diff options
Diffstat (limited to 'drivers/mtd/devices/mchp23k256.c')
| -rw-r--r-- | drivers/mtd/devices/mchp23k256.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/drivers/mtd/devices/mchp23k256.c b/drivers/mtd/devices/mchp23k256.c new file mode 100644 index 000000000000..e237db9f1bdb --- /dev/null +++ b/drivers/mtd/devices/mchp23k256.c @@ -0,0 +1,182 @@ +/* + * mchp23k256.c + * + * Driver for Microchip 23k256 SPI RAM chips + * + * Copyright © 2016 Andrew Lunn <andrew@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@lunn.ch>"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("spi:mchp23k256"); |