2007-02-12 09:52:48 +01:00
|
|
|
/*
|
|
|
|
* 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/init.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>
|
|
|
|
|
|
|
|
|
2007-12-05 08:45:10 +01:00
|
|
|
/*
|
|
|
|
* 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!
|
|
|
|
*/
|
|
|
|
|
2007-02-12 09:52:48 +01:00
|
|
|
struct at25_data {
|
|
|
|
struct spi_device *spi;
|
2009-04-03 01:56:58 +02:00
|
|
|
struct memory_accessor mem;
|
2007-02-12 09:52:48 +01:00
|
|
|
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 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;
|
|
|
|
|
2009-04-03 01:56:58 +02:00
|
|
|
if (unlikely(offset >= at25->bin.size))
|
|
|
|
return 0;
|
|
|
|
if ((offset + count) > at25->bin.size)
|
|
|
|
count = at25->bin.size - offset;
|
|
|
|
if (unlikely(!count))
|
|
|
|
return count;
|
|
|
|
|
2007-02-12 09:52:48 +01:00
|
|
|
cp = command;
|
|
|
|
*cp++ = AT25_READ;
|
|
|
|
|
|
|
|
/* 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
|
2007-06-09 07:57:22 +02:00
|
|
|
at25_bin_read(struct kobject *kobj, struct bin_attribute *bin_attr,
|
|
|
|
char *buf, loff_t off, size_t count)
|
2007-02-12 09:52:48 +01:00
|
|
|
{
|
|
|
|
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, char *buf, loff_t off, size_t count)
|
|
|
|
{
|
|
|
|
ssize_t status = 0;
|
|
|
|
unsigned written = 0;
|
|
|
|
unsigned buf_size;
|
|
|
|
u8 *bounce;
|
|
|
|
|
2009-04-03 01:56:58 +02:00
|
|
|
if (unlikely(off >= at25->bin.size))
|
|
|
|
return -EFBIG;
|
|
|
|
if ((off + count) > at25->bin.size)
|
|
|
|
count = at25->bin.size - off;
|
|
|
|
if (unlikely(!count))
|
|
|
|
return count;
|
|
|
|
|
2007-02-12 09:52:48 +01:00
|
|
|
/* 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.
|
|
|
|
*/
|
|
|
|
bounce[0] = AT25_WRITE;
|
|
|
|
mutex_lock(&at25->lock);
|
|
|
|
do {
|
|
|
|
unsigned long timeout, retries;
|
|
|
|
unsigned segment;
|
|
|
|
unsigned offset = (unsigned) off;
|
|
|
|
u8 *cp = bounce + 1;
|
|
|
|
|
|
|
|
*cp = AT25_WREN;
|
|
|
|
status = spi_write(at25->spi, cp, 1);
|
|
|
|
if (status < 0) {
|
|
|
|
dev_dbg(&at25->spi->dev, "WREN --> %d\n",
|
|
|
|
(int) status);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* 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 {
|
|
|
|
int sr;
|
|
|
|
|
|
|
|
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 (time_after(jiffies, timeout)) {
|
|
|
|
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
|
2007-06-09 07:57:22 +02:00
|
|
|
at25_bin_write(struct kobject *kobj, struct bin_attribute *bin_attr,
|
|
|
|
char *buf, loff_t off, size_t count)
|
2007-02-12 09:52:48 +01:00
|
|
|
{
|
|
|
|
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);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*-------------------------------------------------------------------------*/
|
|
|
|
|
2009-04-03 01:56:58 +02:00
|
|
|
/* 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, 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);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*-------------------------------------------------------------------------*/
|
|
|
|
|
2007-02-12 09:52:48 +01:00
|
|
|
static int at25_probe(struct spi_device *spi)
|
|
|
|
{
|
|
|
|
struct at25_data *at25 = NULL;
|
|
|
|
const struct spi_eeprom *chip;
|
|
|
|
int err;
|
|
|
|
int sr;
|
|
|
|
int addrlen;
|
|
|
|
|
|
|
|
/* Chip description */
|
|
|
|
chip = spi->dev.platform_data;
|
|
|
|
if (!chip) {
|
|
|
|
dev_dbg(&spi->dev, "no chip description\n");
|
|
|
|
err = -ENODEV;
|
|
|
|
goto fail;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* 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");
|
|
|
|
err = -EINVAL;
|
|
|
|
goto fail;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* 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) {
|
2007-03-16 22:38:20 +01:00
|
|
|
dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr);
|
2007-02-12 09:52:48 +01:00
|
|
|
err = -ENXIO;
|
|
|
|
goto fail;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!(at25 = kzalloc(sizeof *at25, GFP_KERNEL))) {
|
|
|
|
err = -ENOMEM;
|
|
|
|
goto fail;
|
|
|
|
}
|
|
|
|
|
|
|
|
mutex_init(&at25->lock);
|
|
|
|
at25->chip = *chip;
|
|
|
|
at25->spi = spi_dev_get(spi);
|
|
|
|
dev_set_drvdata(&spi->dev, at25);
|
|
|
|
at25->addrlen = addrlen;
|
|
|
|
|
|
|
|
/* Export the EEPROM bytes through sysfs, since that's convenient.
|
2009-04-03 01:56:58 +02:00
|
|
|
* And maybe to other kernel code; it might hold a board's Ethernet
|
|
|
|
* address, or board-specific calibration data generated on the
|
|
|
|
* manufacturing floor.
|
|
|
|
*
|
2007-02-12 09:52:48 +01:00
|
|
|
* 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.
|
|
|
|
*/
|
|
|
|
at25->bin.attr.name = "eeprom";
|
|
|
|
at25->bin.attr.mode = S_IRUSR;
|
|
|
|
at25->bin.read = at25_bin_read;
|
2009-04-03 01:56:58 +02:00
|
|
|
at25->mem.read = at25_mem_read;
|
2007-02-12 09:52:48 +01:00
|
|
|
|
|
|
|
at25->bin.size = at25->chip.byte_len;
|
|
|
|
if (!(chip->flags & EE_READONLY)) {
|
|
|
|
at25->bin.write = at25_bin_write;
|
|
|
|
at25->bin.attr.mode |= S_IWUSR;
|
2009-04-03 01:56:58 +02:00
|
|
|
at25->mem.write = at25_mem_write;
|
2007-02-12 09:52:48 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
err = sysfs_create_bin_file(&spi->dev.kobj, &at25->bin);
|
|
|
|
if (err)
|
|
|
|
goto fail;
|
|
|
|
|
2009-04-03 01:56:58 +02:00
|
|
|
if (chip->setup)
|
|
|
|
chip->setup(&at25->mem, chip->context);
|
|
|
|
|
2007-02-12 09:52:48 +01:00
|
|
|
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;
|
|
|
|
fail:
|
|
|
|
dev_dbg(&spi->dev, "probe err %d\n", err);
|
|
|
|
kfree(at25);
|
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int __devexit at25_remove(struct spi_device *spi)
|
|
|
|
{
|
|
|
|
struct at25_data *at25;
|
|
|
|
|
|
|
|
at25 = dev_get_drvdata(&spi->dev);
|
|
|
|
sysfs_remove_bin_file(&spi->dev.kobj, &at25->bin);
|
|
|
|
kfree(at25);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*-------------------------------------------------------------------------*/
|
|
|
|
|
|
|
|
static struct spi_driver at25_driver = {
|
|
|
|
.driver = {
|
|
|
|
.name = "at25",
|
|
|
|
.owner = THIS_MODULE,
|
|
|
|
},
|
|
|
|
.probe = at25_probe,
|
|
|
|
.remove = __devexit_p(at25_remove),
|
|
|
|
};
|
|
|
|
|
|
|
|
static int __init at25_init(void)
|
|
|
|
{
|
|
|
|
return spi_register_driver(&at25_driver);
|
|
|
|
}
|
|
|
|
module_init(at25_init);
|
|
|
|
|
|
|
|
static void __exit at25_exit(void)
|
|
|
|
{
|
|
|
|
spi_unregister_driver(&at25_driver);
|
|
|
|
}
|
|
|
|
module_exit(at25_exit);
|
|
|
|
|
|
|
|
MODULE_DESCRIPTION("Driver for most SPI EEPROMs");
|
|
|
|
MODULE_AUTHOR("David Brownell");
|
|
|
|
MODULE_LICENSE("GPL");
|
|
|
|
|