Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / i2c / i2c-slave-eeprom.c

diff --git a/kernel/drivers/i2c/i2c-slave-eeprom.c b/kernel/drivers/i2c/i2c-slave-eeprom.c
new file mode 100644 (file)
index 0000000..8223746
--- /dev/null
+++ b/kernel/drivers/i2c/i2c-slave-eeprom.c
@@ -0,0 +1,176 @@
+/*
+ * 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;
+
+       if (off + count > attr->size)
+               return -EFBIG;
+
+       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;
+
+       if (off + count > attr->size)
+               return -EFBIG;
+
+       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",
+               .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");