM;
goto out_release_mem_region;
}
+
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
@@ -689,6 +817,23 @@ static int __devinit omap_nand_probe(str
== 0x1000)
info->nand.options |= NAND_BUSWIDTH_16;

+ if (use_prefetch) {
+ /* copy the virtual address of nand base for fifo access */
+ info->nand_pref_fifo_add = info->nand.IO_ADDR_R;
+
+ 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;
@@ -746,7 +891,7 @@ static int omap_nand_remove(struct platf
platform_set_drvdata(pdev, NULL);
/* 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;
}