// 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 {
unsigned int size;
unsigned int page_size;
};
struct mchp48l640_flash {
struct spi_device *spi;
struct mutex lock;
struct mtd_info mtd;
const struct mchp48_caps *caps;
};
#define MCHP48L640_CMD_WREN 0x06
#define MCHP48L640_CMD_WRDI 0x04
#define MCHP48L640_CMD_WRITE 0x02
#define MCHP48L640_CMD_READ 0x03
#define MCHP48L640_CMD_WRSR 0x01
#define MCHP48L640_CMD_RDSR 0x05
#define MCHP48L640_STATUS_RDY 0x01
#define MCHP48L640_STATUS_WEL 0x02
#define MCHP48L640_STATUS_BP0 0x04
#define MCHP48L640_STATUS_BP1 0x08
#define MCHP48L640_STATUS_SWM 0x10
#define MCHP48L640_STATUS_PRO 0x20
#define MCHP48L640_STATUS_ASE 0x40
#define MCHP48L640_TIMEOUT 100
#define MAX_CMD_SIZE 0x10
#define to_mchp48l640_flash(x) container_of(x, struct mchp48l640_flash, mtd)
static int mchp48l640_mkcmd(struct mchp48l640_flash *flash, u8 cmd, loff_t addr, char *buf)
{
buf[0] = cmd;
buf[1] = addr >> 8;
buf[2] = addr;
return 3;
}
static int mchp48l640_read_status(struct mchp48l640_flash *flash, int *status)
{
unsigned char cmd[2];
int ret;
cmd[0] = MCHP48L640_CMD_RDSR;
cmd[1] = 0x00;
mutex_lock(&flash->lock);
ret = spi_write_then_read(flash->spi, &cmd[0], 1, &cmd[1], 1);
mutex_unlock(&flash->lock);
if (!ret)
*status = cmd[1];
dev_dbg(&flash->spi->dev, "read status ret: %d status: %x", ret, *status);
return ret;
}
static int mchp48l640_waitforbit(struct mchp48l640_flash *flash, int bit, bool set)
{
int ret, status;
unsigned long deadline;
deadline = jiffies + msecs_to_jiffies(MCHP48L640_TIMEOUT);
do {
ret = mchp48l640_read_status(flash, &status);
dev_dbg(&flash->spi->dev, "read status ret: %d bit: %x %sset status: %x",
ret, bit, (set ? "" : "not"), status);
if (ret)
return ret;
if (set) {
if ((status & bit) == bit)
return 0;
} else {
if ((status & bit) == 0)
return 0;
}
usleep_range(1000, 2000);
} while (!time_after_eq(jiffies, deadline));
dev_err(&flash->spi->dev, "Timeout waiting for bit %x %s set in status register.",
bit, (set ? "" : "not"));
return -ETIMEDOUT;
}
static int mchp48l640_write_prepare(struct mchp48l640_flash *flash, bool enable)
{
unsigned char cmd[2];
int ret;
if (enable)
cmd[0] = MCHP48L640_CMD_WREN;
else
cmd[0] = MCHP48L640_CMD_WRDI;
mutex_lock(&flash->lock);
ret = spi_write(flash->spi, cmd, 1);
mutex_unlock(&flash->lock);
if (ret)
dev_err(&flash->spi->dev, "write %sable failed ret: %d",
(enable ? "en" : "dis"), ret);
dev_dbg(&flash->spi->dev, "write %sable success ret: %d",
(enable ? "en" : "dis"), ret);
if (enable)
return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_WEL, true);
return ret;
}
static int mchp48l640_set_mode(struct mchp48l640_flash *flash)
{
unsigned char cmd[2];
int ret;
ret = mchp48l640_write_prepare(flash, true);
if (ret)
return ret;
cmd[0] = MCHP48L640_CMD_WRSR;
cmd[1] = MCHP48L640_STATUS_PRO;
mutex_lock(&flash->lock);
ret = spi_write(flash->spi, cmd, 2);
mutex_unlock(&flash->lock);
if (ret)
dev_err(&flash->spi->dev, "Could not set continuous mode ret: %d", ret);
return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_PRO, true);
}
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)
{
struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
int ret;
size_t wlen = 0;
loff_t woff = to;
size_t ws;
size_t page_sz = flash->caps->page_size;
/*
* we set PRO bit (page rollover), but writing length > page size
* does result in total chaos, so write in 32 byte chunks.
*/
while (wlen < len) {
ws = min((len - wlen), page_sz);
ret = mchp48l640_write_page(mtd, woff, ws, retlen, &buf[wlen]);
if (ret)
return ret;
wlen += ws;
woff += ws;
}
return 0;
}
static int mchp48l640_read_page(struct mtd_info *mtd, loff_t from, size_t len,
size_t *retlen, 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;
mutex_lock(&flash->lock);
cmdlen = mchp48l640_mkcmd(flash, MCHP48L640_CMD_READ, from, cmd);
ret = spi_write_then_read(flash->spi, cmd, cmdlen, buf, len);
mutex_unlock(&flash->lock);
if (!ret)
*retlen += len;
kfree(cmd);
return ret;
fail:
kfree(cmd);
dev_err(&flash->spi->dev, "read fail with: %d", ret);
return ret;
}
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 = {
.size = SZ_8K,
.page_size = 32,
};
static int mchp48l640_probe(struct spi_device *spi)
{
struct mchp48l640_flash *flash;
struct flash_platform_data *data;
int err;
int status;
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 = mchp48l640_read_status(flash, &status);
if (err)
return err;
err = mchp48l640_set_mode(flash);
if (err)
return err;
data = dev_get_platdata(&spi->dev);
flash->caps = of_device_get_match_data(&spi->dev);
if (!flash->caps)
flash->caps = &mchp48l640_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 = flash->caps->page_size;
flash->mtd.size = flash->caps->size;
flash->mtd._read = mchp48l640_read;
flash->mtd._write = mchp48l640_write;
err = mtd_device_register(&flash->mtd, data ? data->parts : NULL,
data ? data->nr_parts : 0);
if (err)
return err;
return 0;
}
static void mchp48l640_remove(struct spi_device *spi)
{
struct mchp48l640_flash *flash = spi_get_drvdata(spi);
WARN_ON(mtd_device_unregister(&flash->mtd));
}
static const struct of_device_id mchp48l640_of_table[] = {
{
.compatible = "microchip,48l640",
.data = &mchp48l640_caps,
},
{}
};
MODULE_DEVICE_TABLE(of, mchp48l640_of_table);
static const struct spi_device_id mchp48l640_spi_ids[] = {
{
.name = "48l640",
.driver_data = (kernel_ulong_t)&mchp48l640_caps,
},
{}
};
MODULE_DEVICE_TABLE(spi, mchp48l640_spi_ids);
static struct spi_driver mchp48l640_driver = {
.driver = {
.name = "mchp48l640",
.of_match_table = mchp48l640_of_table,
},
.probe = mchp48l640_probe,
.remove = mchp48l640_remove,
.id_table = mchp48l640_spi_ids,
};
module_spi_driver(mchp48l640_driver);
MODULE_DESCRIPTION("MTD SPI driver for Microchip 48l640 EERAM chips");
MODULE_AUTHOR("Heiko Schocher <[email protected]>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("spi:mchp48l640");
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