kernel-ark/drivers/spi/at25.c

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/*
* 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>
struct at25_data {
struct spi_device *spi;
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;
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
sysfs: add parameter "struct bin_attribute *" in .read/.write methods for sysfs binary attributes Well, first of all, I don't want to change so many files either. What I do: Adding a new parameter "struct bin_attribute *" in the .read/.write methods for the sysfs binary attributes. In fact, only the four lines change in fs/sysfs/bin.c and include/linux/sysfs.h do the real work. But I have to update all the files that use binary attributes to make them compatible with the new .read and .write methods. I'm not sure if I missed any. :( Why I do this: For a sysfs attribute, we can get a pointer pointing to the struct attribute in the .show/.store method, while we can't do this for the binary attributes. I don't know why this is different, but this does make it not so handy to use the binary attributes as the regular ones. So I think this patch is reasonable. :) Who benefits from it: The patch that exposes ACPI tables in sysfs requires such an improvement. All the table binary attributes share the same .read method. Parameter "struct bin_attribute *" is used to get the table signature and instance number which are used to distinguish different ACPI table binary attributes. Without this parameter, we need to offer different .read methods for different ACPI table binary attributes. This is impossible as there are various ACPI tables on different platforms, and we don't know what they are until they are loaded. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-09 05:57:22 +00:00
at25_bin_read(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);
if (unlikely(off >= at25->bin.size))
return 0;
if ((off + count) > at25->bin.size)
count = at25->bin.size - off;
if (unlikely(!count))
return count;
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;
/* 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
sysfs: add parameter "struct bin_attribute *" in .read/.write methods for sysfs binary attributes Well, first of all, I don't want to change so many files either. What I do: Adding a new parameter "struct bin_attribute *" in the .read/.write methods for the sysfs binary attributes. In fact, only the four lines change in fs/sysfs/bin.c and include/linux/sysfs.h do the real work. But I have to update all the files that use binary attributes to make them compatible with the new .read and .write methods. I'm not sure if I missed any. :( Why I do this: For a sysfs attribute, we can get a pointer pointing to the struct attribute in the .show/.store method, while we can't do this for the binary attributes. I don't know why this is different, but this does make it not so handy to use the binary attributes as the regular ones. So I think this patch is reasonable. :) Who benefits from it: The patch that exposes ACPI tables in sysfs requires such an improvement. All the table binary attributes share the same .read method. Parameter "struct bin_attribute *" is used to get the table signature and instance number which are used to distinguish different ACPI table binary attributes. Without this parameter, we need to offer different .read methods for different ACPI table binary attributes. This is impossible as there are various ACPI tables on different platforms, and we don't know what they are until they are loaded. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-06-09 05:57:22 +00:00
at25_bin_write(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);
if (unlikely(off >= at25->bin.size))
return -EFBIG;
if ((off + count) > at25->bin.size)
count = at25->bin.size - off;
if (unlikely(!count))
return count;
return at25_ee_write(at25, buf, off, count);
}
/*-------------------------------------------------------------------------*/
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) {
dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr);
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.
* 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;
at25->bin.size = at25->chip.byte_len;
if (!(chip->flags & EE_READONLY)) {
at25->bin.write = at25_bin_write;
at25->bin.attr.mode |= S_IWUSR;
}
err = sysfs_create_bin_file(&spi->dev.kobj, &at25->bin);
if (err)
goto fail;
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");