[PATCH v2 3/8] mtd: rawnand: loongson: Add 6-byte NAND ID reading support

[Huacai Chen]

Hi, Binbin,

On Mon, Aug 11, 2025 at 2:02 PM Binbin Zhou <zhoubinbin at loongson.cn> wrote:
>
> From: Keguang Zhang <keguang.zhang at gmail.com>
>
> Loongson-1C and Loongson-2K SoCs support NAND flash chips with 6-byte ID.
> However, the current implementation only handles 5-byte ID which can lead
> to incorrect chip detection.
>
> Extend loongson_nand_read_id_type_exec() to support 6-byte NAND ID.
>
> Signed-off-by: Keguang Zhang <keguang.zhang at gmail.com>
> Signed-off-by: Binbin Zhou <zhoubinbin at loongson.cn>
> ---
>  .../mtd/nand/raw/loongson-nand-controller.c   | 29 +++++++++++++++----
>  1 file changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/loongson-nand-controller.c b/drivers/mtd/nand/raw/loongson-nand-controller.c
> index b5a7be0fcacc..97cd566420a8 100644
> --- a/drivers/mtd/nand/raw/loongson-nand-controller.c
> +++ b/drivers/mtd/nand/raw/loongson-nand-controller.c
> @@ -50,6 +50,9 @@
>  #define LOONGSON_NAND_COL_ADDR_CYC     2U
>  #define LOONGSON_NAND_MAX_ADDR_CYC     5U
>
> +#define LOONGSON_NAND_READ_ID_SLEEP_US         1000
> +#define LOONGSON_NAND_READ_ID_TIMEOUT_US       5000
> +
>  #define BITS_PER_WORD                  (4 * BITS_PER_BYTE)
>
>  struct loongson_nand_host;
> @@ -73,6 +76,8 @@ struct loongson_nand_op {
>  };
>
>  struct loongson_nand_data {
> +       unsigned int max_id_cycle;
> +       unsigned int id_cycle_field;
>         unsigned int status_field;
>         unsigned int op_scope_field;
>         unsigned int hold_cycle;
> @@ -458,10 +463,10 @@ static int loongson_nand_read_id_type_exec(struct nand_chip *chip, const struct
>         struct loongson_nand_op op = {};
>         int i, ret;
>         union {
> -               char ids[5];
> +               char ids[6];
>                 struct {
>                         int idl;
> -                       char idh;
> +                       u16 idh;
>                 };
>         } nand_id;
>
> @@ -469,11 +474,16 @@ static int loongson_nand_read_id_type_exec(struct nand_chip *chip, const struct
>         if (ret)
>                 return ret;
>
> -       nand_id.idl = readl(host->reg_base + LOONGSON_NAND_IDL);
> -       nand_id.idh = readb(host->reg_base + LOONGSON_NAND_IDH_STATUS);
> +       ret = regmap_read_poll_timeout(host->regmap, LOONGSON_NAND_IDL, nand_id.idl, nand_id.idl,
> +                                      LOONGSON_NAND_READ_ID_SLEEP_US,
> +                                      LOONGSON_NAND_READ_ID_TIMEOUT_US);
The last two lines can be merged.

Huacai

> +       if (ret)
> +               return ret;
>
> -       for (i = 0; i < min(sizeof(nand_id.ids), op.orig_len); i++)
> -               op.buf[i] = nand_id.ids[sizeof(nand_id.ids) - 1 - i];
> +       nand_id.idh = readw(host->reg_base + LOONGSON_NAND_IDH_STATUS);
> +
> +       for (i = 0; i < min(host->data->max_id_cycle, op.orig_len); i++)
> +               op.buf[i] = nand_id.ids[host->data->max_id_cycle - 1 - i];
>
>         return ret;
>  }
> @@ -676,6 +686,10 @@ static int loongson_nand_controller_init(struct loongson_nand_host *host)
>         if (IS_ERR(host->regmap))
>                 return dev_err_probe(dev, PTR_ERR(host->regmap), "failed to init regmap\n");
>
> +       if (host->data->id_cycle_field)
> +               regmap_update_bits(host->regmap, LOONGSON_NAND_PARAM, host->data->id_cycle_field,
> +                                  host->data->max_id_cycle << __ffs(host->data->id_cycle_field));
> +
>         chan = dma_request_chan(dev, "rxtx");
>         if (IS_ERR(chan))
>                 return dev_err_probe(dev, PTR_ERR(chan), "failed to request DMA channel\n");
> @@ -800,6 +814,7 @@ static void loongson_nand_remove(struct platform_device *pdev)
>  }
>
>  static const struct loongson_nand_data ls1b_nand_data = {
> +       .max_id_cycle = 5,
>         .status_field = GENMASK(15, 8),
>         .hold_cycle = 0x2,
>         .wait_cycle = 0xc,
> @@ -807,6 +822,8 @@ static const struct loongson_nand_data ls1b_nand_data = {
>  };
>
>  static const struct loongson_nand_data ls1c_nand_data = {
> +       .max_id_cycle = 6,
> +       .id_cycle_field = GENMASK(14, 12),
>         .status_field = GENMASK(23, 16),
>         .op_scope_field = GENMASK(29, 16),
>         .hold_cycle = 0x2,
> --
> 2.47.3
>