linux/drivers/i2c/i2c-smbus.c
Guenter Roeck f6c29f710c i2c: smbus: Send alert notifications to all devices if source not found
If a SMBus alert is received and the originating device is not found,
the reason may be that the address reported on the SMBus alert address
is corrupted, for example because multiple devices asserted alert and
do not correctly implement SMBus arbitration.

If this happens, call alert handlers on all devices connected to the
given I2C bus, in the hope that this cleans up the situation.

This change reliably fixed the problem on a system with multiple devices
on a single bus. Example log where the device on address 0x18 (ADM1021)
and on address 0x4c (ADT7461A) both had the alert line asserted:

smbus_alert 3-000c: SMBALERT# from dev 0x0c, flag 0
smbus_alert 3-000c: no driver alert()!
smbus_alert 3-000c: SMBALERT# from dev 0x0c, flag 0
smbus_alert 3-000c: no driver alert()!
lm90 3-0018: temp1 out of range, please check!
lm90 3-0018: Disabling ALERT#
lm90 3-0029: Everything OK
lm90 3-002a: Everything OK
lm90 3-004c: temp1 out of range, please check!
lm90 3-004c: temp2 out of range, please check!
lm90 3-004c: Disabling ALERT#

Fixes: b5527a7766 ("i2c: Add SMBus alert support")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
[wsa: fixed a typo in the commit message]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
2024-08-04 16:29:34 +02:00

468 lines
12 KiB
C

// 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/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 <jdelvare@suse.de>");
MODULE_DESCRIPTION("SMBus protocol extensions support");
MODULE_LICENSE("GPL");