Re: [Qemu-devel] [PATCH 6/6] aspeed: add support for the SMC segment registers

[Andrew Jeffery <andrew@aj.id.au>]

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On Tue, 2016-09-27 at 13:57 +0200, Cédric Le Goater wrote:
> The SMC controller on the Aspeed SoC has a set of registers to
> configure the mapping of each flash module in the SoC address
> space. Writing to these registers triggers a remap of the memory
> region and the spec requires a certain number of checks before doing
> so.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>

Reviewed-by: Andrew Jeffery <andrew@aj.id.au>

> ---
>  hw/ssi/aspeed_smc.c | 135 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 130 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/ssi/aspeed_smc.c b/hw/ssi/aspeed_smc.c
> index ecf39ccfde0e..6e8403ebc246 100644
> --- a/hw/ssi/aspeed_smc.c
> +++ b/hw/ssi/aspeed_smc.c
> @@ -79,10 +79,10 @@
>  
>  /* CEx Segment Address Register */
>  #define R_SEG_ADDR0       (0x30 / 4)
> -#define   SEG_SIZE_SHIFT       24   /* 8MB units */
> -#define   SEG_SIZE_MASK        0x7f
> +#define   SEG_END_SHIFT        24   /* 8MB units */
> +#define   SEG_END_MASK         0xff

Was this a bug? The top bit is reserved as 0 in the 2500 datasheet, but
valid as your change suggests in the 2400.

>  #define   SEG_START_SHIFT      16   /* address bit [A29-A23] */
> -#define   SEG_START_MASK       0x7f
> +#define   SEG_START_MASK       0xff

As above.

>  #define R_SEG_ADDR1       (0x34 / 4)
>  #define R_SEG_ADDR2       (0x38 / 4)
>  #define R_SEG_ADDR3       (0x3C / 4)
> @@ -135,8 +135,7 @@
>  /*
>   * Default segments mapping addresses and size for each slave per
>   * controller. These can be changed when board is initialized with the
> - * Segment Address Registers but they don't seem do be used on the
> - * field.
> + * Segment Address Registers.
>   */
>  static const AspeedSegments aspeed_segments_legacy[] = {
>      { 0x10000000, 32 * 1024 * 1024 },
> @@ -191,6 +190,118 @@ static const AspeedSMCController controllers[] = {
>        ASPEED_SOC_SPI2_FLASH_BASE, 0x8000000 },
>  };
>  
> +/*
> + * The Segment Register uses a 8MB unit to encode the start address
> + * and the end address of the mapping window of a flash SPI slave :
> + *
> + *        | byte 1 | byte 2 | byte 3 | byte 4 |
> + *        +--------+--------+--------+--------+
> + *        |  end   |  start |   0    |   0    |
> + *
> + */
> +static inline uint32_t aspeed_smc_segment_to_reg(const AspeedSegments *seg)
> +{
> +    uint32_t reg = 0;
> +    reg |= ((seg->addr >> 23) & SEG_START_MASK) << SEG_START_SHIFT;
> +    reg |= (((seg->addr + seg->size) >> 23) & SEG_END_MASK) << SEG_END_SHIFT;
> +    return reg;
> +}
> +
> +static inline void aspeed_smc_reg_to_segment(uint32_t reg, AspeedSegments *seg)
> +{
> +    seg->addr = ((reg >> SEG_START_SHIFT) & SEG_START_MASK) << 23;
> +    seg->size = (((reg >> SEG_END_SHIFT) & SEG_END_MASK) << 23) - seg->addr;
> +}
> +
> +static bool aspeed_smc_flash_overlap(const AspeedSMCState *s,
> +                                     const AspeedSegments *new,
> +                                     int cs)
> +{
> +    AspeedSegments seg;
> +    int i;
> +
> +    for (i = 0; i < s->ctrl->max_slaves; i++) {
> +        if (i == cs) {
> +            continue;
> +        }
> +
> +        aspeed_smc_reg_to_segment(s->regs[R_SEG_ADDR0 + i], &seg);
> +
> +        if (new->addr + new->size > seg.addr &&
> +            new->addr < seg.addr + seg.size) {
> +            qemu_log_mask(LOG_GUEST_ERROR, "%s: new segment CS%d [ 0x%"
> +                          HWADDR_PRIx" - 0x%"HWADDR_PRIx" ] overlaps with "
> +                          "CS%d [ 0x%"HWADDR_PRIx" - 0x%"HWADDR_PRIx" ]\n",
> +                          s->ctrl->name, cs, new->addr, new->addr + new->size,
> +                          i, seg.addr, seg.addr + seg.size);
> +            return true;
> +        }
> +    }
> +    return false;
> +}
> +
> +static void aspeed_smc_flash_set_segment(AspeedSMCState *s, int cs,
> +                                         uint64_t new)
> +{
> +    AspeedSMCFlash *fl = &s->flashes[cs];
> +    AspeedSegments seg;
> +
> +    aspeed_smc_reg_to_segment(new, &seg);
> +
> +    /* The start address of CS0 is read-only */
> +    if (cs == 0 && seg.addr != s->ctrl->flash_window_base) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s: Tried to change CS0 start address to 0x%"
> +                      HWADDR_PRIx "\n", s->ctrl->name, seg.addr);
> +        return;
> +    }
> +
> +    /*
> +     * The end address of the AST2500 spi controllers is also
> +     * read-only.
> +     */
> +    if ((s->ctrl->segments == aspeed_segments_ast2500_spi1 ||
> +         s->ctrl->segments == aspeed_segments_ast2500_spi2) &&
> +        cs == s->ctrl->max_slaves &&
> +        seg.addr + seg.size != s->ctrl->segments[cs].addr +
> +        s->ctrl->segments[cs].size) {
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s: Tried to change CS%d end address to 0x%"
> +                      HWADDR_PRIx "\n", s->ctrl->name, cs, seg.addr);
> +        return;
> +    }
> +
> +    /* Keep the segment in the overall flash window */
> +    if (seg.addr + seg.size <= s->ctrl->flash_window_base ||
> +        seg.addr > s->ctrl->flash_window_base + s->ctrl->flash_window_size) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: new segment for CS%d is invalid : "
> +                      "[ 0x%"HWADDR_PRIx" - 0x%"HWADDR_PRIx" ]\n",
> +                      s->ctrl->name, cs, seg.addr, seg.addr + seg.size);
> +        return;
> +    }
> +
> +    /* Check start address vs. alignment */
> +    if (seg.addr % seg.size) {
> +        qemu_log_mask(LOG_GUEST_ERROR, "%s: new segment for CS%d is not "
> +                      "aligned : [ 0x%"HWADDR_PRIx" - 0x%"HWADDR_PRIx" ]\n",
> +                      s->ctrl->name, cs, seg.addr, seg.addr + seg.size);
> +    }
> +
> +    /* And segments should not overlap */
> +    if (aspeed_smc_flash_overlap(s, &seg, cs)) {
> +        return;
> +    }
> +
> +    /* All should be fine now to move the region */
> +    memory_region_transaction_begin();
> +    memory_region_set_size(&fl->mmio, seg.size);
> +    memory_region_set_address(&fl->mmio, seg.addr - s->ctrl->flash_window_base);
> +    memory_region_set_enabled(&fl->mmio, true);
> +    memory_region_transaction_commit();
> +
> +    s->regs[R_SEG_ADDR0 + cs] = new;
> +}
> +
>  static uint64_t aspeed_smc_flash_default_read(void *opaque, hwaddr addr,
>                                                unsigned size)
>  {
> @@ -314,6 +425,12 @@ static void aspeed_smc_reset(DeviceState *d)
>          s->regs[s->r_ctrl0 + i] |= CTRL_CE_STOP_ACTIVE;
>      }
>  
> +    /* setup default segment register values for all */
> +    for (i = 0; i < s->ctrl->max_slaves; ++i) {
> +        s->regs[R_SEG_ADDR0 + i] =
> +            aspeed_smc_segment_to_reg(&s->ctrl->segments[i]);
> +    }
> +
>      aspeed_smc_update_cs(s);
>  }
>  
> @@ -334,6 +451,7 @@ static uint64_t aspeed_smc_read(void *opaque, hwaddr addr, unsigned int size)
>          addr == s->r_timings ||
>          addr == s->r_ce_ctrl ||
>          addr == R_INTR_CTRL ||
> +        (addr >= R_SEG_ADDR0 && addr < R_SEG_ADDR0 + s->ctrl->max_slaves) ||
>          (addr >= s->r_ctrl0 && addr < s->r_ctrl0 + s->num_cs)) {
>          return s->regs[addr];
>      } else {
> @@ -365,6 +483,13 @@ static void aspeed_smc_write(void *opaque, hwaddr addr, uint64_t data,
>      } else if (addr >= s->r_ctrl0 && addr < s->r_ctrl0 + s->num_cs) {
>          s->regs[addr] = value;
>          aspeed_smc_update_cs(s);
> +    } else if (addr >= R_SEG_ADDR0 &&
> +               addr < R_SEG_ADDR0 + s->ctrl->max_slaves) {
> +        int cs = addr - R_SEG_ADDR0;
> +
> +        if (value != s->regs[R_SEG_ADDR0 + cs]) {
> +            aspeed_smc_flash_set_segment(s, cs, value);
> +        }
>      } else {
>          qemu_log_mask(LOG_UNIMP, "%s: not implemented: 0x%" HWADDR_PRIx "\n",
>                        __func__, addr);

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