kernel: add support for FudanMicro FM25G01B and FM25G02B spi-nand

This commit adds support for FudanMicro FM25G01B and FM25G02B SPI NAND
chips. This is required to:
1. Fix bootloop on new revision of Keenetic KN-1812 and Netcraze NC-1812
   (with FudanMicro FM25G02B SPI NAND)
2. Add Nokia XG-040G-MD support (device has either SkyHigh or FudanMicro
   SPI NAND).

Fixes: https://github.com/openwrt/openwrt/issues/23855
Signed-off-by: Mikhail Zhilkin <csharper2005@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/23864
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

diff --git a/target/linux/generic/pending-6.18/401-mtd-spinand-fmsh-add-support-for-FM25G0102B.patch b/target/linux/generic/pending-6.18/401-mtd-spinand-fmsh-add-support-for-FM25G0102B.patch
new file mode 100644 (file)
index 0000000..e3a5a10
--- /dev/null
+++ b/target/linux/generic/pending-6.18/401-mtd-spinand-fmsh-add-support-for-FM25G0102B.patch
@@ -0,0 +1,152 @@
+From: Ziyang Huang <hzyitc@outlook.com>
+To: miquel.raynal@bootlin.com
+Subject: [PATCH v3] mtd: spinand: fmsh: add support for FM25G{01,02}B
+Date: Sun, 31 May 2026 21:05:17 +0800
+
+Add support for FudanMicro FM25G01B SPI NAND and FudanMicro FM25G02B SPI
+NAND.
+
+FM25G01B datasheet: https://www.fmsh.com/nvm/FM25G01B_ds_eng.pdf
+FM25G02B datasheet: https://www.fmsh.com/nvm/FM25G02B_ds_eng.pdf
+
+Signed-off-by: Ziyang Huang <hzyitc@outlook.com>
+Link: https://lore.kernel.org/all/SEYPR01MB58821E380C5DD8F7B3FFDA23C9142@SEYPR01MB5882.apcprd01.prod.exchangelabs.com/
+[Fix chip names in the commit message, mask macro in the switch operator]
+Signed-off-by: Mikhail Zhilkin <csharper2005@gmail.com>
+---
+Changes since v2:
+  More verbose commit message.
+  Use only one section in fm25g01b_ooblayout_free().
+
+Changes since v1:
+  Fix copy-paste issue. (Correct FM25G01B size.)
+
+ drivers/mtd/nand/spi/fmsh.c | 96 +++++++++++++++++++++++++++++++++++++
+ 1 file changed, 96 insertions(+)
+
+--- a/drivers/mtd/nand/spi/fmsh.c
++++ b/drivers/mtd/nand/spi/fmsh.c
+@@ -9,6 +9,16 @@
+ #include <linux/kernel.h>
+ #include <linux/mtd/spinand.h>
+ 
++#define FM25G01B_STATUS_ECC_MASK              (7 << 4)
++      #define FM25G01B_STATUS_ECC_NO_BITFLIPS         (0 << 4)
++      #define FM25G01B_STATUS_ECC_1_3_BITFLIPS        (1 << 4)
++      #define FM25G01B_STATUS_ECC_4_BITFLIPS          (2 << 4)
++      #define FM25G01B_STATUS_ECC_5_BITFLIPS          (3 << 4)
++      #define FM25G01B_STATUS_ECC_6_BITFLIPS          (4 << 4)
++      #define FM25G01B_STATUS_ECC_7_BITFLIPS          (5 << 4)
++      #define FM25G01B_STATUS_ECC_8_BITFLIPS          (6 << 4)
++      #define FM25G01B_STATUS_ECC_UNCOR_ERROR         (7 << 4)
++
+ #define FM25S01BI3_STATUS_ECC_MASK            (7 << 4)
+       #define FM25S01BI3_STATUS_ECC_NO_BITFLIPS       (0 << 4)
+       #define FM25S01BI3_STATUS_ECC_1_3_BITFLIPS      (1 << 4)
+@@ -34,6 +44,67 @@ static SPINAND_OP_VARIANTS(update_cache_
+               SPINAND_PROG_LOAD_1S_1S_4S_OP(false, 0, NULL, 0),
+               SPINAND_PROG_LOAD_1S_1S_1S_OP(false, 0, NULL, 0));
+ 
++
++static int fm25g01b_ooblayout_ecc(struct mtd_info *mtd, int section,
++                                struct mtd_oob_region *region)
++{
++      if (section)
++              return -ERANGE;
++
++      region->offset = 64;
++      region->length = 64;
++
++      return 0;
++}
++
++static int fm25g01b_ooblayout_free(struct mtd_info *mtd, int section,
++                                 struct mtd_oob_region *region)
++{
++      if (section)
++              return -ERANGE;
++
++      /* reserve 2 bytes for the BBM */
++      region->offset = 2;
++      region->length = 62;
++
++      return 0;
++}
++
++static int fm25g01b_ecc_get_status(struct spinand_device *spinand,
++                                 u8 status)
++{
++      switch (status & FM25G01B_STATUS_ECC_MASK) {
++      case FM25G01B_STATUS_ECC_NO_BITFLIPS:
++              return 0;
++
++      case FM25G01B_STATUS_ECC_1_3_BITFLIPS:
++              return 3;
++
++      case FM25G01B_STATUS_ECC_4_BITFLIPS:
++              return 4;
++
++      case FM25G01B_STATUS_ECC_5_BITFLIPS:
++              return 5;
++
++      case FM25G01B_STATUS_ECC_6_BITFLIPS:
++              return 6;
++
++      case FM25G01B_STATUS_ECC_7_BITFLIPS:
++              return 7;
++
++      case FM25G01B_STATUS_ECC_8_BITFLIPS:
++              return 8;
++
++      case FM25G01B_STATUS_ECC_UNCOR_ERROR:
++              return -EBADMSG;
++
++      default:
++              break;
++      }
++
++      return -EINVAL;
++}
++
+ static int fm25s01a_ooblayout_ecc(struct mtd_info *mtd, int section,
+                                 struct mtd_oob_region *region)
+ {
+@@ -102,6 +173,11 @@ static int fm25s01bi3_ooblayout_free(str
+       return 0;
+ }
+ 
++static const struct mtd_ooblayout_ops fm25g01b_ooblayout = {
++      .ecc = fm25g01b_ooblayout_ecc,
++      .free = fm25g01b_ooblayout_free,
++};
++
+ static const struct mtd_ooblayout_ops fm25s01a_ooblayout = {
+       .ecc = fm25s01a_ooblayout_ecc,
+       .free = fm25s01a_ooblayout_free,
+@@ -113,6 +189,26 @@ static const struct mtd_ooblayout_ops fm
+ };
+ 
+ static const struct spinand_info fmsh_spinand_table[] = {
++      SPINAND_INFO("FM25G01B",
++                   SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xd1),
++                   NAND_MEMORG(1, 2048, 128, 64, 1024, 21, 1, 1, 1),
++                   NAND_ECCREQ(8, 528),
++                   SPINAND_INFO_OP_VARIANTS(&read_cache_variants,
++                                            &write_cache_variants,
++                                            &update_cache_variants),
++                   SPINAND_HAS_QE_BIT,
++                   SPINAND_ECCINFO(&fm25g01b_ooblayout,
++                                   fm25g01b_ecc_get_status)),
++      SPINAND_INFO("FM25G02B",
++                   SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xd2),
++                   NAND_MEMORG(1, 2048, 128, 64, 2048, 41, 1, 1, 1),
++                   NAND_ECCREQ(8, 528),
++                   SPINAND_INFO_OP_VARIANTS(&read_cache_variants,
++                                            &write_cache_variants,
++                                            &update_cache_variants),
++                   SPINAND_HAS_QE_BIT,
++                   SPINAND_ECCINFO(&fm25g01b_ooblayout,
++                                   fm25g01b_ecc_get_status)),
+       SPINAND_INFO("FM25S01A",
+                    SPINAND_ID(SPINAND_READID_METHOD_OPCODE_DUMMY, 0xE4),
+                    NAND_MEMORG(1, 2048, 64, 64, 1024, 20, 1, 1, 1),