diff options
Diffstat (limited to 'drivers/i2c/chips/at24.c')
| -rw-r--r-- | drivers/i2c/chips/at24.c | 582 |
1 files changed, 0 insertions, 582 deletions
diff --git a/drivers/i2c/chips/at24.c b/drivers/i2c/chips/at24.c deleted file mode 100644 index d4775528abc6..000000000000 --- a/drivers/i2c/chips/at24.c +++ /dev/null @@ -1,582 +0,0 @@ -/* - * 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/i2c.h> -#include <linux/i2c/at24.h> - -/* - * 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; - bool 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; - - /* - * 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; - 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. - * - * If the real hardware used four adjacent 24c02 chips and that - * were misconfigured as one 24c08, that would be a similar effect: - * one "eeprom" file not four, but larger reads would fail when - * they crossed certain pages. - */ - - /* - * 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. - */ - client = at24_translate_offset(at24, &offset); - - if (count > io_limit) - count = io_limit; - - /* Smaller eeproms can work given some SMBus extension calls */ - if (at24->use_smbus) { - if (count > I2C_SMBUS_BLOCK_MAX) - count = I2C_SMBUS_BLOCK_MAX; - status = i2c_smbus_read_i2c_block_data(client, offset, - count, buf); - dev_dbg(&client->dev, "smbus read %zu@%d --> %d\n", - count, offset, status); - return (status < 0) ? -EIO : status; - } - - /* - * When we have a better choice than SMBus calls, use a combined - * I2C message. Write address; then read up to io_limit data bytes. - * Note that read page rollover helps us here (unlike writes). - * msgbuf is u8 and will cast to our needs. - */ - i = 0; - if (at24->chip.flags & AT24_FLAG_ADDR16) - msgbuf[i++] = offset >> 8; - msgbuf[i++] = offset; - - msg[0].addr = client->addr; - msg[0].buf = msgbuf; - msg[0].len = i; - - msg[1].addr = client->addr; - msg[1].flags = I2C_M_RD; - msg[1].buf = buf; - msg[1].len = count; - - status = i2c_transfer(client->adapter, msg, 2); - dev_dbg(&client->dev, "i2c read %zu@%d --> %d\n", - count, offset, status); - - if (status == 2) - return count; - else if (status >= 0) - return -EIO; - else - return status; -} - -static ssize_t at24_bin_read(struct kobject *kobj, struct bin_attribute *attr, - char *buf, loff_t off, size_t count) -{ - struct at24_data *at24; - ssize_t retval = 0; - - at24 = dev_get_drvdata(container_of(kobj, struct device, kobj)); - - if (unlikely(!count)) - return count; - - /* - * Read data from chip, protecting against concurrent updates - * from this host, but not from other I2C masters. - */ - mutex_lock(&at24->lock); - - while (count) { - ssize_t status; - - status = at24_eeprom_read(at24, buf, off, count); - if (status <= 0) { - if (retval == 0) - retval = status; - break; - } - buf += status; - off += status; - count -= status; - retval += status; - } - - mutex_unlock(&at24->lock); - - return retval; -} - - -/* - * REVISIT: export at24_bin{read,write}() to let other kernel code use - * eeprom data. For example, it might hold a board's Ethernet address, or - * board-specific calibration data generated on the manufacturing floor. - */ - - -/* - * 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. This routine - * writes at most one page. - */ -static ssize_t at24_eeprom_write(struct at24_data *at24, char *buf, - unsigned offset, size_t count) -{ - struct i2c_client *client; - struct i2c_msg msg; - ssize_t status; - unsigned long timeout, write_time; - unsigned next_page; - - /* Get corresponding I2C address and adjust offset */ - client = at24_translate_offset(at24, &offset); - - /* 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->chip.page_size); - if (offset + count > next_page) - count = next_page - offset; - - /* If we'll use I2C calls for I/O, set up the message */ - if (!at24->use_smbus) { - int i = 0; - - msg.addr = client->addr; - msg.flags = 0; - - /* msg.buf is u8 and casts will mask the values */ - msg.buf = at24->writebuf; - if (at24->chip.flags & AT24_FLAG_ADDR16) - msg.buf[i++] = offset >> 8; - - msg.buf[i++] = offset; - memcpy(&msg.buf[i], buf, count); - msg.len = i + count; - } - - /* - * Writes fail if the previous one didn't complete yet. We may - * loop a few times until this one succeeds, waiting at least - * long enough for one entire page write to work. - */ - timeout = jiffies + msecs_to_jiffies(write_timeout); - do { - write_time = jiffies; - if (at24->use_smbus) { - status = i2c_smbus_write_i2c_block_data(client, - offset, count, buf); - if (status == 0) - status = count; - } else { - status = i2c_transfer(client->adapter, &msg, 1); - if (status == 1) - status = count; - } - dev_dbg(&client->dev, "write %zu@%d --> %zd (%ld)\n", - count, offset, status, jiffies); - - if (status == count) - return count; - - /* REVISIT: at HZ=100, this is sloooow */ - msleep(1); - } while (time_before(write_time, timeout)); - - return -ETIMEDOUT; -} - -static ssize_t at24_bin_write(struct kobject *kobj, struct bin_attribute *attr, - char *buf, loff_t off, size_t count) -{ - struct at24_data *at24; - ssize_t retval = 0; - - at24 = dev_get_drvdata(container_of(kobj, struct device, kobj)); - - if (unlikely(!count)) - return count; - - /* - * Write data to chip, protecting against concurrent updates - * from this host, but not from other I2C masters. - */ - mutex_lock(&at24->lock); - - while (count) { - ssize_t status; - - status = at24_eeprom_write(at24, buf, off, count); - if (status <= 0) { - if (retval == 0) - retval = status; - break; - } - buf += status; - off += status; - count -= status; - retval += status; - } - - mutex_unlock(&at24->lock); - - return retval; -} - -/*-------------------------------------------------------------------------*/ - -static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id) -{ - struct at24_platform_data chip; - bool writable; - bool use_smbus = false; - struct at24_data *at24; - int err; - unsigned i, num_addresses; - kernel_ulong_t magic; - - if (client->dev.platform_data) { - chip = *(struct at24_platform_data *)client->dev.platform_data; - } else { - if (!id->driver_data) { - err = -ENODEV; - goto err_out; - } - magic = id->driver_data; - chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN)); - magic >>= AT24_SIZE_BYTELEN; - chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS); - /* - * This is slow, but we can't know all eeproms, so we better - * play safe. Specifying custom eeprom-types via platform_data - * is recommended anyhow. - */ - chip.page_size = 1; - } - - if (!is_power_of_2(chip.byte_len)) - dev_warn(&client->dev, - "byte_len looks suspicious (no power of 2)!\n"); - 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) { - err = -EPFNOSUPPORT; - goto err_out; - } - if (!i2c_check_functionality(client->adapter, - I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { - err = -EPFNOSUPPORT; - goto err_out; - } - use_smbus = true; - } - - 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 = kzalloc(sizeof(struct at24_data) + - num_addresses * sizeof(struct i2c_client *), GFP_KERNEL); - if (!at24) { - err = -ENOMEM; - goto err_out; - } - - 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) - */ - 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; - - 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->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 = kmalloc(write_max + 2, GFP_KERNEL); - if (!at24->writebuf) { - err = -ENOMEM; - goto err_struct; - } - } 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; - - i2c_set_clientdata(client, at24); - - dev_info(&client->dev, "%zu byte %s EEPROM %s\n", - at24->bin.size, client->name, - writable ? "(writable)" : "(read-only)"); - dev_dbg(&client->dev, - "page_size %d, num_addresses %d, write_max %d%s\n", - chip.page_size, num_addresses, - at24->write_max, - use_smbus ? ", use_smbus" : ""); - - return 0; - -err_clients: - for (i = 1; i < num_addresses; i++) - if (at24->client[i]) - i2c_unregister_device(at24->client[i]); - - kfree(at24->writebuf); -err_struct: - kfree(at24); -err_out: - dev_dbg(&client->dev, "probe error %d\n", err); - return err; -} - -static int __devexit 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]); - - kfree(at24->writebuf); - kfree(at24); - i2c_set_clientdata(client, NULL); - return 0; -} - -/*-------------------------------------------------------------------------*/ - -static struct i2c_driver at24_driver = { - .driver = { - .name = "at24", - .owner = THIS_MODULE, - }, - .probe = at24_probe, - .remove = __devexit_p(at24_remove), - .id_table = at24_ids, -}; - -static int __init at24_init(void) -{ - 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); - -MODULE_DESCRIPTION("Driver for most I2C EEPROMs"); -MODULE_AUTHOR("David Brownell and Wolfram Sang"); -MODULE_LICENSE("GPL"); |
