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