Re: [PATCH v3 09/17] hw/misc: Support 8-bytes memop in NPCM GCR module

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 6/2/25 02:30, Hao Wu wrote:
> The NPCM8xx GCR device can be accessed with 64-bit memory operations.
> This patch supports that.
> 
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Hao Wu <wuhaotsh@google.com>
> ---
>   hw/misc/npcm_gcr.c   | 94 +++++++++++++++++++++++++++++++++-----------
>   hw/misc/trace-events |  4 +-
>   2 files changed, 74 insertions(+), 24 deletions(-)
> 
> diff --git a/hw/misc/npcm_gcr.c b/hw/misc/npcm_gcr.c
> index 820b730606..654e048048 100644
> --- a/hw/misc/npcm_gcr.c
> +++ b/hw/misc/npcm_gcr.c
> @@ -201,6 +201,7 @@ static uint64_t npcm_gcr_read(void *opaque, hwaddr offset, unsigned size)
>       uint32_t reg = offset / sizeof(uint32_t);
>       NPCMGCRState *s = opaque;
>       NPCMGCRClass *c = NPCM_GCR_GET_CLASS(s);
> +    uint64_t value;
>   
>       if (reg >= c->nr_regs) {
>           qemu_log_mask(LOG_GUEST_ERROR,
> @@ -209,9 +210,21 @@ static uint64_t npcm_gcr_read(void *opaque, hwaddr offset, unsigned size)
>           return 0;
>       }
>   
> -    trace_npcm_gcr_read(offset, s->regs[reg]);
> +    switch (size) {
> +    case 4:
> +        value = s->regs[reg];
> +        break;
> +
> +    case 8:

Should we assert(!(reg & 1)) in case someone want to enable unaligned
accesses?

> +        value = deposit64(s->regs[reg], 32, 32, s->regs[reg + 1]);
> +        break;
> +
> +    default:
> +        g_assert_not_reached();
> +    }
>   
> -    return s->regs[reg];
> +    trace_npcm_gcr_read(offset, value);
> +    return value;
>   }
>   
>   static void npcm_gcr_write(void *opaque, hwaddr offset,
> @@ -231,29 +244,65 @@ static void npcm_gcr_write(void *opaque, hwaddr offset,
>           return;
>       }
>   
> -    switch (reg) {
> -    case NPCM7XX_GCR_PDID:
> -    case NPCM7XX_GCR_PWRON:
> -    case NPCM7XX_GCR_INTSR:
> -        qemu_log_mask(LOG_GUEST_ERROR,
> -                      "%s: register @ 0x%04" HWADDR_PRIx " is read-only\n",
> -                      __func__, offset);
> -        return;
> -
> -    case NPCM7XX_GCR_RESSR:
> -    case NPCM7XX_GCR_CP2BST:
> -        /* Write 1 to clear */
> -        value = s->regs[reg] & ~value;
> +    switch (size) {
> +    case 4:
> +        switch (reg) {
> +        case NPCM7XX_GCR_PDID:
> +        case NPCM7XX_GCR_PWRON:
> +        case NPCM7XX_GCR_INTSR:
> +            qemu_log_mask(LOG_GUEST_ERROR,
> +                          "%s: register @ 0x%04" HWADDR_PRIx " is read-only\n",
> +                          __func__, offset);
> +            return;
> +
> +        case NPCM7XX_GCR_RESSR:
> +        case NPCM7XX_GCR_CP2BST:
> +            /* Write 1 to clear */
> +            value = s->regs[reg] & ~value;
> +            break;
> +
> +        case NPCM7XX_GCR_RLOCKR1:
> +        case NPCM7XX_GCR_MDLR:
> +            /* Write 1 to set */
> +            value |= s->regs[reg];
> +            break;
> +        };
> +        s->regs[reg] = value;
>           break;
>   
> -    case NPCM7XX_GCR_RLOCKR1:
> -    case NPCM7XX_GCR_MDLR:
> -        /* Write 1 to set */
> -        value |= s->regs[reg];
> +    case 8:

Ditto.

> +        s->regs[reg] = value;
> +        s->regs[reg + 1] = extract64(v, 32, 32);
>           break;
> -    };
>   
> -    s->regs[reg] = value;
> +    default:
> +        g_assert_not_reached();
> +    }
> +}
> +
> +static bool npcm_gcr_check_mem_op(void *opaque, hwaddr offset,
> +                                  unsigned size, bool is_write,
> +                                  MemTxAttrs attrs)
> +{
> +    NPCMGCRClass *c = NPCM_GCR_GET_CLASS(opaque);
> +
> +    if (offset >= c->nr_regs * sizeof(uint32_t)) {
> +        return false;
> +    }
> +
> +    switch (size) {
> +    case 4:
> +        return true;
> +    case 8:
> +        if (offset >= NPCM8XX_GCR_SCRPAD_00 * sizeof(uint32_t) &&
> +            offset < (NPCM8XX_GCR_NR_REGS - 1) * sizeof(uint32_t)) {
> +            return true;
> +        } else {
> +            return false;
> +        }
> +    default:
> +        return false;
> +    }
>   }
>   
>   static const struct MemoryRegionOps npcm_gcr_ops = {
> @@ -262,7 +311,8 @@ static const struct MemoryRegionOps npcm_gcr_ops = {
>       .endianness = DEVICE_LITTLE_ENDIAN,
>       .valid      = {
>           .min_access_size        = 4,
> -        .max_access_size        = 4,
> +        .max_access_size        = 8,
> +        .accepts                = npcm_gcr_check_mem_op,
>           .unaligned              = false,
>       },
>   };
> diff --git a/hw/misc/trace-events b/hw/misc/trace-events
> index 0f7204a237..f25dbd6030 100644
> --- a/hw/misc/trace-events
> +++ b/hw/misc/trace-events
> @@ -135,8 +135,8 @@ npcm7xx_clk_read(uint64_t offset, uint32_t value) " offset: 0x%04" PRIx64 " valu
>   npcm7xx_clk_write(uint64_t offset, uint32_t value) "offset: 0x%04" PRIx64 " value: 0x%08" PRIx32
>   
>   # npcm_gcr.c
> -npcm_gcr_read(uint64_t offset, uint32_t value) " offset: 0x%04" PRIx64 " value: 0x%08" PRIx32
> -npcm_gcr_write(uint64_t offset, uint32_t value) "offset: 0x%04" PRIx64 " value: 0x%08" PRIx32
> +npcm_gcr_read(uint64_t offset, uint64_t value) " offset: 0x%04" PRIx64 " value: 0x%08" PRIx64
> +npcm_gcr_write(uint64_t offset, uint64_t value) "offset: 0x%04" PRIx64 " value: 0x%08" PRIx64
>   
>   # npcm7xx_mft.c
>   npcm7xx_mft_read(const char *name, uint64_t offset, uint16_t value) "%s: offset: 0x%04" PRIx64 " value: 0x%04" PRIx16