[PATCH v15 15/15] mtd: spi-nor: micron-st: allow using MT35XU512ABA in Octal DTR mode

[Pratyush Yadav]

Since this flash doesn't have a Profile 1.0 table, the Octal DTR
capabilities are enabled in the post SFDP fixup, along with the 8D-8D-8D
fast read settings.

Enable Octal DTR mode with 20 dummy cycles to allow running at the
maximum supported frequency of 200Mhz.

The flash supports the soft reset sequence. So, add the flag in the
flash's info.

Signed-off-by: Pratyush Yadav <p.yadav@xxxxxx>
---
 drivers/mtd/spi-nor/micron-st.c | 100 +++++++++++++++++++++++++++++++-
 1 file changed, 99 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/micron-st.c b/drivers/mtd/spi-nor/micron-st.c
index ef3695080710..bf3c5110742c 100644
--- a/drivers/mtd/spi-nor/micron-st.c
+++ b/drivers/mtd/spi-nor/micron-st.c
@@ -8,10 +8,108 @@
 
 #include "core.h"
 
+#define SPINOR_OP_MT_DTR_RD	0xfd	/* Fast Read opcode in DTR mode */
+#define SPINOR_OP_MT_RD_ANY_REG	0x85	/* Read volatile register */
+#define SPINOR_OP_MT_WR_ANY_REG	0x81	/* Write volatile register */
+#define SPINOR_REG_MT_CFR0V	0x00	/* For setting octal DTR mode */
+#define SPINOR_REG_MT_CFR1V	0x01	/* For setting dummy cycles */
+#define SPINOR_MT_OCT_DTR	0xe7	/* Enable Octal DTR. */
+#define SPINOR_MT_EXSPI		0xff	/* Enable Extended SPI (default) */
+
+static int spi_nor_micron_octal_dtr_enable(struct spi_nor *nor, bool enable)
+{
+	struct spi_mem_op op;
+	u8 *buf = nor->bouncebuf;
+	int ret;
+
+	if (enable) {
+		/* Use 20 dummy cycles for memory array reads. */
+		ret = spi_nor_write_enable(nor);
+		if (ret)
+			return ret;
+
+		*buf = 20;
+		op = (struct spi_mem_op)
+			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_MT_WR_ANY_REG, 1),
+				   SPI_MEM_OP_ADDR(3, SPINOR_REG_MT_CFR1V, 1),
+				   SPI_MEM_OP_NO_DUMMY,
+				   SPI_MEM_OP_DATA_OUT(1, buf, 1));
+
+		ret = spi_mem_exec_op(nor->spimem, &op);
+		if (ret)
+			return ret;
+
+		ret = spi_nor_wait_till_ready(nor);
+		if (ret)
+			return ret;
+	}
+
+	ret = spi_nor_write_enable(nor);
+	if (ret)
+		return ret;
+
+	if (enable)
+		*buf = SPINOR_MT_OCT_DTR;
+	else
+		*buf = SPINOR_MT_EXSPI;
+
+	op = (struct spi_mem_op)
+		SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_MT_WR_ANY_REG, 1),
+			   SPI_MEM_OP_ADDR(enable ? 3 : 4,
+					   SPINOR_REG_MT_CFR0V, 1),
+			   SPI_MEM_OP_NO_DUMMY,
+			   SPI_MEM_OP_DATA_OUT(1, buf, 1));
+
+	if (!enable)
+		spi_nor_spimem_setup_op(nor, &op, SNOR_PROTO_8_8_8_DTR);
+
+	ret = spi_mem_exec_op(nor->spimem, &op);
+	if (ret)
+		return ret;
+
+	/* Give some time for the mode change to take place. */
+	usleep_range(1000, 1500);
+
+	return 0;
+}
+
+static void mt35xu512aba_default_init(struct spi_nor *nor)
+{
+	nor->params->octal_dtr_enable = spi_nor_micron_octal_dtr_enable;
+}
+
+static void mt35xu512aba_post_sfdp_fixup(struct spi_nor *nor)
+{
+	/* Set the Fast Read settings. */
+	nor->params->hwcaps.mask |= SNOR_HWCAPS_READ_8_8_8_DTR;
+	spi_nor_set_read_settings(&nor->params->reads[SNOR_CMD_READ_8_8_8_DTR],
+				  0, 20, SPINOR_OP_MT_DTR_RD,
+				  SNOR_PROTO_8_8_8_DTR);
+
+	nor->cmd_ext_type = SPI_NOR_EXT_REPEAT;
+	nor->params->rdsr_dummy = 8;
+	nor->params->rdsr_addr_nbytes = 0;
+
+	/*
+	 * The BFPT quad enable field is set to a reserved value so the quad
+	 * enable function is ignored by spi_nor_parse_bfpt(). Make sure we
+	 * disable it.
+	 */
+	nor->params->quad_enable = NULL;
+}
+
+static struct spi_nor_fixups mt35xu512aba_fixups = {
+	.default_init = mt35xu512aba_default_init,
+	.post_sfdp = mt35xu512aba_post_sfdp_fixup,
+};
+
 static const struct flash_info micron_parts[] = {
 	{ "mt35xu512aba", INFO(0x2c5b1a, 0, 128 * 1024, 512,
 			       SECT_4K | USE_FSR | SPI_NOR_OCTAL_READ |
-			       SPI_NOR_4B_OPCODES) },
+			       SPI_NOR_4B_OPCODES | SPI_NOR_OCTAL_DTR_READ |
+			       SPI_NOR_OCTAL_DTR_PP |
+			       SPI_NOR_IO_MODE_EN_VOLATILE)
+	  .fixups = &mt35xu512aba_fixups},
 	{ "mt35xu02g", INFO(0x2c5b1c, 0, 128 * 1024, 2048,
 			    SECT_4K | USE_FSR | SPI_NOR_OCTAL_READ |
 			    SPI_NOR_4B_OPCODES) },
-- 
2.28.0