| Message ID | 1593070769-9106-2-git-send-email-alain.volmat@st.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | stm32-f7: Addition of SMBus Alert / Host-notify features | expand |
On Thu, Jun 25, 2020 at 09:39:26AM +0200, Alain Volmat wrote: > 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_smbus_host_notify_device > * i2c_free_smbus_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> > --- > v2: remove useless dev_err message in case of hnotify handling error > prevent handling hnotify in case of a incomplete write Okay, now I got it to work, I also noted a few more issues. First, I'd suggest s/i2c_smbus_host_notify/i2c_slave_host_notify/g for all occurences in this patch. This makes a stronger distinction between the generic HostNotify support and the slave specific one. Also, I wonder if this shouldn't go to i2c-smbus.c instead but I haven't checked if we end up in dependency hell then. Second best thought: at least move to i2c-core-slave.c, then we could save the #ifdeffery in the c-file? > > drivers/i2c/i2c-core-smbus.c | 110 +++++++++++++++++++++++++++++++++++++++++++ > include/linux/i2c-smbus.h | 2 + > 2 files changed, 112 insertions(+) > > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c > index 56bb840142e3..3a37664fb5f6 100644 > --- a/drivers/i2c/i2c-core-smbus.c > +++ b/drivers/i2c/i2c-core-smbus.c > @@ -708,3 +708,113 @@ int of_i2c_setup_smbus_alert(struct i2c_adapter *adapter) > } > EXPORT_SYMBOL_GPL(of_i2c_setup_smbus_alert); > #endif > + > +#if IS_ENABLED(CONFIG_I2C_SLAVE) > +struct i2c_smbus_host_notify_status { > + bool notify_start; > + u8 addr; > +}; > + > +static int i2c_smbus_host_notify_cb(struct i2c_client *client, > + enum i2c_slave_event event, u8 *val) > +{ > + struct i2c_smbus_host_notify_status *status = client->dev.platform_data; > + int ret; > + > + switch (event) { > + case I2C_SLAVE_WRITE_REQUESTED: > + status->notify_start = true; > + break; > + 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->notify_start) > + break; > + status->addr = *val; > + status->notify_start = false; So, we are safe if the message is too short. Otherwise, we capture the first byte (== address) only, right. Further bytes until STOP are discarded. So, we don't check if the message is too long and contains more than the status word. Maybe we should add that? > + break; > + case I2C_SLAVE_STOP: > + /* In case of incomplete write, don't handle host-notify */ > + if (status->notify_start) { > + status->notify_start = false; > + break; > + } > + > + ret = i2c_handle_smbus_host_notify(client->adapter, > + status->addr); > + if (ret < 0) > + return ret; > + break; > + default: The missing cases are mandatory. From my testunit driver: case I2C_SLAVE_READ_REQUESTED: case I2C_SLAVE_READ_PROCESSED: *val = 0xff; break; > + /* Only handle necessary events */ > + break; > + } > + > + return 0; > +} > + ... > --- a/include/linux/i2c-smbus.h > +++ b/include/linux/i2c-smbus.h > @@ -38,6 +38,8 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap) > return 0; > } > #endif > +struct i2c_client *i2c_new_smbus_host_notify_device(struct i2c_adapter *adapter); > +void i2c_free_smbus_host_notify_device(struct i2c_client *client); Those need to be guarded with I2C_SLAVE as well. And an #else branch with empty/successful placeholders. > > #if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_DMI) > void i2c_register_spd(struct i2c_adapter *adap); > -- > 2.7.4 >
Hi Wolfram, > Okay, now I got it to work, I also noted a few more issues. > > First, I'd suggest s/i2c_smbus_host_notify/i2c_slave_host_notify/g for > all occurences in this patch. This makes a stronger distinction between > the generic HostNotify support and the slave specific one. Ok with that. > Also, I wonder if this shouldn't go to i2c-smbus.c instead but I haven't > checked if we end up in dependency hell then. Second best thought: at > least move to i2c-core-slave.c, then we could save the #ifdeffery in the > c-file? I have actually difficulties to understand clearly what should go within i2c-smbus.c vs i2c-core-smbus or i2c-core-slave. My feeling is that i2c-core-slave is more about the registering of a slave rather than one usage of the slave mechanism. Hence I am not sure those functions/cb belong there. But at the same time, I don't know about i2c-smbus vs i2c-core-smbus. I putted it within i2c-core-smbus considering that the creation of the alert device is also done there. .... > > +{ > > + struct i2c_smbus_host_notify_status *status = client->dev.platform_data; > > + int ret; > > + > > + switch (event) { > > + case I2C_SLAVE_WRITE_REQUESTED: > > + status->notify_start = true; > > + break; > > + 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->notify_start) > > + break; > > + status->addr = *val; > > + status->notify_start = false; > > So, we are safe if the message is too short. Otherwise, we capture the > first byte (== address) only, right. Further bytes until STOP are > discarded. So, we don't check if the message is too long and contains > more than the status word. Maybe we should add that? Yes I modified that. > > + break; > > + case I2C_SLAVE_STOP: > > + /* In case of incomplete write, don't handle host-notify */ > > + if (status->notify_start) { > > + status->notify_start = false; > > + break; > > + } > > + > > + ret = i2c_handle_smbus_host_notify(client->adapter, > > + status->addr); > > + if (ret < 0) > > + return ret; > > + break; > > + default: > > The missing cases are mandatory. From my testunit driver: > > case I2C_SLAVE_READ_REQUESTED: > case I2C_SLAVE_READ_PROCESSED: > *val = 0xff; > break; Ok, done as well. > > --- a/include/linux/i2c-smbus.h > > +++ b/include/linux/i2c-smbus.h > > @@ -38,6 +38,8 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap) > > return 0; > > } > > #endif > > +struct i2c_client *i2c_new_smbus_host_notify_device(struct i2c_adapter *adapter); > > +void i2c_free_smbus_host_notify_device(struct i2c_client *client); > > Those need to be guarded with I2C_SLAVE as well. And an #else branch > with empty/successful placeholders. Ok understood.
diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c index 56bb840142e3..3a37664fb5f6 100644 --- a/drivers/i2c/i2c-core-smbus.c +++ b/drivers/i2c/i2c-core-smbus.c @@ -708,3 +708,113 @@ int of_i2c_setup_smbus_alert(struct i2c_adapter *adapter) } EXPORT_SYMBOL_GPL(of_i2c_setup_smbus_alert); #endif + +#if IS_ENABLED(CONFIG_I2C_SLAVE) +struct i2c_smbus_host_notify_status { + bool notify_start; + u8 addr; +}; + +static int i2c_smbus_host_notify_cb(struct i2c_client *client, + enum i2c_slave_event event, u8 *val) +{ + struct i2c_smbus_host_notify_status *status = client->dev.platform_data; + int ret; + + switch (event) { + case I2C_SLAVE_WRITE_REQUESTED: + status->notify_start = true; + break; + 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->notify_start) + break; + status->addr = *val; + status->notify_start = false; + break; + case I2C_SLAVE_STOP: + /* In case of incomplete write, don't handle host-notify */ + if (status->notify_start) { + status->notify_start = false; + break; + } + + ret = i2c_handle_smbus_host_notify(client->adapter, + status->addr); + if (ret < 0) + return ret; + break; + default: + /* Only handle necessary events */ + break; + } + + return 0; +} + +/** + * i2c_new_smbus_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_smbus_host_notify_device(); or an ERRPTR to indicate an error. + */ +struct i2c_client *i2c_new_smbus_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_smbus_host_notify_status *status; + struct i2c_client *client; + int ret; + + status = kzalloc(sizeof(struct i2c_smbus_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_smbus_host_notify_cb); + if (ret) { + i2c_unregister_device(client); + kfree(status); + return ERR_PTR(ret); + } + + return client; +} +EXPORT_SYMBOL_GPL(i2c_new_smbus_host_notify_device); + +/** + * i2c_free_smbus_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_smbus_host_notify_device + */ +void i2c_free_smbus_host_notify_device(struct i2c_client *client) +{ + i2c_slave_unregister(client); + kfree(client->dev.platform_data); + i2c_unregister_device(client); +} +EXPORT_SYMBOL_GPL(i2c_free_smbus_host_notify_device); +#endif diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h index 1e4e0de4ef8b..974038a684ed 100644 --- a/include/linux/i2c-smbus.h +++ b/include/linux/i2c-smbus.h @@ -38,6 +38,8 @@ static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap) return 0; } #endif +struct i2c_client *i2c_new_smbus_host_notify_device(struct i2c_adapter *adapter); +void i2c_free_smbus_host_notify_device(struct i2c_client *client); #if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_DMI) void i2c_register_spd(struct i2c_adapter *adap);
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_smbus_host_notify_device * i2c_free_smbus_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> --- v2: remove useless dev_err message in case of hnotify handling error prevent handling hnotify in case of a incomplete write drivers/i2c/i2c-core-smbus.c | 110 +++++++++++++++++++++++++++++++++++++++++++ include/linux/i2c-smbus.h | 2 + 2 files changed, 112 insertions(+)