On Wed, Jan 22, 2014 at 5:23 PM, Curt Brune <curt@xxxxxxxxxxxxxxxxxxx> wrote:
> During device instantiation have the at24 driver add the new device to
> the eeprom_dev hardware class. The functionality is enabled by
> CONFIG_EEPROM_CLASS.
>
> Signed-off-by: Curt Brune <curt@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/misc/eeprom/at24.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index d87f77f..07782ea 100644
> --- a/drivers/misc/eeprom/at24.c
> +++ b/drivers/misc/eeprom/at24.c
> @@ -1,170 +1,177 @@
> /*
> * at24.c - handle most I2C EEPROMs
> *
> * Copyright (C) 2005-2007 David Brownell
> * Copyright (C) 2008 Wolfram Sang, Pengutronix
> *
> * 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/mutex.h>
> #include <linux/sysfs.h>
> #include <linux/mod_devicetable.h>
> #include <linux/log2.h>
> #include <linux/bitops.h>
> #include <linux/jiffies.h>
> #include <linux/of.h>
> #include <linux/i2c.h>
> #include <linux/platform_data/at24.h>
>
> +#ifdef CONFIG_EEPROM_CLASS
> +#include <linux/eeprom_class.h>
> +#endif
> +
> /*
> * 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_data {
> struct at24_platform_data chip;
> struct memory_accessor macc;
> int use_smbus;
>
> /*
> * Lock protects against activities from other Linux tasks,
> * but not from changes by other I2C masters.
> */
> struct mutex lock;
> struct bin_attribute bin;
>
> u8 *writebuf;
> unsigned write_max;
> unsigned num_addresses;
>
> +#ifdef CONFIG_EEPROM_CLASS
> + struct device *eeprom_dev;
> +#endif
> /*
> * Some chips tie up multiple I2C addresses; dummy devices reserve
> * them for us, and we'll use them with SMBus calls.
> */
> struct i2c_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 io_limit = 128;
> module_param(io_limit, uint, 0);
> MODULE_PARM_DESC(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 write_timeout = 25;
> module_param(write_timeout, uint, 0);
> MODULE_PARM_DESC(write_timeout, "Time (in ms) to try writes (default 25)");
>
> #define AT24_SIZE_BYTELEN 5
> #define AT24_SIZE_FLAGS 8
>
> #define AT24_BITMASK(x) (BIT(x) - 1)
>
> /* create non-zero magic value for given eeprom parameters */
> #define AT24_DEVICE_MAGIC(_len, _flags) \
> ((1 << AT24_SIZE_FLAGS | (_flags)) \
> << AT24_SIZE_BYTELEN | ilog2(_len))
>
> static const struct i2c_device_id at24_ids[] = {
> /* needs 8 addresses as A0-A2 are ignored */
> { "24c00", AT24_DEVICE_MAGIC(128 / 8, AT24_FLAG_TAKE8ADDR) },
> /* old variants can't be handled with this generic entry! */
> { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) },
> { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) },
> /* spd is a 24c02 in memory DIMMs */
> { "spd", AT24_DEVICE_MAGIC(2048 / 8,
> AT24_FLAG_READONLY | AT24_FLAG_IRUGO) },
> { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) },
> /* 24rf08 quirk is handled at i2c-core */
> { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) },
> { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) },
> { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) },
> { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) },
> { "24c128", AT24_DEVICE_MAGIC(131072 / 8, AT24_FLAG_ADDR16) },
> { "24c256", AT24_DEVICE_MAGIC(262144 / 8, AT24_FLAG_ADDR16) },
> { "24c512", AT24_DEVICE_MAGIC(524288 / 8, AT24_FLAG_ADDR16) },
> { "24c1024", AT24_DEVICE_MAGIC(1048576 / 8, AT24_FLAG_ADDR16) },
> { "at24", 0 },
> { /* END OF LIST */ }
> };
> MODULE_DEVICE_TABLE(i2c, at24_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.
> */
> static struct i2c_client *at24_translate_offset(struct at24_data *at24,
> unsigned *offset)
> {
> unsigned i;
>
> if (at24->chip.flags & AT24_FLAG_ADDR16) {
> i = *offset >> 16;
> *offset &= 0xffff;
> } else {
> i = *offset >> 8;
> *offset &= 0xff;
> }
>
> return at24->client[i];
> }
>
> static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf,
> unsigned offset, size_t count)
> {
> struct i2c_msg msg[2];
> u8 msgbuf[2];
> struct i2c_client *client;
> unsigned long timeout, read_time;
> int status, i;
>
> memset(msg, 0, sizeof(msg));
>
> /*
> * REVISIT some multi-address chips don't rollover page reads to
> * the next slave address, so we may need to truncate the count.
> * Those chips might need another quirk flag.
> @@ -524,173 +531,186 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
> return -EINVAL;
> }
> if (!is_power_of_2(chip.page_size))
> dev_warn(&client->dev,
> "page_size looks suspicious (no power of 2)!\n");
>
> /* Use I2C operations unless we're stuck with SMBus extensions. */
> if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> if (chip.flags & AT24_FLAG_ADDR16)
> return -EPFNOSUPPORT;
>
> if (i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
> use_smbus = I2C_SMBUS_I2C_BLOCK_DATA;
> } else if (i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_READ_WORD_DATA)) {
> use_smbus = I2C_SMBUS_WORD_DATA;
> } else if (i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
> use_smbus = I2C_SMBUS_BYTE_DATA;
> } else {
> return -EPFNOSUPPORT;
> }
> }
>
> if (chip.flags & AT24_FLAG_TAKE8ADDR)
> num_addresses = 8;
> else
> num_addresses = DIV_ROUND_UP(chip.byte_len,
> (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256);
>
> at24 = devm_kzalloc(&client->dev, sizeof(struct at24_data) +
> num_addresses * sizeof(struct i2c_client *), GFP_KERNEL);
> if (!at24)
> return -ENOMEM;
>
> mutex_init(&at24->lock);
> at24->use_smbus = use_smbus;
> at24->chip = chip;
> at24->num_addresses = num_addresses;
>
> /*
> * Export the EEPROM bytes through sysfs, since that's convenient.
> * By default, only root should see the data (maybe passwords etc)
> */
> sysfs_bin_attr_init(&at24->bin);
> at24->bin.attr.name = "eeprom";
> at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;
> at24->bin.read = at24_bin_read;
> at24->bin.size = chip.byte_len;
>
> at24->macc.read = at24_macc_read;
>
> writable = !(chip.flags & AT24_FLAG_READONLY);
> if (writable) {
> if (!use_smbus || i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
>
> unsigned write_max = chip.page_size;
>
> at24->macc.write = at24_macc_write;
>
> at24->bin.write = at24_bin_write;
> at24->bin.attr.mode |= S_IWUSR;
>
> if (write_max > io_limit)
> write_max = io_limit;
> if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX)
> write_max = I2C_SMBUS_BLOCK_MAX;
> at24->write_max = write_max;
>
> /* buffer (data + address at the beginning) */
> at24->writebuf = devm_kzalloc(&client->dev,
> write_max + 2, GFP_KERNEL);
> if (!at24->writebuf)
> return -ENOMEM;
> } else {
> dev_warn(&client->dev,
> "cannot write due to controller restrictions.");
> }
> }
>
> at24->client[0] = client;
>
> /* use dummy devices for multiple-address chips */
> for (i = 1; i < num_addresses; i++) {
> at24->client[i] = i2c_new_dummy(client->adapter,
> client->addr + i);
> if (!at24->client[i]) {
> dev_err(&client->dev, "address 0x%02x unavailable\n",
> client->addr + i);
> err = -EADDRINUSE;
> goto err_clients;
> }
> }
>
> err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin);
> if (err)
> goto err_clients;
>
> +#ifdef CONFIG_EEPROM_CLASS
> + at24->eeprom_dev = eeprom_device_register(&client->dev);
> + if (IS_ERR(at24->eeprom_dev)) {
> + dev_err(&client->dev, "error registering eeprom device.\n");
> + err = PTR_ERR(at24->eeprom_dev);
> + goto err_clients;
> + }
> +#endif
> +
> i2c_set_clientdata(client, at24);
>
> dev_info(&client->dev, "%zu byte %s EEPROM, %s, %u bytes/write\n",
> at24->bin.size, client->name,
> writable ? "writable" : "read-only", at24->write_max);
> if (use_smbus == I2C_SMBUS_WORD_DATA ||
> use_smbus == I2C_SMBUS_BYTE_DATA) {
> dev_notice(&client->dev, "Falling back to %s reads, "
> "performance will suffer\n", use_smbus ==
> I2C_SMBUS_WORD_DATA ? "word" : "byte");
> }
>
> /* export data to kernel code */
> if (chip.setup)
> chip.setup(&at24->macc, chip.context);
>
> return 0;
>
> err_clients:
> for (i = 1; i < num_addresses; i++)
> if (at24->client[i])
> i2c_unregister_device(at24->client[i]);
>
> return err;
> }
>
> static int at24_remove(struct i2c_client *client)
> {
> struct at24_data *at24;
> int i;
>
> at24 = i2c_get_clientdata(client);
> sysfs_remove_bin_file(&client->dev.kobj, &at24->bin);
>
> for (i = 1; i < at24->num_addresses; i++)
> i2c_unregister_device(at24->client[i]);
>
> +#ifdef CONFIG_EEPROM_CLASS
> + eeprom_device_unregister(at24->eeprom_dev);
> +#endif
> +
> return 0;
> }
>
> /*-------------------------------------------------------------------------*/
>
> static struct i2c_driver at24_driver = {
> .driver = {
> .name = "at24",
> .owner = THIS_MODULE,
> },
> .probe = at24_probe,
> .remove = at24_remove,
> .id_table = at24_ids,
> };
>
> static int __init at24_init(void)
> {
> if (!io_limit) {
> pr_err("at24: io_limit must not be 0!\n");
> return -EINVAL;
> }
>
> io_limit = rounddown_pow_of_two(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);
Couldn't you use module_i2c_driver() instead of this?
> MODULE_DESCRIPTION("Driver for most I2C EEPROMs");
> MODULE_AUTHOR("David Brownell and Wolfram Sang");
I would personally put your name in here if I were you, otherwise
David and Wolfram might get contacted by some people instead of you
(at least based on this).
PS.: Fixing the broken i2c mailing list typo, and updating Wolfram's
address from the broken (obsolete?) version.
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