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-rw-r--r--drivers/mtd/devices/mchp23k256.c260
1 files changed, 260 insertions, 0 deletions
diff --git a/drivers/mtd/devices/mchp23k256.c b/drivers/mtd/devices/mchp23k256.c
new file mode 100644
index 000000000..3a6ea7a6a
--- /dev/null
+++ b/drivers/mtd/devices/mchp23k256.c
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mchp23k256.c
+ *
+ * Driver for Microchip 23k256 SPI RAM chips
+ *
+ * Copyright © 2016 Andrew Lunn <andrew@lunn.ch>
+ */
+#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>
+#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
+#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 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[MAX_CMD_SIZE];
+ int ret, cmd_len;
+
+ spi_message_init(&message);
+
+ cmd_len = mchp23k256_cmdsz(flash);
+
+ command[0] = MCHP23K256_CMD_WRITE;
+ mchp23k256_addr2cmd(flash, to, command);
+
+ transfer[0].tx_buf = command;
+ transfer[0].len = cmd_len;
+ 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);
+
+ ret = spi_sync(flash->spi, &message);
+
+ mutex_unlock(&flash->lock);
+
+ if (ret)
+ return ret;
+
+ if (retlen && message.actual_length > cmd_len)
+ *retlen += message.actual_length - cmd_len;
+
+ 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[MAX_CMD_SIZE];
+ int ret, cmd_len;
+
+ spi_message_init(&message);
+
+ cmd_len = mchp23k256_cmdsz(flash);
+
+ memset(&transfer, 0, sizeof(transfer));
+ command[0] = MCHP23K256_CMD_READ;
+ mchp23k256_addr2cmd(flash, from, command);
+
+ transfer[0].tx_buf = command;
+ transfer[0].len = cmd_len;
+ 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);
+
+ ret = spi_sync(flash->spi, &message);
+
+ mutex_unlock(&flash->lock);
+
+ if (ret)
+ return ret;
+
+ if (retlen && message.actual_length > cmd_len)
+ *retlen += message.actual_length - cmd_len;
+
+ 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 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;
+ 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->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 = flash->caps->size;
+ flash->mtd._read = mchp23k256_read;
+ flash->mtd._write = mchp23k256_write;
+
+ err = mtd_device_register(&flash->mtd, data ? data->parts : NULL,
+ data ? data->nr_parts : 0);
+ if (err)
+ return err;
+
+ return 0;
+}
+
+static void mchp23k256_remove(struct spi_device *spi)
+{
+ struct mchp23k256_flash *flash = spi_get_drvdata(spi);
+
+ WARN_ON(mtd_device_unregister(&flash->mtd));
+}
+
+static const struct of_device_id mchp23k256_of_table[] = {
+ {
+ .compatible = "microchip,mchp23k256",
+ .data = &mchp23k256_caps,
+ },
+ {
+ .compatible = "microchip,mchp23lcv1024",
+ .data = &mchp23lcv1024_caps,
+ },
+ {}
+};
+MODULE_DEVICE_TABLE(of, mchp23k256_of_table);
+
+static const struct spi_device_id mchp23k256_spi_ids[] = {
+ {
+ .name = "mchp23k256",
+ .driver_data = (kernel_ulong_t)&mchp23k256_caps,
+ },
+ {
+ .name = "mchp23lcv1024",
+ .driver_data = (kernel_ulong_t)&mchp23lcv1024_caps,
+ },
+ {}
+};
+MODULE_DEVICE_TABLE(spi, mchp23k256_spi_ids);
+
+static struct spi_driver mchp23k256_driver = {
+ .driver = {
+ .name = "mchp23k256",
+ .of_match_table = mchp23k256_of_table,
+ },
+ .probe = mchp23k256_probe,
+ .remove = mchp23k256_remove,
+ .id_table = mchp23k256_spi_ids,
+};
+
+module_spi_driver(mchp23k256_driver);
+
+MODULE_DESCRIPTION("MTD SPI driver for MCHP23K256 RAM chips");
+MODULE_AUTHOR("Andrew Lunn <andre@lunn.ch>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("spi:mchp23k256");