mtd: omap: add support for nand prefetch-read and post-write

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>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 62 insertions, 1 deletions

diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
index f91934b2b092..15876828db23 100644
--- a/arch/arm/mach-omap2/gpmc.c
+++ b/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();
 }