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: Anatolij Gustschin <agust@denx.de>
Cc: Jonathan Cameron <jic23@cam.ac.uk>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 424 insertions, 0 deletions

diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
index 9118613af321..620de283b40b 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 df3d68ffa9d1..ec55aad24cfb 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 000000000000..0c7ebb1e19e5
--- /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@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");