FROMLIST: mtd: spi-nor: add support to SST sst26* QSPI memories

This patch adds support to the SST sst26* QSPI memories.
It also adds a new SST_BLOCK_PROTECT flag so spi_nor_scan() sends
a SST Global Block Protection Unlock (98h) command once for all
otherwise later Sector Erase and Page Program commands would fail.

It was tested with sst26vf016b, sst26vf032b, sst26vf032ba and sst26vf064b
on a sama5d2 xplained board at 55.3MHz and 3.3V.

sst26wf040b and sst26wf080b were not tested since they are 1.8V memories
hence don't fit the sama5d2 xplained board requirements.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
(pwclient git-am 9392589)

drivers/mtd/spi-nor/spi-nor.c

@@ -55,6 +55,7 @@ struct flash_info {
 #define	SPI_NOR_DUAL_READ	0x20    /* Flash supports Dual Read */
 #define	SPI_NOR_QUAD_READ	0x40    /* Flash supports Quad Read */
 #define	USE_FSR			0x80	/* use flag status register */
+#define SST_BLOCK_PROTECT	BIT(12)	/* use SST Unlock Block-Protection */
 };
 
 #define JEDEC_MFR(info)	((info)->id[0])
@@ -610,6 +611,11 @@ static const struct spi_device_id spi_nor_ids[] = {
 	{ "sst25wf020",  INFO(0xbf2503, 0, 64 * 1024,  4, SECT_4K | SST_WRITE) },
 	{ "sst25wf040",  INFO(0xbf2504, 0, 64 * 1024,  8, SECT_4K | SST_WRITE) },
 	{ "sst25wf080",  INFO(0xbf2505, 0, 64 * 1024, 16, SECT_4K | SST_WRITE) },
+	{ "sst26vf016b", INFO(0xbf2641, 0, 64 * 1024, 32, SECT_4K | SST_BLOCK_PROTECT) },
+	{ "sst26vf032b", INFO(0xbf2642, 0, 64 * 1024, 64, SECT_4K | SST_BLOCK_PROTECT) },
+	{ "sst26vf064b", INFO(0xbf2643, 0, 64 * 1024, 128, SECT_4K | SST_BLOCK_PROTECT) },
+	{ "sst26wf040b", INFO(0xbf2654, 0, 64 * 1024,  8, SECT_4K | SST_BLOCK_PROTECT) },
+	{ "sst26wf080b", INFO(0xbf2658, 0, 64 * 1024, 16, SECT_4K | SST_BLOCK_PROTECT) },
 
 	/* ST Microelectronics -- newer production may have feature updates */
 	{ "m25p05",  INFO(0x202010,  0,  32 * 1024,   2, 0) },
@@ -714,6 +720,14 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
 	return ret;
 }
 
+static int sst_unlock_block_protection(struct spi_nor *nor)
+{
+	int ret;
+
+	ret = write_enable(nor);
+	return ret ? ret : nor->write_reg(nor, SPINOR_OP_ULBPR, NULL, 0, 0);
+}
+
 static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
 		size_t *retlen, const u_char *buf)
 {
@@ -1161,6 +1175,12 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 
 	nor->read_dummy = spi_nor_read_dummy_cycles(nor);
 
+	if (info->flags & SST_BLOCK_PROTECT) {
+		ret = sst_unlock_block_protection(nor);
+		if (ret)
+			return ret;
+	}
+
 	dev_info(dev, "%s (%lld Kbytes)\n", id->name,
 			(long long)mtd->size >> 10);
 

include/linux/mtd/spi-nor.h

@@ -48,6 +48,7 @@
 #define SPINOR_OP_BP		0x02	/* Byte program */
 #define SPINOR_OP_WRDI		0x04	/* Write disable */
 #define SPINOR_OP_AAI_WP	0xad	/* Auto address increment word program */
+#define SPINOR_OP_ULBPR		0x98	/* Global Block Protection Unlock */
 
 /* Used for Macronix and Winbond flashes. */
 #define SPINOR_OP_EN4B		0xb7	/* Enter 4-byte mode */