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i2c: smbus: add core function handling SMBus host-notify

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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>
This commit is contained in:
Alain Volmat 2020-08-03 07:17:55 +02:00 committed by Wolfram Sang
parent e6277308ac
commit 2a71593da3
2 changed files with 119 additions and 0 deletions
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107
drivers/i2c/i2c-smbus.c
View File

@ -197,6 +197,113 @@ 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.

12
include/linux/i2c-smbus.h
View File

@ -38,6 +38,18 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap)
return 0;
}
#endif
#if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_I2C_SLAVE)
struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter);
void i2c_free_slave_host_notify_device(struct i2c_client *client);
#else
static inline struct i2c_client *i2c_new_slave_host_notify_device(struct i2c_adapter *adapter)
{
return ERR_PTR(-ENOSYS);
}
static inline void i2c_free_slave_host_notify_device(struct i2c_client *client)
{
}
#endif
#if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_DMI)
void i2c_register_spd(struct i2c_adapter *adap);