// 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* 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, ®map_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, ®map_config); if (err) return err; } nvmem_config.name = dev_name(dev); nvmem_config.dev = dev; nvmem_config.read_only = !writable; nvmem_config.root_only = !(flags & AT24_FLAG_IRUGO); 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");