[RFC 2/4] i2c: slave: add eeprom simulator driver

Wolfram Sang
2014-09-09T14:59:17Z

From: Wolfram Sang <wsa+renesas@sang-engineering.com>

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
drivers/i2c/Kconfig | 10 +++
drivers/i2c/Makefile | 1 +
drivers/i2c/i2c-slave-eeprom.c | 152 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 163 insertions(+)
create mode 100644 drivers/i2c/i2c-slave-eeprom.c

diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index b51a402752c4..f7800104b2ff 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -110,6 +110,16 @@ config I2C_STUB

If you don't know what to do here, definitely say N.

+config I2C_SLAVE
+ bool "I2C slave support"
+
+if I2C_SLAVE
+
+config I2C_SLAVE_EEPROM
+ bool "I2C eeprom slave driver"
+
+endif
+
config I2C_DEBUG_CORE
bool "I2C Core debugging messages"
help
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index e0228b228256..d78f81caad8a 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
obj-$(CONFIG_I2C_MUX) += i2c-mux.o
obj-y += algos/ busses/ muxes/
obj-$(CONFIG_I2C_STUB) += i2c-stub.o
+obj-$(CONFIG_I2C_SLAVE_EEPROM) += i2c-slave-eeprom.o

ccflags-$(CONFIG_I2C_DEBUG_CORE) := -DDEBUG
CFLAGS_i2c-core.o := -Wno-deprecated-declarations
diff --git a/drivers/i2c/i2c-slave-eeprom.c b/drivers/i2c/i2c-slave-eeprom.c
new file mode 100644
index 000000000000..e512a40a3c36
--- /dev/null
+++ b/drivers/i2c/i2c-slave-eeprom.c
@@ -0,0 +1,152 @@
+/*
+ * I2C Slave mode EEPROM simulator
+ *
+ * Copyright (C) 2014 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
+ * Copyright (C) 2014 by Renesas Solutions Corp.
+ *
+ * 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/i2c.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+
+//TODO: simulate 24c32 as well
+#define EEPROM_SIZE 256
+
+struct at24s_data {
+ //TODO: use lock
+ struct mutex lock;
+ struct bin_attribute bin;
+ u8 buffer[EEPROM_SIZE];
+ u8 eeprom_ptr;
+ bool first_write;
+};
+
+static int at24s_slave_cb(struct i2c_client *client, enum i2c_slave_event event, u8 *val)
+{
+ struct at24s_data *at24s = i2c_get_clientdata(client);
+
+ switch (event) {
+ case I2C_SLAVE_REQ_WRITE_END:
+ if (at24s->first_write) {
+ at24s->eeprom_ptr = *val;
+ at24s->first_write = false;
+ } else {
+ at24s->buffer[at24s->eeprom_ptr++] = *val;
+ }
+ break;
+
+ case I2C_SLAVE_REQ_READ_START:
+ *val = at24s->buffer[at24s->eeprom_ptr];
+ break;
+
+ case I2C_SLAVE_REQ_READ_END:
+ at24s->eeprom_ptr++;
+ break;
+
+ case I2C_SLAVE_STOP:
+ at24s->first_write = true;
+ break;
+
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+static ssize_t at24s_bin_read(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *attr, char *buf, loff_t off, size_t count)
+{
+ struct at24s_data *at24s;
+
+ at24s = dev_get_drvdata(container_of(kobj, struct device, kobj));
+
+ //TODO: boundary checks
+ memcpy(buf, &at24s->buffer[off], count);
+
+ return count;
+}
+
+static ssize_t at24s_bin_write(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *attr, char *buf, loff_t off, size_t count)
+{
+ struct at24s_data *at24s;
+
+ if (unlikely(off >= attr->size))
+ return -EFBIG;
+
+ at24s = dev_get_drvdata(container_of(kobj, struct device, kobj));
+
+ //TODO: boundary checks
+ memcpy(&at24s->buffer[off], buf, count);
+
+ return count;
+}
+
+static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+ struct at24s_data *at24s;
+ int ret;
+
+ at24s = devm_kzalloc(&client->dev, sizeof(struct at24s_data), GFP_KERNEL);
+ if (!at24s)
+ return -ENOMEM;
+
+ at24s->first_write = true;
+ i2c_set_clientdata(client, at24s);
+
+ ret = i2c_slave_register(client, at24s_slave_cb);
+ if (ret)
+ return ret;
+
+ sysfs_bin_attr_init(&at24s->bin);
+ at24s->bin.attr.name = "slave-eeprom";
+ at24s->bin.attr.mode = S_IRUSR | S_IWUSR;
+ at24s->bin.read = at24s_bin_read;
+ at24s->bin.write = at24s_bin_write;
+ at24s->bin.size = EEPROM_SIZE;
+
+ ret = sysfs_create_bin_file(&client->dev.kobj, &at24s->bin);
+ if (ret)
+ return ret;
+
+ return 0;
+};
+
+static int i2c_slave_eeprom_remove(struct i2c_client *client)
+{
+ struct at24s_data *at24s;
+
+ at24s = i2c_get_clientdata(client);
+ sysfs_remove_bin_file(&client->dev.kobj, &at24s->bin);
+
+ return i2c_slave_unregister(client);
+}
+
+static const struct i2c_device_id i2c_slave_eeprom_id[] = {
+ { "slave-24c02", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, i2c_slave_eeprom_id);
+
+static struct i2c_driver i2c_slave_eeprom_driver = {
+ .driver = {
+ .name = "i2c-slave-eeprom",
+ .owner = THIS_MODULE,
+ },
+ .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");
--
2.0.0