drivers/fsi/i2cr-scom.c

   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
  14 struct i2cr_scom {
  15         struct device dev;
  16         struct cdev cdev;
  17         struct fsi_master_i2cr *i2cr;
  18 };
  19
  20 static 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
  35 static 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
  55 static 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
  76 static 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
  84 static 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
 118 static 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
 128 static const struct of_device_id i2cr_scom_of_ids[] = {
 129         { .compatible = "ibm,i2cr-scom" },
 130         { }
 131 };
 132 MODULE_DEVICE_TABLE(of, i2cr_scom_of_ids);
 133
 134 static const struct fsi_device_id i2cr_scom_ids[] = {
 135         { 0x5, FSI_VERSION_ANY },
 136         { }
 137 };
 138
 139 static 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
 150 module_fsi_driver(i2cr_scom_driver);
 151
 152 MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
 153 MODULE_DESCRIPTION("IBM I2C Responder SCOM driver");
 154 MODULE_LICENSE("GPL");