[PATCH v2] mtd: mchp23k256: Add driver for this SPI SRAM device
Andrew Lunn
andrew at lunn.ch
Fri Mar 10 12:17:53 PST 2017
The Microchip 23k256 is a 32K Byte SRAM connected via SPI.
Signed-off-by: Andrew Lunn <andrew at lunn.ch>
---
v2: Remove multiple blank lines.
Make MODULE_LICENSE() consistent with license text.
Fix copyright year.
---
drivers/mtd/devices/Kconfig | 10 +++
drivers/mtd/devices/Makefile | 1 +
drivers/mtd/devices/mchp23k256.c | 181 +++++++++++++++++++++++++++++++++++++++
3 files changed, 192 insertions(+)
create mode 100644 drivers/mtd/devices/mchp23k256.c
diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig
index 58329d2dacd1..6def5445e03e 100644
--- a/drivers/mtd/devices/Kconfig
+++ b/drivers/mtd/devices/Kconfig
@@ -95,6 +95,16 @@ config MTD_M25P80
if you want to specify device partitioning or to use a device which
doesn't support the JEDEC ID instruction.
+config MTD_MCHP23K256
+ tristate "Microchip 23K256 SRAM"
+ depends on SPI_MASTER
+ help
+ This enables access to Microchip 23K256 SRAM chips, using SPI.
+
+ Set up your spi devices with the right board-specific
+ platform data, or a device tree description if you want to
+ specify device partitioning
+
config MTD_SPEAR_SMI
tristate "SPEAR MTD NOR Support through SMI controller"
depends on PLAT_SPEAR
diff --git a/drivers/mtd/devices/Makefile b/drivers/mtd/devices/Makefile
index 7912d3a0ee34..f0f767624cc6 100644
--- a/drivers/mtd/devices/Makefile
+++ b/drivers/mtd/devices/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_MTD_LART) += lart.o
obj-$(CONFIG_MTD_BLOCK2MTD) += block2mtd.o
obj-$(CONFIG_MTD_DATAFLASH) += mtd_dataflash.o
obj-$(CONFIG_MTD_M25P80) += m25p80.o
+obj-$(CONFIG_MTD_MCHP23K256) += mchp23k256.o
obj-$(CONFIG_MTD_SPEAR_SMI) += spear_smi.o
obj-$(CONFIG_MTD_SST25L) += sst25l.o
obj-$(CONFIG_MTD_BCM47XXSFLASH) += bcm47xxsflash.o
diff --git a/drivers/mtd/devices/mchp23k256.c b/drivers/mtd/devices/mchp23k256.c
new file mode 100644
index 000000000000..ce464d2a7bbe
--- /dev/null
+++ b/drivers/mtd/devices/mchp23k256.c
@@ -0,0 +1,181 @@
+/*
+ * mchp23k256.c
+ *
+ * Driver for Microchip 23k256 SPI RAM chips
+ *
+ * Copyright (c) 2017 Andrew Lunn <andrew at lunn.ch>
+ *
+ * This code is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mutex.h>
+#include <linux/sched.h>
+#include <linux/sizes.h>
+#include <linux/spi/flash.h>
+#include <linux/spi/spi.h>
+
+struct mchp23k256_flash {
+ struct spi_device *spi;
+ struct mutex lock;
+ struct mtd_info mtd;
+};
+
+#define MCHP23K256_CMD_WRITE_STATUS 0x01
+#define MCHP23K256_CMD_WRITE 0x02
+#define MCHP23K256_CMD_READ 0x03
+#define MCHP23K256_MODE_SEQ BIT(6)
+
+#define to_mchp23k256_flash(x) container_of(x, struct mchp23k256_flash, mtd)
+
+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];
+
+ spi_message_init(&message);
+
+ command[0] = MCHP23K256_CMD_WRITE;
+ command[1] = to >> 8;
+ command[2] = to;
+
+ transfer[0].tx_buf = command;
+ transfer[0].len = sizeof(command);
+ spi_message_add_tail(&transfer[0], &message);
+
+ transfer[1].tx_buf = buf;
+ transfer[1].len = len;
+ spi_message_add_tail(&transfer[1], &message);
+
+ mutex_lock(&flash->lock);
+
+ spi_sync(flash->spi, &message);
+
+ if (retlen && message.actual_length > sizeof(command))
+ *retlen += message.actual_length - sizeof(command);
+
+ mutex_unlock(&flash->lock);
+ return 0;
+}
+
+static int mchp23k256_read(struct mtd_info *mtd, loff_t from, size_t len,
+ size_t *retlen, unsigned char *buf)
+{
+ struct mchp23k256_flash *flash = to_mchp23k256_flash(mtd);
+ struct spi_transfer transfer[2] = {};
+ struct spi_message message;
+ unsigned char command[3];
+
+ spi_message_init(&message);
+
+ memset(&transfer, 0, sizeof(transfer));
+ command[0] = MCHP23K256_CMD_READ;
+ command[1] = from >> 8;
+ command[2] = from;
+
+ transfer[0].tx_buf = command;
+ transfer[0].len = sizeof(command);
+ spi_message_add_tail(&transfer[0], &message);
+
+ transfer[1].rx_buf = buf;
+ transfer[1].len = len;
+ spi_message_add_tail(&transfer[1], &message);
+
+ mutex_lock(&flash->lock);
+
+ spi_sync(flash->spi, &message);
+
+ if (retlen && message.actual_length > sizeof(command))
+ *retlen += message.actual_length - sizeof(command);
+
+ mutex_unlock(&flash->lock);
+ return 0;
+}
+
+/* Set the device into sequential mode. This allows read/writes to
+ * the entire SRAM in a single operation
+ */
+static int mchp23k256_set_mode(struct spi_device *spi)
+{
+ struct spi_transfer transfer = {};
+ struct spi_message message;
+ unsigned char command[2];
+
+ spi_message_init(&message);
+
+ command[0] = MCHP23K256_CMD_WRITE_STATUS;
+ command[1] = MCHP23K256_MODE_SEQ;
+
+ transfer.tx_buf = command;
+ transfer.len = sizeof(command);
+ spi_message_add_tail(&transfer, &message);
+
+ return spi_sync(spi, &message);
+}
+
+static int mchp23k256_probe(struct spi_device *spi)
+{
+ struct mchp23k256_flash *flash;
+ struct flash_platform_data *data;
+ int err;
+
+ flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
+ if (!flash)
+ return -ENOMEM;
+
+ flash->spi = spi;
+ mutex_init(&flash->lock);
+ spi_set_drvdata(spi, flash);
+
+ err = mchp23k256_set_mode(spi);
+ if (err)
+ return err;
+
+ data = dev_get_platdata(&spi->dev);
+
+ 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._read = mchp23k256_read;
+ flash->mtd._write = mchp23k256_write;
+
+ err = mtd_device_parse_register(&flash->mtd, NULL, NULL,
+ data ? data->parts : NULL,
+ data ? data->nr_parts : 0);
+ if (err)
+ return err;
+
+ return 0;
+}
+
+static int mchp23k256_remove(struct spi_device *spi)
+{
+ struct mchp23k256_flash *flash = spi_get_drvdata(spi);
+
+ return mtd_device_unregister(&flash->mtd);
+}
+
+static struct spi_driver mchp23k256_driver = {
+ .driver = {
+ .name = "mchp23k256",
+ },
+ .probe = mchp23k256_probe,
+ .remove = mchp23k256_remove,
+};
+
+module_spi_driver(mchp23k256_driver);
+
+MODULE_DESCRIPTION("MTD SPI driver for MCHP23K256 RAM chips");
+MODULE_AUTHOR("Andrew Lunn <andre at lunn.ch>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("spi:mchp23k256");
--
2.11.0
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