1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright (C) IBM Corporation 2023 */
  3
  4#include <linux/cdev.h>
  5#include <linux/device.h>
  6#include <linux/fs.h>
  7#include <linux/fsi.h>
  8#include <linux/module.h>
  9#include <linux/mod_devicetable.h>
 10
 11#include "fsi-master-i2cr.h"
 12#include "fsi-slave.h"
 13
 14struct i2cr_scom {
 15	struct device dev;
 16	struct cdev cdev;
 17	struct fsi_master_i2cr *i2cr;
 18};
 19
 20static loff_t i2cr_scom_llseek(struct file *file, loff_t offset, int whence)
 21{
 22	switch (whence) {
 23	case SEEK_CUR:
 24		break;
 25	case SEEK_SET:
 26		file->f_pos = offset;
 27		break;
 28	default:
 29		return -EINVAL;
 30	}
 31
 32	return offset;
 33}
 34
 35static ssize_t i2cr_scom_read(struct file *filep, char __user *buf, size_t len, loff_t *offset)
 36{
 37	struct i2cr_scom *scom = filep->private_data;
 38	u64 data;
 39	int ret;
 40
 41	if (len != sizeof(data))
 42		return -EINVAL;
 43
 44	ret = fsi_master_i2cr_read(scom->i2cr, (u32)*offset, &data);
 45	if (ret)
 46		return ret;
 47
 48	ret = copy_to_user(buf, &data, len);
 49	if (ret)
 50		return ret;
 51
 52	return len;
 53}
 54
 55static ssize_t i2cr_scom_write(struct file *filep, const char __user *buf, size_t len,
 56			       loff_t *offset)
 57{
 58	struct i2cr_scom *scom = filep->private_data;
 59	u64 data;
 60	int ret;
 61
 62	if (len != sizeof(data))
 63		return -EINVAL;
 64
 65	ret = copy_from_user(&data, buf, len);
 66	if (ret)
 67		return ret;
 68
 69	ret = fsi_master_i2cr_write(scom->i2cr, (u32)*offset, data);
 70	if (ret)
 71		return ret;
 72
 73	return len;
 74}
 75
 76static const struct file_operations i2cr_scom_fops = {
 77	.owner		= THIS_MODULE,
 78	.open		= simple_open,
 79	.llseek		= i2cr_scom_llseek,
 80	.read		= i2cr_scom_read,
 81	.write		= i2cr_scom_write,
 82};
 83
 84static int i2cr_scom_probe(struct device *dev)
 85{
 86	struct fsi_device *fsi_dev = to_fsi_dev(dev);
 87	struct i2cr_scom *scom;
 88	int didx;
 89	int ret;
 90
 91	if (!is_fsi_master_i2cr(fsi_dev->slave->master))
 92		return -ENODEV;
 93
 94	scom = devm_kzalloc(dev, sizeof(*scom), GFP_KERNEL);
 95	if (!scom)
 96		return -ENOMEM;
 97
 98	scom->i2cr = to_fsi_master_i2cr(fsi_dev->slave->master);
 99	dev_set_drvdata(dev, scom);
100
101	scom->dev.type = &fsi_cdev_type;
102	scom->dev.parent = dev;
103	device_initialize(&scom->dev);
104
105	ret = fsi_get_new_minor(fsi_dev, fsi_dev_scom, &scom->dev.devt, &didx);
106	if (ret)
107		return ret;
108
109	dev_set_name(&scom->dev, "scom%d", didx);
110	cdev_init(&scom->cdev, &i2cr_scom_fops);
111	ret = cdev_device_add(&scom->cdev, &scom->dev);
112	if (ret)
113		fsi_free_minor(scom->dev.devt);
114
115	return ret;
116}
117
118static int i2cr_scom_remove(struct device *dev)
119{
120	struct i2cr_scom *scom = dev_get_drvdata(dev);
121
122	cdev_device_del(&scom->cdev, &scom->dev);
123	fsi_free_minor(scom->dev.devt);
124
125	return 0;
126}
127
128static const struct of_device_id i2cr_scom_of_ids[] = {
129	{ .compatible = "ibm,i2cr-scom" },
130	{ }
131};
132MODULE_DEVICE_TABLE(of, i2cr_scom_of_ids);
133
134static const struct fsi_device_id i2cr_scom_ids[] = {
135	{ 0x5, FSI_VERSION_ANY },
136	{ }
137};
138
139static struct fsi_driver i2cr_scom_driver = {
140	.id_table = i2cr_scom_ids,
141	.drv = {
142		.name = "i2cr_scom",
143		.bus = &fsi_bus_type,
144		.of_match_table = i2cr_scom_of_ids,
145		.probe = i2cr_scom_probe,
146		.remove = i2cr_scom_remove,
147	}
148};
149
150module_fsi_driver(i2cr_scom_driver);
151
152MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
153MODULE_DESCRIPTION("IBM I2C Responder SCOM driver");
154MODULE_LICENSE("GPL");