From 2a71593da34d473461f2f5c3dbb53b883596188a Mon Sep 17 00:00:00 2001 From: Alain Volmat Date: Mon, 3 Aug 2020 07:17:55 +0200 Subject: [PATCH] i2c: smbus: add core function handling SMBus host-notify 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 Reviewed-by: Pierre-Yves MORDRET Signed-off-by: Wolfram Sang --- drivers/i2c/i2c-smbus.c | 107 ++++++++++++++++++++++++++++++++++++++ include/linux/i2c-smbus.h | 12 +++++ 2 files changed, 119 insertions(+) diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c index dc0108287ccf..d3d06e3b4f3b 100644 --- a/drivers/i2c/i2c-smbus.c +++ b/drivers/i2c/i2c-smbus.c @@ -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. diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h index 1e4e0de4ef8b..1ef421818d3a 100644 --- a/include/linux/i2c-smbus.h +++ b/include/linux/i2c-smbus.h @@ -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);