Initial import

1 files changed, 477 insertions, 0 deletions

diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
new file mode 100644
index 000000000..0a1af93ec
--- /dev/null
+++ b/drivers/misc/eeprom/at25.c
@@ -0,0 +1,477 @@
+/*
+ * at25.c -- support most SPI EEPROMs, such as Atmel AT25 models
+ *
+ * Copyright (C) 2006 David Brownell
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/sched.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/eeprom.h>
+#include <linux/property.h>
+
+/*
+ * NOTE: this is an *EEPROM* driver.  The vagaries of product naming
+ * mean that some AT25 products are EEPROMs, and others are FLASH.
+ * Handle FLASH chips with the drivers/mtd/devices/m25p80.c driver,
+ * not this one!
+ */
+
+struct at25_data {
+	struct spi_device	*spi;
+	struct memory_accessor	mem;
+	struct mutex		lock;
+	struct spi_eeprom	chip;
+	struct bin_attribute	bin;
+	unsigned		addrlen;
+};
+
+#define	AT25_WREN	0x06		/* latch the write enable */
+#define	AT25_WRDI	0x04		/* reset the write enable */
+#define	AT25_RDSR	0x05		/* read status register */
+#define	AT25_WRSR	0x01		/* write status register */
+#define	AT25_READ	0x03		/* read byte(s) */
+#define	AT25_WRITE	0x02		/* write byte(s)/sector */
+
+#define	AT25_SR_nRDY	0x01		/* nRDY = write-in-progress */
+#define	AT25_SR_WEN	0x02		/* write enable (latched) */
+#define	AT25_SR_BP0	0x04		/* BP for software writeprotect */
+#define	AT25_SR_BP1	0x08
+#define	AT25_SR_WPEN	0x80		/* writeprotect enable */
+
+#define	AT25_INSTR_BIT3	0x08		/* Additional address bit in instr */
+
+#define EE_MAXADDRLEN	3		/* 24 bit addresses, up to 2 MBytes */
+
+/* Specs often allow 5 msec for a page write, sometimes 20 msec;
+ * it's important to recover from write timeouts.
+ */
+#define	EE_TIMEOUT	25
+
+/*-------------------------------------------------------------------------*/
+
+#define	io_limit	PAGE_SIZE	/* bytes */
+
+static ssize_t
+at25_ee_read(
+	struct at25_data	*at25,
+	char			*buf,
+	unsigned		offset,
+	size_t			count
+)
+{
+	u8			command[EE_MAXADDRLEN + 1];
+	u8			*cp;
+	ssize_t			status;
+	struct spi_transfer	t[2];
+	struct spi_message	m;
+	u8			instr;
+
+	if (unlikely(offset >= at25->bin.size))
+		return 0;
+	if ((offset + count) > at25->bin.size)
+		count = at25->bin.size - offset;
+	if (unlikely(!count))
+		return count;
+
+	cp = command;
+
+	instr = AT25_READ;
+	if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
+		if (offset >= (1U << (at25->addrlen * 8)))
+			instr |= AT25_INSTR_BIT3;
+	*cp++ = instr;
+
+	/* 8/16/24-bit address is written MSB first */
+	switch (at25->addrlen) {
+	default:	/* case 3 */
+		*cp++ = offset >> 16;
+	case 2:
+		*cp++ = offset >> 8;
+	case 1:
+	case 0:	/* can't happen: for better codegen */
+		*cp++ = offset >> 0;
+	}
+
+	spi_message_init(&m);
+	memset(t, 0, sizeof t);
+
+	t[0].tx_buf = command;
+	t[0].len = at25->addrlen + 1;
+	spi_message_add_tail(&t[0], &m);
+
+	t[1].rx_buf = buf;
+	t[1].len = count;
+	spi_message_add_tail(&t[1], &m);
+
+	mutex_lock(&at25->lock);
+
+	/* Read it all at once.
+	 *
+	 * REVISIT that's potentially a problem with large chips, if
+	 * other devices on the bus need to be accessed regularly or
+	 * this chip is clocked very slowly
+	 */
+	status = spi_sync(at25->spi, &m);
+	dev_dbg(&at25->spi->dev,
+		"read %Zd bytes at %d --> %d\n",
+		count, offset, (int) status);
+
+	mutex_unlock(&at25->lock);
+	return status ? status : count;
+}
+
+static ssize_t
+at25_bin_read(struct file *filp, struct kobject *kobj,
+	      struct bin_attribute *bin_attr,
+	      char *buf, loff_t off, size_t count)
+{
+	struct device		*dev;
+	struct at25_data	*at25;
+
+	dev = container_of(kobj, struct device, kobj);
+	at25 = dev_get_drvdata(dev);
+
+	return at25_ee_read(at25, buf, off, count);
+}
+
+
+static ssize_t
+at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
+	      size_t count)
+{
+	ssize_t			status = 0;
+	unsigned		written = 0;
+	unsigned		buf_size;
+	u8			*bounce;
+
+	if (unlikely(off >= at25->bin.size))
+		return -EFBIG;
+	if ((off + count) > at25->bin.size)
+		count = at25->bin.size - off;
+	if (unlikely(!count))
+		return count;
+
+	/* Temp buffer starts with command and address */
+	buf_size = at25->chip.page_size;
+	if (buf_size > io_limit)
+		buf_size = io_limit;
+	bounce = kmalloc(buf_size + at25->addrlen + 1, GFP_KERNEL);
+	if (!bounce)
+		return -ENOMEM;
+
+	/* For write, rollover is within the page ... so we write at
+	 * most one page, then manually roll over to the next page.
+	 */
+	mutex_lock(&at25->lock);
+	do {
+		unsigned long	timeout, retries;
+		unsigned	segment;
+		unsigned	offset = (unsigned) off;
+		u8		*cp = bounce;
+		int		sr;
+		u8		instr;
+
+		*cp = AT25_WREN;
+		status = spi_write(at25->spi, cp, 1);
+		if (status < 0) {
+			dev_dbg(&at25->spi->dev, "WREN --> %d\n",
+					(int) status);
+			break;
+		}
+
+		instr = AT25_WRITE;
+		if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
+			if (offset >= (1U << (at25->addrlen * 8)))
+				instr |= AT25_INSTR_BIT3;
+		*cp++ = instr;
+
+		/* 8/16/24-bit address is written MSB first */
+		switch (at25->addrlen) {
+		default:	/* case 3 */
+			*cp++ = offset >> 16;
+		case 2:
+			*cp++ = offset >> 8;
+		case 1:
+		case 0:	/* can't happen: for better codegen */
+			*cp++ = offset >> 0;
+		}
+
+		/* Write as much of a page as we can */
+		segment = buf_size - (offset % buf_size);
+		if (segment > count)
+			segment = count;
+		memcpy(cp, buf, segment);
+		status = spi_write(at25->spi, bounce,
+				segment + at25->addrlen + 1);
+		dev_dbg(&at25->spi->dev,
+				"write %u bytes at %u --> %d\n",
+				segment, offset, (int) status);
+		if (status < 0)
+			break;
+
+		/* REVISIT this should detect (or prevent) failed writes
+		 * to readonly sections of the EEPROM...
+		 */
+
+		/* Wait for non-busy status */
+		timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT);
+		retries = 0;
+		do {
+
+			sr = spi_w8r8(at25->spi, AT25_RDSR);
+			if (sr < 0 || (sr & AT25_SR_nRDY)) {
+				dev_dbg(&at25->spi->dev,
+					"rdsr --> %d (%02x)\n", sr, sr);
+				/* at HZ=100, this is sloooow */
+				msleep(1);
+				continue;
+			}
+			if (!(sr & AT25_SR_nRDY))
+				break;
+		} while (retries++ < 3 || time_before_eq(jiffies, timeout));
+
+		if ((sr < 0) || (sr & AT25_SR_nRDY)) {
+			dev_err(&at25->spi->dev,
+				"write %d bytes offset %d, "
+				"timeout after %u msecs\n",
+				segment, offset,
+				jiffies_to_msecs(jiffies -
+					(timeout - EE_TIMEOUT)));
+			status = -ETIMEDOUT;
+			break;
+		}
+
+		off += segment;
+		buf += segment;
+		count -= segment;
+		written += segment;
+
+	} while (count > 0);
+
+	mutex_unlock(&at25->lock);
+
+	kfree(bounce);
+	return written ? written : status;
+}
+
+static ssize_t
+at25_bin_write(struct file *filp, struct kobject *kobj,
+	       struct bin_attribute *bin_attr,
+	       char *buf, loff_t off, size_t count)
+{
+	struct device		*dev;
+	struct at25_data	*at25;
+
+	dev = container_of(kobj, struct device, kobj);
+	at25 = dev_get_drvdata(dev);
+
+	return at25_ee_write(at25, buf, off, count);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Let in-kernel code access the eeprom data. */
+
+static ssize_t at25_mem_read(struct memory_accessor *mem, char *buf,
+			 off_t offset, size_t count)
+{
+	struct at25_data *at25 = container_of(mem, struct at25_data, mem);
+
+	return at25_ee_read(at25, buf, offset, count);
+}
+
+static ssize_t at25_mem_write(struct memory_accessor *mem, const char *buf,
+			  off_t offset, size_t count)
+{
+	struct at25_data *at25 = container_of(mem, struct at25_data, mem);
+
+	return at25_ee_write(at25, buf, offset, count);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip)
+{
+	u32 val;
+
+	memset(chip, 0, sizeof(*chip));
+	strncpy(chip->name, "at25", sizeof(chip->name));
+
+	if (device_property_read_u32(dev, "size", &val) == 0 ||
+	    device_property_read_u32(dev, "at25,byte-len", &val) == 0) {
+		chip->byte_len = val;
+	} else {
+		dev_err(dev, "Error: missing \"size\" property\n");
+		return -ENODEV;
+	}
+
+	if (device_property_read_u32(dev, "pagesize", &val) == 0 ||
+	    device_property_read_u32(dev, "at25,page-size", &val) == 0) {
+		chip->page_size = (u16)val;
+	} else {
+		dev_err(dev, "Error: missing \"pagesize\" property\n");
+		return -ENODEV;
+	}
+
+	if (device_property_read_u32(dev, "at25,addr-mode", &val) == 0) {
+		chip->flags = (u16)val;
+	} else {
+		if (device_property_read_u32(dev, "address-width", &val)) {
+			dev_err(dev,
+				"Error: missing \"address-width\" property\n");
+			return -ENODEV;
+		}
+		switch (val) {
+		case 8:
+			chip->flags |= EE_ADDR1;
+			break;
+		case 16:
+			chip->flags |= EE_ADDR2;
+			break;
+		case 24:
+			chip->flags |= EE_ADDR3;
+			break;
+		default:
+			dev_err(dev,
+				"Error: bad \"address-width\" property: %u\n",
+				val);
+			return -ENODEV;
+		}
+		if (device_property_present(dev, "read-only"))
+			chip->flags |= EE_READONLY;
+	}
+	return 0;
+}
+
+static int at25_probe(struct spi_device *spi)
+{
+	struct at25_data	*at25 = NULL;
+	struct spi_eeprom	chip;
+	int			err;
+	int			sr;
+	int			addrlen;
+
+	/* Chip description */
+	if (!spi->dev.platform_data) {
+		err = at25_fw_to_chip(&spi->dev, &chip);
+		if (err)
+			return err;
+	} else
+		chip = *(struct spi_eeprom *)spi->dev.platform_data;
+
+	/* For now we only support 8/16/24 bit addressing */
+	if (chip.flags & EE_ADDR1)
+		addrlen = 1;
+	else if (chip.flags & EE_ADDR2)
+		addrlen = 2;
+	else if (chip.flags & EE_ADDR3)
+		addrlen = 3;
+	else {
+		dev_dbg(&spi->dev, "unsupported address type\n");
+		return -EINVAL;
+	}
+
+	/* Ping the chip ... the status register is pretty portable,
+	 * unlike probing manufacturer IDs.  We do expect that system
+	 * firmware didn't write it in the past few milliseconds!
+	 */
+	sr = spi_w8r8(spi, AT25_RDSR);
+	if (sr < 0 || sr & AT25_SR_nRDY) {
+		dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr);
+		return -ENXIO;
+	}
+
+	at25 = devm_kzalloc(&spi->dev, sizeof(struct at25_data), GFP_KERNEL);
+	if (!at25)
+		return -ENOMEM;
+
+	mutex_init(&at25->lock);
+	at25->chip = chip;
+	at25->spi = spi_dev_get(spi);
+	spi_set_drvdata(spi, at25);
+	at25->addrlen = addrlen;
+
+	/* Export the EEPROM bytes through sysfs, since that's convenient.
+	 * And maybe to other kernel code; it might hold a board's Ethernet
+	 * address, or board-specific calibration data generated on the
+	 * manufacturing floor.
+	 *
+	 * Default to root-only access to the data; EEPROMs often hold data
+	 * that's sensitive for read and/or write, like ethernet addresses,
+	 * security codes, board-specific manufacturing calibrations, etc.
+	 */
+	sysfs_bin_attr_init(&at25->bin);
+	at25->bin.attr.name = "eeprom";
+	at25->bin.attr.mode = S_IRUSR;
+	at25->bin.read = at25_bin_read;
+	at25->mem.read = at25_mem_read;
+
+	at25->bin.size = at25->chip.byte_len;
+	if (!(chip.flags & EE_READONLY)) {
+		at25->bin.write = at25_bin_write;
+		at25->bin.attr.mode |= S_IWUSR;
+		at25->mem.write = at25_mem_write;
+	}
+
+	err = sysfs_create_bin_file(&spi->dev.kobj, &at25->bin);
+	if (err)
+		return err;
+
+	if (chip.setup)
+		chip.setup(&at25->mem, chip.context);
+
+	dev_info(&spi->dev, "%Zd %s %s eeprom%s, pagesize %u\n",
+		(at25->bin.size < 1024)
+			? at25->bin.size
+			: (at25->bin.size / 1024),
+		(at25->bin.size < 1024) ? "Byte" : "KByte",
+		at25->chip.name,
+		(chip.flags & EE_READONLY) ? " (readonly)" : "",
+		at25->chip.page_size);
+	return 0;
+}
+
+static int at25_remove(struct spi_device *spi)
+{
+	struct at25_data	*at25;
+
+	at25 = spi_get_drvdata(spi);
+	sysfs_remove_bin_file(&spi->dev.kobj, &at25->bin);
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+static const struct of_device_id at25_of_match[] = {
+	{ .compatible = "atmel,at25", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, at25_of_match);
+
+static struct spi_driver at25_driver = {
+	.driver = {
+		.name		= "at25",
+		.owner		= THIS_MODULE,
+		.of_match_table = at25_of_match,
+	},
+	.probe		= at25_probe,
+	.remove		= at25_remove,
+};
+
+module_spi_driver(at25_driver);
+
+MODULE_DESCRIPTION("Driver for most SPI EEPROMs");
+MODULE_AUTHOR("David Brownell");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("spi:at25");