468 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * i2c-smbus.c - SMBus extensions to the I2C protocol4 *5 * Copyright (C) 2008 David Brownell6 * 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 20struct i2c_smbus_alert {21 struct work_struct alert;22 struct i2c_client *ara; /* Alert response address */23};24 25struct 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 */32static 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 int ret;38 39 if (!client || client->addr != data->addr)40 return 0;41 if (client->flags & I2C_CLIENT_TEN)42 return 0;43 44 /*45 * Drivers should either disable alerts, or provide at least46 * a minimal handler. Lock so the driver won't change.47 */48 device_lock(dev);49 if (client->dev.driver) {50 driver = to_i2c_driver(client->dev.driver);51 if (driver->alert) {52 /* Stop iterating after we find the device */53 driver->alert(client, data->type, data->data);54 ret = -EBUSY;55 } else {56 dev_warn(&client->dev, "no driver alert()!\n");57 ret = -EOPNOTSUPP;58 }59 } else {60 dev_dbg(&client->dev, "alert with no driver\n");61 ret = -ENODEV;62 }63 device_unlock(dev);64 65 return ret;66}67 68/* Same as above, but call back all drivers with alert handler */69 70static int smbus_do_alert_force(struct device *dev, void *addrp)71{72 struct i2c_client *client = i2c_verify_client(dev);73 struct alert_data *data = addrp;74 struct i2c_driver *driver;75 76 if (!client || (client->flags & I2C_CLIENT_TEN))77 return 0;78 79 /*80 * Drivers should either disable alerts, or provide at least81 * a minimal handler. Lock so the driver won't change.82 */83 device_lock(dev);84 if (client->dev.driver) {85 driver = to_i2c_driver(client->dev.driver);86 if (driver->alert)87 driver->alert(client, data->type, data->data);88 }89 device_unlock(dev);90 91 return 0;92}93 94/*95 * The alert IRQ handler needs to hand work off to a task which can issue96 * SMBus calls, because those sleeping calls can't be made in IRQ context.97 */98static irqreturn_t smbus_alert(int irq, void *d)99{100 struct i2c_smbus_alert *alert = d;101 struct i2c_client *ara;102 unsigned short prev_addr = I2C_CLIENT_END; /* Not a valid address */103 104 ara = alert->ara;105 106 for (;;) {107 s32 status;108 struct alert_data data;109 110 /*111 * Devices with pending alerts reply in address order, low112 * to high, because of slave transmit arbitration. After113 * responding, an SMBus device stops asserting SMBALERT#.114 *115 * Note that SMBus 2.0 reserves 10-bit addresses for future116 * use. We neither handle them, nor try to use PEC here.117 */118 status = i2c_smbus_read_byte(ara);119 if (status < 0)120 break;121 122 data.data = status & 1;123 data.addr = status >> 1;124 data.type = I2C_PROTOCOL_SMBUS_ALERT;125 126 dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n",127 data.addr, data.data);128 129 /* Notify driver for the device which issued the alert */130 status = device_for_each_child(&ara->adapter->dev, &data,131 smbus_do_alert);132 /*133 * If we read the same address more than once, and the alert134 * was not handled by a driver, it won't do any good to repeat135 * the loop because it will never terminate. Try again, this136 * time calling the alert handlers of all devices connected to137 * the bus, and abort the loop afterwards. If this helps, we138 * are all set. If it doesn't, there is nothing else we can do,139 * so we might as well abort the loop.140 * Note: This assumes that a driver with alert handler handles141 * the alert properly and clears it if necessary.142 */143 if (data.addr == prev_addr && status != -EBUSY) {144 device_for_each_child(&ara->adapter->dev, &data,145 smbus_do_alert_force);146 break;147 }148 prev_addr = data.addr;149 }150 151 return IRQ_HANDLED;152}153 154static void smbalert_work(struct work_struct *work)155{156 struct i2c_smbus_alert *alert;157 158 alert = container_of(work, struct i2c_smbus_alert, alert);159 160 smbus_alert(0, alert);161 162}163 164/* Setup SMBALERT# infrastructure */165static int smbalert_probe(struct i2c_client *ara)166{167 struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev);168 struct i2c_smbus_alert *alert;169 struct i2c_adapter *adapter = ara->adapter;170 int res, irq;171 172 alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert),173 GFP_KERNEL);174 if (!alert)175 return -ENOMEM;176 177 if (setup) {178 irq = setup->irq;179 } else {180 irq = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent),181 "smbus_alert");182 if (irq <= 0)183 return irq;184 }185 186 INIT_WORK(&alert->alert, smbalert_work);187 alert->ara = ara;188 189 if (irq > 0) {190 res = devm_request_threaded_irq(&ara->dev, irq,191 NULL, smbus_alert,192 IRQF_SHARED | IRQF_ONESHOT,193 "smbus_alert", alert);194 if (res)195 return res;196 }197 198 i2c_set_clientdata(ara, alert);199 dev_info(&adapter->dev, "supports SMBALERT#\n");200 201 return 0;202}203 204/* IRQ and memory resources are managed so they are freed automatically */205static void smbalert_remove(struct i2c_client *ara)206{207 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);208 209 cancel_work_sync(&alert->alert);210}211 212static const struct i2c_device_id smbalert_ids[] = {213 { "smbus_alert" },214 { /* LIST END */ }215};216MODULE_DEVICE_TABLE(i2c, smbalert_ids);217 218static struct i2c_driver smbalert_driver = {219 .driver = {220 .name = "smbus_alert",221 },222 .probe = smbalert_probe,223 .remove = smbalert_remove,224 .id_table = smbalert_ids,225};226 227/**228 * i2c_handle_smbus_alert - Handle an SMBus alert229 * @ara: the ARA client on the relevant adapter230 * Context: can't sleep231 *232 * Helper function to be called from an I2C bus driver's interrupt233 * handler. It will schedule the alert work, in turn calling the234 * corresponding I2C device driver's alert function.235 *236 * It is assumed that ara is a valid i2c client previously returned by237 * i2c_new_smbus_alert_device().238 */239int i2c_handle_smbus_alert(struct i2c_client *ara)240{241 struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);242 243 return schedule_work(&alert->alert);244}245EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert);246 247module_i2c_driver(smbalert_driver);248 249#if IS_ENABLED(CONFIG_I2C_SLAVE)250#define SMBUS_HOST_NOTIFY_LEN 3251struct i2c_slave_host_notify_status {252 u8 index;253 u8 addr;254};255 256static int i2c_slave_host_notify_cb(struct i2c_client *client,257 enum i2c_slave_event event, u8 *val)258{259 struct i2c_slave_host_notify_status *status = client->dev.platform_data;260 261 switch (event) {262 case I2C_SLAVE_WRITE_RECEIVED:263 /* We only retrieve the first byte received (addr)264 * since there is currently no support to retrieve the data265 * parameter from the client.266 */267 if (status->index == 0)268 status->addr = *val;269 if (status->index < U8_MAX)270 status->index++;271 break;272 case I2C_SLAVE_STOP:273 if (status->index == SMBUS_HOST_NOTIFY_LEN)274 i2c_handle_smbus_host_notify(client->adapter,275 status->addr);276 fallthrough;277 case I2C_SLAVE_WRITE_REQUESTED:278 status->index = 0;279 break;280 case I2C_SLAVE_READ_REQUESTED:281 case I2C_SLAVE_READ_PROCESSED:282 *val = 0xff;283 break;284 }285 286 return 0;287}288 289/**290 * i2c_new_slave_host_notify_device - get a client for SMBus host-notify support291 * @adapter: the target adapter292 * Context: can sleep293 *294 * Setup handling of the SMBus host-notify protocol on a given I2C bus segment.295 *296 * Handling is done by creating a device and its callback and handling data297 * received via the SMBus host-notify address (0x8)298 *299 * This returns the client, which should be ultimately freed using300 * i2c_free_slave_host_notify_device(); or an ERRPTR to indicate an error.301 */302struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter)303{304 struct i2c_board_info host_notify_board_info = {305 I2C_BOARD_INFO("smbus_host_notify", 0x08),306 .flags = I2C_CLIENT_SLAVE,307 };308 struct i2c_slave_host_notify_status *status;309 struct i2c_client *client;310 int ret;311 312 status = kzalloc(sizeof(struct i2c_slave_host_notify_status),313 GFP_KERNEL);314 if (!status)315 return ERR_PTR(-ENOMEM);316 317 host_notify_board_info.platform_data = status;318 319 client = i2c_new_client_device(adapter, &host_notify_board_info);320 if (IS_ERR(client)) {321 kfree(status);322 return client;323 }324 325 ret = i2c_slave_register(client, i2c_slave_host_notify_cb);326 if (ret) {327 i2c_unregister_device(client);328 kfree(status);329 return ERR_PTR(ret);330 }331 332 return client;333}334EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device);335 336/**337 * i2c_free_slave_host_notify_device - free the client for SMBus host-notify338 * support339 * @client: the client to free340 * Context: can sleep341 *342 * Free the i2c_client allocated via i2c_new_slave_host_notify_device343 */344void i2c_free_slave_host_notify_device(struct i2c_client *client)345{346 if (IS_ERR_OR_NULL(client))347 return;348 349 i2c_slave_unregister(client);350 kfree(client->dev.platform_data);351 i2c_unregister_device(client);352}353EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device);354#endif355 356/*357 * SPD is not part of SMBus but we include it here for convenience as the358 * target systems are the same.359 * Restrictions to automatic SPD instantiation:360 * - Only works if all filled slots have the same memory type361 * - Only works for (LP)DDR memory types up to DDR5362 * - Only works on systems with 1 to 8 memory slots363 */364#if IS_ENABLED(CONFIG_DMI)365void i2c_register_spd(struct i2c_adapter *adap)366{367 int n, slot_count = 0, dimm_count = 0;368 u16 handle;369 u8 common_mem_type = 0x0, mem_type;370 u64 mem_size;371 const char *name;372 373 while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) {374 slot_count++;375 376 /* Skip empty slots */377 mem_size = dmi_memdev_size(handle);378 if (!mem_size)379 continue;380 381 /* Skip undefined memory type */382 mem_type = dmi_memdev_type(handle);383 if (mem_type <= 0x02) /* Invalid, Other, Unknown */384 continue;385 386 if (!common_mem_type) {387 /* First filled slot */388 common_mem_type = mem_type;389 } else {390 /* Check that all filled slots have the same type */391 if (mem_type != common_mem_type) {392 dev_warn(&adap->dev,393 "Different memory types mixed, not instantiating SPD\n");394 return;395 }396 }397 dimm_count++;398 }399 400 /* No useful DMI data, bail out */401 if (!dimm_count)402 return;403 404 /*405 * The max number of SPD EEPROMs that can be addressed per bus is 8.406 * If more slots are present either muxed or multiple busses are407 * necessary or the additional slots are ignored.408 */409 slot_count = min(slot_count, 8);410 411 /*412 * Memory types could be found at section 7.18.2 (Memory Device — Type), table 78413 * https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf414 */415 switch (common_mem_type) {416 case 0x12: /* DDR */417 case 0x13: /* DDR2 */418 case 0x18: /* DDR3 */419 case 0x1B: /* LPDDR */420 case 0x1C: /* LPDDR2 */421 case 0x1D: /* LPDDR3 */422 name = "spd";423 break;424 case 0x1A: /* DDR4 */425 case 0x1E: /* LPDDR4 */426 name = "ee1004";427 break;428 case 0x22: /* DDR5 */429 case 0x23: /* LPDDR5 */430 name = "spd5118";431 break;432 default:433 dev_info(&adap->dev,434 "Memory type 0x%02x not supported yet, not instantiating SPD\n",435 common_mem_type);436 return;437 }438 439 /*440 * We don't know in which slots the memory modules are. We could441 * try to guess from the slot names, but that would be rather complex442 * and unreliable, so better probe all possible addresses until we443 * have found all memory modules.444 */445 for (n = 0; n < slot_count && dimm_count; n++) {446 struct i2c_board_info info;447 unsigned short addr_list[2];448 449 memset(&info, 0, sizeof(struct i2c_board_info));450 strscpy(info.type, name, I2C_NAME_SIZE);451 addr_list[0] = 0x50 + n;452 addr_list[1] = I2C_CLIENT_END;453 454 if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) {455 dev_info(&adap->dev,456 "Successfully instantiated SPD at 0x%hx\n",457 addr_list[0]);458 dimm_count--;459 }460 }461}462EXPORT_SYMBOL_GPL(i2c_register_spd);463#endif464 465MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");466MODULE_DESCRIPTION("SMBus protocol extensions support");467MODULE_LICENSE("GPL");468