i2c: slave-eeprom: add eeprom simulator driver
The first user of the i2c-slave interface is an eeprom simulator. It is a shared memory which can be accessed by the remote master via I2C and locally via sysfs. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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@ -110,6 +110,16 @@ config I2C_STUB
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If you don't know what to do here, definitely say N.
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config I2C_SLAVE
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bool "I2C slave support"
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if I2C_SLAVE
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config I2C_SLAVE_EEPROM
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tristate "I2C eeprom slave driver"
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endif
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config I2C_DEBUG_CORE
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bool "I2C Core debugging messages"
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help
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@ -9,6 +9,7 @@ obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
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obj-$(CONFIG_I2C_MUX) += i2c-mux.o
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obj-y += algos/ busses/ muxes/
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obj-$(CONFIG_I2C_STUB) += i2c-stub.o
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obj-$(CONFIG_I2C_SLAVE_EEPROM) += i2c-slave-eeprom.o
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ccflags-$(CONFIG_I2C_DEBUG_CORE) := -DDEBUG
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CFLAGS_i2c-core.o := -Wno-deprecated-declarations
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170
drivers/i2c/i2c-slave-eeprom.c
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170
drivers/i2c/i2c-slave-eeprom.c
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@ -0,0 +1,170 @@
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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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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; version 2 of the License.
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*
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* Because most IP blocks can only detect one I2C slave address anyhow, this
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* driver does not support simulating EEPROM types which take more than one
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* address. It is prepared to simulate bigger EEPROMs with an internal 16 bit
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* pointer, yet implementation is deferred until the need actually arises.
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*/
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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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bool first_write;
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spinlock_t buffer_lock;
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u8 buffer_idx;
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u8 buffer[];
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};
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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_REQ_WRITE_END:
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if (eeprom->first_write) {
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eeprom->buffer_idx = *val;
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eeprom->first_write = false;
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} else {
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spin_lock(&eeprom->buffer_lock);
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eeprom->buffer[eeprom->buffer_idx++] = *val;
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spin_unlock(&eeprom->buffer_lock);
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}
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break;
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case I2C_SLAVE_REQ_READ_START:
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spin_lock(&eeprom->buffer_lock);
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*val = eeprom->buffer[eeprom->buffer_idx];
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spin_unlock(&eeprom->buffer_lock);
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break;
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case I2C_SLAVE_REQ_READ_END:
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eeprom->buffer_idx++;
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break;
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case I2C_SLAVE_STOP:
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eeprom->first_write = true;
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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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if (off + count >= attr->size)
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return -EFBIG;
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eeprom = dev_get_drvdata(container_of(kobj, struct device, 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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if (off + count >= attr->size)
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return -EFBIG;
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eeprom = dev_get_drvdata(container_of(kobj, struct device, 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_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 size = 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->first_write = true;
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spin_lock_init(&eeprom->buffer_lock);
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i2c_set_clientdata(client, eeprom);
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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", 2048 / 8 },
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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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.owner = THIS_MODULE,
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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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