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mtd: devices: add support for microchip 48l640 EERAM
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The Microchip 48l640 is a 8KByte EERAM connected via SPI.

Signed-off-by: Heiko Schocher <hs@denx.de>
Tested-by: Fabio Estevam <festevam@denx.de>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210607033909.1424605-3-hs@denx.de
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Heiko Schocher authored and Miquel Raynal committed Jun 11, 2021
1 parent 9fd795e commit 88d1250
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6 changes: 6 additions & 0 deletions drivers/mtd/devices/Kconfig
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Expand Up @@ -89,6 +89,12 @@ config MTD_MCHP23K256
platform data, or a device tree description if you want to
specify device partitioning

config MTD_MCHP48L640
tristate "Microchip 48L640 EERAM"
depends on SPI_MASTER
help
This enables access to Microchip 48L640 EERAM chips, using SPI.

config MTD_SPEAR_SMI
tristate "SPEAR MTD NOR Support through SMI controller"
depends on PLAT_SPEAR || COMPILE_TEST
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1 change: 1 addition & 0 deletions drivers/mtd/devices/Makefile
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Expand Up @@ -13,6 +13,7 @@ obj-$(CONFIG_MTD_LART) += lart.o
obj-$(CONFIG_MTD_BLOCK2MTD) += block2mtd.o
obj-$(CONFIG_MTD_DATAFLASH) += mtd_dataflash.o
obj-$(CONFIG_MTD_MCHP23K256) += mchp23k256.o
obj-$(CONFIG_MTD_MCHP48L640) += mchp48l640.o
obj-$(CONFIG_MTD_SPEAR_SMI) += spear_smi.o
obj-$(CONFIG_MTD_SST25L) += sst25l.o
obj-$(CONFIG_MTD_BCM47XXSFLASH) += bcm47xxsflash.o
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373 changes: 373 additions & 0 deletions drivers/mtd/devices/mchp48l640.c
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@@ -0,0 +1,373 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Driver for Microchip 48L640 64 Kb SPI Serial EERAM
*
* Copyright Heiko Schocher <hs@denx.de>
*
* 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_device.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 ret;
}

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;

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 ret;
};

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 int mchp48l640_remove(struct spi_device *spi)
{
struct mchp48l640_flash *flash = spi_get_drvdata(spi);

return 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 struct spi_driver mchp48l640_driver = {
.driver = {
.name = "mchp48l640",
.of_match_table = of_match_ptr(mchp48l640_of_table),
},
.probe = mchp48l640_probe,
.remove = mchp48l640_remove,
};

module_spi_driver(mchp48l640_driver);

MODULE_DESCRIPTION("MTD SPI driver for Microchip 48l640 EERAM chips");
MODULE_AUTHOR("Heiko Schocher <hs@denx.de>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("spi:mchp48l640");

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