Date:	Mon,  6 Jun 2011 10:11:21 +0200
From:	Anatolij Gustschin <agust@...x.de>
To:	linux-kernel@...r.kernel.org
Cc:	akpm@...ux-foundation.org, jic23@....ac.uk, dzu@...x.de,
	Anatolij Gustschin <agust@...x.de>
Subject: [PATCH 1/2] 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.

Signed-off-by: Anatolij Gustschin <agust@...x.de>
---
 drivers/misc/eeprom/Kconfig         |   13 +
 drivers/misc/eeprom/Makefile        |    1 +
 drivers/misc/eeprom/eeprom_93xx46.c |  410 +++++++++++++++++++++++++++++++++++
 include/linux/eeprom_93xx46.h       |   18 ++
 4 files changed, 442 insertions(+), 0 deletions(-)
 create mode 100644 drivers/misc/eeprom/eeprom_93xx46.c
 create mode 100644 include/linux/eeprom_93xx46.h

diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
index 9118613..620de28 100644
--- a/drivers/misc/eeprom/Kconfig
+++ b/drivers/misc/eeprom/Kconfig
@@ -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
diff --git a/drivers/misc/eeprom/Makefile b/drivers/misc/eeprom/Makefile
index df3d68f..ec55aad 100644
--- a/drivers/misc/eeprom/Makefile
+++ b/drivers/misc/eeprom/Makefile
@@ -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
diff --git a/drivers/misc/eeprom/eeprom_93xx46.c b/drivers/misc/eeprom/eeprom_93xx46.c
new file mode 100644
index 0000000..d73317c
--- /dev/null
+++ b/drivers/misc/eeprom/eeprom_93xx46.c
@@ -0,0 +1,410 @@
+/*
+ * Driver for 93xx46 EEPROMs
+ *
+ * (C) 2011 DENX Software Engineering, Anatolij Gustschin <agust@...x.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 %d 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@...x.de>");
+MODULE_ALIAS("spi:93xx46");
diff --git a/include/linux/eeprom_93xx46.h b/include/linux/eeprom_93xx46.h
new file mode 100644
index 0000000..0679181
--- /dev/null
+++ b/include/linux/eeprom_93xx46.h
@@ -0,0 +1,18 @@
+/*
+ * 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 *);
+};
-- 
1.7.1

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