[U-Boot] [PATCHv4 2/7] nand_spl_simple: Add a simple NAND read function

Ladislav Michl
2016-01-17T03:12:18Z

From: Thomas Gleixner <tglx@linutronix.de>

To support UBI in SPL we need a simple NAND read function. Add one to
nand_spl_simple and keep it as simple as it goes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Acked-by: Scott Wood <oss@buserror.net>
Reviewed-by: Tom Rini <trini@konsulko.com>
---
Changes in v3:
- Rename nand_spl_read_flash to nand_spl_read_block and optimize it.

drivers/mtd/nand/nand_spl_simple.c | 62 ++++++++++++++++++++++++++++++++++++++
include/nand.h | 1 +
2 files changed, 63 insertions(+)

diff --git a/drivers/mtd/nand/nand_spl_simple.c b/drivers/mtd/nand/nand_spl_simple.c
index e69f662..cf80903 100644
--- a/drivers/mtd/nand/nand_spl_simple.c
+++ b/drivers/mtd/nand/nand_spl_simple.c
@@ -209,6 +209,68 @@ static int nand_read_page(int block, int page, void *dst)
}
#endif

+#ifdef CONFIG_SPL_UBI
+/*
+ * Temporary storage for non NAND page aligned and non NAND page sized
+ * reads. Note: This does not support runtime detected FLASH yet, but
+ * that should be reasonably easy to fix by making the buffer large
+ * enough :)
+ */
+static u8 scratch_buf[CONFIG_SYS_NAND_PAGE_SIZE];
+
+/**
+ * nand_spl_read_block - Read data from physical eraseblock into a buffer
+ * @block: Number of the physical eraseblock
+ * @offset: Data offset from the start of @peb
+ * @len: Data size to read
+ * @dst: Address of the destination buffer
+ *
+ * This could be further optimized if we'd have a subpage read
+ * function in the simple code. On NAND which allows subpage reads
+ * this would spare quite some time to readout e.g. the VID header of
+ * UBI.
+ *
+ * Notes:
+ * @offset + @len are not allowed to be larger than a physical
+ * erase block. No sanity check done for simplicity reasons.
+ *
+ * To support runtime detected flash this needs to be extended by
+ * information about the actual flash geometry, but thats beyond the
+ * scope of this effort and for most applications where fast boot is
+ * required it is not an issue anyway.
+ */
+int nand_spl_read_block(int block, int offset, int len, void *dst)
+{
+ int page, read;
+
+ /* Calculate the page number */
+ page = offset / CONFIG_SYS_NAND_PAGE_SIZE;
+
+ /* Offset to the start of a flash page */
+ offset = offset % CONFIG_SYS_NAND_PAGE_SIZE;
+
+ while (len) {
+ /*
+ * Non page aligned reads go to the scratch buffer.
+ * Page aligned reads go directly to the destination.
+ */
+ if (offset || len < CONFIG_SYS_NAND_PAGE_SIZE) {
+ nand_read_page(block, page, scratch_buf);
+ read = min(len, CONFIG_SYS_NAND_PAGE_SIZE - offset);
+ memcpy(dst, scratch_buf + offset, read);
+ offset = 0;
+ } else {
+ nand_read_page(block, page, dst);
+ read = CONFIG_SYS_NAND_PAGE_SIZE;
+ }
+ page++;
+ len -= read;
+ dst += read;
+ }
+ return 0;
+}
+#endif
+
int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst)
{
unsigned int block, lastblock;
diff --git a/include/nand.h b/include/nand.h
index d2a53ab..2f9a1ec 100644
--- a/include/nand.h
+++ b/include/nand.h
@@ -124,6 +124,7 @@ int nand_unlock(nand_info_t *meminfo, loff_t start, size_t length,
int nand_get_lock_status(nand_info_t *meminfo, loff_t offset);

int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst);
+int nand_spl_read_block(int block, int offset, int len, void *dst);
void nand_deselect(void);

#ifdef CONFIG_SYS_NAND_SELECT_DEVICE
--
2.1.4