drivers/char/ipmi/ipmb_dev_int.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 /*
   4  * IPMB driver to receive a request and send a response
   5  *
   6  * Copyright (C) 2019 Mellanox Techologies, Ltd.
   7  *
   8  * This was inspired by Brendan Higgins' ipmi-bmc-bt-i2c driver.
   9  */
  10
  11 #include <linux/acpi.h>
  12 #include <linux/errno.h>
  13 #include <linux/i2c.h>
  14 #include <linux/miscdevice.h>
  15 #include <linux/module.h>
  16 #include <linux/mutex.h>
  17 #include <linux/poll.h>
  18 #include <linux/slab.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/wait.h>
  21
  22 #define MAX_MSG_LEN             240
  23 #define IPMB_REQUEST_LEN_MIN    7
  24 #define NETFN_RSP_BIT_MASK      0x4
  25 #define REQUEST_QUEUE_MAX_LEN   256
  26
  27 #define IPMB_MSG_LEN_IDX        0
  28 #define RQ_SA_8BIT_IDX          1
  29 #define NETFN_LUN_IDX           2
  30
  31 #define GET_7BIT_ADDR(addr_8bit)        (addr_8bit >> 1)
  32 #define GET_8BIT_ADDR(addr_7bit)        ((addr_7bit << 1) & 0xff)
  33
  34 #define IPMB_MSG_PAYLOAD_LEN_MAX (MAX_MSG_LEN - IPMB_REQUEST_LEN_MIN - 1)
  35
  36 #define SMBUS_MSG_HEADER_LENGTH 2
  37 #define SMBUS_MSG_IDX_OFFSET    (SMBUS_MSG_HEADER_LENGTH + 1)
  38
  39 struct ipmb_msg {
  40         u8 len;
  41         u8 rs_sa;
  42         u8 netfn_rs_lun;
  43         u8 checksum1;
  44         u8 rq_sa;
  45         u8 rq_seq_rq_lun;
  46         u8 cmd;
  47         u8 payload[IPMB_MSG_PAYLOAD_LEN_MAX];
  48         /* checksum2 is included in payload */
  49 } __packed;
  50
  51 struct ipmb_request_elem {
  52         struct list_head list;
  53         struct ipmb_msg request;
  54 };
  55
  56 struct ipmb_dev {
  57         struct i2c_client *client;
  58         struct miscdevice miscdev;
  59         struct ipmb_msg request;
  60         struct list_head request_queue;
  61         atomic_t request_queue_len;
  62         size_t msg_idx;
  63         spinlock_t lock;
  64         wait_queue_head_t wait_queue;
  65         struct mutex file_mutex;
  66         bool is_i2c_protocol;
  67 };
  68
  69 static inline struct ipmb_dev *to_ipmb_dev(struct file *file)
  70 {
  71         return container_of(file->private_data, struct ipmb_dev, miscdev);
  72 }
  73
  74 static ssize_t ipmb_read(struct file *file, char __user *buf, size_t count,
  75                         loff_t *ppos)
  76 {
  77         struct ipmb_dev *ipmb_dev = to_ipmb_dev(file);
  78         struct ipmb_request_elem *queue_elem;
  79         struct ipmb_msg msg;
  80         ssize_t ret = 0;
  81
  82         memset(&msg, 0, sizeof(msg));
  83
  84         spin_lock_irq(&ipmb_dev->lock);
  85
  86         while (list_empty(&ipmb_dev->request_queue)) {
  87                 spin_unlock_irq(&ipmb_dev->lock);
  88
  89                 if (file->f_flags & O_NONBLOCK)
  90                         return -EAGAIN;
  91
  92                 ret = wait_event_interruptible(ipmb_dev->wait_queue,
  93                                 !list_empty(&ipmb_dev->request_queue));
  94                 if (ret)
  95                         return ret;
  96
  97                 spin_lock_irq(&ipmb_dev->lock);
  98         }
  99
 100         queue_elem = list_first_entry(&ipmb_dev->request_queue,
 101                                         struct ipmb_request_elem, list);
 102         memcpy(&msg, &queue_elem->request, sizeof(msg));
 103         list_del(&queue_elem->list);
 104         kfree(queue_elem);
 105         atomic_dec(&ipmb_dev->request_queue_len);
 106
 107         spin_unlock_irq(&ipmb_dev->lock);
 108
 109         count = min_t(size_t, count, msg.len + 1);
 110         if (copy_to_user(buf, &msg, count))
 111                 ret = -EFAULT;
 112
 113         return ret < 0 ? ret : count;
 114 }
 115
 116 static int ipmb_i2c_write(struct i2c_client *client, u8 *msg, u8 addr)
 117 {
 118         struct i2c_msg i2c_msg;
 119
 120         /*
 121          * subtract 1 byte (rq_sa) from the length of the msg passed to
 122          * raw i2c_transfer
 123          */
 124         i2c_msg.len = msg[IPMB_MSG_LEN_IDX] - 1;
 125
 126         /* Assign message to buffer except first 2 bytes (length and address) */
 127         i2c_msg.buf = msg + 2;
 128
 129         i2c_msg.addr = addr;
 130         i2c_msg.flags = client->flags & I2C_CLIENT_PEC;
 131
 132         return i2c_transfer(client->adapter, &i2c_msg, 1);
 133 }
 134
 135 static ssize_t ipmb_write(struct file *file, const char __user *buf,
 136                         size_t count, loff_t *ppos)
 137 {
 138         struct ipmb_dev *ipmb_dev = to_ipmb_dev(file);
 139         u8 rq_sa, netf_rq_lun, msg_len;
 140         struct i2c_client *temp_client;
 141         u8 msg[MAX_MSG_LEN];
 142         ssize_t ret;
 143
 144         if (count > sizeof(msg))
 145                 return -EINVAL;
 146
 147         if (copy_from_user(&msg, buf, count))
 148                 return -EFAULT;
 149
 150         if (count < msg[0])
 151                 return -EINVAL;
 152
 153         rq_sa = GET_7BIT_ADDR(msg[RQ_SA_8BIT_IDX]);
 154         netf_rq_lun = msg[NETFN_LUN_IDX];
 155
 156         /* Check i2c block transfer vs smbus */
 157         if (ipmb_dev->is_i2c_protocol) {
 158                 ret = ipmb_i2c_write(ipmb_dev->client, msg, rq_sa);
 159                 return (ret == 1) ? count : ret;
 160         }
 161
 162         /*
 163          * subtract rq_sa and netf_rq_lun from the length of the msg. Fill the
 164          * temporary client. Note that its use is an exception for IPMI.
 165          */
 166         msg_len = msg[IPMB_MSG_LEN_IDX] - SMBUS_MSG_HEADER_LENGTH;
 167         temp_client = kmemdup(ipmb_dev->client, sizeof(*temp_client), GFP_KERNEL);
 168         if (!temp_client)
 169                 return -ENOMEM;
 170
 171         temp_client->addr = rq_sa;
 172
 173         ret = i2c_smbus_write_block_data(temp_client, netf_rq_lun, msg_len,
 174                                          msg + SMBUS_MSG_IDX_OFFSET);
 175         kfree(temp_client);
 176
 177         return ret < 0 ? ret : count;
 178 }
 179
 180 static __poll_t ipmb_poll(struct file *file, poll_table *wait)
 181 {
 182         struct ipmb_dev *ipmb_dev = to_ipmb_dev(file);
 183         __poll_t mask = EPOLLOUT;
 184
 185         mutex_lock(&ipmb_dev->file_mutex);
 186         poll_wait(file, &ipmb_dev->wait_queue, wait);
 187
 188         if (atomic_read(&ipmb_dev->request_queue_len))
 189                 mask |= EPOLLIN;
 190         mutex_unlock(&ipmb_dev->file_mutex);
 191
 192         return mask;
 193 }
 194
 195 static const struct file_operations ipmb_fops = {
 196         .owner  = THIS_MODULE,
 197         .read   = ipmb_read,
 198         .write  = ipmb_write,
 199         .poll   = ipmb_poll,
 200 };
 201
 202 /* Called with ipmb_dev->lock held. */
 203 static void ipmb_handle_request(struct ipmb_dev *ipmb_dev)
 204 {
 205         struct ipmb_request_elem *queue_elem;
 206
 207         if (atomic_read(&ipmb_dev->request_queue_len) >=
 208                         REQUEST_QUEUE_MAX_LEN)
 209                 return;
 210
 211         queue_elem = kmalloc(sizeof(*queue_elem), GFP_ATOMIC);
 212         if (!queue_elem)
 213                 return;
 214
 215         memcpy(&queue_elem->request, &ipmb_dev->request,
 216                 sizeof(struct ipmb_msg));
 217         list_add(&queue_elem->list, &ipmb_dev->request_queue);
 218         atomic_inc(&ipmb_dev->request_queue_len);
 219         wake_up_all(&ipmb_dev->wait_queue);
 220 }
 221
 222 static u8 ipmb_verify_checksum1(struct ipmb_dev *ipmb_dev, u8 rs_sa)
 223 {
 224         /* The 8 lsb of the sum is 0 when the checksum is valid */
 225         return (rs_sa + ipmb_dev->request.netfn_rs_lun +
 226                 ipmb_dev->request.checksum1);
 227 }
 228
 229 /*
 230  * Verify if message has proper ipmb header with minimum length
 231  * and correct checksum byte.
 232  */
 233 static bool is_ipmb_msg(struct ipmb_dev *ipmb_dev, u8 rs_sa)
 234 {
 235         if ((ipmb_dev->msg_idx >= IPMB_REQUEST_LEN_MIN) &&
 236            (!ipmb_verify_checksum1(ipmb_dev, rs_sa)))
 237                 return true;
 238
 239         return false;
 240 }
 241
 242 /*
 243  * The IPMB protocol only supports I2C Writes so there is no need
 244  * to support I2C_SLAVE_READ* events.
 245  * This i2c callback function only monitors IPMB request messages
 246  * and adds them in a queue, so that they can be handled by
 247  * receive_ipmb_request.
 248  */
 249 static int ipmb_slave_cb(struct i2c_client *client,
 250                         enum i2c_slave_event event, u8 *val)
 251 {
 252         struct ipmb_dev *ipmb_dev = i2c_get_clientdata(client);
 253         u8 *buf = (u8 *)&ipmb_dev->request;
 254         unsigned long flags;
 255
 256         spin_lock_irqsave(&ipmb_dev->lock, flags);
 257         switch (event) {
 258         case I2C_SLAVE_WRITE_REQUESTED:
 259                 memset(&ipmb_dev->request, 0, sizeof(ipmb_dev->request));
 260                 ipmb_dev->msg_idx = 0;
 261
 262                 /*
 263                  * At index 0, ipmb_msg stores the length of msg,
 264                  * skip it for now.
 265                  * The len will be populated once the whole
 266                  * buf is populated.
 267                  *
 268                  * The I2C bus driver's responsibility is to pass the
 269                  * data bytes to the backend driver; it does not
 270                  * forward the i2c slave address.
 271                  * Since the first byte in the IPMB message is the
 272                  * address of the responder, it is the responsibility
 273                  * of the IPMB driver to format the message properly.
 274                  * So this driver prepends the address of the responder
 275                  * to the received i2c data before the request message
 276                  * is handled in userland.
 277                  */
 278                 buf[++ipmb_dev->msg_idx] = GET_8BIT_ADDR(client->addr);
 279                 break;
 280
 281         case I2C_SLAVE_WRITE_RECEIVED:
 282                 if (ipmb_dev->msg_idx >= sizeof(struct ipmb_msg) - 1)
 283                         break;
 284
 285                 buf[++ipmb_dev->msg_idx] = *val;
 286                 break;
 287
 288         case I2C_SLAVE_STOP:
 289                 ipmb_dev->request.len = ipmb_dev->msg_idx;
 290                 if (is_ipmb_msg(ipmb_dev, GET_8BIT_ADDR(client->addr)))
 291                         ipmb_handle_request(ipmb_dev);
 292                 break;
 293
 294         default:
 295                 break;
 296         }
 297         spin_unlock_irqrestore(&ipmb_dev->lock, flags);
 298
 299         return 0;
 300 }
 301
 302 static int ipmb_probe(struct i2c_client *client,
 303                         const struct i2c_device_id *id)
 304 {
 305         struct ipmb_dev *ipmb_dev;
 306         int ret;
 307
 308         ipmb_dev = devm_kzalloc(&client->dev, sizeof(*ipmb_dev),
 309                                         GFP_KERNEL);
 310         if (!ipmb_dev)
 311                 return -ENOMEM;
 312
 313         spin_lock_init(&ipmb_dev->lock);
 314         init_waitqueue_head(&ipmb_dev->wait_queue);
 315         atomic_set(&ipmb_dev->request_queue_len, 0);
 316         INIT_LIST_HEAD(&ipmb_dev->request_queue);
 317
 318         mutex_init(&ipmb_dev->file_mutex);
 319
 320         ipmb_dev->miscdev.minor = MISC_DYNAMIC_MINOR;
 321
 322         ipmb_dev->miscdev.name = devm_kasprintf(&client->dev, GFP_KERNEL,
 323                                                 "%s%d", "ipmb-",
 324                                                 client->adapter->nr);
 325         ipmb_dev->miscdev.fops = &ipmb_fops;
 326         ipmb_dev->miscdev.parent = &client->dev;
 327         ret = misc_register(&ipmb_dev->miscdev);
 328         if (ret)
 329                 return ret;
 330
 331         ipmb_dev->is_i2c_protocol
 332                 = device_property_read_bool(&client->dev, "i2c-protocol");
 333
 334         ipmb_dev->client = client;
 335         i2c_set_clientdata(client, ipmb_dev);
 336         ret = i2c_slave_register(client, ipmb_slave_cb);
 337         if (ret) {
 338                 misc_deregister(&ipmb_dev->miscdev);
 339                 return ret;
 340         }
 341
 342         return 0;
 343 }
 344
 345 static int ipmb_remove(struct i2c_client *client)
 346 {
 347         struct ipmb_dev *ipmb_dev = i2c_get_clientdata(client);
 348
 349         i2c_slave_unregister(client);
 350         misc_deregister(&ipmb_dev->miscdev);
 351
 352         return 0;
 353 }
 354
 355 static const struct i2c_device_id ipmb_id[] = {
 356         { "ipmb-dev", 0 },
 357         {},
 358 };
 359 MODULE_DEVICE_TABLE(i2c, ipmb_id);
 360
 361 static const struct acpi_device_id acpi_ipmb_id[] = {
 362         { "IPMB0001", 0 },
 363         {},
 364 };
 365 MODULE_DEVICE_TABLE(acpi, acpi_ipmb_id);
 366
 367 static struct i2c_driver ipmb_driver = {
 368         .driver = {
 369                 .name = "ipmb-dev",
 370                 .acpi_match_table = ACPI_PTR(acpi_ipmb_id),
 371         },
 372         .probe = ipmb_probe,
 373         .remove = ipmb_remove,
 374         .id_table = ipmb_id,
 375 };
 376 module_i2c_driver(ipmb_driver);
 377
 378 MODULE_AUTHOR("Mellanox Technologies");
 379 MODULE_DESCRIPTION("IPMB driver");
 380 MODULE_LICENSE("GPL v2");