linux/drivers/mtd/devices/mchp48l640.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for Microchip 48L640 64 Kb SPI Serial EERAM
 *
 * Copyright Heiko Schocher <[email protected]>
 *
 * datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/20006055B.pdf
 *
 * we set continuous mode but reading/writing more bytes than
 * pagesize seems to bring chip into state where readden values
 * are wrong ... no idea why.
 *
 */
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/jiffies.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.h>

struct mchp48_caps { … };

struct mchp48l640_flash { … };

#define MCHP48L640_CMD_WREN …
#define MCHP48L640_CMD_WRDI …
#define MCHP48L640_CMD_WRITE …
#define MCHP48L640_CMD_READ …
#define MCHP48L640_CMD_WRSR …
#define MCHP48L640_CMD_RDSR …

#define MCHP48L640_STATUS_RDY …
#define MCHP48L640_STATUS_WEL …
#define MCHP48L640_STATUS_BP0 …
#define MCHP48L640_STATUS_BP1 …
#define MCHP48L640_STATUS_SWM …
#define MCHP48L640_STATUS_PRO …
#define MCHP48L640_STATUS_ASE …

#define MCHP48L640_TIMEOUT …

#define MAX_CMD_SIZE …

#define to_mchp48l640_flash(x) …

static int mchp48l640_mkcmd(struct mchp48l640_flash *flash, u8 cmd, loff_t addr, char *buf)
{ … }

static int mchp48l640_read_status(struct mchp48l640_flash *flash, int *status)
{ … }

static int mchp48l640_waitforbit(struct mchp48l640_flash *flash, int bit, bool set)
{ … }

static int mchp48l640_write_prepare(struct mchp48l640_flash *flash, bool enable)
{ … }

static int mchp48l640_set_mode(struct mchp48l640_flash *flash)
{ … }

static int mchp48l640_wait_rdy(struct mchp48l640_flash *flash)
{
	return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_RDY, false);
};

static int mchp48l640_write_page(struct mtd_info *mtd, loff_t to, size_t len,
			    size_t *retlen, const unsigned char *buf)
{
	struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
	unsigned char *cmd;
	int ret;
	int cmdlen;

	cmd = kmalloc((3 + len), GFP_KERNEL | GFP_DMA);
	if (!cmd)
		return -ENOMEM;

	ret = mchp48l640_wait_rdy(flash);
	if (ret)
		goto fail;

	ret = mchp48l640_write_prepare(flash, true);
	if (ret)
		goto fail;

	mutex_lock(&flash->lock);
	cmdlen = mchp48l640_mkcmd(flash, MCHP48L640_CMD_WRITE, to, cmd);
	memcpy(&cmd[cmdlen], buf, len);
	ret = spi_write(flash->spi, cmd, cmdlen + len);
	mutex_unlock(&flash->lock);
	if (!ret)
		*retlen += len;
	else
		goto fail;

	ret = mchp48l640_waitforbit(flash, MCHP48L640_STATUS_WEL, false);
	if (ret)
		goto fail;

	kfree(cmd);
	return 0;
fail:
	kfree(cmd);
	dev_err(&flash->spi->dev, "write fail with: %d", ret);
	return ret;
};

static int mchp48l640_write(struct mtd_info *mtd, loff_t to, size_t len,
			    size_t *retlen, const unsigned char *buf)
{ … }

static int mchp48l640_read_page(struct mtd_info *mtd, loff_t from, size_t len,
			   size_t *retlen, unsigned char *buf)
{ … }

static int mchp48l640_read(struct mtd_info *mtd, loff_t from, size_t len,
			   size_t *retlen, unsigned char *buf)
{
	struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
	int ret;
	size_t wlen = 0;
	loff_t woff = from;
	size_t ws;
	size_t page_sz = flash->caps->page_size;

	/*
	 * we set PRO bit (page rollover), but if read length > page size
	 * does result in total chaos in result ...
	 */
	while (wlen < len) {
		ws = min((len - wlen), page_sz);
		ret = mchp48l640_read_page(mtd, woff, ws, retlen, &buf[wlen]);
		if (ret)
			return ret;
		wlen += ws;
		woff += ws;
	}

	return 0;
};

static const struct mchp48_caps mchp48l640_caps = …;

static int mchp48l640_probe(struct spi_device *spi)
{ … }

static void mchp48l640_remove(struct spi_device *spi)
{ … }

static const struct of_device_id mchp48l640_of_table[] = …;
MODULE_DEVICE_TABLE(of, mchp48l640_of_table);

static const struct spi_device_id mchp48l640_spi_ids[] = …;
MODULE_DEVICE_TABLE(spi, mchp48l640_spi_ids);

static struct spi_driver mchp48l640_driver = …;

module_spi_driver(…) …;

MODULE_DESCRIPTION(…) …;
MODULE_AUTHOR(…) …;
MODULE_LICENSE(…) …;
MODULE_ALIAS(…) …;