RE: [PATCH 1/2] riscv: defconfig: enable spi nor on Hifive Unleashed A00 board.

[Sagar Kadam]

Hello Palmer,

> -----Original Message-----
> From: Palmer Dabbelt <palmer@xxxxxxxxxxx>
> Sent: Tuesday, May 5, 2020 3:40 AM
> To: Sagar Kadam <sagar.kadam@xxxxxxxxxx>
> Cc: tudor.ambarus@xxxxxxxxxxxxx; miquel.raynal@xxxxxxxxxxx;
> richard@xxxxxx; vigneshr@xxxxxx; Paul Walmsley
> <paul.walmsley@xxxxxxxxxx>; linux-riscv@xxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; linux-mtd@xxxxxxxxxxxxxxxxxxx; Sagar Kadam
> <sagar.kadam@xxxxxxxxxx>
> Subject: Re: [PATCH 1/2] riscv: defconfig: enable spi nor on Hifive Unleashed
> A00 board.
> 
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> On Thu, 30 Apr 2020 02:58:51 PDT (-0700), sagar.kadam@xxxxxxxxxx wrote:
> > Enable MTD based SPI-NOR framework in order to use spi flash available
> > on HiFive Unleashed A00 board.
> >
> > Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@xxxxxxxxxx>
> > ---
> >  arch/riscv/configs/defconfig | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/riscv/configs/defconfig
> > b/arch/riscv/configs/defconfig index 4da4886..970580b 100644
> > --- a/arch/riscv/configs/defconfig
> > +++ b/arch/riscv/configs/defconfig
> > @@ -80,6 +80,8 @@ CONFIG_USB_STORAGE=y  CONFIG_USB_UAS=y
> CONFIG_MMC=y
> > CONFIG_MMC_SPI=y
> > +CONFIG_MTD=y
> > +CONFIG_MTD_SPI_NOR=y
> >  CONFIG_RTC_CLASS=y
> >  CONFIG_VIRTIO_PCI=y
> >  CONFIG_VIRTIO_BALLOON=y
> 
> From the second patch's description I'm assuming that MTD still functions
> correctly without that change?

Yes Palmer, the second patch is to enable QUAD write to nor flash..
MTD  function's correctly without second patch.

Using the character interface (/dev/mtd0) mtd_utils (mtd_debug : erase/read/write) work fine.
We might require CONFIG_MTD_BLOCK, CONFIG_MTD_CMDLINE_PARTS  in order to use MTD partitioning.
IMHO it can be at user's choice weather to use flash partitions or not, so I have not enabled. Please let me 
know if I should enable these features as well.

To demonstrate a bit more with linux 5.7-rc3 

Specify on U-boot prompt:
# setenv bootargs "root=/dev/ram rw console=ttySIF0 mtdparts=spi0.0:1024k(loader1),4096K(loader2),26M(rootfs)"

After booting linux will enumerate mtd partitions:
# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00100000 00001000 "loader1"
mtd1: 00400000 00001000 "loader2"
mtd2: 01a00000 00001000 "rootfs"

# cat /proc/partitions
major minor  #blocks  name
  31        0       1024 mtdblock0
  31        1       4096 mtdblock1
  31        2      26624 mtdblock2

#Format mtdblock2 with mkfs.ext3/4 and mount results in
# mkfs.ext3 /dev/mtdblock2
mke2fs 1.44.5 (15-Dec-2018)
/dev/mtdblock2 contains a ext3 file system
        last mounted on /mnt on Thu Jan  1 00:00:14 1970
Proceed anyway? (y,N) y
Creating filesystem with 26624 1k blocks and 6656 inodes
Filesystem UUID: 1b09252d-e313-430c-9ecb-79b0cef003ca
Superblock backups stored on blocks:
        8193, 24577

Allocating group tables: done
Writing inode tables: done
Creating journal (1024 blocks): done
Writing superblocks and filesystem accounting information: done

# mount
none on / type rootfs (rw)
proc on /proc type proc (rw,relatime)
devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620,ptmxmode=666)
tmpfs on /dev/shm type tmpfs (rw,relatime,mode=777)
tmpfs on /tmp type tmpfs (rw,relatime)
tmpfs on /run type tmpfs (rw,nosuid,nodev,relatime,mode=755)
sysfs on /sys type sysfs (rw,relatime)
/dev/mtdblock2 on /mnt type ext3 (rw,relatime)

Thanks & BR,
Sagar Kadam