Re: [RFC PATCH v4 1/2] hw/riscv: sifive_u: Add backend drive support

[Green Wan]

Hi Bin,

Thanks for the remindings. I didn't notice the write operation and
will add the write functionality based on bit by bit mechanism.

Regards,
Green


On Fri, Aug 28, 2020 at 8:54 PM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> Hi Green,
>
> On Thu, Aug 27, 2020 at 3:47 PM Green Wan <green.wan@sifive.com> wrote:
> >
> > Add '-drive' support to OTP device. Allow users to assign a raw file
> > as OTP image.
> >
> > Signed-off-by: Green Wan <green.wan@sifive.com>
> > ---
> >  hw/riscv/sifive_u_otp.c         | 50 +++++++++++++++++++++++++++++++++
> >  include/hw/riscv/sifive_u_otp.h |  2 ++
> >  2 files changed, 52 insertions(+)
> >
> > diff --git a/hw/riscv/sifive_u_otp.c b/hw/riscv/sifive_u_otp.c
> > index f6ecbaa2ca..aab2220494 100644
> > --- a/hw/riscv/sifive_u_otp.c
> > +++ b/hw/riscv/sifive_u_otp.c
> > @@ -24,6 +24,8 @@
> >  #include "qemu/log.h"
> >  #include "qemu/module.h"
> >  #include "hw/riscv/sifive_u_otp.h"
> > +#include "sysemu/blockdev.h"
> > +#include "sysemu/block-backend.h"
> >
> >  static uint64_t sifive_u_otp_read(void *opaque, hwaddr addr, unsigned int 
> > size)
> >  {
> > @@ -46,6 +48,16 @@ static uint64_t sifive_u_otp_read(void *opaque, hwaddr 
> > addr, unsigned int size)
> >          if ((s->pce & SIFIVE_U_OTP_PCE_EN) &&
> >              (s->pdstb & SIFIVE_U_OTP_PDSTB_EN) &&
> >              (s->ptrim & SIFIVE_U_OTP_PTRIM_EN)) {
> > +
> > +            /* read from backend */
> > +            if (s->blk) {
> > +                int32_t buf;
> > +
> > +                blk_pread(s->blk, s->pa * SIFIVE_U_OTP_FUSE_WORD, &buf,
> > +                          SIFIVE_U_OTP_FUSE_WORD);
> > +                return buf;
> > +            }
> > +
> >              return s->fuse[s->pa & SIFIVE_U_OTP_PA_MASK];
> >          } else {
> >              return 0xff;
> > @@ -123,6 +135,12 @@ static void sifive_u_otp_write(void *opaque, hwaddr 
> > addr,
> >          s->ptrim = val32;
> >          break;
> >      case SIFIVE_U_OTP_PWE:
> > +        /* write to backend */
> > +        if (s->blk) {
> > +            blk_pwrite(s->blk, s->pa * SIFIVE_U_OTP_FUSE_WORD, &val32,
>
> The logic looks wrong to me. According to the U-Boot driver
> (sifive-otp.c) the content to be written to the OTP memory comes from
> s->pdin bit by bit. Here val32 represents whether to disable write or
> enable write.
>
> I think we should arrange patches like this:
>
> patch 1 to add OTP write functionality, to the existing s->fuse[] mechanism
> patch 2 to add file based backend write support
>
> > +                       SIFIVE_U_OTP_FUSE_WORD, 0);
> > +        }
> > +
> >          s->pwe = val32;
> >          break;
> >      default:
> > @@ -143,16 +161,48 @@ static const MemoryRegionOps sifive_u_otp_ops = {
> >
> >  static Property sifive_u_otp_properties[] = {
> >      DEFINE_PROP_UINT32("serial", SiFiveUOTPState, serial, 0),
> > +    DEFINE_PROP_DRIVE("drive", SiFiveUOTPState, blk),
> >      DEFINE_PROP_END_OF_LIST(),
> >  };
> >
> >  static void sifive_u_otp_realize(DeviceState *dev, Error **errp)
> >  {
> >      SiFiveUOTPState *s = SIFIVE_U_OTP(dev);
> > +    DriveInfo *dinfo;
> >
> >      memory_region_init_io(&s->mmio, OBJECT(dev), &sifive_u_otp_ops, s,
> >                            TYPE_SIFIVE_U_OTP, SIFIVE_U_OTP_REG_SIZE);
> >      sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->mmio);
> > +
> > +    dinfo = drive_get_next(IF_NONE);
> > +    if (dinfo) {
> > +        int ret;
> > +        uint64_t perm;
> > +        int filesize;
> > +        BlockBackend *blk;
> > +
> > +        blk = blk_by_legacy_dinfo(dinfo);
> > +        filesize = SIFIVE_U_OTP_NUM_FUSES * SIFIVE_U_OTP_FUSE_WORD;
> > +        if (blk_getlength(blk) < filesize) {
> > +            qemu_log_mask(LOG_GUEST_ERROR, "OTP drive size < 16K\n");
> > +            return;
> > +        }
> > +
> > +        qdev_prop_set_drive(dev, "drive", blk);
> > +
> > +        perm = BLK_PERM_CONSISTENT_READ |
> > +                        (blk_is_read_only(s->blk) ? 0 : BLK_PERM_WRITE);
> > +        ret = blk_set_perm(s->blk, perm, BLK_PERM_ALL, errp);
> > +        if (ret < 0) {
> > +            qemu_log_mask(LOG_GUEST_ERROR, "set perm error.");
> > +        }
> > +
> > +        if (blk_pread(s->blk, 0, s->fuse, filesize) != filesize) {
> > +            qemu_log_mask(LOG_GUEST_ERROR,
> > +                          "failed to read the initial flash content");
> > +            return;
> > +        }
> > +    }
> >  }
> >
> >  static void sifive_u_otp_reset(DeviceState *dev)
> > diff --git a/include/hw/riscv/sifive_u_otp.h 
> > b/include/hw/riscv/sifive_u_otp.h
> > index 639297564a..13d2552e43 100644
> > --- a/include/hw/riscv/sifive_u_otp.h
> > +++ b/include/hw/riscv/sifive_u_otp.h
> > @@ -43,6 +43,7 @@
> >
> >  #define SIFIVE_U_OTP_PA_MASK        0xfff
> >  #define SIFIVE_U_OTP_NUM_FUSES      0x1000
> > +#define SIFIVE_U_OTP_FUSE_WORD      4
> >  #define SIFIVE_U_OTP_SERIAL_ADDR    0xfc
> >
> >  #define SIFIVE_U_OTP_REG_SIZE       0x1000
> > @@ -75,6 +76,7 @@ typedef struct SiFiveUOTPState {
> >      uint32_t fuse[SIFIVE_U_OTP_NUM_FUSES];
> >      /* config */
> >      uint32_t serial;
> > +    BlockBackend *blk;
> >  } SiFiveUOTPState;
> >
> >  #endif /* HW_SIFIVE_U_OTP_H */
> > --
>
> Regards,
> Bin