220 строки
6.3 KiB
C
220 строки
6.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* I2C slave mode EEPROM simulator
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*
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* Copyright (C) 2014 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
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* Copyright (C) 2014 by Renesas Electronics Corporation
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*
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* Because most slave IP cores can only detect one I2C slave address anyhow,
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* this driver does not support simulating EEPROM types which take more than
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* one address.
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*/
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/*
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* FIXME: What to do if only 8 bits of a 16 bit address are sent?
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* The ST-M24C64 sends only 0xff then. Needs verification with other
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* EEPROMs, though. We currently use the 8 bit as a valid address.
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*/
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#include <linux/bitfield.h>
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#include <linux/firmware.h>
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#include <linux/i2c.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/sysfs.h>
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struct eeprom_data {
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struct bin_attribute bin;
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spinlock_t buffer_lock;
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u16 buffer_idx;
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u16 address_mask;
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u8 num_address_bytes;
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u8 idx_write_cnt;
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bool read_only;
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u8 buffer[];
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};
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#define I2C_SLAVE_BYTELEN GENMASK(15, 0)
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#define I2C_SLAVE_FLAG_ADDR16 BIT(16)
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#define I2C_SLAVE_FLAG_RO BIT(17)
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#define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) | ((_len) - 1))
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static int i2c_slave_eeprom_slave_cb(struct i2c_client *client,
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enum i2c_slave_event event, u8 *val)
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{
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struct eeprom_data *eeprom = i2c_get_clientdata(client);
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switch (event) {
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case I2C_SLAVE_WRITE_RECEIVED:
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if (eeprom->idx_write_cnt < eeprom->num_address_bytes) {
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if (eeprom->idx_write_cnt == 0)
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eeprom->buffer_idx = 0;
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eeprom->buffer_idx = *val | (eeprom->buffer_idx << 8);
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eeprom->idx_write_cnt++;
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} else {
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if (!eeprom->read_only) {
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spin_lock(&eeprom->buffer_lock);
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eeprom->buffer[eeprom->buffer_idx++ & eeprom->address_mask] = *val;
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spin_unlock(&eeprom->buffer_lock);
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}
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}
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break;
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case I2C_SLAVE_READ_PROCESSED:
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/* The previous byte made it to the bus, get next one */
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eeprom->buffer_idx++;
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fallthrough;
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case I2C_SLAVE_READ_REQUESTED:
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spin_lock(&eeprom->buffer_lock);
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*val = eeprom->buffer[eeprom->buffer_idx & eeprom->address_mask];
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spin_unlock(&eeprom->buffer_lock);
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/*
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* Do not increment buffer_idx here, because we don't know if
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* this byte will be actually used. Read Linux I2C slave docs
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* for details.
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*/
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break;
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case I2C_SLAVE_STOP:
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case I2C_SLAVE_WRITE_REQUESTED:
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eeprom->idx_write_cnt = 0;
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break;
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default:
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break;
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}
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return 0;
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}
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static ssize_t i2c_slave_eeprom_bin_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr, char *buf, loff_t off, size_t count)
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{
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struct eeprom_data *eeprom;
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unsigned long flags;
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eeprom = dev_get_drvdata(kobj_to_dev(kobj));
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spin_lock_irqsave(&eeprom->buffer_lock, flags);
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memcpy(buf, &eeprom->buffer[off], count);
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spin_unlock_irqrestore(&eeprom->buffer_lock, flags);
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return count;
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}
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static ssize_t i2c_slave_eeprom_bin_write(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr, char *buf, loff_t off, size_t count)
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{
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struct eeprom_data *eeprom;
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unsigned long flags;
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eeprom = dev_get_drvdata(kobj_to_dev(kobj));
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spin_lock_irqsave(&eeprom->buffer_lock, flags);
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memcpy(&eeprom->buffer[off], buf, count);
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spin_unlock_irqrestore(&eeprom->buffer_lock, flags);
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return count;
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}
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static int i2c_slave_init_eeprom_data(struct eeprom_data *eeprom, struct i2c_client *client,
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unsigned int size)
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{
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const struct firmware *fw;
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const char *eeprom_data;
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int ret = device_property_read_string(&client->dev, "firmware-name", &eeprom_data);
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if (!ret) {
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ret = request_firmware_into_buf(&fw, eeprom_data, &client->dev,
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eeprom->buffer, size);
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if (ret)
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return ret;
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release_firmware(fw);
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} else {
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/* An empty eeprom typically has all bits set to 1 */
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memset(eeprom->buffer, 0xff, size);
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}
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return 0;
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}
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static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_device_id *id)
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{
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struct eeprom_data *eeprom;
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int ret;
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unsigned int size = FIELD_GET(I2C_SLAVE_BYTELEN, id->driver_data) + 1;
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unsigned int flag_addr16 = FIELD_GET(I2C_SLAVE_FLAG_ADDR16, id->driver_data);
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eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
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if (!eeprom)
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return -ENOMEM;
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eeprom->num_address_bytes = flag_addr16 ? 2 : 1;
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eeprom->address_mask = size - 1;
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eeprom->read_only = FIELD_GET(I2C_SLAVE_FLAG_RO, id->driver_data);
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spin_lock_init(&eeprom->buffer_lock);
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i2c_set_clientdata(client, eeprom);
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ret = i2c_slave_init_eeprom_data(eeprom, client, size);
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if (ret)
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return ret;
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sysfs_bin_attr_init(&eeprom->bin);
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eeprom->bin.attr.name = "slave-eeprom";
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eeprom->bin.attr.mode = S_IRUSR | S_IWUSR;
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eeprom->bin.read = i2c_slave_eeprom_bin_read;
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eeprom->bin.write = i2c_slave_eeprom_bin_write;
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eeprom->bin.size = size;
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ret = sysfs_create_bin_file(&client->dev.kobj, &eeprom->bin);
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if (ret)
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return ret;
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ret = i2c_slave_register(client, i2c_slave_eeprom_slave_cb);
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if (ret) {
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sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
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return ret;
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}
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return 0;
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};
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static int i2c_slave_eeprom_remove(struct i2c_client *client)
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{
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struct eeprom_data *eeprom = i2c_get_clientdata(client);
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i2c_slave_unregister(client);
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sysfs_remove_bin_file(&client->dev.kobj, &eeprom->bin);
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return 0;
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}
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static const struct i2c_device_id i2c_slave_eeprom_id[] = {
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{ "slave-24c02", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, 0) },
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{ "slave-24c02ro", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, I2C_SLAVE_FLAG_RO) },
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{ "slave-24c32", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16) },
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{ "slave-24c32ro", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
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{ "slave-24c64", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16) },
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{ "slave-24c64ro", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
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{ "slave-24c512", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16) },
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{ "slave-24c512ro", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);
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static struct i2c_driver i2c_slave_eeprom_driver = {
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.driver = {
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.name = "i2c-slave-eeprom",
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},
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.probe = i2c_slave_eeprom_probe,
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.remove = i2c_slave_eeprom_remove,
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.id_table = i2c_slave_eeprom_id,
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};
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module_i2c_driver(i2c_slave_eeprom_driver);
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MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
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MODULE_DESCRIPTION("I2C slave mode EEPROM simulator");
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MODULE_LICENSE("GPL v2");
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