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![Alain Volmat](/assets/img/avatar_default.png)
SMBus Host-Notify protocol, from the adapter point of view consist of receiving a message from a client, including the client address and some other data. It can be simply handled by creating a new slave device and registering a callback performing the parsing of the message received from the client. This commit introduces two new core functions * i2c_new_slave_host_notify_device * i2c_free_slave_host_notify_device that take care of registration of the new slave device and callback and will call i2c_handle_smbus_host_notify once a Host-Notify event is received. Signed-off-by: Alain Volmat <alain.volmat@st.com> Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com> Signed-off-by: Wolfram Sang <wsa@kernel.org>
410 lines
10 KiB
C
410 lines
10 KiB
C
// 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 <jdelvare@suse.de>
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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 <jdelvare@suse.de>");
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MODULE_DESCRIPTION("SMBus protocol extensions support");
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MODULE_LICENSE("GPL");
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