// 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 <[email protected]>
*/
#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/property.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;
int ret;
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) {
/* Stop iterating after we find the device */
driver->alert(client, data->type, data->data);
ret = -EBUSY;
} else {
dev_warn(&client->dev, "no driver alert()!\n");
ret = -EOPNOTSUPP;
}
} else {
dev_dbg(&client->dev, "alert with no driver\n");
ret = -ENODEV;
}
device_unlock(dev);
return ret;
}
/* Same as above, but call back all drivers with alert handler */
static int smbus_do_alert_force(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->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);
}
device_unlock(dev);
return 0;
}
/*
* 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;
unsigned short prev_addr = I2C_CLIENT_END; /* Not a valid address */
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 */
status = device_for_each_child(&ara->adapter->dev, &data,
smbus_do_alert);
/*
* If we read the same address more than once, and the alert
* was not handled by a driver, it won't do any good to repeat
* the loop because it will never terminate. Try again, this
* time calling the alert handlers of all devices connected to
* the bus, and abort the loop afterwards. If this helps, we
* are all set. If it doesn't, there is nothing else we can do,
* so we might as well abort the loop.
* Note: This assumes that a driver with alert handler handles
* the alert properly and clears it if necessary.
*/
if (data.addr == prev_addr && status != -EBUSY) {
device_for_each_child(&ara->adapter->dev, &data,
smbus_do_alert_force);
break;
}
prev_addr = data.addr;
}
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)
{
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 = fwnode_irq_get_byname(dev_fwnode(adapter->dev.parent),
"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 void smbalert_remove(struct i2c_client *ara)
{
struct i2c_smbus_alert *alert = i2c_get_clientdata(ara);
cancel_work_sync(&alert->alert);
}
static const struct i2c_device_id smbalert_ids[] = {
{ "smbus_alert" },
{ /* 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 (LP)DDR memory types up to DDR5
* - Only works on systems with 1 to 8 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;
/*
* The max number of SPD EEPROMs that can be addressed per bus is 8.
* If more slots are present either muxed or multiple busses are
* necessary or the additional slots are ignored.
*/
slot_count = min(slot_count, 8);
/*
* Memory types could be found at section 7.18.2 (Memory Device — Type), table 78
* https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf
*/
switch (common_mem_type) {
case 0x12: /* DDR */
case 0x13: /* DDR2 */
case 0x18: /* DDR3 */
case 0x1B: /* LPDDR */
case 0x1C: /* LPDDR2 */
case 0x1D: /* LPDDR3 */
name = "spd";
break;
case 0x1A: /* DDR4 */
case 0x1E: /* LPDDR4 */
name = "ee1004";
break;
case 0x22: /* DDR5 */
case 0x23: /* LPDDR5 */
name = "spd5118";
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));
strscpy(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 <[email protected]>");
MODULE_DESCRIPTION("SMBus protocol extensions support");
MODULE_LICENSE("GPL");
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