1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * i2c-smbus.c - SMBus extensions to the I2C protocol 4 * 5 * Copyright (C) 2008 David Brownell 6 * Copyright (C) 2010-2019 Jean Delvare <jdelvare@suse.de> 7 */ 8 9 #include <linux/device.h> 10 #include <linux/dmi.h> 11 #include <linux/i2c.h> 12 #include <linux/i2c-smbus.h> 13 #include <linux/interrupt.h> 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/property.h> 17 #include <linux/slab.h> 18 #include <linux/workqueue.h> 19 20 struct i2c_smbus_alert { 21 struct work_struct alert; 22 struct i2c_client *ara; /* Alert response address */ 23 }; 24 25 struct alert_data { 26 unsigned short addr; 27 enum i2c_alert_protocol type; 28 unsigned int data; 29 }; 30 31 /* If this is the alerting device, notify its driver */ 32 static int smbus_do_alert(struct device *dev, void *addrp) 33 { 34 struct i2c_client *client = i2c_verify_client(dev); 35 struct alert_data *data = addrp; 36 struct i2c_driver *driver; 37 38 if (!client || client->addr != data->addr) 39 return 0; 40 if (client->flags & I2C_CLIENT_TEN) 41 return 0; 42 43 /* 44 * Drivers should either disable alerts, or provide at least 45 * a minimal handler. Lock so the driver won't change. 46 */ 47 device_lock(dev); 48 if (client->dev.driver) { 49 driver = to_i2c_driver(client->dev.driver); 50 if (driver->alert) 51 driver->alert(client, data->type, data->data); 52 else 53 dev_warn(&client->dev, "no driver alert()!\n"); 54 } else 55 dev_dbg(&client->dev, "alert with no driver\n"); 56 device_unlock(dev); 57 58 /* Stop iterating after we find the device */ 59 return -EBUSY; 60 } 61 62 /* 63 * The alert IRQ handler needs to hand work off to a task which can issue 64 * SMBus calls, because those sleeping calls can't be made in IRQ context. 65 */ 66 static irqreturn_t smbus_alert(int irq, void *d) 67 { 68 struct i2c_smbus_alert *alert = d; 69 struct i2c_client *ara; 70 71 ara = alert->ara; 72 73 for (;;) { 74 s32 status; 75 struct alert_data data; 76 77 /* 78 * Devices with pending alerts reply in address order, low 79 * to high, because of slave transmit arbitration. After 80 * responding, an SMBus device stops asserting SMBALERT#. 81 * 82 * Note that SMBus 2.0 reserves 10-bit addresses for future 83 * use. We neither handle them, nor try to use PEC here. 84 */ 85 status = i2c_smbus_read_byte(ara); 86 if (status < 0) 87 break; 88 89 data.data = status & 1; 90 data.addr = status >> 1; 91 data.type = I2C_PROTOCOL_SMBUS_ALERT; 92 93 dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n", 94 data.addr, data.data); 95 96 /* Notify driver for the device which issued the alert */ 97 device_for_each_child(&ara->adapter->dev, &data, 98 smbus_do_alert); 99 } 100 101 return IRQ_HANDLED; 102 } 103 104 static void smbalert_work(struct work_struct *work) 105 { 106 struct i2c_smbus_alert *alert; 107 108 alert = container_of(work, struct i2c_smbus_alert, alert); 109 110 smbus_alert(0, alert); 111 112 } 113 114 /* Setup SMBALERT# infrastructure */ 115 static int smbalert_probe(struct i2c_client *ara, 116 const struct i2c_device_id *id) 117 { 118 struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev); 119 struct i2c_smbus_alert *alert; 120 struct i2c_adapter *adapter = ara->adapter; 121 int res, irq; 122 123 alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert), 124 GFP_KERNEL); 125 if (!alert) 126 return -ENOMEM; 127 128 if (setup) { 129 irq = setup->irq; 130 } else { 131 irq = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent), 132 "smbus_alert"); 133 if (irq <= 0) 134 return irq; 135 } 136 137 INIT_WORK(&alert->alert, smbalert_work); 138 alert->ara = ara; 139 140 if (irq > 0) { 141 res = devm_request_threaded_irq(&ara->dev, irq, 142 NULL, smbus_alert, 143 IRQF_SHARED | IRQF_ONESHOT, 144 "smbus_alert", alert); 145 if (res) 146 return res; 147 } 148 149 i2c_set_clientdata(ara, alert); 150 dev_info(&adapter->dev, "supports SMBALERT#\n"); 151 152 return 0; 153 } 154 155 /* IRQ and memory resources are managed so they are freed automatically */ 156 static int smbalert_remove(struct i2c_client *ara) 157 { 158 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); 159 160 cancel_work_sync(&alert->alert); 161 return 0; 162 } 163 164 static const struct i2c_device_id smbalert_ids[] = { 165 { "smbus_alert", 0 }, 166 { /* LIST END */ } 167 }; 168 MODULE_DEVICE_TABLE(i2c, smbalert_ids); 169 170 static struct i2c_driver smbalert_driver = { 171 .driver = { 172 .name = "smbus_alert", 173 }, 174 .probe = smbalert_probe, 175 .remove = smbalert_remove, 176 .id_table = smbalert_ids, 177 }; 178 179 /** 180 * i2c_handle_smbus_alert - Handle an SMBus alert 181 * @ara: the ARA client on the relevant adapter 182 * Context: can't sleep 183 * 184 * Helper function to be called from an I2C bus driver's interrupt 185 * handler. It will schedule the alert work, in turn calling the 186 * corresponding I2C device driver's alert function. 187 * 188 * It is assumed that ara is a valid i2c client previously returned by 189 * i2c_new_smbus_alert_device(). 190 */ 191 int i2c_handle_smbus_alert(struct i2c_client *ara) 192 { 193 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); 194 195 return schedule_work(&alert->alert); 196 } 197 EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); 198 199 module_i2c_driver(smbalert_driver); 200 201 #if IS_ENABLED(CONFIG_I2C_SLAVE) 202 #define SMBUS_HOST_NOTIFY_LEN 3 203 struct i2c_slave_host_notify_status { 204 u8 index; 205 u8 addr; 206 }; 207 208 static int i2c_slave_host_notify_cb(struct i2c_client *client, 209 enum i2c_slave_event event, u8 *val) 210 { 211 struct i2c_slave_host_notify_status *status = client->dev.platform_data; 212 213 switch (event) { 214 case I2C_SLAVE_WRITE_RECEIVED: 215 /* We only retrieve the first byte received (addr) 216 * since there is currently no support to retrieve the data 217 * parameter from the client. 218 */ 219 if (status->index == 0) 220 status->addr = *val; 221 if (status->index < U8_MAX) 222 status->index++; 223 break; 224 case I2C_SLAVE_STOP: 225 if (status->index == SMBUS_HOST_NOTIFY_LEN) 226 i2c_handle_smbus_host_notify(client->adapter, 227 status->addr); 228 fallthrough; 229 case I2C_SLAVE_WRITE_REQUESTED: 230 status->index = 0; 231 break; 232 case I2C_SLAVE_READ_REQUESTED: 233 case I2C_SLAVE_READ_PROCESSED: 234 *val = 0xff; 235 break; 236 } 237 238 return 0; 239 } 240 241 /** 242 * i2c_new_slave_host_notify_device - get a client for SMBus host-notify support 243 * @adapter: the target adapter 244 * Context: can sleep 245 * 246 * Setup handling of the SMBus host-notify protocol on a given I2C bus segment. 247 * 248 * Handling is done by creating a device and its callback and handling data 249 * received via the SMBus host-notify address (0x8) 250 * 251 * This returns the client, which should be ultimately freed using 252 * i2c_free_slave_host_notify_device(); or an ERRPTR to indicate an error. 253 */ 254 struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter) 255 { 256 struct i2c_board_info host_notify_board_info = { 257 I2C_BOARD_INFO("smbus_host_notify", 0x08), 258 .flags = I2C_CLIENT_SLAVE, 259 }; 260 struct i2c_slave_host_notify_status *status; 261 struct i2c_client *client; 262 int ret; 263 264 status = kzalloc(sizeof(struct i2c_slave_host_notify_status), 265 GFP_KERNEL); 266 if (!status) 267 return ERR_PTR(-ENOMEM); 268 269 host_notify_board_info.platform_data = status; 270 271 client = i2c_new_client_device(adapter, &host_notify_board_info); 272 if (IS_ERR(client)) { 273 kfree(status); 274 return client; 275 } 276 277 ret = i2c_slave_register(client, i2c_slave_host_notify_cb); 278 if (ret) { 279 i2c_unregister_device(client); 280 kfree(status); 281 return ERR_PTR(ret); 282 } 283 284 return client; 285 } 286 EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device); 287 288 /** 289 * i2c_free_slave_host_notify_device - free the client for SMBus host-notify 290 * support 291 * @client: the client to free 292 * Context: can sleep 293 * 294 * Free the i2c_client allocated via i2c_new_slave_host_notify_device 295 */ 296 void i2c_free_slave_host_notify_device(struct i2c_client *client) 297 { 298 if (IS_ERR_OR_NULL(client)) 299 return; 300 301 i2c_slave_unregister(client); 302 kfree(client->dev.platform_data); 303 i2c_unregister_device(client); 304 } 305 EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device); 306 #endif 307 308 /* 309 * SPD is not part of SMBus but we include it here for convenience as the 310 * target systems are the same. 311 * Restrictions to automatic SPD instantiation: 312 * - Only works if all filled slots have the same memory type 313 * - Only works for DDR2, DDR3 and DDR4 for now 314 * - Only works on systems with 1 to 4 memory slots 315 */ 316 #if IS_ENABLED(CONFIG_DMI) 317 void i2c_register_spd(struct i2c_adapter *adap) 318 { 319 int n, slot_count = 0, dimm_count = 0; 320 u16 handle; 321 u8 common_mem_type = 0x0, mem_type; 322 u64 mem_size; 323 const char *name; 324 325 while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) { 326 slot_count++; 327 328 /* Skip empty slots */ 329 mem_size = dmi_memdev_size(handle); 330 if (!mem_size) 331 continue; 332 333 /* Skip undefined memory type */ 334 mem_type = dmi_memdev_type(handle); 335 if (mem_type <= 0x02) /* Invalid, Other, Unknown */ 336 continue; 337 338 if (!common_mem_type) { 339 /* First filled slot */ 340 common_mem_type = mem_type; 341 } else { 342 /* Check that all filled slots have the same type */ 343 if (mem_type != common_mem_type) { 344 dev_warn(&adap->dev, 345 "Different memory types mixed, not instantiating SPD\n"); 346 return; 347 } 348 } 349 dimm_count++; 350 } 351 352 /* No useful DMI data, bail out */ 353 if (!dimm_count) 354 return; 355 356 dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n", 357 dimm_count, slot_count); 358 359 if (slot_count > 4) { 360 dev_warn(&adap->dev, 361 "Systems with more than 4 memory slots not supported yet, not instantiating SPD\n"); 362 return; 363 } 364 365 switch (common_mem_type) { 366 case 0x13: /* DDR2 */ 367 case 0x18: /* DDR3 */ 368 case 0x1C: /* LPDDR2 */ 369 case 0x1D: /* LPDDR3 */ 370 name = "spd"; 371 break; 372 case 0x1A: /* DDR4 */ 373 case 0x1E: /* LPDDR4 */ 374 name = "ee1004"; 375 break; 376 default: 377 dev_info(&adap->dev, 378 "Memory type 0x%02x not supported yet, not instantiating SPD\n", 379 common_mem_type); 380 return; 381 } 382 383 /* 384 * We don't know in which slots the memory modules are. We could 385 * try to guess from the slot names, but that would be rather complex 386 * and unreliable, so better probe all possible addresses until we 387 * have found all memory modules. 388 */ 389 for (n = 0; n < slot_count && dimm_count; n++) { 390 struct i2c_board_info info; 391 unsigned short addr_list[2]; 392 393 memset(&info, 0, sizeof(struct i2c_board_info)); 394 strlcpy(info.type, name, I2C_NAME_SIZE); 395 addr_list[0] = 0x50 + n; 396 addr_list[1] = I2C_CLIENT_END; 397 398 if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) { 399 dev_info(&adap->dev, 400 "Successfully instantiated SPD at 0x%hx\n", 401 addr_list[0]); 402 dimm_count--; 403 } 404 } 405 } 406 EXPORT_SYMBOL_GPL(i2c_register_spd); 407 #endif 408 409 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); 410 MODULE_DESCRIPTION("SMBus protocol extensions support"); 411 MODULE_LICENSE("GPL"); 412