From 87947eac809fee0a2d40936d83cc8b216e7134bf Mon Sep 17 00:00:00 2001
From: JaimeLiao <jaimeliao.tw@gmail.com>
Date: Mon, 4 Jul 2022 14:12:41 +0800
Subject: [PATCH] mtd: spi-nor: Parse SFDP SCCR Map

Parse SCCR 22nd dword and check DTR Octal Mode Enable
Volatile bit for Octal DTR enable

Signed-off-by: JaimeLiao <jaimeliao.tw@gmail.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
---
 drivers/mtd/spi/spi-nor-core.c | 52 ++++++++++++++++++++++++++++++++++
 include/linux/mtd/spi-nor.h    |  1 +
 2 files changed, 53 insertions(+)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 50460feaf8..1ff34cc317 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -65,6 +65,10 @@ struct sfdp_parameter_header {
 #define SFDP_SECTOR_MAP_ID	0xff81	/* Sector Map Table */
 #define SFDP_SST_ID		0x01bf	/* Manufacturer specific Table */
 #define SFDP_PROFILE1_ID	0xff05	/* xSPI Profile 1.0 Table */
+#define SFDP_SCCR_MAP_ID	0xff87	/*
+					 * Status, Control and Configuration
+					 * Register Map.
+					 */
 
 #define SFDP_SIGNATURE		0x50444653U
 #define SFDP_JESD216_MAJOR	1
@@ -174,6 +178,9 @@ struct sfdp_header {
 #define PROFILE1_DWORD5_DUMMY_100MHZ		GENMASK(11, 7)
 #define PROFILE1_DUMMY_DEFAULT			20
 
+/* Status, Control and Configuration Register Map(SCCR) */
+#define SCCR_DWORD22_OCTAL_DTR_EN_VOLATILE      BIT(31)
+
 struct sfdp_bfpt {
 	u32	dwords[BFPT_DWORD_MAX];
 };
@@ -2456,6 +2463,44 @@ out:
 	return ret;
 }
 
+/**
+ * spi_nor_parse_sccr() - Parse the Status, Control and Configuration Register
+ *			  Map.
+ * @nor:		  pointer to a 'struct spi_nor'
+ * @sccr_header:	  pointer to the 'struct sfdp_parameter_header' describing
+ * 			  the SCCR Map table length and version.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_parse_sccr(struct spi_nor *nor,
+			      const struct sfdp_parameter_header *sccr_header)
+{
+	u32 *table, addr;
+	size_t len;
+	int ret, i;
+
+	len = sccr_header->length * sizeof(*table);
+	table = kmalloc(len, GFP_KERNEL);
+	if (!table)
+		return -ENOMEM;
+
+	addr = SFDP_PARAM_HEADER_PTP(sccr_header);
+	ret = spi_nor_read_sfdp(nor, addr, len, table);
+	if (ret)
+		goto out;
+
+	/* Fix endianness of the table DWORDs. */
+	for (i = 0; i < sccr_header->length; i++)
+		table[i] = le32_to_cpu(table[i]);
+
+	if (FIELD_GET(SCCR_DWORD22_OCTAL_DTR_EN_VOLATILE, table[22]))
+		nor->flags |= SNOR_F_IO_MODE_EN_VOLATILE;
+
+out:
+	kfree(table);
+	return ret;
+}
+
 /**
  * spi_nor_parse_sfdp() - parse the Serial Flash Discoverable Parameters.
  * @nor:		pointer to a 'struct spi_nor'
@@ -2562,6 +2607,10 @@ static int spi_nor_parse_sfdp(struct spi_nor *nor,
 			err = spi_nor_parse_profile1(nor, param_header, params);
 			break;
 
+		case SFDP_SCCR_MAP_ID:
+			err = spi_nor_parse_sccr(nor, param_header);
+			break;
+
 		default:
 			break;
 		}
@@ -3620,6 +3669,9 @@ static int spi_nor_octal_dtr_enable(struct spi_nor *nor)
 	      nor->write_proto == SNOR_PROTO_8_8_8_DTR))
 		return 0;
 
+	if (!(nor->flags & SNOR_F_IO_MODE_EN_VOLATILE))
+		return 0;
+
 	ret = nor->octal_dtr_enable(nor);
 	if (ret)
 		return ret;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index c76235d701..ba98ad467f 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -290,6 +290,7 @@ enum spi_nor_option_flags {
 	SNOR_F_USE_CLSR		= BIT(5),
 	SNOR_F_BROKEN_RESET	= BIT(6),
 	SNOR_F_SOFT_RESET	= BIT(7),
+	SNOR_F_IO_MODE_EN_VOLATILE = BIT(8),
 };
 
 struct spi_nor;
-- 
2.39.5