Commit 06b4501e authored by Anatolij Gustschin's avatar Anatolij Gustschin Committed by Linus Torvalds
Browse files

misc/eeprom: add driver for microwire 93xx46 EEPROMs 



Add EEPROM driver for 93xx46 chips.  It can also be used with spi_gpio
driver to access 93xx46 EEPROMs connected over GPIO lines.  This driver
supports read/write/erase access to the EEPROM chips over sysfs files.

[rdunlap@xenotime.net: fix printk format]
Signed-off-by: default avatarAnatolij Gustschin <agust@denx.de>
Cc: Jonathan Cameron <jic23@cam.ac.uk>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: default avatarRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6e60c02e

drivers/misc/eeprom/Kconfig

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@@ -70,4 +70,17 @@ config EEPROM_93CX6 


	  If unsure, say N.



config EEPROM_93XX46

	tristate "Microwire EEPROM 93XX46 support"

	depends on SPI && SYSFS

	help

	  Driver for the microwire EEPROM chipsets 93xx46x. The driver

	  supports both read and write commands and also the command to

	  erase the whole EEPROM.



	  This driver can also be built as a module.  If so, the module

	  will be called eeprom_93xx46.



	  If unsure, say N.



endmenu

drivers/misc/eeprom/Makefile

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@@ -3,3 +3,4 @@ obj-$(CONFIG_EEPROM_AT25) += at25.o 
obj-$(CONFIG_EEPROM_LEGACY)	+= eeprom.o

obj-$(CONFIG_EEPROM_MAX6875)	+= max6875.o

obj-$(CONFIG_EEPROM_93CX6)	+= eeprom_93cx6.o

obj-$(CONFIG_EEPROM_93XX46)	+= eeprom_93xx46.o

drivers/misc/eeprom/eeprom_93xx46.c

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/*

 * Driver for 93xx46 EEPROMs

 *

 * (C) 2011 DENX Software Engineering, Anatolij Gustschin <agust@denx.de>

 *

 * This program 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/delay.h>

#include <linux/device.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/mutex.h>

#include <linux/slab.h>

#include <linux/spi/spi.h>

#include <linux/sysfs.h>

#include <linux/eeprom_93xx46.h>



#define OP_START	0x4

#define OP_WRITE	(OP_START | 0x1)

#define OP_READ		(OP_START | 0x2)

#define ADDR_EWDS	0x00

#define ADDR_ERAL	0x20

#define ADDR_EWEN	0x30



struct eeprom_93xx46_dev {

	struct spi_device *spi;

	struct eeprom_93xx46_platform_data *pdata;

	struct bin_attribute bin;

	struct mutex lock;

	int addrlen;

};



static ssize_t

eeprom_93xx46_bin_read(struct file *filp, struct kobject *kobj,

		       struct bin_attribute *bin_attr,

		       char *buf, loff_t off, size_t count)

{

	struct eeprom_93xx46_dev *edev;

	struct device *dev;

	struct spi_message m;

	struct spi_transfer t[2];

	int bits, ret;

	u16 cmd_addr;



	dev = container_of(kobj, struct device, kobj);

	edev = dev_get_drvdata(dev);



	if (unlikely(off >= edev->bin.size))

		return 0;

	if ((off + count) > edev->bin.size)

		count = edev->bin.size - off;

	if (unlikely(!count))

		return count;



	cmd_addr = OP_READ << edev->addrlen;



	if (edev->addrlen == 7) {

		cmd_addr |= off & 0x7f;

		bits = 10;

	} else {

		cmd_addr |= off & 0x3f;

		bits = 9;

	}



	dev_dbg(&edev->spi->dev, "read cmd 0x%x, %d Hz\n",

		cmd_addr, edev->spi->max_speed_hz);



	spi_message_init(&m);

	memset(t, 0, sizeof(t));



	t[0].tx_buf = (char *)&cmd_addr;

	t[0].len = 2;

	t[0].bits_per_word = bits;

	spi_message_add_tail(&t[0], &m);



	t[1].rx_buf = buf;

	t[1].len = count;

	t[1].bits_per_word = 8;

	spi_message_add_tail(&t[1], &m);



	mutex_lock(&edev->lock);



	if (edev->pdata->prepare)

		edev->pdata->prepare(edev);



	ret = spi_sync(edev->spi, &m);

	/* have to wait at least Tcsl ns */

	ndelay(250);

	if (ret) {

		dev_err(&edev->spi->dev, "read %zu bytes at %d: err. %d\n",

			count, (int)off, ret);

	}



	if (edev->pdata->finish)

		edev->pdata->finish(edev);



	mutex_unlock(&edev->lock);

	return ret ? : count;

}



static int eeprom_93xx46_ew(struct eeprom_93xx46_dev *edev, int is_on)

{

	struct spi_message m;

	struct spi_transfer t;

	int bits, ret;

	u16 cmd_addr;



	cmd_addr = OP_START << edev->addrlen;

	if (edev->addrlen == 7) {

		cmd_addr |= (is_on ? ADDR_EWEN : ADDR_EWDS) << 1;

		bits = 10;

	} else {

		cmd_addr |= (is_on ? ADDR_EWEN : ADDR_EWDS);

		bits = 9;

	}



	dev_dbg(&edev->spi->dev, "ew cmd 0x%04x\n", cmd_addr);



	spi_message_init(&m);

	memset(&t, 0, sizeof(t));



	t.tx_buf = &cmd_addr;

	t.len = 2;

	t.bits_per_word = bits;

	spi_message_add_tail(&t, &m);



	mutex_lock(&edev->lock);



	if (edev->pdata->prepare)

		edev->pdata->prepare(edev);



	ret = spi_sync(edev->spi, &m);

	/* have to wait at least Tcsl ns */

	ndelay(250);

	if (ret)

		dev_err(&edev->spi->dev, "erase/write %sable error %d\n",

			is_on ? "en" : "dis", ret);



	if (edev->pdata->finish)

		edev->pdata->finish(edev);



	mutex_unlock(&edev->lock);

	return ret;

}



static ssize_t

eeprom_93xx46_write_word(struct eeprom_93xx46_dev *edev,

			 const char *buf, unsigned off)

{

	struct spi_message m;

	struct spi_transfer t[2];

	int bits, data_len, ret;

	u16 cmd_addr;



	cmd_addr = OP_WRITE << edev->addrlen;



	if (edev->addrlen == 7) {

		cmd_addr |= off & 0x7f;

		bits = 10;

		data_len = 1;

	} else {

		cmd_addr |= off & 0x3f;

		bits = 9;

		data_len = 2;

	}



	dev_dbg(&edev->spi->dev, "write cmd 0x%x\n", cmd_addr);



	spi_message_init(&m);

	memset(t, 0, sizeof(t));



	t[0].tx_buf = (char *)&cmd_addr;

	t[0].len = 2;

	t[0].bits_per_word = bits;

	spi_message_add_tail(&t[0], &m);



	t[1].tx_buf = buf;

	t[1].len = data_len;

	t[1].bits_per_word = 8;

	spi_message_add_tail(&t[1], &m);



	ret = spi_sync(edev->spi, &m);

	/* have to wait program cycle time Twc ms */

	mdelay(6);

	return ret;

}



static ssize_t

eeprom_93xx46_bin_write(struct file *filp, struct kobject *kobj,

			struct bin_attribute *bin_attr,

			char *buf, loff_t off, size_t count)

{

	struct eeprom_93xx46_dev *edev;

	struct device *dev;

	int i, ret, step = 1;



	dev = container_of(kobj, struct device, kobj);

	edev = dev_get_drvdata(dev);



	if (unlikely(off >= edev->bin.size))

		return 0;

	if ((off + count) > edev->bin.size)

		count = edev->bin.size - off;

	if (unlikely(!count))

		return count;



	/* only write even number of bytes on 16-bit devices */

	if (edev->addrlen == 6) {

		step = 2;

		count &= ~1;

	}



	/* erase/write enable */

	ret = eeprom_93xx46_ew(edev, 1);

	if (ret)

		return ret;



	mutex_lock(&edev->lock);



	if (edev->pdata->prepare)

		edev->pdata->prepare(edev);



	for (i = 0; i < count; i += step) {

		ret = eeprom_93xx46_write_word(edev, &buf[i], off + i);

		if (ret) {

			dev_err(&edev->spi->dev, "write failed at %d: %d\n",

				(int)off + i, ret);

			break;

		}

	}



	if (edev->pdata->finish)

		edev->pdata->finish(edev);



	mutex_unlock(&edev->lock);



	/* erase/write disable */

	eeprom_93xx46_ew(edev, 0);

	return ret ? : count;

}



static int eeprom_93xx46_eral(struct eeprom_93xx46_dev *edev)

{

	struct eeprom_93xx46_platform_data *pd = edev->pdata;

	struct spi_message m;

	struct spi_transfer t;

	int bits, ret;

	u16 cmd_addr;



	cmd_addr = OP_START << edev->addrlen;

	if (edev->addrlen == 7) {

		cmd_addr |= ADDR_ERAL << 1;

		bits = 10;

	} else {

		cmd_addr |= ADDR_ERAL;

		bits = 9;

	}



	spi_message_init(&m);

	memset(&t, 0, sizeof(t));



	t.tx_buf = &cmd_addr;

	t.len = 2;

	t.bits_per_word = bits;

	spi_message_add_tail(&t, &m);



	mutex_lock(&edev->lock);



	if (edev->pdata->prepare)

		edev->pdata->prepare(edev);



	ret = spi_sync(edev->spi, &m);

	if (ret)

		dev_err(&edev->spi->dev, "erase error %d\n", ret);

	/* have to wait erase cycle time Tec ms */

	mdelay(6);



	if (pd->finish)

		pd->finish(edev);



	mutex_unlock(&edev->lock);

	return ret;

}



static ssize_t eeprom_93xx46_store_erase(struct device *dev,

					 struct device_attribute *attr,

					 const char *buf, size_t count)

{

	struct eeprom_93xx46_dev *edev = dev_get_drvdata(dev);

	int erase = 0, ret;



	sscanf(buf, "%d", &erase);

	if (erase) {

		ret = eeprom_93xx46_ew(edev, 1);

		if (ret)

			return ret;

		ret = eeprom_93xx46_eral(edev);

		if (ret)

			return ret;

		ret = eeprom_93xx46_ew(edev, 0);

		if (ret)

			return ret;

	}

	return count;

}

static DEVICE_ATTR(erase, S_IWUSR, NULL, eeprom_93xx46_store_erase);



static int __devinit eeprom_93xx46_probe(struct spi_device *spi)

{

	struct eeprom_93xx46_platform_data *pd;

	struct eeprom_93xx46_dev *edev;

	int err;



	pd = spi->dev.platform_data;

	if (!pd) {

		dev_err(&spi->dev, "missing platform data\n");

		return -ENODEV;

	}



	edev = kzalloc(sizeof(*edev), GFP_KERNEL);

	if (!edev)

		return -ENOMEM;



	if (pd->flags & EE_ADDR8)

		edev->addrlen = 7;

	else if (pd->flags & EE_ADDR16)

		edev->addrlen = 6;

	else {

		dev_err(&spi->dev, "unspecified address type\n");

		err = -EINVAL;

		goto fail;

	}



	mutex_init(&edev->lock);



	edev->spi = spi_dev_get(spi);

	edev->pdata = pd;



	sysfs_bin_attr_init(&edev->bin);

	edev->bin.attr.name = "eeprom";

	edev->bin.attr.mode = S_IRUSR;

	edev->bin.read = eeprom_93xx46_bin_read;

	edev->bin.size = 128;

	if (!(pd->flags & EE_READONLY)) {

		edev->bin.write = eeprom_93xx46_bin_write;

		edev->bin.attr.mode |= S_IWUSR;

	}



	err = sysfs_create_bin_file(&spi->dev.kobj, &edev->bin);

	if (err)

		goto fail;



	dev_info(&spi->dev, "%d-bit eeprom %s\n",

		(pd->flags & EE_ADDR8) ? 8 : 16,

		(pd->flags & EE_READONLY) ? "(readonly)" : "");



	if (!(pd->flags & EE_READONLY)) {

		if (device_create_file(&spi->dev, &dev_attr_erase))

			dev_err(&spi->dev, "can't create erase interface\n");

	}



	dev_set_drvdata(&spi->dev, edev);

	return 0;

fail:

	kfree(edev);

	return err;

}



static int __devexit eeprom_93xx46_remove(struct spi_device *spi)

{

	struct eeprom_93xx46_dev *edev = dev_get_drvdata(&spi->dev);



	if (!(edev->pdata->flags & EE_READONLY))

		device_remove_file(&spi->dev, &dev_attr_erase);



	sysfs_remove_bin_file(&spi->dev.kobj, &edev->bin);

	dev_set_drvdata(&spi->dev, NULL);

	kfree(edev);

	return 0;

}



static struct spi_driver eeprom_93xx46_driver = {

	.driver = {

		.name	= "93xx46",

		.owner	= THIS_MODULE,

	},

	.probe		= eeprom_93xx46_probe,

	.remove		= __devexit_p(eeprom_93xx46_remove),

};



static int __init eeprom_93xx46_init(void)

{

	return spi_register_driver(&eeprom_93xx46_driver);

}

module_init(eeprom_93xx46_init);



static void __exit eeprom_93xx46_exit(void)

{

	spi_unregister_driver(&eeprom_93xx46_driver);

}

module_exit(eeprom_93xx46_exit);



MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("Driver for 93xx46 EEPROMs");

MODULE_AUTHOR("Anatolij Gustschin <agust@denx.de>");

MODULE_ALIAS("spi:93xx46");

include/linux/eeprom_93xx46.h

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/*

 * Module: eeprom_93xx46

 * platform description for 93xx46 EEPROMs.

 */



struct eeprom_93xx46_platform_data {

	unsigned char	flags;

#define EE_ADDR8	0x01		/*  8 bit addr. cfg */

#define EE_ADDR16	0x02		/* 16 bit addr. cfg */

#define EE_READONLY	0x08		/* forbid writing */



	/*

	 * optional hooks to control additional logic

	 * before and after spi transfer.

	 */

	void (*prepare)(void *);

	void (*finish)(void *);

};

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