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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 | /* * I2C slave mode EEPROM simulator * * Copyright (C) 2014 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com> * Copyright (C) 2014 by Renesas Electronics Corporation * * 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. * * Because most IP blocks can only detect one I2C slave address anyhow, this * driver does not support simulating EEPROM types which take more than one * address. It is prepared to simulate bigger EEPROMs with an internal 16 bit * pointer, yet implementation is deferred until the need actually arises. */ #include <linux/i2c.h> #include <linux/init.h> #include <linux/module.h> #include <linux/of.h> #include <linux/slab.h> #include <linux/spinlock.h> #include <linux/sysfs.h> struct eeprom_data { struct bin_attribute bin; bool first_write; spinlock_t buffer_lock; u8 buffer_idx; u8 buffer[]; }; static int i2c_slave_eeprom_slave_cb(struct i2c_client *client, enum i2c_slave_event event, u8 *val) { struct eeprom_data *eeprom = i2c_get_clientdata(client); switch (event) { case I2C_SLAVE_WRITE_RECEIVED: if (eeprom->first_write) { eeprom->buffer_idx = *val; eeprom->first_write = false; } else { spin_lock(&eeprom->buffer_lock); eeprom->buffer[eeprom->buffer_idx++] = *val; spin_unlock(&eeprom->buffer_lock); } break; case I2C_SLAVE_READ_PROCESSED: /* The previous byte made it to the bus, get next one */ eeprom->buffer_idx++; /* fallthrough */ case I2C_SLAVE_READ_REQUESTED: spin_lock(&eeprom->buffer_lock); *val = eeprom->buffer[eeprom->buffer_idx]; spin_unlock(&eeprom->buffer_lock); /* * Do not increment buffer_idx here, because we don't know if * this byte will be actually used. Read Linux I2C slave docs * for details. */ break; case I2C_SLAVE_STOP: case I2C_SLAVE_WRITE_REQUESTED: eeprom->first_write = true; break; default: break; } return 0; } static ssize_t i2c_slave_eeprom_bin_read(struct file *filp, struct kobject *kobj, struct bin_attribute *attr, char *buf, loff_t off, size_t count) { struct eeprom_data *eeprom; unsigned long flags; eeprom = dev_get_drvdata(container_of(kobj, struct device, kobj)); spin_lock_irqsave(&eeprom->buffer_lock, flags); memcpy(buf, &eeprom->buffer[off], count); spin_unlock_irqrestore(&eeprom->buffer_lock, flags); return count; } static ssize_t i2c_slave_eeprom_bin_write(struct file *filp, struct kobject *kobj, struct bin_attribute *attr, char *buf, loff_t off, size_t count) { struct eeprom_data *eeprom; unsigned long flags; eeprom = dev_get_drvdata(container_of(kobj, struct device, kobj)); spin_lock_irqsave(&eeprom->buffer_lock, flags); memcpy(&eeprom->buffer[off], buf, count); spin_unlock_irqrestore(&eeprom->buffer_lock, flags); return count; } static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct eeprom_data *eeprom; int ret; unsigned size = id->driver_data; eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL); if (!eeprom) return -ENOMEM; eeprom->first_write = true; spin_lock_init(&eeprom->buffer_lock); i2c_set_clientdata(client, eeprom); sysfs_bin_attr_init(&eeprom->bin); eeprom->bin.attr.name = "slave-eeprom"; eeprom->bin.attr.mode = S_IRUSR | S_IWUSR; eeprom->bin.read = i2c_slave_eeprom_bin_read; eeprom->bin.write = i2c_slave_eeprom_bin_write; eeprom->bin.size = size; ret = sysfs_create_bin_file(&client->dev.kobj, &eeprom->bin); if (ret) return ret; ret = i2c_slave_register(client, i2c_slave_eeprom_slave_cb); if (ret) { sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin); return ret; } return 0; }; static int i2c_slave_eeprom_remove(struct i2c_client *client) { struct eeprom_data *eeprom = i2c_get_clientdata(client); i2c_slave_unregister(client); sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin); return 0; } static const struct i2c_device_id i2c_slave_eeprom_id[] = { { "slave-24c02", 2048 / 8 }, { } }; MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id); static struct i2c_driver i2c_slave_eeprom_driver = { .driver = { .name = "i2c-slave-eeprom", }, .probe = i2c_slave_eeprom_probe, .remove = i2c_slave_eeprom_remove, .id_table = i2c_slave_eeprom_id, }; module_i2c_driver(i2c_slave_eeprom_driver); MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>"); MODULE_DESCRIPTION("I2C slave mode EEPROM simulator"); MODULE_LICENSE("GPL v2"); |