| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * i2c-smbus.c - SMBus extensions to the I2C protocol |
| * |
| * Copyright (C) 2008 David Brownell |
| * Copyright (C) 2010-2019 Jean Delvare <jdelvare@suse.de> |
| */ |
| |
| #include <linux/device.h> |
| #include <linux/dmi.h> |
| #include <linux/i2c.h> |
| #include <linux/i2c-smbus.h> |
| #include <linux/interrupt.h> |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/of_irq.h> |
| #include <linux/slab.h> |
| #include <linux/workqueue.h> |
| |
| struct i2c_smbus_alert { |
| struct work_struct alert; |
| struct i2c_client *ara; /* Alert response address */ |
| }; |
| |
| struct alert_data { |
| unsigned short addr; |
| enum i2c_alert_protocol type; |
| unsigned int data; |
| }; |
| |
| /* If this is the alerting device, notify its driver */ |
| static int smbus_do_alert(struct device *dev, void *addrp) |
| { |
| struct i2c_client *client = i2c_verify_client(dev); |
| struct alert_data *data = addrp; |
| struct i2c_driver *driver; |
| |
| if (!client || client->addr != data->addr) |
| return 0; |
| if (client->flags & I2C_CLIENT_TEN) |
| return 0; |
| |
| /* |
| * Drivers should either disable alerts, or provide at least |
| * a minimal handler. Lock so the driver won't change. |
| */ |
| device_lock(dev); |
| if (client->dev.driver) { |
| driver = to_i2c_driver(client->dev.driver); |
| if (driver->alert) |
| driver->alert(client, data->type, data->data); |
| else |
| dev_warn(&client->dev, "no driver alert()!\n"); |
| } else |
| dev_dbg(&client->dev, "alert with no driver\n"); |
| device_unlock(dev); |
| |
| /* Stop iterating after we find the device */ |
| return -EBUSY; |
| } |
| |
| /* |
| * The alert IRQ handler needs to hand work off to a task which can issue |
| * SMBus calls, because those sleeping calls can't be made in IRQ context. |
| */ |
| static irqreturn_t smbus_alert(int irq, void *d) |
| { |
| struct i2c_smbus_alert *alert = d; |
| struct i2c_client *ara; |
| |
| ara = alert->ara; |
| |
| for (;;) { |
| s32 status; |
| struct alert_data data; |
| |
| /* |
| * Devices with pending alerts reply in address order, low |
| * to high, because of slave transmit arbitration. After |
| * responding, an SMBus device stops asserting SMBALERT#. |
| * |
| * Note that SMBus 2.0 reserves 10-bit addresses for future |
| * use. We neither handle them, nor try to use PEC here. |
| */ |
| status = i2c_smbus_read_byte(ara); |
| if (status < 0) |
| break; |
| |
| data.data = status & 1; |
| data.addr = status >> 1; |
| data.type = I2C_PROTOCOL_SMBUS_ALERT; |
| |
| dev_dbg(&ara->dev, "SMBALERT# from dev 0x%02x, flag %d\n", |
| data.addr, data.data); |
| |
| /* Notify driver for the device which issued the alert */ |
| device_for_each_child(&ara->adapter->dev, &data, |
| smbus_do_alert); |
| } |
| |
| return IRQ_HANDLED; |
| } |
| |
| static void smbalert_work(struct work_struct *work) |
| { |
| struct i2c_smbus_alert *alert; |
| |
| alert = container_of(work, struct i2c_smbus_alert, alert); |
| |
| smbus_alert(0, alert); |
| |
| } |
| |
| /* Setup SMBALERT# infrastructure */ |
| static int smbalert_probe(struct i2c_client *ara, |
| const struct i2c_device_id *id) |
| { |
| struct i2c_smbus_alert_setup *setup = dev_get_platdata(&ara->dev); |
| struct i2c_smbus_alert *alert; |
| struct i2c_adapter *adapter = ara->adapter; |
| int res, irq; |
| |
| alert = devm_kzalloc(&ara->dev, sizeof(struct i2c_smbus_alert), |
| GFP_KERNEL); |
| if (!alert) |
| return -ENOMEM; |
| |
| if (setup) { |
| irq = setup->irq; |
| } else { |
| irq = of_irq_get_byname(adapter->dev.of_node, "smbus_alert"); |
| if (irq <= 0) |
| return irq; |
| } |
| |
| INIT_WORK(&alert->alert, smbalert_work); |
| alert->ara = ara; |
| |
| if (irq > 0) { |
| res = devm_request_threaded_irq(&ara->dev, irq, |
| NULL, smbus_alert, |
| IRQF_SHARED | IRQF_ONESHOT, |
| "smbus_alert", alert); |
| if (res) |
| return res; |
| } |
| |
| i2c_set_clientdata(ara, alert); |
| dev_info(&adapter->dev, "supports SMBALERT#\n"); |
| |
| return 0; |
| } |
| |
| /* IRQ and memory resources are managed so they are freed automatically */ |
| static int smbalert_remove(struct i2c_client *ara) |
| { |
| struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); |
| |
| cancel_work_sync(&alert->alert); |
| return 0; |
| } |
| |
| static const struct i2c_device_id smbalert_ids[] = { |
| { "smbus_alert", 0 }, |
| { /* LIST END */ } |
| }; |
| MODULE_DEVICE_TABLE(i2c, smbalert_ids); |
| |
| static struct i2c_driver smbalert_driver = { |
| .driver = { |
| .name = "smbus_alert", |
| }, |
| .probe = smbalert_probe, |
| .remove = smbalert_remove, |
| .id_table = smbalert_ids, |
| }; |
| |
| /** |
| * i2c_handle_smbus_alert - Handle an SMBus alert |
| * @ara: the ARA client on the relevant adapter |
| * Context: can't sleep |
| * |
| * Helper function to be called from an I2C bus driver's interrupt |
| * handler. It will schedule the alert work, in turn calling the |
| * corresponding I2C device driver's alert function. |
| * |
| * It is assumed that ara is a valid i2c client previously returned by |
| * i2c_new_smbus_alert_device(). |
| */ |
| int i2c_handle_smbus_alert(struct i2c_client *ara) |
| { |
| struct i2c_smbus_alert *alert = i2c_get_clientdata(ara); |
| |
| return schedule_work(&alert->alert); |
| } |
| EXPORT_SYMBOL_GPL(i2c_handle_smbus_alert); |
| |
| module_i2c_driver(smbalert_driver); |
| |
| #if IS_ENABLED(CONFIG_I2C_SLAVE) |
| #define SMBUS_HOST_NOTIFY_LEN 3 |
| struct i2c_slave_host_notify_status { |
| u8 index; |
| u8 addr; |
| }; |
| |
| static int i2c_slave_host_notify_cb(struct i2c_client *client, |
| enum i2c_slave_event event, u8 *val) |
| { |
| struct i2c_slave_host_notify_status *status = client->dev.platform_data; |
| |
| switch (event) { |
| case I2C_SLAVE_WRITE_RECEIVED: |
| /* We only retrieve the first byte received (addr) |
| * since there is currently no support to retrieve the data |
| * parameter from the client. |
| */ |
| if (status->index == 0) |
| status->addr = *val; |
| if (status->index < U8_MAX) |
| status->index++; |
| break; |
| case I2C_SLAVE_STOP: |
| if (status->index == SMBUS_HOST_NOTIFY_LEN) |
| i2c_handle_smbus_host_notify(client->adapter, |
| status->addr); |
| fallthrough; |
| case I2C_SLAVE_WRITE_REQUESTED: |
| status->index = 0; |
| break; |
| case I2C_SLAVE_READ_REQUESTED: |
| case I2C_SLAVE_READ_PROCESSED: |
| *val = 0xff; |
| break; |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * i2c_new_slave_host_notify_device - get a client for SMBus host-notify support |
| * @adapter: the target adapter |
| * Context: can sleep |
| * |
| * Setup handling of the SMBus host-notify protocol on a given I2C bus segment. |
| * |
| * Handling is done by creating a device and its callback and handling data |
| * received via the SMBus host-notify address (0x8) |
| * |
| * This returns the client, which should be ultimately freed using |
| * i2c_free_slave_host_notify_device(); or an ERRPTR to indicate an error. |
| */ |
| struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter) |
| { |
| struct i2c_board_info host_notify_board_info = { |
| I2C_BOARD_INFO("smbus_host_notify", 0x08), |
| .flags = I2C_CLIENT_SLAVE, |
| }; |
| struct i2c_slave_host_notify_status *status; |
| struct i2c_client *client; |
| int ret; |
| |
| status = kzalloc(sizeof(struct i2c_slave_host_notify_status), |
| GFP_KERNEL); |
| if (!status) |
| return ERR_PTR(-ENOMEM); |
| |
| host_notify_board_info.platform_data = status; |
| |
| client = i2c_new_client_device(adapter, &host_notify_board_info); |
| if (IS_ERR(client)) { |
| kfree(status); |
| return client; |
| } |
| |
| ret = i2c_slave_register(client, i2c_slave_host_notify_cb); |
| if (ret) { |
| i2c_unregister_device(client); |
| kfree(status); |
| return ERR_PTR(ret); |
| } |
| |
| return client; |
| } |
| EXPORT_SYMBOL_GPL(i2c_new_slave_host_notify_device); |
| |
| /** |
| * i2c_free_slave_host_notify_device - free the client for SMBus host-notify |
| * support |
| * @client: the client to free |
| * Context: can sleep |
| * |
| * Free the i2c_client allocated via i2c_new_slave_host_notify_device |
| */ |
| void i2c_free_slave_host_notify_device(struct i2c_client *client) |
| { |
| if (IS_ERR_OR_NULL(client)) |
| return; |
| |
| i2c_slave_unregister(client); |
| kfree(client->dev.platform_data); |
| i2c_unregister_device(client); |
| } |
| EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device); |
| #endif |
| |
| /* |
| * SPD is not part of SMBus but we include it here for convenience as the |
| * target systems are the same. |
| * Restrictions to automatic SPD instantiation: |
| * - Only works if all filled slots have the same memory type |
| * - Only works for DDR2, DDR3 and DDR4 for now |
| * - Only works on systems with 1 to 4 memory slots |
| */ |
| #if IS_ENABLED(CONFIG_DMI) |
| void i2c_register_spd(struct i2c_adapter *adap) |
| { |
| int n, slot_count = 0, dimm_count = 0; |
| u16 handle; |
| u8 common_mem_type = 0x0, mem_type; |
| u64 mem_size; |
| const char *name; |
| |
| while ((handle = dmi_memdev_handle(slot_count)) != 0xffff) { |
| slot_count++; |
| |
| /* Skip empty slots */ |
| mem_size = dmi_memdev_size(handle); |
| if (!mem_size) |
| continue; |
| |
| /* Skip undefined memory type */ |
| mem_type = dmi_memdev_type(handle); |
| if (mem_type <= 0x02) /* Invalid, Other, Unknown */ |
| continue; |
| |
| if (!common_mem_type) { |
| /* First filled slot */ |
| common_mem_type = mem_type; |
| } else { |
| /* Check that all filled slots have the same type */ |
| if (mem_type != common_mem_type) { |
| dev_warn(&adap->dev, |
| "Different memory types mixed, not instantiating SPD\n"); |
| return; |
| } |
| } |
| dimm_count++; |
| } |
| |
| /* No useful DMI data, bail out */ |
| if (!dimm_count) |
| return; |
| |
| dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n", |
| dimm_count, slot_count); |
| |
| if (slot_count > 4) { |
| dev_warn(&adap->dev, |
| "Systems with more than 4 memory slots not supported yet, not instantiating SPD\n"); |
| return; |
| } |
| |
| switch (common_mem_type) { |
| case 0x13: /* DDR2 */ |
| case 0x18: /* DDR3 */ |
| case 0x1C: /* LPDDR2 */ |
| case 0x1D: /* LPDDR3 */ |
| name = "spd"; |
| break; |
| case 0x1A: /* DDR4 */ |
| case 0x1E: /* LPDDR4 */ |
| name = "ee1004"; |
| break; |
| default: |
| dev_info(&adap->dev, |
| "Memory type 0x%02x not supported yet, not instantiating SPD\n", |
| common_mem_type); |
| return; |
| } |
| |
| /* |
| * We don't know in which slots the memory modules are. We could |
| * try to guess from the slot names, but that would be rather complex |
| * and unreliable, so better probe all possible addresses until we |
| * have found all memory modules. |
| */ |
| for (n = 0; n < slot_count && dimm_count; n++) { |
| struct i2c_board_info info; |
| unsigned short addr_list[2]; |
| |
| memset(&info, 0, sizeof(struct i2c_board_info)); |
| strlcpy(info.type, name, I2C_NAME_SIZE); |
| addr_list[0] = 0x50 + n; |
| addr_list[1] = I2C_CLIENT_END; |
| |
| if (!IS_ERR(i2c_new_scanned_device(adap, &info, addr_list, NULL))) { |
| dev_info(&adap->dev, |
| "Successfully instantiated SPD at 0x%hx\n", |
| addr_list[0]); |
| dimm_count--; |
| } |
| } |
| } |
| EXPORT_SYMBOL_GPL(i2c_register_spd); |
| #endif |
| |
| MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); |
| MODULE_DESCRIPTION("SMBus protocol extensions support"); |
| MODULE_LICENSE("GPL"); |