[PATCH v4 5/5] mtd: mchp23k256: Add support for mchp23lcv1024

[Chris Packham]

The mchp23lcv1024 is similar to the mchp23k256, the differences (from a
software point of view) are the capacity of the chip and the size of the
addresses used.

There is no way to detect the specific chip so we must be told via a
Device Tree or default to mchp23k256 when device tree is not used.

Signed-off-by: Chris Packham <chris.packham at alliedtelesis.co.nz>
Reviewed-by: Andrew Lunn <andrew at lunn.ch>
---
Changes in v2:
- fix formatting in switch statement
- add support for 24-bit addressing
Changes in v3:
- None
Changes in v4:
- reword commit message (thanks Andrew)
- introduce mchp23_caps struct (thanks Boris)

 .../bindings/mtd/microchip,mchp23k256.txt          |  2 +-
 drivers/mtd/devices/mchp23k256.c                   | 66 ++++++++++++++++++----
 2 files changed, 57 insertions(+), 11 deletions(-)

diff --git a/Documentation/devicetree/bindings/mtd/microchip,mchp23k256.txt b/Documentation/devicetree/bindings/mtd/microchip,mchp23k256.txt
index 25e5ad38b0f0..7328eb92a03c 100644
--- a/Documentation/devicetree/bindings/mtd/microchip,mchp23k256.txt
+++ b/Documentation/devicetree/bindings/mtd/microchip,mchp23k256.txt
@@ -3,7 +3,7 @@
 Required properties:
 - #address-cells, #size-cells : Must be present if the device has sub-nodes
   representing partitions.
-- compatible : Must be "microchip,mchp23k256"
+- compatible : Must be one of "microchip,mchp23k256" or "microchip,mchp23lcv1024"
 - reg : Chip-Select number
 - spi-max-frequency : Maximum frequency of the SPI bus the chip can operate at
 
diff --git a/drivers/mtd/devices/mchp23k256.c b/drivers/mtd/devices/mchp23k256.c
index 3e5feb454644..8956b7dcc984 100644
--- a/drivers/mtd/devices/mchp23k256.c
+++ b/drivers/mtd/devices/mchp23k256.c
@@ -21,10 +21,18 @@
 #include <linux/spi/spi.h>
 #include <linux/of_device.h>
 
+#define MAX_CMD_SIZE		4
+
+struct mchp23_caps {
+	u8 addr_width;
+	unsigned int size;
+};
+
 struct mchp23k256_flash {
 	struct spi_device	*spi;
 	struct mutex		lock;
 	struct mtd_info		mtd;
+	const struct mchp23_caps	*caps;
 };
 
 #define MCHP23K256_CMD_WRITE_STATUS	0x01
@@ -34,22 +42,40 @@ struct mchp23k256_flash {
 
 #define to_mchp23k256_flash(x) container_of(x, struct mchp23k256_flash, mtd)
 
+static void mchp23k256_addr2cmd(struct mchp23k256_flash *flash,
+				unsigned int addr, u8 *cmd)
+{
+	int i;
+
+	/*
+	 * Address is sent in big endian (MSB first) and we skip
+	 * the first entry of the cmd array which contains the cmd
+	 * opcode.
+	 */
+	for (i = flash->caps->addr_width; i > 0; i--, addr >>= 8)
+		cmd[i] = addr;
+}
+
+static int mchp23k256_cmdsz(struct mchp23k256_flash *flash)
+{
+	return 1 + flash->caps->addr_width;
+}
+
 static int mchp23k256_write(struct mtd_info *mtd, loff_t to, size_t len,
 			    size_t *retlen, const unsigned char *buf)
 {
 	struct mchp23k256_flash *flash = to_mchp23k256_flash(mtd);
 	struct spi_transfer transfer[2] = {};
 	struct spi_message message;
-	unsigned char command[3];
+	unsigned char command[MAX_CMD_SIZE];
 
 	spi_message_init(&message);
 
 	command[0] = MCHP23K256_CMD_WRITE;
-	command[1] = to >> 8;
-	command[2] = to;
+	mchp23k256_addr2cmd(flash, to, command);
 
 	transfer[0].tx_buf = command;
-	transfer[0].len = sizeof(command);
+	transfer[0].len = mchp23k256_cmdsz(flash);
 	spi_message_add_tail(&transfer[0], &message);
 
 	transfer[1].tx_buf = buf;
@@ -73,17 +99,16 @@ static int mchp23k256_read(struct mtd_info *mtd, loff_t from, size_t len,
 	struct mchp23k256_flash *flash = to_mchp23k256_flash(mtd);
 	struct spi_transfer transfer[2] = {};
 	struct spi_message message;
-	unsigned char command[3];
+	unsigned char command[MAX_CMD_SIZE];
 
 	spi_message_init(&message);
 
 	memset(&transfer, 0, sizeof(transfer));
 	command[0] = MCHP23K256_CMD_READ;
-	command[1] = from >> 8;
-	command[2] = from;
+	mchp23k256_addr2cmd(flash, from, command);
 
 	transfer[0].tx_buf = command;
-	transfer[0].len = sizeof(command);
+	transfer[0].len = mchp23k256_cmdsz(flash);
 	spi_message_add_tail(&transfer[0], &message);
 
 	transfer[1].rx_buf = buf;
@@ -123,6 +148,16 @@ static int mchp23k256_set_mode(struct spi_device *spi)
 	return spi_sync(spi, &message);
 }
 
+static const struct mchp23_caps mchp23k256_caps = {
+	.size = SZ_32K,
+	.addr_width = 2,
+};
+
+static const struct mchp23_caps mchp23lcv1024_caps = {
+	.size = SZ_128K,
+	.addr_width = 3,
+};
+
 static int mchp23k256_probe(struct spi_device *spi)
 {
 	struct mchp23k256_flash *flash;
@@ -143,12 +178,16 @@ static int mchp23k256_probe(struct spi_device *spi)
 
 	data = dev_get_platdata(&spi->dev);
 
+	flash->caps = of_device_get_match_data(&spi->dev);
+	if (!flash->caps)
+		flash->caps = &mchp23k256_caps;
+
 	mtd_set_of_node(&flash->mtd, spi->dev.of_node);
 	flash->mtd.dev.parent	= &spi->dev;
 	flash->mtd.type		= MTD_RAM;
 	flash->mtd.flags	= MTD_CAP_RAM;
 	flash->mtd.writesize	= 1;
-	flash->mtd.size		= SZ_32K;
+	flash->mtd.size		= flash->caps->size;
 	flash->mtd._read	= mchp23k256_read;
 	flash->mtd._write	= mchp23k256_write;
 
@@ -168,7 +207,14 @@ static int mchp23k256_remove(struct spi_device *spi)
 }
 
 static const struct of_device_id mchp23k256_of_table[] = {
-	{ .compatible = "microchip,mchp23k256" },
+	{
+		.compatible = "microchip,mchp23k256",
+		.data = &mchp23k256_caps,
+	},
+	{
+		.compatible = "microchip,mchp23lcv1024",
+		.data = &mchp23lcv1024_caps,
+	},
 	{}
 };
 MODULE_DEVICE_TABLE(of, mchp23k256_of_table);
-- 
2.13.0