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/*
* 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");
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