[U-Boot] [PATCHv2 1/3] nand_spl_simple: Add a simple flash read function

Ladislav Michl ladis at linux-mips.org
Mon Jan 4 22:17:50 CET 2016


On Mon, Jan 04, 2016 at 07:38:23PM +0100, Ladislav Michl wrote:
> On Mon, Jan 04, 2016 at 12:23:36PM -0600, Scott Wood wrote:
> > On Mon, 2016-01-04 at 16:54 +0100, Ladislav Michl wrote:
> > > From: Thomas Gleixner <tglx at linutronix.de>
> > > 
> > > To support UBI in SPL we need a simple flash read function. Add one to
> > > nand_spl_simple and keep it as simple as it goes.
> > > 
> > > Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
> > 
> > Where is your signoff?
> 
> I'm only messenger and have nothing to do with this part of patch. The other
> part which I touched has my signoff.
> 
> > Did Thomas really write this patch for U-Boot (if so, why isn't he on CC?) or
> > is it taken from some other project?
> 
> Ha! It is my mailer which broke Cc. Thomas was on Cc list and still is in my
> sent-mail folder. Also apologize to Marek, let's see how Cc will end this time.
> And yes, patch was written for U-Boot: https://patchwork.ozlabs.org/patch/367305/

Well, seems to be mailman configuration:
https://mail.python.org/pipermail/mailman-users/2006-May/051194.html
so those who received post via mailman are seeing striped Cc line. Thanks to
Nathan Lynch for pointing it out.
Full Cc list:
Cc: Scott Wood <oss at buserror.net>
Cc: Tom Rini <trini at konsulko.com>
Cc: Heiko Schocher <hs at denx.de>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Richard Weinberger <richard at nod.at>
Cc: Marek Vasut <marex at denx.de>

> > > ---
> > >  drivers/mtd/nand/nand_spl_simple.c | 64
> > > ++++++++++++++++++++++++++++++++++++++
> > >  include/nand.h                     |  1 +
> > >  2 files changed, 65 insertions(+)
> > > 
> > > diff --git a/drivers/mtd/nand/nand_spl_simple.c
> > > b/drivers/mtd/nand/nand_spl_simple.c
> > > index e69f662..2e1af53 100644
> > > --- a/drivers/mtd/nand/nand_spl_simple.c
> > > +++ b/drivers/mtd/nand/nand_spl_simple.c
> > > @@ -209,6 +209,70 @@ 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_flash - Read data from flash into a buffer
> > > + * @pnum:	Number of the physical eraseblock
> > 
> > s/pnum/block/g
> > 
> > > + * @offset:	Data offset from the start of @pnum
> > > + * @len:	Data size to read
> > > + * @dest:	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 its a non issue anyway.
> > > + */
> > > +int nand_spl_read_flash(u32 pnum, u32 offset, u32 len, void *dest)
> > 
> > This name is too generic and doesn't suggest what's different compared to
> > nand_spl_load_image (they both read data from flash into a buffer).
> > 
> > How about nand_spl_read_block()?
> 
> ok.

Thinking about it more, I'd rather see nand_spl_read_peb(int peb, ...
but that is not consistent with other nand reading functions.

> > > +{
> > > +	u32 offs, page, read, toread = len;
> > > +
> > > +	/* Calculate the page number */
> > > +	page = offset / CONFIG_SYS_NAND_PAGE_SIZE;
> > > +
> > > +	/* Offset to the start of a flash page */
> > > +	offs = offset % CONFIG_SYS_NAND_PAGE_SIZE;
> > > +
> > > +	while (toread) {
> > > +		/*
> > > +		 * Non page aligned reads go to the scratch buffer.
> > > +		 * Page aligned reads go directly to the destination.
> > > +		 */
> > > +		if (offs || toread < CONFIG_SYS_NAND_PAGE_SIZE) {
> > > +			nand_read_page(pnum, page, scratch_buf);
> > > +			read = min(len, toread);
> > 
> > toread is always <= len, so this is pointless.  As this is the only use of len
> > after the toread init, once this is gone you could also eliminate toread and
> > just use len.
> 
> ok, will change that.

What about something like this? Changelog will be appended to v3.
Btw, any comments to other patches in this serie?

-- >8 --

From: Thomas Gleixner <tglx at linutronix.de>
Subject: nand_spl_simple: Add a simple NAND read function
    
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 at linutronix.de>
Signed-off-by: Ladislav Michl <ladis at linux-mips.org>

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


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