diff options
Diffstat (limited to 'drivers/i2c/chips/max6875.c')
| -rw-r--r-- | drivers/i2c/chips/max6875.c | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/drivers/i2c/chips/max6875.c b/drivers/i2c/chips/max6875.c new file mode 100644 index 000000000000..0230375f72e5 --- /dev/null +++ b/drivers/i2c/chips/max6875.c @@ -0,0 +1,479 @@ +/* + max6875.c - driver for MAX6874/MAX6875 + + Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com> + + Based on i2c/chips/eeprom.c + + The MAX6875 has two EEPROM sections: config and user. + At reset, the config EEPROM is read into the registers. + + This driver make 3 binary files available in sysfs: + reg_config - direct access to the registers + eeprom_config - acesses configuration eeprom space + eeprom_user - free for application use + + In our application, we put device serial & model numbers in user eeprom. + + Notes: + 1) The datasheet says that register 0x44 / EEPROM 0x8044 should NOT + be overwritten, so the driver explicitly prevents that. + 2) It's a good idea to keep the config (0x45) locked in config EEPROM. + You can temporarily enable config writes by changing register 0x45. + + 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; version 2 of the License. +*/ + +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/sched.h> +#include <linux/delay.h> +#include <linux/i2c.h> +#include <linux/i2c-sensor.h> + +/* Addresses to scan */ +/* No address scanned by default, as this could corrupt standard EEPROMS. */ +static unsigned short normal_i2c[] = {I2C_CLIENT_END}; +static unsigned int normal_isa[] = {I2C_CLIENT_ISA_END}; + +/* Insmod parameters */ +SENSORS_INSMOD_1(max6875); + +/* this param will prevent 'accidental' writes to the eeprom */ +static int allow_write = 0; +module_param(allow_write, int, 0); +MODULE_PARM_DESC(allow_write, + "Enable write access:\n" + "*0: Read only\n" + " 1: Read/Write access"); + +/* The MAX6875 can only read/write 16 bytes at a time */ +#define SLICE_SIZE 16 +#define SLICE_BITS 4 + +/* CONFIG EEPROM is at addresses 0x8000 - 0x8045, registers are at 0 - 0x45 */ +#define CONFIG_EEPROM_BASE 0x8000 +#define CONFIG_EEPROM_SIZE 0x0046 +#define CONFIG_EEPROM_SLICES 5 + +/* USER EEPROM is at addresses 0x8100 - 0x82FF */ +#define USER_EEPROM_BASE 0x8100 +#define USER_EEPROM_SIZE 0x0200 +#define USER_EEPROM_SLICES 32 + +/* MAX6875 commands */ +#define MAX6875_CMD_BLOCK_WRITE 0x83 +#define MAX6875_CMD_BLOCK_READ 0x84 +#define MAX6875_CMD_REBOOT 0x88 + +enum max6875_area_type { + max6875_register_config=0, + max6875_eeprom_config, + max6875_eeprom_user, + max6857_max +}; + +struct eeprom_block { + enum max6875_area_type type; + u8 slices; + u32 size; + u32 valid; + u32 base; + unsigned long *updated; + u8 *data; +}; + +/* Each client has this additional data */ +struct max6875_data { + struct i2c_client client; + struct semaphore update_lock; + struct eeprom_block blocks[max6857_max]; + /* the above structs point into the arrays below */ + u8 data[USER_EEPROM_SIZE + (CONFIG_EEPROM_SIZE*2)]; + unsigned long last_updated[USER_EEPROM_SLICES + (CONFIG_EEPROM_SLICES*2)]; +}; + +static int max6875_attach_adapter(struct i2c_adapter *adapter); +static int max6875_detect(struct i2c_adapter *adapter, int address, int kind); +static int max6875_detach_client(struct i2c_client *client); + +/* This is the driver that will be inserted */ +static struct i2c_driver max6875_driver = { + .owner = THIS_MODULE, + .name = "max6875", + .flags = I2C_DF_NOTIFY, + .attach_adapter = max6875_attach_adapter, + .detach_client = max6875_detach_client, +}; + +static int max6875_update_slice(struct i2c_client *client, + struct eeprom_block *blk, + int slice) +{ + struct max6875_data *data = i2c_get_clientdata(client); + int i, j, addr, count; + u8 rdbuf[SLICE_SIZE]; + int retval = 0; + + if (slice >= blk->slices) + return -1; + + down(&data->update_lock); + + if (!(blk->valid & (1 << slice)) || + (jiffies - blk->updated[slice] > 300 * HZ) || + (jiffies < blk->updated[slice])) { + dev_dbg(&client->dev, "Starting eeprom update, slice %u, base %u\n", + slice, blk->base); + + addr = blk->base + (slice << SLICE_BITS); + count = blk->size - (slice << SLICE_BITS); + if (count > SLICE_SIZE) { + count = SLICE_SIZE; + } + + /* Preset the read address */ + if (addr < 0x100) { + /* select the register */ + if (i2c_smbus_write_byte(client, addr & 0xFF)) { + dev_dbg(&client->dev, "max6875 register select has failed!\n"); + retval = -1; + goto exit; + } + } else { + /* select the eeprom */ + if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) { + dev_dbg(&client->dev, "max6875 address set has failed!\n"); + retval = -1; + goto exit; + } + } + + if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { + if (i2c_smbus_read_i2c_block_data(client, MAX6875_CMD_BLOCK_READ, + rdbuf) != SLICE_SIZE) + { + retval = -1; + goto exit; + } + + memcpy(&blk->data[slice << SLICE_BITS], rdbuf, count); + } else { + for (i = 0; i < count; i++) { + j = i2c_smbus_read_byte(client); + if (j < 0) + { + retval = -1; + goto exit; + } + blk->data[(slice << SLICE_BITS) + i] = (u8) j; + } + } + blk->updated[slice] = jiffies; + blk->valid |= (1 << slice); + } + exit: + up(&data->update_lock); + return retval; +} + +static ssize_t max6875_read(struct kobject *kobj, char *buf, loff_t off, size_t count, + enum max6875_area_type area_type) +{ + struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj)); + struct max6875_data *data = i2c_get_clientdata(client); + struct eeprom_block *blk; + int slice; + + blk = &data->blocks[area_type]; + + if (off > blk->size) + return 0; + if (off + count > blk->size) + count = blk->size - off; + + /* Only refresh slices which contain requested bytes */ + for (slice = (off >> SLICE_BITS); slice <= ((off + count - 1) >> SLICE_BITS); slice++) + max6875_update_slice(client, blk, slice); + + memcpy(buf, &blk->data[off], count); + + return count; +} + +static ssize_t max6875_user_read(struct kobject *kobj, char *buf, loff_t off, size_t count) +{ + return max6875_read(kobj, buf, off, count, max6875_eeprom_user); +} + +static ssize_t max6875_config_read(struct kobject *kobj, char *buf, loff_t off, size_t count) +{ + return max6875_read(kobj, buf, off, count, max6875_eeprom_config); +} + +static ssize_t max6875_cfgreg_read(struct kobject *kobj, char *buf, loff_t off, size_t count) +{ + return max6875_read(kobj, buf, off, count, max6875_register_config); +} + + +static ssize_t max6875_write(struct kobject *kobj, char *buf, loff_t off, size_t count, + enum max6875_area_type area_type) +{ + struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj)); + struct max6875_data *data = i2c_get_clientdata(client); + struct eeprom_block *blk; + int slice, addr, retval; + ssize_t sent = 0; + + blk = &data->blocks[area_type]; + + if (off > blk->size) + return 0; + if ((off + count) > blk->size) + count = blk->size - off; + + if (down_interruptible(&data->update_lock)) + return -EAGAIN; + + /* writing to a register is done with i2c_smbus_write_byte_data() */ + if (blk->type == max6875_register_config) { + for (sent = 0; sent < count; sent++) { + addr = off + sent; + if (addr == 0x44) + continue; + + retval = i2c_smbus_write_byte_data(client, addr, buf[sent]); + } + } else { + int cmd, val; + + /* We are writing to EEPROM */ + for (sent = 0; sent < count; sent++) { + addr = blk->base + off + sent; + cmd = addr >> 8; + val = (addr & 0xff) | (buf[sent] << 8); // reversed + + if (addr == 0x8044) + continue; + + retval = i2c_smbus_write_word_data(client, cmd, val); + + if (retval) { + goto error_exit; + } + + /* A write takes up to 11 ms */ + msleep(11); + } + } + + /* Invalidate the scratch buffer */ + for (slice = (off >> SLICE_BITS); slice <= ((off + count - 1) >> SLICE_BITS); slice++) + blk->valid &= ~(1 << slice); + + error_exit: + up(&data->update_lock); + + return sent; +} + +static ssize_t max6875_user_write(struct kobject *kobj, char *buf, loff_t off, size_t count) +{ + return max6875_write(kobj, buf, off, count, max6875_eeprom_user); +} + +static ssize_t max6875_config_write(struct kobject *kobj, char *buf, loff_t off, size_t count) +{ + return max6875_write(kobj, buf, off, count, max6875_eeprom_config); +} + +static ssize_t max6875_cfgreg_write(struct kobject *kobj, char *buf, loff_t off, size_t count) +{ + return max6875_write(kobj, buf, off, count, max6875_register_config); +} + +static struct bin_attribute user_eeprom_attr = { + .attr = { + .name = "eeprom_user", + .mode = S_IRUGO | S_IWUSR | S_IWGRP, + .owner = THIS_MODULE, + }, + .size = USER_EEPROM_SIZE, + .read = max6875_user_read, + .write = max6875_user_write, +}; + +static struct bin_attribute config_eeprom_attr = { + .attr = { + .name = "eeprom_config", + .mode = S_IRUGO | S_IWUSR, + .owner = THIS_MODULE, + }, + .size = CONFIG_EEPROM_SIZE, + .read = max6875_config_read, + .write = max6875_config_write, +}; + +static struct bin_attribute config_register_attr = { + .attr = { + .name = "reg_config", + .mode = S_IRUGO | S_IWUSR, + .owner = THIS_MODULE, + }, + .size = CONFIG_EEPROM_SIZE, + .read = max6875_cfgreg_read, + .write = max6875_cfgreg_write, +}; + +static int max6875_attach_adapter(struct i2c_adapter *adapter) +{ + return i2c_detect(adapter, &addr_data, max6875_detect); +} + +/* This function is called by i2c_detect */ +static int max6875_detect(struct i2c_adapter *adapter, int address, int kind) +{ + struct i2c_client *new_client; + struct max6875_data *data; + int err = 0; + + /* Prevent 24RF08 corruption (in case of user error) */ + if (kind < 0) + i2c_smbus_xfer(adapter, address, 0, 0, 0, + I2C_SMBUS_QUICK, NULL); + + /* There are three ways we can read the EEPROM data: + (1) I2C block reads (faster, but unsupported by most adapters) + (2) Consecutive byte reads (100% overhead) + (3) Regular byte data reads (200% overhead) + The third method is not implemented by this driver because all + known adapters support at least the second. */ + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA | + I2C_FUNC_SMBUS_BYTE | + I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) + goto exit; + + /* OK. For now, we presume we have a valid client. We now create the + client structure, even though we cannot fill it completely yet. + But it allows us to access eeprom_{read,write}_value. */ + if (!(data = kmalloc(sizeof(struct max6875_data), GFP_KERNEL))) { + err = -ENOMEM; + goto exit; + } + memset(data, 0, sizeof(struct max6875_data)); + + new_client = &data->client; + i2c_set_clientdata(new_client, data); + new_client->addr = address; + new_client->adapter = adapter; + new_client->driver = &max6875_driver; + new_client->flags = 0; + + /* Setup the user section */ + data->blocks[max6875_eeprom_user].type = max6875_eeprom_user; + data->blocks[max6875_eeprom_user].slices = USER_EEPROM_SLICES; + data->blocks[max6875_eeprom_user].size = USER_EEPROM_SIZE; + data->blocks[max6875_eeprom_user].base = USER_EEPROM_BASE; + data->blocks[max6875_eeprom_user].data = data->data; + data->blocks[max6875_eeprom_user].updated = data->last_updated; + + /* Setup the config section */ + data->blocks[max6875_eeprom_config].type = max6875_eeprom_config; + data->blocks[max6875_eeprom_config].slices = CONFIG_EEPROM_SLICES; + data->blocks[max6875_eeprom_config].size = CONFIG_EEPROM_SIZE; + data->blocks[max6875_eeprom_config].base = CONFIG_EEPROM_BASE; + data->blocks[max6875_eeprom_config].data = &data->data[USER_EEPROM_SIZE]; + data->blocks[max6875_eeprom_config].updated = &data->last_updated[USER_EEPROM_SLICES]; + + /* Setup the register section */ + data->blocks[max6875_register_config].type = max6875_register_config; + data->blocks[max6875_register_config].slices = CONFIG_EEPROM_SLICES; + data->blocks[max6875_register_config].size = CONFIG_EEPROM_SIZE; + data->blocks[max6875_register_config].base = 0; + data->blocks[max6875_register_config].data = &data->data[USER_EEPROM_SIZE+CONFIG_EEPROM_SIZE]; + data->blocks[max6875_register_config].updated = &data->last_updated[USER_EEPROM_SLICES+CONFIG_EEPROM_SLICES]; + + /* Init the data */ + memset(data->data, 0xff, sizeof(data->data)); + + /* Fill in the remaining client fields */ + strlcpy(new_client->name, "max6875", I2C_NAME_SIZE); + init_MUTEX(&data->update_lock); + + /* Verify that the chip is really what we think it is */ + if ((max6875_update_slice(new_client, &data->blocks[max6875_eeprom_config], 4) < 0) || + (max6875_update_slice(new_client, &data->blocks[max6875_register_config], 4) < 0)) + goto exit_kfree; + + /* 0x41,0x42 must be zero and 0x40 must match in eeprom and registers */ + if ((data->blocks[max6875_eeprom_config].data[0x41] != 0) || + (data->blocks[max6875_eeprom_config].data[0x42] != 0) || + (data->blocks[max6875_register_config].data[0x41] != 0) || + (data->blocks[max6875_register_config].data[0x42] != 0) || + (data->blocks[max6875_eeprom_config].data[0x40] != + data->blocks[max6875_register_config].data[0x40])) + goto exit_kfree; + + /* Tell the I2C layer a new client has arrived */ + if ((err = i2c_attach_client(new_client))) + goto exit_kfree; + + /* create the sysfs eeprom files with the correct permissions */ + if (allow_write == 0) { + user_eeprom_attr.attr.mode &= ~S_IWUGO; + user_eeprom_attr.write = NULL; + config_eeprom_attr.attr.mode &= ~S_IWUGO; + config_eeprom_attr.write = NULL; + config_register_attr.attr.mode &= ~S_IWUGO; + config_register_attr.write = NULL; + } + sysfs_create_bin_file(&new_client->dev.kobj, &user_eeprom_attr); + sysfs_create_bin_file(&new_client->dev.kobj, &config_eeprom_attr); + sysfs_create_bin_file(&new_client->dev.kobj, &config_register_attr); + + return 0; + +exit_kfree: + kfree(data); +exit: + return err; +} + +static int max6875_detach_client(struct i2c_client *client) +{ + int err; + + err = i2c_detach_client(client); + if (err) { + dev_err(&client->dev, "Client deregistration failed, client not detached.\n"); + return err; + } + + kfree(i2c_get_clientdata(client)); + + return 0; +} + +static int __init max6875_init(void) +{ + return i2c_add_driver(&max6875_driver); +} + +static void __exit max6875_exit(void) +{ + i2c_del_driver(&max6875_driver); +} + + +MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); +MODULE_DESCRIPTION("MAX6875 driver"); +MODULE_LICENSE("GPL"); + +module_init(max6875_init); +module_exit(max6875_exit); |
