Re: [PATCH 1/2] hw: m25p80: Add Block Protect and Top Bottom bits for write protect

[Cédric Le Goater]

On 6/27/22 20:52, Iris Chen wrote:
> Signed-off-by: Iris Chen <irischenlj@fb.com>
> ---
>   hw/block/m25p80.c | 74 +++++++++++++++++++++++++++++++++++++++--------
>   1 file changed, 62 insertions(+), 12 deletions(-)
>
> diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c
> index 50b523e5b1..0156a70f5e 100644
> --- a/hw/block/m25p80.c
> +++ b/hw/block/m25p80.c
> @@ -38,21 +38,19 @@
>   #include "trace.h"
>   #include "qom/object.h"
>   
> -/* Fields for FlashPartInfo->flags */
> -
> -/* erase capabilities */
> -#define ER_4K 1
> -#define ER_32K 2
> -/* set to allow the page program command to write 0s back to 1. Useful for
> - * modelling EEPROM with SPI flash command set
> - */
> -#define EEPROM 0x100
> -
>   /* 16 MiB max in 3 byte address mode */
>   #define MAX_3BYTES_SIZE 0x1000000
> -
>   #define SPI_NOR_MAX_ID_LEN 6
>   
> +/* Fields for FlashPartInfo->flags */
> +enum spi_nor_option_flags {
> +    ER_4K                  = BIT(0),
> +    ER_32K                 = BIT(1),
> +    EEPROM                 = BIT(2),
> +    SNOR_F_HAS_SR_TB       = BIT(3),
> +    SNOR_F_HAS_SR_BP3_BIT6 = BIT(4),
> +};
> +
>   typedef struct FlashPartInfo {
>       const char *part_name;
>       /*
> @@ -253,7 +251,8 @@ static const FlashPartInfo known_devices[] = {
>       { INFO("n25q512a11",  0x20bb20,      0,  64 << 10, 1024, ER_4K) },
>       { INFO("n25q512a13",  0x20ba20,      0,  64 << 10, 1024, ER_4K) },
>       { INFO("n25q128",     0x20ba18,      0,  64 << 10, 256, 0) },
> -    { INFO("n25q256a",    0x20ba19,      0,  64 << 10, 512, ER_4K) },
> +    { INFO("n25q256a",    0x20ba19,      0,  64 << 10, 512,
> +           ER_4K | SNOR_F_HAS_SR_BP3_BIT6 | SNOR_F_HAS_SR_TB) },
>       { INFO("n25q512a",    0x20ba20,      0,  64 << 10, 1024, ER_4K) },
>       { INFO("n25q512ax3",  0x20ba20,  0x1000,  64 << 10, 1024, ER_4K) },
>       { INFO("mt25ql512ab", 0x20ba20, 0x1044, 64 << 10, 1024, ER_4K | ER_32K) },
> @@ -480,6 +479,11 @@ struct Flash {
>       bool reset_enable;
>       bool quad_enable;
>       bool aai_enable;
> +    bool block_protect0;
> +    bool block_protect1;
> +    bool block_protect2;
> +    bool block_protect3;
> +    bool top_bottom_bit;
>       bool status_register_write_disabled;
>       uint8_t ear;
>   
> @@ -630,6 +634,29 @@ void flash_write8(Flash *s, uint32_t addr, uint8_t data)
>           qemu_log_mask(LOG_GUEST_ERROR, "M25P80: write with write protect!\n");
>           return;
>       }
> +    uint32_t block_protect_value = (s->block_protect3 << 3) |
> +                                   (s->block_protect2 << 2) |
> +                                   (s->block_protect1 << 1) |
> +                                   (s->block_protect0 << 0);
> +
> +     uint32_t num_protected_sectors = 1 << (block_protect_value - 1);

Something wrong will occur if all block_protect[0123] are zeroes.

C.

> +     uint32_t sector = addr / s->pi->sector_size;
> +
> +     /* top_bottom_bit == 0 means TOP */
> +    if (!s->top_bottom_bit) {
> +        if (block_protect_value > 0 &&
> +            s->pi->n_sectors <= sector + num_protected_sectors) {
> +            qemu_log_mask(LOG_GUEST_ERROR,
> +                          "M25P80: write with write protect!\n");
> +            return;
> +        }
> +    } else {
> +        if (block_protect_value > 0 && sector < num_protected_sectors) {
> +            qemu_log_mask(LOG_GUEST_ERROR,
> +                          "M25P80: write with write protect!\n");
> +            return;
> +        }
> +    }
>   
>       if ((prev ^ data) & data) {
>           trace_m25p80_programming_zero_to_one(s, addr, prev, data);
> @@ -728,6 +755,15 @@ static void complete_collecting_data(Flash *s)
>           break;
>       case WRSR:
>           s->status_register_write_disabled = extract32(s->data[0], 7, 1);
> +        s->block_protect0 = extract32(s->data[0], 2, 1);
> +        s->block_protect1 = extract32(s->data[0], 3, 1);
> +        s->block_protect2 = extract32(s->data[0], 4, 1);
> +        if (s->pi->flags & SNOR_F_HAS_SR_TB) {
> +            s->top_bottom_bit = extract32(s->data[0], 5, 1);
> +        }
> +        if (s->pi->flags & SNOR_F_HAS_SR_BP3_BIT6) {
> +            s->block_protect3 = extract32(s->data[0], 6, 1);
> +        }
>   
>           switch (get_man(s)) {
>           case MAN_SPANSION:
> @@ -1213,6 +1249,15 @@ static void decode_new_cmd(Flash *s, uint32_t value)
>       case RDSR:
>           s->data[0] = (!!s->write_enable) << 1;
>           s->data[0] |= (!!s->status_register_write_disabled) << 7;
> +        s->data[0] |= (!!s->block_protect0) << 2;
> +        s->data[0] |= (!!s->block_protect1) << 3;
> +        s->data[0] |= (!!s->block_protect2) << 4;
> +        if (s->pi->flags & SNOR_F_HAS_SR_TB) {
> +            s->data[0] |= (!!s->top_bottom_bit) << 5;
> +        }
> +        if (s->pi->flags & SNOR_F_HAS_SR_BP3_BIT6) {
> +            s->data[0] |= (!!s->block_protect3) << 6;
> +        }
>   
>           if (get_man(s) == MAN_MACRONIX || get_man(s) == MAN_ISSI) {
>               s->data[0] |= (!!s->quad_enable) << 6;
> @@ -1553,6 +1598,11 @@ static void m25p80_reset(DeviceState *d)
>   
>       s->wp_level = true;
>       s->status_register_write_disabled = false;
> +    s->block_protect0 = false;
> +    s->block_protect1 = false;
> +    s->block_protect2 = false;
> +    s->block_protect3 = false;
> +    s->top_bottom_bit = false;
>   
>       reset_memory(s);
>   }