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/of_irq.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 = of_irq_get_byname(adapter->dev.of_node, "smbus_alert"); 132 if (irq <= 0) 133 return irq; 134 } 135 136 INIT_WORK(&alert->alert, smbalert_work); 137 alert->ara = ara; 138 139 if (irq > 0) { 140 res = devm_request_threaded_irq(&ara->dev, irq, 141 NULL, smbus_alert, 142 IRQF_SHARED | IRQF_ONESHOT, 143 "smbus_alert", alert); 144 if (res) 145 return res; 146 } 147 148 i2c_set_clientdata(ara, alert); 149 dev_info(&adapter->dev, "supports SMBALERT#\n"); 150 151 return 0; 152 } 153 154 /* IRQ and memory resources are managed so they are freed automatically */ 155 static int smbalert_remove(struct i2c_client *ara) 156 { 157 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); 158 159 cancel_work_sync(&alert->alert); 160 return 0; 161 } 162 163 static const struct i2c_device_id smbalert_ids[] = { 164 { "smbus_alert", 0 }, 165 { /* LIST END */ } 166 }; 167 MODULE_DEVICE_TABLE(i2c, smbalert_ids); 168 169 static struct i2c_driver smbalert_driver = { 170 .driver = { 171 .name = "smbus_alert", 172 }, 173 .probe = smbalert_probe, 174 .remove = smbalert_remove, 175 .id_table = smbalert_ids, 176 }; 177 178 /** 179 * i2c_handle_smbus_alert - Handle an SMBus alert 180 * @ara: the ARA client on the relevant adapter 181 * Context: can't sleep 182 * 183 * Helper function to be called from an I2C bus driver's interrupt 184 * handler. It will schedule the alert work, in turn calling the 185 * corresponding I2C device driver's alert function. 186 * 187 * It is assumed that ara is a valid i2c client previously returned by 188 * i2c_new_smbus_alert_device(). 189 */ 190 int i2c_handle_smbus_alert(struct i2c_client *ara) 191 { 192 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); 193 194 return schedule_work(&alert->alert); 195 } 196 EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); 197 198 module_i2c_driver(smbalert_driver); 199 200 #if IS_ENABLED(CONFIG_I2C_SLAVE) 201 #define SMBUS_HOST_NOTIFY_LEN 3 202 struct i2c_slave_host_notify_status { 203 u8 index; 204 u8 addr; 205 }; 206 207 static int i2c_slave_host_notify_cb(struct i2c_client *client, 208 enum i2c_slave_event event, u8 *val) 209 { 210 struct i2c_slave_host_notify_status *status = client->dev.platform_data; 211 212 switch (event) { 213 case I2C_SLAVE_WRITE_RECEIVED: 214 /* We only retrieve the first byte received (addr) 215 * since there is currently no support to retrieve the data 216 * parameter from the client. 217 */ 218 if (status->index == 0) 219 status->addr = *val; 220 if (status->index < U8_MAX) 221 status->index++; 222 break; 223 case I2C_SLAVE_STOP: 224 if (status->index == SMBUS_HOST_NOTIFY_LEN) 225 i2c_handle_smbus_host_notify(client->adapter, 226 status->addr); 227 fallthrough; 228 case I2C_SLAVE_WRITE_REQUESTED: 229 status->index = 0; 230 break; 231 case I2C_SLAVE_READ_REQUESTED: 232 case I2C_SLAVE_READ_PROCESSED: 233 *val = 0xff; 234 break; 235 } 236 237 return 0; 238 } 239 240 /** 241 * i2c_new_slave_host_notify_device - get a client for SMBus host-notify support 242 * @adapter: the target adapter 243 * Context: can sleep 244 * 245 * Setup handling of the SMBus host-notify protocol on a given I2C bus segment. 246 * 247 * Handling is done by creating a device and its callback and handling data 248 * received via the SMBus host-notify address (0x8) 249 * 250 * This returns the client, which should be ultimately freed using 251 * i2c_free_slave_host_notify_device(); or an ERRPTR to indicate an error. 252 */ 253 struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter) 254 { 255 struct i2c_board_info host_notify_board_info = { 256 I2C_BOARD_INFO("smbus_host_notify", 0x08), 257 .flags = I2C_CLIENT_SLAVE, 258 }; 259 struct i2c_slave_host_notify_status *status; 260 struct i2c_client *client; 261 int ret; 262 263 status = kzalloc(sizeof(struct i2c_slave_host_notify_status), 264 GFP_KERNEL); 265 if (!status) 266 return ERR_PTR(-ENOMEM); 267 268 host_notify_board_info.platform_data = status; 269 270 client = i2c_new_client_device(adapter, &host_notify_board_info); 271 if (IS_ERR(client)) { 272 kfree(status); 273 return client; 274 } 275 276 ret = i2c_slave_register(client, i2c_slave_host_notify_cb); 277 if (ret) { 278 i2c_unregister_device(client); 279 kfree(status); 280 return ERR_PTR(ret); 281 } 282 283 return client; 284 } 285 EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device); 286 287 /** 288 * i2c_free_slave_host_notify_device - free the client for SMBus host-notify 289 * support 290 * @client: the client to free 291 * Context: can sleep 292 * 293 * Free the i2c_client allocated via i2c_new_slave_host_notify_device 294 */ 295 void i2c_free_slave_host_notify_device(struct i2c_client *client) 296 { 297 if (IS_ERR_OR_NULL(client)) 298 return; 299 300 i2c_slave_unregister(client); 301 kfree(client->dev.platform_data); 302 i2c_unregister_device(client); 303 } 304 EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device); 305 #endif 306 307 /* 308 * SPD is not part of SMBus but we include it here for convenience as the 309 * target systems are the same. 310 * Restrictions to automatic SPD instantiation: 311 * - Only works if all filled slots have the same memory type 312 * - Only works for DDR2, DDR3 and DDR4 for now 313 * - Only works on systems with 1 to 4 memory slots 314 */ 315 #if IS_ENABLED(CONFIG_DMI) 316 void i2c_register_spd(struct i2c_adapter *adap) 317 { 318 int n, slot_count = 0, dimm_count = 0; 319 u16 handle; 320 u8 common_mem_type = 0x0, mem_type; 321 u64 mem_size; 322 const char *name; 323 324 while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) { 325 slot_count++; 326 327 /* Skip empty slots */ 328 mem_size = dmi_memdev_size(handle); 329 if (!mem_size) 330 continue; 331 332 /* Skip undefined memory type */ 333 mem_type = dmi_memdev_type(handle); 334 if (mem_type <= 0x02) /* Invalid, Other, Unknown */ 335 continue; 336 337 if (!common_mem_type) { 338 /* First filled slot */ 339 common_mem_type = mem_type; 340 } else { 341 /* Check that all filled slots have the same type */ 342 if (mem_type != common_mem_type) { 343 dev_warn(&adap->dev, 344 "Different memory types mixed, not instantiating SPD\n"); 345 return; 346 } 347 } 348 dimm_count++; 349 } 350 351 /* No useful DMI data, bail out */ 352 if (!dimm_count) 353 return; 354 355 dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n", 356 dimm_count, slot_count); 357 358 if (slot_count > 4) { 359 dev_warn(&adap->dev, 360 "Systems with more than 4 memory slots not supported yet, not instantiating SPD\n"); 361 return; 362 } 363 364 switch (common_mem_type) { 365 case 0x13: /* DDR2 */ 366 case 0x18: /* DDR3 */ 367 case 0x1C: /* LPDDR2 */ 368 case 0x1D: /* LPDDR3 */ 369 name = "spd"; 370 break; 371 case 0x1A: /* DDR4 */ 372 case 0x1E: /* LPDDR4 */ 373 name = "ee1004"; 374 break; 375 default: 376 dev_info(&adap->dev, 377 "Memory type 0x%02x not supported yet, not instantiating SPD\n", 378 common_mem_type); 379 return; 380 } 381 382 /* 383 * We don't know in which slots the memory modules are. We could 384 * try to guess from the slot names, but that would be rather complex 385 * and unreliable, so better probe all possible addresses until we 386 * have found all memory modules. 387 */ 388 for (n = 0; n < slot_count && dimm_count; n++) { 389 struct i2c_board_info info; 390 unsigned short addr_list[2]; 391 392 memset(&info, 0, sizeof(struct i2c_board_info)); 393 strlcpy(info.type, name, I2C_NAME_SIZE); 394 addr_list[0] = 0x50 + n; 395 addr_list[1] = I2C_CLIENT_END; 396 397 if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) { 398 dev_info(&adap->dev, 399 "Successfully instantiated SPD at 0x%hx\n", 400 addr_list[0]); 401 dimm_count--; 402 } 403 } 404 } 405 EXPORT_SYMBOL_GPL(i2c_register_spd); 406 #endif 407 408 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); 409 MODULE_DESCRIPTION("SMBus protocol extensions support"); 410 MODULE_LICENSE("GPL"); 411