[PATCH v3 5/7] mtd: spi-nor-core: Add overlaid sector erase feature

[tkuw584924 at gmail.com]

From: Takahiro Kuwano <Takahiro.Kuwano at infineon.com>

Some of Spansion/Cypress chips have overlaid 4KB sectors at top and/or
bottom, depending on the device configuration, while U-Boot supports
uniform sector layout only. This patch adds an erase hook that emulates
uniform sector layout.

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano at infineon.com>
---
 drivers/mtd/spi/spi-nor-core.c | 48 ++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 6553a7f211..042da329da 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -732,6 +732,54 @@ erase_err:
 	return ret;
 }
 
+#ifdef CONFIG_SPI_FLASH_SPANSION
+/*
+ * Erase for Spansion/Cypress Flash devices that has overlaid 4KB sectors at
+ * the top and/or bottom.
+ */
+static int spansion_overlaid_erase(struct mtd_info *mtd,
+				   struct erase_info *instr)
+{
+	struct spi_nor *nor = mtd_to_spi_nor(mtd);
+	struct erase_info instr_4k;
+	u8 opcode;
+	u32 erasesize;
+	int ret;
+
+	/* Perform default erase operation (non-overlaid portion is erased) */
+	ret = spi_nor_erase(mtd, instr);
+	if (ret)
+		return ret;
+
+	/* Backup default erase opcode and size */
+	opcode = nor->erase_opcode;
+	erasesize = mtd->erasesize;
+
+	/*
+	 * Erase 4KB sectors. Use the possible max length of 4KB sector region.
+	 * The Flash just ignores the command if the address is not configured
+	 * as 4KB sector and reports ready status immediately.
+	 */
+	instr_4k.len = SZ_128K;
+	nor->erase_opcode = SPINOR_OP_BE_4K_4B;
+	mtd->erasesize = SZ_4K;
+	if (instr->addr == 0) {
+		instr_4k.addr = 0;
+		ret = spi_nor_erase(mtd, &instr_4k);
+	}
+	if (!ret && instr->addr + instr->len == mtd->size) {
+		instr_4k.addr = mtd->size - instr_4k.len;
+		ret = spi_nor_erase(mtd, &instr_4k);
+	}
+
+	/* Restore erase opcode and size */
+	nor->erase_opcode = opcode;
+	mtd->erasesize = erasesize;
+
+	return ret;
+}
+#endif
+
 #if defined(CONFIG_SPI_FLASH_STMICRO) || defined(CONFIG_SPI_FLASH_SST)
 /* Write status register and ensure bits in mask match written values */
 static int write_sr_and_check(struct spi_nor *nor, u8 status_new, u8 mask)
-- 
2.25.1