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-rw-r--r--drivers/i2c/i2c-slave-eeprom.c217
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-slave-eeprom.c b/drivers/i2c/i2c-slave-eeprom.c
new file mode 100644
index 000000000..4abc2d919
--- /dev/null
+++ b/drivers/i2c/i2c-slave-eeprom.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * I2C slave mode EEPROM simulator
+ *
+ * Copyright (C) 2014 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
+ * Copyright (C) 2014 by Renesas Electronics Corporation
+ *
+ * Because most slave IP cores can only detect one I2C slave address anyhow,
+ * this driver does not support simulating EEPROM types which take more than
+ * one address.
+ */
+
+/*
+ * FIXME: What to do if only 8 bits of a 16 bit address are sent?
+ * The ST-M24C64 sends only 0xff then. Needs verification with other
+ * EEPROMs, though. We currently use the 8 bit as a valid address.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/firmware.h>
+#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;
+ spinlock_t buffer_lock;
+ u16 buffer_idx;
+ u16 address_mask;
+ u8 num_address_bytes;
+ u8 idx_write_cnt;
+ bool read_only;
+ u8 buffer[];
+};
+
+#define I2C_SLAVE_BYTELEN GENMASK(15, 0)
+#define I2C_SLAVE_FLAG_ADDR16 BIT(16)
+#define I2C_SLAVE_FLAG_RO BIT(17)
+#define I2C_SLAVE_DEVICE_MAGIC(_len, _flags) ((_flags) | ((_len) - 1))
+
+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->idx_write_cnt < eeprom->num_address_bytes) {
+ if (eeprom->idx_write_cnt == 0)
+ eeprom->buffer_idx = 0;
+ eeprom->buffer_idx = *val | (eeprom->buffer_idx << 8);
+ eeprom->idx_write_cnt++;
+ } else {
+ if (!eeprom->read_only) {
+ spin_lock(&eeprom->buffer_lock);
+ eeprom->buffer[eeprom->buffer_idx++ & eeprom->address_mask] = *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 & eeprom->address_mask];
+ 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->idx_write_cnt = 0;
+ 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(kobj_to_dev(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(kobj_to_dev(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_init_eeprom_data(struct eeprom_data *eeprom, struct i2c_client *client,
+ unsigned int size)
+{
+ const struct firmware *fw;
+ const char *eeprom_data;
+ int ret = device_property_read_string(&client->dev, "firmware-name", &eeprom_data);
+
+ if (!ret) {
+ ret = request_firmware_into_buf(&fw, eeprom_data, &client->dev,
+ eeprom->buffer, size);
+ if (ret)
+ return ret;
+ release_firmware(fw);
+ } else {
+ /* An empty eeprom typically has all bits set to 1 */
+ memset(eeprom->buffer, 0xff, size);
+ }
+ return 0;
+}
+
+static int i2c_slave_eeprom_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+ struct eeprom_data *eeprom;
+ int ret;
+ unsigned int size = FIELD_GET(I2C_SLAVE_BYTELEN, id->driver_data) + 1;
+ unsigned int flag_addr16 = FIELD_GET(I2C_SLAVE_FLAG_ADDR16, id->driver_data);
+
+ eeprom = devm_kzalloc(&client->dev, sizeof(struct eeprom_data) + size, GFP_KERNEL);
+ if (!eeprom)
+ return -ENOMEM;
+
+ eeprom->num_address_bytes = flag_addr16 ? 2 : 1;
+ eeprom->address_mask = size - 1;
+ eeprom->read_only = FIELD_GET(I2C_SLAVE_FLAG_RO, id->driver_data);
+ spin_lock_init(&eeprom->buffer_lock);
+ i2c_set_clientdata(client, eeprom);
+
+ ret = i2c_slave_init_eeprom_data(eeprom, client, size);
+ if (ret)
+ return ret;
+
+ 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 void 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);
+}
+
+static const struct i2c_device_id i2c_slave_eeprom_id[] = {
+ { "slave-24c02", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, 0) },
+ { "slave-24c02ro", I2C_SLAVE_DEVICE_MAGIC(2048 / 8, I2C_SLAVE_FLAG_RO) },
+ { "slave-24c32", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16) },
+ { "slave-24c32ro", I2C_SLAVE_DEVICE_MAGIC(32768 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
+ { "slave-24c64", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16) },
+ { "slave-24c64ro", I2C_SLAVE_DEVICE_MAGIC(65536 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
+ { "slave-24c512", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16) },
+ { "slave-24c512ro", I2C_SLAVE_DEVICE_MAGIC(524288 / 8, I2C_SLAVE_FLAG_ADDR16 | I2C_SLAVE_FLAG_RO) },
+ { }
+};
+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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 18:49:12 +0000