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 union i2c_smbus_data data; 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 passed to 164 * i2c_smbus_xfer 165 */ 166 msg_len = msg[IPMB_MSG_LEN_IDX] - SMBUS_MSG_HEADER_LENGTH; 167 if (msg_len > I2C_SMBUS_BLOCK_MAX) 168 msg_len = I2C_SMBUS_BLOCK_MAX; 169 170 data.block[0] = msg_len; 171 memcpy(&data.block[1], msg + SMBUS_MSG_IDX_OFFSET, msg_len); 172 ret = i2c_smbus_xfer(ipmb_dev->client->adapter, rq_sa, 173 ipmb_dev->client->flags, 174 I2C_SMBUS_WRITE, netf_rq_lun, 175 I2C_SMBUS_BLOCK_DATA, &data); 176 177 return 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"); 381