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/*
* Copyright (C) 2018 Toradex AG
*
* 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; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* Simulated I2C adapter which provides EDID data out of the device tree.
*/
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
/* This will be the driver name the kernel reports */
#define DRIVER_NAME "i2c-sw-edid"
struct i2c_sw_edid_struct {
struct i2c_adapter adapter;
unsigned char edid_data[512];
};
static const struct of_device_id i2c_sw_edid_dt_ids[] = {
{ .compatible = "sw-edid", .data = 0, },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, i2c_sw_edid_dt_ids);
static int i2c_sw_edid_xfer(struct i2c_adapter *adapter,
struct i2c_msg *msgs, int num)
{
static int data_ptr = 0;
unsigned int i;
int result = -EINVAL;
struct i2c_sw_edid_struct *i2c_sw_edid = i2c_get_adapdata(adapter);
dev_dbg(&i2c_sw_edid->adapter.dev, "<%s>\n", __func__);
/* read/write data */
for (i = 0; i < num; i++) {
result = 0;
/* we only simulate I2C device 0x50 */
if(msgs[i].addr != 0x50) {
result = -ENXIO;
goto out;
} else if (msgs[i].flags & I2C_M_RD) {
if ((data_ptr + msgs[i].len) >
sizeof(i2c_sw_edid->edid_data)) {
result = -EINVAL;
goto out;
}
memcpy(msgs[i].buf, &(i2c_sw_edid->edid_data[data_ptr]),
msgs[i].len);
data_ptr += msgs[i].len;
} else {
if (msgs[i].len == 1)
data_ptr = msgs[i].buf[0];
}
}
out:
dev_dbg(&i2c_sw_edid->adapter.dev, "<%s> exit with: %s: %d\n", __func__,
(result < 0) ? "error" : "success msg",
(result < 0) ? result : num);
return (result < 0) ? result : num;
}
static u32 i2c_sw_edid_func(struct i2c_adapter *adapter)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
}
static struct i2c_algorithm i2c_sw_edid_algo = {
.master_xfer = i2c_sw_edid_xfer,
.functionality = i2c_sw_edid_func,
};
static int i2c_sw_edid_probe(struct platform_device *pdev)
{
struct i2c_sw_edid_struct *i2c_sw_edid;
int lenp, ret;
dev_dbg(&pdev->dev, "<%s>\n", __func__);
i2c_sw_edid = devm_kzalloc(&pdev->dev, sizeof(*i2c_sw_edid),
GFP_KERNEL);
if (!i2c_sw_edid)
return -ENOMEM;
/* Setup i2c_sw_edid driver structure */
strlcpy(i2c_sw_edid->adapter.name, pdev->name,
sizeof(i2c_sw_edid->adapter.name));
i2c_sw_edid->adapter.owner = THIS_MODULE;
i2c_sw_edid->adapter.algo = &i2c_sw_edid_algo;
i2c_sw_edid->adapter.dev.parent = &pdev->dev;
i2c_sw_edid->adapter.nr = pdev->id;
i2c_sw_edid->adapter.dev.of_node = pdev->dev.of_node;
/* Get EDID data */
(void) of_find_property(pdev->dev.of_node,"edid-data", &lenp);
lenp = min(lenp, (int)sizeof(i2c_sw_edid->edid_data));
of_property_read_u8_array(pdev->dev.of_node, "edid-data",
&i2c_sw_edid->edid_data[0], lenp);
/* Set up adapter data */
i2c_set_adapdata(&i2c_sw_edid->adapter, i2c_sw_edid);
/* Set up platform driver data */
platform_set_drvdata(pdev, i2c_sw_edid);
/* Add I2C adapter */
ret = i2c_add_numbered_adapter(&i2c_sw_edid->adapter);
if (ret < 0)
return ret;
dev_info(&i2c_sw_edid->adapter.dev, "SW EDID I2C adapter registered\n");
return 0; /* Return OK */
}
static int i2c_sw_edid_remove(struct platform_device *pdev)
{
struct i2c_sw_edid_struct *i2c_sw_edid = platform_get_drvdata(pdev);
/* remove adapter */
dev_dbg(&i2c_sw_edid->adapter.dev, "adapter removed\n");
i2c_del_adapter(&i2c_sw_edid->adapter);
return 0;
}
static struct platform_driver i2c_sw_edid_driver = {
.probe = i2c_sw_edid_probe,
.remove = i2c_sw_edid_remove,
.driver = {
.name = DRIVER_NAME,
.of_match_table = i2c_sw_edid_dt_ids,
},
};
static int __init i2c_adap_sw_edid_init(void)
{
return platform_driver_register(&i2c_sw_edid_driver);
}
subsys_initcall(i2c_adap_sw_edid_init);
static void __exit i2c_adap_sw_edid_exit(void)
{
platform_driver_unregister(&i2c_sw_edid_driver);
}
module_exit(i2c_adap_sw_edid_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Max Krummenacher");
MODULE_DESCRIPTION("Simulated I2C adapter serving EDID data from the device tree");
MODULE_ALIAS("platform:" DRIVER_NAME);
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