[U-Boot] [PATCH v2 16/16] sf: Add Flag status register polling support

[Simon Glass]

Hi Jagan,

On Sat, Jun 8, 2013 at 1:32 AM, Jagan Teki <jagannadh.teki at gmail.com> wrote:

> Hi Simon,
>
> Please let know your comments.
>
> I have changed the logic, but removed spi_flash_cmd_poll_bit() use
> poll code on spi_flash_cmd_wait_ready()
> as no other call for spi_flash_cmd_poll_bit() this.
>
> And also for read_status the check_status i assigned as 0,earlier it
> has direct 0 (w/o check_status variable).
>
> To add the support for flag status on the same code, i define this
> check_status.
> I don't see any coding functionality change for now, compared to before.
>

This is not the right patch, but in one of them you remove
spi_flash_cmd_poll_bit(),
so that it no longer works the same way. You will get lots of individual
SPI transactions on the bus instead of a single one that reads the status
byte continuously.

Do we need to change this?

Regards,
Simon


>
> --
> Thanks,
> Jagan.
>
> On Fri, May 31, 2013 at 6:22 PM, Jagannadha Sutradharudu Teki
> <jagannadha.sutradharudu-teki at xilinx.com> wrote:
> > Flag status register polling is required for micron 512Mb flash
> > devices onwards, for performing erase/program operations.
> >
> > Like polling for WIP(Write-In-Progress) bit in read status register,
> > spi_flash_cmd_wait_ready will poll for PEC(Program-Erase-Control)
> > bit in flag status register.
> >
> > Signed-off-by: Jagannadha Sutradharudu Teki <jaganna at xilinx.com>
> > ---
> > Changes for v2:
> >         - none
> >
> >  drivers/mtd/spi/spi_flash.c          | 15 ++++++++++++---
> >  drivers/mtd/spi/spi_flash_internal.h |  3 +++
> >  2 files changed, 15 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
> > index 527423d..8cd2988 100644
> > --- a/drivers/mtd/spi/spi_flash.c
> > +++ b/drivers/mtd/spi/spi_flash.c
> > @@ -195,25 +195,34 @@ int spi_flash_cmd_wait_ready(struct spi_flash
> *flash, unsigned long timeout)
> >         unsigned long timebase;
> >         int ret;
> >         u8 status;
> > +       u8 check_status = 0x0;
> >         u8 poll_bit = STATUS_WIP;
> >         u8 cmd = CMD_READ_STATUS;
> >
> > +       if ((flash->idcode0 == 0x20) &&
> > +                       (flash->size >= SPI_FLASH_512MB_STMIC)) {
> > +               poll_bit = STATUS_PEC;
> > +               check_status = poll_bit;
> > +               cmd = CMD_FLAG_STATUS;
> > +       }
> > +
> >         timebase = get_timer(0);
> >         do {
> >                 WATCHDOG_RESET();
> >
> >                 ret = spi_flash_read_common(flash, &cmd, 1, &status, 1);
> >                 if (ret < 0) {
> > -                       debug("SF: fail to read read status register\n");
> > +                       debug("SF: fail to read %s status register\n",
> > +                               cmd == CMD_READ_STATUS ? "read" :
> "flag");
> >                         return ret;
> >                 }
> >
> > -               if ((status & poll_bit) == 0)
> > +               if ((status & poll_bit) == check_status)
> >                         break;
> >
> >         } while (get_timer(timebase) < timeout);
> >
> > -       if ((status & poll_bit) == 0)
> > +       if ((status & poll_bit) == check_status)
> >                 return 0;
> >
> >         /* Timed out */
> > diff --git a/drivers/mtd/spi/spi_flash_internal.h
> b/drivers/mtd/spi/spi_flash_internal.h
> > index ac4530f..cb7a505 100644
> > --- a/drivers/mtd/spi/spi_flash_internal.h
> > +++ b/drivers/mtd/spi/spi_flash_internal.h
> > @@ -13,6 +13,7 @@
> >  #define SPI_FLASH_SECTOR_ERASE_TIMEOUT (10 * CONFIG_SYS_HZ)
> >
> >  #define SPI_FLASH_16MB_BOUN            0x1000000
> > +#define SPI_FLASH_512MB_STMIC          0x4000000
> >
> >  /* Common commands */
> >  #define CMD_READ_ID                    0x9f
> > @@ -24,6 +25,7 @@
> >  #define CMD_PAGE_PROGRAM               0x02
> >  #define CMD_WRITE_DISABLE              0x04
> >  #define CMD_READ_STATUS                        0x05
> > +#define CMD_FLAG_STATUS                        0x70
> >  #define CMD_WRITE_ENABLE               0x06
> >  #define CMD_ERASE_4K                   0x20
> >  #define CMD_ERASE_32K                  0x52
> > @@ -38,6 +40,7 @@
> >
> >  /* Common status */
> >  #define STATUS_WIP                     0x01
> > +#define STATUS_PEC                     0x80
> >
> >  /* Send a single-byte command to the device and read the response */
> >  int spi_flash_cmd(struct spi_slave *spi, u8 cmd, void *response, size_t
> len);
> > --
> > 1.8.3
> >
>