[PATCH v3 4/8] mtd: spi-nor: sfdp: Add support for SCCR map for multi-chip device

[tkuw584924 at gmail.com]

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

SCCR map for multi-chip devices contains the number of additional dice in
the device and register offset values for each additional dice.

spi_nor_parse_sccr_mc() is added to determine the number of dice and
volatile register offset for each die. The volatile register offset table
may already be allocated and contains offset value for die-0 via SCCR map
parse. So, we should use devm_krealloc() to expand the table with
preserving die-0 offset.

Signed-off-by: Takahiro Kuwano <Takahiro.Kuwano at infineon.com>
---
 drivers/mtd/spi-nor/sfdp.c | 73 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)

diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
index 9d43e18d3770..00a40bd8aa1e 100644
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -26,6 +26,11 @@
 					 * Status, Control and Configuration
 					 * Register Map.
 					 */
+#define SFDP_SCCR_MAP_MC_ID	0xff88	/*
+					 * Status, Control and Configuration
+					 * Register Map Offsets for Multi-Chip
+					 * SPI Memory Devices.
+					 */
 
 #define SFDP_SIGNATURE		0x50444653U
 
@@ -1264,6 +1269,70 @@ static int spi_nor_parse_sccr(struct spi_nor *nor,
 	return ret;
 }
 
+#define SCCR_MC_MAX_DICE		255
+
+/**
+ * spi_nor_parse_sccr_mc() - Parse the Status, Control and Configuration
+ *                           Register Map Offsets for Multi-Chip SPI Memory
+ *                           Devices.
+ * @nor:		pointer to a 'struct spi_nor'
+ * @sccr_mc_header:	pointer to the 'struct sfdp_parameter_header' describing
+ *			the SCCR Map offsets table length and version.
+ *
+ * Return: 0 on success, -errno otherwise.
+ */
+static int spi_nor_parse_sccr_mc(struct spi_nor *nor,
+				 const struct sfdp_parameter_header *sccr_mc_header)
+{
+	struct spi_nor_flash_parameter *params = nor->params;
+	u32 *dwords, addr;
+	u8 i, n_dice;
+	size_t len;
+	int ret;
+
+	len = sccr_mc_header->length * sizeof(*dwords);
+	dwords = kmalloc(len, GFP_KERNEL);
+	if (!dwords)
+		return -ENOMEM;
+
+	addr = SFDP_PARAM_HEADER_PTP(sccr_mc_header);
+	ret = spi_nor_read_sfdp(nor, addr, len, dwords);
+	if (ret)
+		goto out;
+
+	le32_to_cpu_array(dwords, sccr_mc_header->length);
+
+	/*
+	 * Pair of DOWRDs (volatile and non-volatile register offsets) per
+	 * additional die. Hence, length = 2 * (number of additional dice).
+	 */
+	n_dice = 1 + sccr_mc_header->length / 2;
+	if (params->n_dice > SCCR_MC_MAX_DICE) {
+		dev_dbg(nor->dev, "Improbable number of dice defined in SCCR MC table, use one die.\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Address offset for volatile registers of additional dice */
+	params->vreg_offset =
+			devm_krealloc(nor->dev, params->vreg_offset,
+				      n_dice * sizeof(*dwords),
+				      GFP_KERNEL);
+	if (!params->vreg_offset) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	for (i = 1; i < n_dice; i++)
+		params->vreg_offset[i] = dwords[SFDP_DWORD(i) * 2];
+
+	params->n_dice = n_dice;
+
+out:
+	kfree(dwords);
+	return ret;
+}
+
 /**
  * spi_nor_post_sfdp_fixups() - Updates the flash's parameters and settings
  * after SFDP has been parsed. Called only for flashes that define JESD216 SFDP
@@ -1480,6 +1549,10 @@ int spi_nor_parse_sfdp(struct spi_nor *nor)
 			err = spi_nor_parse_sccr(nor, param_header);
 			break;
 
+		case SFDP_SCCR_MAP_MC_ID:
+			err = spi_nor_parse_sccr_mc(nor, param_header);
+			break;
+
 		default:
 			break;
 		}
-- 
2.34.1