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linux-sg2042/drivers/misc/eeprom/at24.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* at24.c - handle most I2C EEPROMs
*
* Copyright (C) 2005-2007 David Brownell
* Copyright (C) 2008 Wolfram Sang, Pengutronix
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include <linux/mod_devicetable.h>
#include <linux/log2.h>
#include <linux/bitops.h>
#include <linux/jiffies.h>
#include <linux/property.h>
#include <linux/acpi.h>
#include <linux/i2c.h>
#include <linux/nvmem-provider.h>
#include <linux/regmap.h>
#include <linux/pm_runtime.h>
#include <linux/gpio/consumer.h>
/* Address pointer is 16 bit. */
#define AT24_FLAG_ADDR16 BIT(7)
/* sysfs-entry will be read-only. */
#define AT24_FLAG_READONLY BIT(6)
/* sysfs-entry will be world-readable. */
#define AT24_FLAG_IRUGO BIT(5)
/* Take always 8 addresses (24c00). */
#define AT24_FLAG_TAKE8ADDR BIT(4)
/* Factory-programmed serial number. */
#define AT24_FLAG_SERIAL BIT(3)
/* Factory-programmed mac address. */
#define AT24_FLAG_MAC BIT(2)
/* Does not auto-rollover reads to the next slave address. */
#define AT24_FLAG_NO_RDROL BIT(1)
/*
* I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
* Differences between different vendor product lines (like Atmel AT24C or
* MicroChip 24LC, etc) won't much matter for typical read/write access.
* There are also I2C RAM chips, likewise interchangeable. One example
* would be the PCF8570, which acts like a 24c02 EEPROM (256 bytes).
*
* However, misconfiguration can lose data. "Set 16-bit memory address"
* to a part with 8-bit addressing will overwrite data. Writing with too
* big a page size also loses data. And it's not safe to assume that the
* conventional addresses 0x50..0x57 only hold eeproms; a PCF8563 RTC
* uses 0x51, for just one example.
*
* Accordingly, explicit board-specific configuration data should be used
* in almost all cases. (One partial exception is an SMBus used to access
* "SPD" data for DRAM sticks. Those only use 24c02 EEPROMs.)
*
* So this driver uses "new style" I2C driver binding, expecting to be
* told what devices exist. That may be in arch/X/mach-Y/board-Z.c or
* similar kernel-resident tables; or, configuration data coming from
* a bootloader.
*
* Other than binding model, current differences from "eeprom" driver are
* that this one handles write access and isn't restricted to 24c02 devices.
* It also handles larger devices (32 kbit and up) with two-byte addresses,
* which won't work on pure SMBus systems.
*/
struct at24_client {
struct i2c_client *client;
struct regmap *regmap;
};
struct at24_data {
/*
* Lock protects against activities from other Linux tasks,
* but not from changes by other I2C masters.
*/
struct mutex lock;
unsigned int write_max;
unsigned int num_addresses;
unsigned int offset_adj;
u32 byte_len;
u16 page_size;
u8 flags;
struct nvmem_device *nvmem;
struct gpio_desc *wp_gpio;
/*
* Some chips tie up multiple I2C addresses; dummy devices reserve
* them for us, and we'll use them with SMBus calls.
*/
struct at24_client client[];
};
/*
* This parameter is to help this driver avoid blocking other drivers out
* of I2C for potentially troublesome amounts of time. With a 100 kHz I2C
* clock, one 256 byte read takes about 1/43 second which is excessive;
* but the 1/170 second it takes at 400 kHz may be quite reasonable; and
* at 1 MHz (Fm+) a 1/430 second delay could easily be invisible.
*
* This value is forced to be a power of two so that writes align on pages.
*/
static unsigned int at24_io_limit = 128;
module_param_named(io_limit, at24_io_limit, uint, 0);
MODULE_PARM_DESC(at24_io_limit, "Maximum bytes per I/O (default 128)");
/*
* Specs often allow 5 msec for a page write, sometimes 20 msec;
* it's important to recover from write timeouts.
*/
static unsigned int at24_write_timeout = 25;
module_param_named(write_timeout, at24_write_timeout, uint, 0);
MODULE_PARM_DESC(at24_write_timeout, "Time (in ms) to try writes (default 25)");
struct at24_chip_data {
u32 byte_len;
u8 flags;
};
#define AT24_CHIP_DATA(_name, _len, _flags) \
static const struct at24_chip_data _name = { \
.byte_len = _len, .flags = _flags, \
}
/* needs 8 addresses as A0-A2 are ignored */
AT24_CHIP_DATA(at24_data_24c00, 128 / 8, AT24_FLAG_TAKE8ADDR);
/* old variants can't be handled with this generic entry! */
AT24_CHIP_DATA(at24_data_24c01, 1024 / 8, 0);
AT24_CHIP_DATA(at24_data_24cs01, 16,
AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
AT24_CHIP_DATA(at24_data_24c02, 2048 / 8, 0);
AT24_CHIP_DATA(at24_data_24cs02, 16,
AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
AT24_CHIP_DATA(at24_data_24mac402, 48 / 8,
AT24_FLAG_MAC | AT24_FLAG_READONLY);
AT24_CHIP_DATA(at24_data_24mac602, 64 / 8,
AT24_FLAG_MAC | AT24_FLAG_READONLY);
/* spd is a 24c02 in memory DIMMs */
AT24_CHIP_DATA(at24_data_spd, 2048 / 8,
AT24_FLAG_READONLY | AT24_FLAG_IRUGO);
AT24_CHIP_DATA(at24_data_24c04, 4096 / 8, 0);
AT24_CHIP_DATA(at24_data_24cs04, 16,
AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
/* 24rf08 quirk is handled at i2c-core */
AT24_CHIP_DATA(at24_data_24c08, 8192 / 8, 0);
AT24_CHIP_DATA(at24_data_24cs08, 16,
AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
AT24_CHIP_DATA(at24_data_24c16, 16384 / 8, 0);
AT24_CHIP_DATA(at24_data_24cs16, 16,
AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
AT24_CHIP_DATA(at24_data_24c32, 32768 / 8, AT24_FLAG_ADDR16);
AT24_CHIP_DATA(at24_data_24cs32, 16,
AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
AT24_CHIP_DATA(at24_data_24c64, 65536 / 8, AT24_FLAG_ADDR16);
AT24_CHIP_DATA(at24_data_24cs64, 16,
AT24_FLAG_ADDR16 | AT24_FLAG_SERIAL | AT24_FLAG_READONLY);
AT24_CHIP_DATA(at24_data_24c128, 131072 / 8, AT24_FLAG_ADDR16);
AT24_CHIP_DATA(at24_data_24c256, 262144 / 8, AT24_FLAG_ADDR16);
AT24_CHIP_DATA(at24_data_24c512, 524288 / 8, AT24_FLAG_ADDR16);
AT24_CHIP_DATA(at24_data_24c1024, 1048576 / 8, AT24_FLAG_ADDR16);
AT24_CHIP_DATA(at24_data_24c2048, 2097152 / 8, AT24_FLAG_ADDR16);
/* identical to 24c08 ? */
AT24_CHIP_DATA(at24_data_INT3499, 8192 / 8, 0);
static const struct i2c_device_id at24_ids[] = {
{ "24c00", (kernel_ulong_t)&at24_data_24c00 },
{ "24c01", (kernel_ulong_t)&at24_data_24c01 },
{ "24cs01", (kernel_ulong_t)&at24_data_24cs01 },
{ "24c02", (kernel_ulong_t)&at24_data_24c02 },
{ "24cs02", (kernel_ulong_t)&at24_data_24cs02 },
{ "24mac402", (kernel_ulong_t)&at24_data_24mac402 },
{ "24mac602", (kernel_ulong_t)&at24_data_24mac602 },
{ "spd", (kernel_ulong_t)&at24_data_spd },
{ "24c04", (kernel_ulong_t)&at24_data_24c04 },
{ "24cs04", (kernel_ulong_t)&at24_data_24cs04 },
{ "24c08", (kernel_ulong_t)&at24_data_24c08 },
{ "24cs08", (kernel_ulong_t)&at24_data_24cs08 },
{ "24c16", (kernel_ulong_t)&at24_data_24c16 },
{ "24cs16", (kernel_ulong_t)&at24_data_24cs16 },
{ "24c32", (kernel_ulong_t)&at24_data_24c32 },
{ "24cs32", (kernel_ulong_t)&at24_data_24cs32 },
{ "24c64", (kernel_ulong_t)&at24_data_24c64 },
{ "24cs64", (kernel_ulong_t)&at24_data_24cs64 },
{ "24c128", (kernel_ulong_t)&at24_data_24c128 },
{ "24c256", (kernel_ulong_t)&at24_data_24c256 },
{ "24c512", (kernel_ulong_t)&at24_data_24c512 },
{ "24c1024", (kernel_ulong_t)&at24_data_24c1024 },
{ "24c2048", (kernel_ulong_t)&at24_data_24c2048 },
{ "at24", 0 },
{ /* END OF LIST */ }
};
MODULE_DEVICE_TABLE(i2c, at24_ids);
static const struct of_device_id at24_of_match[] = {
{ .compatible = "atmel,24c00", .data = &at24_data_24c00 },
{ .compatible = "atmel,24c01", .data = &at24_data_24c01 },
{ .compatible = "atmel,24cs01", .data = &at24_data_24cs01 },
{ .compatible = "atmel,24c02", .data = &at24_data_24c02 },
{ .compatible = "atmel,24cs02", .data = &at24_data_24cs02 },
{ .compatible = "atmel,24mac402", .data = &at24_data_24mac402 },
{ .compatible = "atmel,24mac602", .data = &at24_data_24mac602 },
{ .compatible = "atmel,spd", .data = &at24_data_spd },
{ .compatible = "atmel,24c04", .data = &at24_data_24c04 },
{ .compatible = "atmel,24cs04", .data = &at24_data_24cs04 },
{ .compatible = "atmel,24c08", .data = &at24_data_24c08 },
{ .compatible = "atmel,24cs08", .data = &at24_data_24cs08 },
{ .compatible = "atmel,24c16", .data = &at24_data_24c16 },
{ .compatible = "atmel,24cs16", .data = &at24_data_24cs16 },
{ .compatible = "atmel,24c32", .data = &at24_data_24c32 },
{ .compatible = "atmel,24cs32", .data = &at24_data_24cs32 },
{ .compatible = "atmel,24c64", .data = &at24_data_24c64 },
{ .compatible = "atmel,24cs64", .data = &at24_data_24cs64 },
{ .compatible = "atmel,24c128", .data = &at24_data_24c128 },
{ .compatible = "atmel,24c256", .data = &at24_data_24c256 },
{ .compatible = "atmel,24c512", .data = &at24_data_24c512 },
{ .compatible = "atmel,24c1024", .data = &at24_data_24c1024 },
{ .compatible = "atmel,24c2048", .data = &at24_data_24c2048 },
{ /* END OF LIST */ },
};
MODULE_DEVICE_TABLE(of, at24_of_match);
static const struct acpi_device_id at24_acpi_ids[] = {
{ "INT3499", (kernel_ulong_t)&at24_data_INT3499 },
{ /* END OF LIST */ }
};
MODULE_DEVICE_TABLE(acpi, at24_acpi_ids);
/*
* This routine supports chips which consume multiple I2C addresses. It
* computes the addressing information to be used for a given r/w request.
* Assumes that sanity checks for offset happened at sysfs-layer.
*
* Slave address and byte offset derive from the offset. Always
* set the byte address; on a multi-master board, another master
* may have changed the chip's "current" address pointer.
*/
static struct at24_client *at24_translate_offset(struct at24_data *at24,
unsigned int *offset)
{
unsigned int i;
if (at24->flags & AT24_FLAG_ADDR16) {
i = *offset >> 16;
*offset &= 0xffff;
} else {
i = *offset >> 8;
*offset &= 0xff;
}
return &at24->client[i];
}
static struct device *at24_base_client_dev(struct at24_data *at24)
{
return &at24->client[0].client->dev;
}
static size_t at24_adjust_read_count(struct at24_data *at24,
unsigned int offset, size_t count)
{
unsigned int bits;
size_t remainder;
/*
* In case of multi-address chips that don't rollover reads to
* the next slave address: truncate the count to the slave boundary,
* so that the read never straddles slaves.
*/
if (at24->flags & AT24_FLAG_NO_RDROL) {
bits = (at24->flags & AT24_FLAG_ADDR16) ? 16 : 8;
remainder = BIT(bits) - offset;
if (count > remainder)
count = remainder;
}
if (count > at24_io_limit)
count = at24_io_limit;
return count;
}
static ssize_t at24_regmap_read(struct at24_data *at24, char *buf,
unsigned int offset, size_t count)
{
unsigned long timeout, read_time;
struct at24_client *at24_client;
struct i2c_client *client;
struct regmap *regmap;
int ret;
at24_client = at24_translate_offset(at24, &offset);
regmap = at24_client->regmap;
client = at24_client->client;
count = at24_adjust_read_count(at24, offset, count);
/* adjust offset for mac and serial read ops */
offset += at24->offset_adj;
timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
do {
/*
* The timestamp shall be taken before the actual operation
* to avoid a premature timeout in case of high CPU load.
*/
read_time = jiffies;
ret = regmap_bulk_read(regmap, offset, buf, count);
dev_dbg(&client->dev, "read %zu@%d --> %d (%ld)\n",
count, offset, ret, jiffies);
if (!ret)
return count;
usleep_range(1000, 1500);
} while (time_before(read_time, timeout));
return -ETIMEDOUT;
}
/*
* Note that if the hardware write-protect pin is pulled high, the whole
* chip is normally write protected. But there are plenty of product
* variants here, including OTP fuses and partial chip protect.
*
* We only use page mode writes; the alternative is sloooow. These routines
* write at most one page.
*/
static size_t at24_adjust_write_count(struct at24_data *at24,
unsigned int offset, size_t count)
{
unsigned int next_page;
/* write_max is at most a page */
if (count > at24->write_max)
count = at24->write_max;
/* Never roll over backwards, to the start of this page */
next_page = roundup(offset + 1, at24->page_size);
if (offset + count > next_page)
count = next_page - offset;
return count;
}
static ssize_t at24_regmap_write(struct at24_data *at24, const char *buf,
unsigned int offset, size_t count)
{
unsigned long timeout, write_time;
struct at24_client *at24_client;
struct i2c_client *client;
struct regmap *regmap;
int ret;
at24_client = at24_translate_offset(at24, &offset);
regmap = at24_client->regmap;
client = at24_client->client;
count = at24_adjust_write_count(at24, offset, count);
timeout = jiffies + msecs_to_jiffies(at24_write_timeout);
do {
/*
* The timestamp shall be taken before the actual operation
* to avoid a premature timeout in case of high CPU load.
*/
write_time = jiffies;
ret = regmap_bulk_write(regmap, offset, buf, count);
dev_dbg(&client->dev, "write %zu@%d --> %d (%ld)\n",
count, offset, ret, jiffies);
if (!ret)
return count;
usleep_range(1000, 1500);
} while (time_before(write_time, timeout));
return -ETIMEDOUT;
}
static int at24_read(void *priv, unsigned int off, void *val, size_t count)
{
struct at24_data *at24;
struct device *dev;
char *buf = val;
int ret;
at24 = priv;
dev = at24_base_client_dev(at24);
if (unlikely(!count))
return count;
if (off + count > at24->byte_len)
return -EINVAL;
ret = pm_runtime_get_sync(dev);
if (ret < 0) {
pm_runtime_put_noidle(dev);
return ret;
}
/*
* Read data from chip, protecting against concurrent updates
* from this host, but not from other I2C masters.
*/
mutex_lock(&at24->lock);
while (count) {
ret = at24_regmap_read(at24, buf, off, count);
if (ret < 0) {
mutex_unlock(&at24->lock);
pm_runtime_put(dev);
return ret;
}
buf += ret;
off += ret;
count -= ret;
}
mutex_unlock(&at24->lock);
pm_runtime_put(dev);
return 0;
}
static int at24_write(void *priv, unsigned int off, void *val, size_t count)
{
struct at24_data *at24;
struct device *dev;
char *buf = val;
int ret;
at24 = priv;
dev = at24_base_client_dev(at24);
if (unlikely(!count))
return -EINVAL;
if (off + count > at24->byte_len)
return -EINVAL;
ret = pm_runtime_get_sync(dev);
if (ret < 0) {
pm_runtime_put_noidle(dev);
return ret;
}
/*
* Write data to chip, protecting against concurrent updates
* from this host, but not from other I2C masters.
*/
mutex_lock(&at24->lock);
gpiod_set_value_cansleep(at24->wp_gpio, 0);
while (count) {
ret = at24_regmap_write(at24, buf, off, count);
if (ret < 0) {
gpiod_set_value_cansleep(at24->wp_gpio, 1);
mutex_unlock(&at24->lock);
pm_runtime_put(dev);
return ret;
}
buf += ret;
off += ret;
count -= ret;
}
gpiod_set_value_cansleep(at24->wp_gpio, 1);
mutex_unlock(&at24->lock);
pm_runtime_put(dev);
return 0;
}
static const struct at24_chip_data *at24_get_chip_data(struct device *dev)
{
struct device_node *of_node = dev->of_node;
const struct at24_chip_data *cdata;
const struct i2c_device_id *id;
id = i2c_match_id(at24_ids, to_i2c_client(dev));
/*
* The I2C core allows OF nodes compatibles to match against the
* I2C device ID table as a fallback, so check not only if an OF
* node is present but also if it matches an OF device ID entry.
*/
if (of_node && of_match_device(at24_of_match, dev))
cdata = of_device_get_match_data(dev);
else if (id)
cdata = (void *)id->driver_data;
else
cdata = acpi_device_get_match_data(dev);
if (!cdata)
return ERR_PTR(-ENODEV);
return cdata;
}
static int at24_make_dummy_client(struct at24_data *at24, unsigned int index,
struct regmap_config *regmap_config)
{
struct i2c_client *base_client, *dummy_client;
struct regmap *regmap;
struct device *dev;
base_client = at24->client[0].client;
dev = &base_client->dev;
dummy_client = devm_i2c_new_dummy_device(dev, base_client->adapter,
base_client->addr + index);
if (IS_ERR(dummy_client))
return PTR_ERR(dummy_client);
regmap = devm_regmap_init_i2c(dummy_client, regmap_config);
if (IS_ERR(regmap))
return PTR_ERR(regmap);
at24->client[index].client = dummy_client;
at24->client[index].regmap = regmap;
return 0;
}
static unsigned int at24_get_offset_adj(u8 flags, unsigned int byte_len)
{
if (flags & AT24_FLAG_MAC) {
/* EUI-48 starts from 0x9a, EUI-64 from 0x98 */
return 0xa0 - byte_len;
} else if (flags & AT24_FLAG_SERIAL && flags & AT24_FLAG_ADDR16) {
/*
* For 16 bit address pointers, the word address must contain
* a '10' sequence in bits 11 and 10 regardless of the
* intended position of the address pointer.
*/
return 0x0800;
} else if (flags & AT24_FLAG_SERIAL) {
/*
* Otherwise the word address must begin with a '10' sequence,
* regardless of the intended address.
*/
return 0x0080;
} else {
return 0;
}
}
static int at24_probe(struct i2c_client *client)
{
struct regmap_config regmap_config = { };
struct nvmem_config nvmem_config = { };
u32 byte_len, page_size, flags, addrw;
const struct at24_chip_data *cdata;
struct device *dev = &client->dev;
bool i2c_fn_i2c, i2c_fn_block;
unsigned int i, num_addresses;
struct at24_data *at24;
struct regmap *regmap;
bool writable;
u8 test_byte;
int err;
i2c_fn_i2c = i2c_check_functionality(client->adapter, I2C_FUNC_I2C);
i2c_fn_block = i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WRITE_I2C_BLOCK);
cdata = at24_get_chip_data(dev);
if (IS_ERR(cdata))
return PTR_ERR(cdata);
err = device_property_read_u32(dev, "pagesize", &page_size);
if (err)
/*
* This is slow, but we can't know all eeproms, so we better
* play safe. Specifying custom eeprom-types via device tree
* or properties is recommended anyhow.
*/
page_size = 1;
flags = cdata->flags;
if (device_property_present(dev, "read-only"))
flags |= AT24_FLAG_READONLY;
if (device_property_present(dev, "no-read-rollover"))
flags |= AT24_FLAG_NO_RDROL;
err = device_property_read_u32(dev, "address-width", &addrw);
if (!err) {
switch (addrw) {
case 8:
if (flags & AT24_FLAG_ADDR16)
dev_warn(dev,
"Override address width to be 8, while default is 16\n");
flags &= ~AT24_FLAG_ADDR16;
break;
case 16:
flags |= AT24_FLAG_ADDR16;
break;
default:
dev_warn(dev, "Bad \"address-width\" property: %u\n",
addrw);
}
}
err = device_property_read_u32(dev, "size", &byte_len);
if (err)
byte_len = cdata->byte_len;
if (!i2c_fn_i2c && !i2c_fn_block)
page_size = 1;
if (!page_size) {
dev_err(dev, "page_size must not be 0!\n");
return -EINVAL;
}
if (!is_power_of_2(page_size))
dev_warn(dev, "page_size looks suspicious (no power of 2)!\n");
err = device_property_read_u32(dev, "num-addresses", &num_addresses);
if (err) {
if (flags & AT24_FLAG_TAKE8ADDR)
num_addresses = 8;
else
num_addresses = DIV_ROUND_UP(byte_len,
(flags & AT24_FLAG_ADDR16) ? 65536 : 256);
}
if ((flags & AT24_FLAG_SERIAL) && (flags & AT24_FLAG_MAC)) {
dev_err(dev,
"invalid device data - cannot have both AT24_FLAG_SERIAL & AT24_FLAG_MAC.");
return -EINVAL;
}
regmap_config.val_bits = 8;
regmap_config.reg_bits = (flags & AT24_FLAG_ADDR16) ? 16 : 8;
regmap_config.disable_locking = true;
regmap = devm_regmap_init_i2c(client, &regmap_config);
if (IS_ERR(regmap))
return PTR_ERR(regmap);
at24 = devm_kzalloc(dev, struct_size(at24, client, num_addresses),
GFP_KERNEL);
if (!at24)
return -ENOMEM;
mutex_init(&at24->lock);
at24->byte_len = byte_len;
at24->page_size = page_size;
at24->flags = flags;
at24->num_addresses = num_addresses;
at24->offset_adj = at24_get_offset_adj(flags, byte_len);
at24->client[0].client = client;
at24->client[0].regmap = regmap;
at24->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_HIGH);
if (IS_ERR(at24->wp_gpio))
return PTR_ERR(at24->wp_gpio);
writable = !(flags & AT24_FLAG_READONLY);
if (writable) {
at24->write_max = min_t(unsigned int,
page_size, at24_io_limit);
if (!i2c_fn_i2c && at24->write_max > I2C_SMBUS_BLOCK_MAX)
at24->write_max = I2C_SMBUS_BLOCK_MAX;
}
/* use dummy devices for multiple-address chips */
for (i = 1; i < num_addresses; i++) {
err = at24_make_dummy_client(at24, i, &regmap_config);
if (err)
return err;
}
nvmem_config.name = dev_name(dev);
nvmem_config.dev = dev;
nvmem_config.read_only = !writable;
nvmem_config.root_only = true;
nvmem_config.owner = THIS_MODULE;
nvmem_config.compat = true;
nvmem_config.base_dev = dev;
nvmem_config.reg_read = at24_read;
nvmem_config.reg_write = at24_write;
nvmem_config.priv = at24;
nvmem_config.stride = 1;
nvmem_config.word_size = 1;
nvmem_config.size = byte_len;
at24->nvmem = devm_nvmem_register(dev, &nvmem_config);
if (IS_ERR(at24->nvmem))
return PTR_ERR(at24->nvmem);
i2c_set_clientdata(client, at24);
/* enable runtime pm */
pm_runtime_set_active(dev);
pm_runtime_enable(dev);
/*
* Perform a one-byte test read to verify that the
* chip is functional.
*/
err = at24_read(at24, 0, &test_byte, 1);
pm_runtime_idle(dev);
if (err) {
pm_runtime_disable(dev);
return -ENODEV;
}
dev_info(dev, "%u byte %s EEPROM, %s, %u bytes/write\n",
byte_len, client->name,
writable ? "writable" : "read-only", at24->write_max);
return 0;
}
static int at24_remove(struct i2c_client *client)
{
pm_runtime_disable(&client->dev);
pm_runtime_set_suspended(&client->dev);
return 0;
}
static struct i2c_driver at24_driver = {
.driver = {
.name = "at24",
.of_match_table = at24_of_match,
.acpi_match_table = ACPI_PTR(at24_acpi_ids),
},
.probe_new = at24_probe,
.remove = at24_remove,
.id_table = at24_ids,
};
static int __init at24_init(void)
{
if (!at24_io_limit) {
pr_err("at24: at24_io_limit must not be 0!\n");
return -EINVAL;
}
at24_io_limit = rounddown_pow_of_two(at24_io_limit);
return i2c_add_driver(&at24_driver);
}
module_init(at24_init);
static void __exit at24_exit(void)
{
i2c_del_driver(&at24_driver);
}
module_exit(at24_exit);
MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
MODULE_AUTHOR("David Brownell and Wolfram Sang");
MODULE_LICENSE("GPL");
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