Re: [RFC Patch v0 1/3] i2c-smbus: Add poll interface for smbus alert
On 03/29/2014 03:15 AM, Jonathan Cameron wrote: On 27/03/14 21:50, Srinivas Pandruvada wrote: On 03/27/2014 10:34 AM, Jonathan Cameron wrote: On March 27, 2014 7:44:56 AM GMT+00:00, Jean Delvarejdelv...@suse.de wrote: On Wed, 26 Mar 2014 17:42:10 -0700, Srinivas Pandruvada wrote: The current i2c smbus alert module depends on smbus alert mechanism supported by underlying bus drivers. By specifications, these alerts can be polled if there is no hardware support. Currently multiple drivers who needs smbus alerts are creating a new i2c dummy device with address 0x0C (ARA register), by luck they don't co-exist. Otherwise i2c device creation will fail. Added a poll interface, so that all these driver can call a common interface to poll. Even if they polli, all drivers bound to an adapater will be notified by their alert callback if ARA register read is successful. Signed-off-by: Srinivas Pandruvada srinivas.pandruv...@linux.intel.com --- drivers/i2c/i2c-smbus.c | 23 +++ include/linux/i2c-smbus.h | 3 +++ 2 files changed, 26 insertions(+) diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c index fc99f0d..e274f20 100644 --- a/drivers/i2c/i2c-smbus.c +++ b/drivers/i2c/i2c-smbus.c @@ -72,6 +72,29 @@ static int smbus_do_alert(struct device *dev, void *addrp) return -EBUSY; } +int i2c_smbus_ara_poll(const struct i2c_client *client) +{ +union i2c_smbus_data data; +int status; +struct alert_data alert_data; + +status = i2c_smbus_xfer(client-adapter, 0x0C, 0, +I2C_SMBUS_READ, 0, +I2C_SMBUS_BYTE, data); +if (status 0) +return status; + +alert_data.flag = data.byte 1; +alert_data.addr = data.byte 1; + +/* Notify driver for the device which issued the alert */ + device_for_each_child(client-adapter-dev, alert_data, +smbus_do_alert); + +return data.byte; +} This is essentially duplicating code from smbus_alert(), but in a hackish way, as the ARA is never properly reserved. Your bus driver should really register the ARA with i2c_setup_smbus_alert(). I see that the code may not properly deal with the polled case everywhere but it should be pretty trivial to deal with. For example, check for alert-irq 0 before re-enabling the irq in smbus_alert(). I don't immediately see any other change needed. If SMBus alert polling is done from the i2c device driver, we'll have to find a standard way for i2c device drivers to retrieve the ara client associated with an i2c_adapter. However I still need to be convinced that this makes any sense at all. Ultimately the alert will call the i2c device drivers's alert() callback. If the i2c device driver needs to do that, there's no need to go through ARA, it might as well just call the callback by itself. So can you please explain what problem exactly you are trying to solve? As I understand it the issue is that some parts will not clear their internal interrupt status unless an at a read occurs and presumably the read has to get the correct address? To my mind we should have polling inside the core and it should ensure all devices that want to have replied. Have I miss understood how Ara is supposed to work but should we not know which device to call the callback on? Ah, I was barking up the wrong tree with this one and had missed the check that was conducted to ensure that only the right device is notified. Sorry about that. This is summary: May be Jean can suggest some better solution: - We have some sensor devices on i2C bus, which need to read ARA register to ack smbus alert signal. Without acking this, they will not allow further reads. They currently are calling i2c_new_dummy() for reserving ARA (0x0C) register. But the problem is if there are two devices on this bus both have to read ARA, they can't call i2c_new_dummy() as one of them will fail (__i2c_check_addr_busy() will return -EBUSY). - In above case, If they use hacked way to use i2_transfer function, but it will not address the real issue. Because one driver is reading ARA basically can acknowledge ALERT from wrong device. So their needs to be a core level poll so that devices can be notified, if there is an alert for their device only. Agreed. Right now at a quick glance, all devices are notified which seems odd... From physical interface level many i2controllers (including x86s) don't have separate signal for SMBALERT#. So somewhere it needs polling. For some devices SMBALERT is wired through a GPIO for GPIO interrupt. But they still need to read ARA to ACK. If it is wired through a gpio interrupt (and that interrupt is shared by various smbalert equipped devices - or there is only one present on the i2c bus) then it should be handled using the existing infrastructure. (perhaps modified slightly) If we somehow know that the interrupt is for SMBALERT, we could do with the current mechanisms. The ACPI configuration only provides an IRQ number for each
Re: [RFC Patch v0 1/3] i2c-smbus: Add poll interface for smbus alert
On 27/03/14 21:50, Srinivas Pandruvada wrote: On 03/27/2014 10:34 AM, Jonathan Cameron wrote: On March 27, 2014 7:44:56 AM GMT+00:00, Jean Delvarejdelv...@suse.de wrote: On Wed, 26 Mar 2014 17:42:10 -0700, Srinivas Pandruvada wrote: The current i2c smbus alert module depends on smbus alert mechanism supported by underlying bus drivers. By specifications, these alerts can be polled if there is no hardware support. Currently multiple drivers who needs smbus alerts are creating a new i2c dummy device with address 0x0C (ARA register), by luck they don't co-exist. Otherwise i2c device creation will fail. Added a poll interface, so that all these driver can call a common interface to poll. Even if they polli, all drivers bound to an adapater will be notified by their alert callback if ARA register read is successful. Signed-off-by: Srinivas Pandruvada srinivas.pandruv...@linux.intel.com --- drivers/i2c/i2c-smbus.c | 23 +++ include/linux/i2c-smbus.h | 3 +++ 2 files changed, 26 insertions(+) diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c index fc99f0d..e274f20 100644 --- a/drivers/i2c/i2c-smbus.c +++ b/drivers/i2c/i2c-smbus.c @@ -72,6 +72,29 @@ static int smbus_do_alert(struct device *dev, void *addrp) return -EBUSY; } +int i2c_smbus_ara_poll(const struct i2c_client *client) +{ + union i2c_smbus_data data; + int status; + struct alert_data alert_data; + + status = i2c_smbus_xfer(client-adapter, 0x0C, 0, + I2C_SMBUS_READ, 0, + I2C_SMBUS_BYTE, data); + if (status 0) + return status; + + alert_data.flag = data.byte 1; + alert_data.addr = data.byte 1; + + /* Notify driver for the device which issued the alert */ + device_for_each_child(client-adapter-dev, alert_data, + smbus_do_alert); + + return data.byte; +} This is essentially duplicating code from smbus_alert(), but in a hackish way, as the ARA is never properly reserved. Your bus driver should really register the ARA with i2c_setup_smbus_alert(). I see that the code may not properly deal with the polled case everywhere but it should be pretty trivial to deal with. For example, check for alert-irq 0 before re-enabling the irq in smbus_alert(). I don't immediately see any other change needed. If SMBus alert polling is done from the i2c device driver, we'll have to find a standard way for i2c device drivers to retrieve the ara client associated with an i2c_adapter. However I still need to be convinced that this makes any sense at all. Ultimately the alert will call the i2c device drivers's alert() callback. If the i2c device driver needs to do that, there's no need to go through ARA, it might as well just call the callback by itself. So can you please explain what problem exactly you are trying to solve? As I understand it the issue is that some parts will not clear their internal interrupt status unless an at a read occurs and presumably the read has to get the correct address? To my mind we should have polling inside the core and it should ensure all devices that want to have replied. Have I miss understood how Ara is supposed to work but should we not know which device to call the callback on? Ah, I was barking up the wrong tree with this one and had missed the check that was conducted to ensure that only the right device is notified. Sorry about that. This is summary: May be Jean can suggest some better solution: - We have some sensor devices on i2C bus, which need to read ARA register to ack smbus alert signal. Without acking this, they will not allow further reads. They currently are calling i2c_new_dummy() for reserving ARA (0x0C) register. But the problem is if there are two devices on this bus both have to read ARA, they can't call i2c_new_dummy() as one of them will fail (__i2c_check_addr_busy() will return -EBUSY). - In above case, If they use hacked way to use i2_transfer function, but it will not address the real issue. Because one driver is reading ARA basically can acknowledge ALERT from wrong device. So their needs to be a core level poll so that devices can be notified, if there is an alert for their device only. Agreed. Right now at a quick glance, all devices are notified which seems odd... From physical interface level many i2controllers (including x86s) don't have separate signal for SMBALERT#. So somewhere it needs polling. For some devices SMBALERT is wired through a GPIO for GPIO interrupt. But they still need to read ARA to ACK. If it is wired through a gpio interrupt (and that interrupt is shared by various smbalert equipped devices - or there is only one present on the i2c bus) then it should be handled using the existing infrastructure. (perhaps modified slightly) Also we can't blindly reserve 0x0c for every i2c-bus as 0x0C is a valid i2C address. There are already occupied (e.g. AK8963
Re: [RFC Patch v0 1/3] i2c-smbus: Add poll interface for smbus alert
On Wed, 26 Mar 2014 17:42:10 -0700, Srinivas Pandruvada wrote: The current i2c smbus alert module depends on smbus alert mechanism supported by underlying bus drivers. By specifications, these alerts can be polled if there is no hardware support. Currently multiple drivers who needs smbus alerts are creating a new i2c dummy device with address 0x0C (ARA register), by luck they don't co-exist. Otherwise i2c device creation will fail. Added a poll interface, so that all these driver can call a common interface to poll. Even if they polli, all drivers bound to an adapater will be notified by their alert callback if ARA register read is successful. Signed-off-by: Srinivas Pandruvada srinivas.pandruv...@linux.intel.com --- drivers/i2c/i2c-smbus.c | 23 +++ include/linux/i2c-smbus.h | 3 +++ 2 files changed, 26 insertions(+) diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c index fc99f0d..e274f20 100644 --- a/drivers/i2c/i2c-smbus.c +++ b/drivers/i2c/i2c-smbus.c @@ -72,6 +72,29 @@ static int smbus_do_alert(struct device *dev, void *addrp) return -EBUSY; } +int i2c_smbus_ara_poll(const struct i2c_client *client) +{ + union i2c_smbus_data data; + int status; + struct alert_data alert_data; + + status = i2c_smbus_xfer(client-adapter, 0x0C, 0, + I2C_SMBUS_READ, 0, + I2C_SMBUS_BYTE, data); + if (status 0) + return status; + + alert_data.flag = data.byte 1; + alert_data.addr = data.byte 1; + + /* Notify driver for the device which issued the alert */ + device_for_each_child(client-adapter-dev, alert_data, + smbus_do_alert); + + return data.byte; +} This is essentially duplicating code from smbus_alert(), but in a hackish way, as the ARA is never properly reserved. Your bus driver should really register the ARA with i2c_setup_smbus_alert(). I see that the code may not properly deal with the polled case everywhere but it should be pretty trivial to deal with. For example, check for alert-irq 0 before re-enabling the irq in smbus_alert(). I don't immediately see any other change needed. If SMBus alert polling is done from the i2c device driver, we'll have to find a standard way for i2c device drivers to retrieve the ara client associated with an i2c_adapter. However I still need to be convinced that this makes any sense at all. Ultimately the alert will call the i2c device drivers's alert() callback. If the i2c device driver needs to do that, there's no need to go through ARA, it might as well just call the callback by itself. So can you please explain what problem exactly you are trying to solve? +EXPORT_SYMBOL_GPL(i2c_smbus_ara_poll); + /* * 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. diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h index 8f1b086..f70755d 100644 --- a/include/linux/i2c-smbus.h +++ b/include/linux/i2c-smbus.h @@ -48,4 +48,7 @@ struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter, struct i2c_smbus_alert_setup *setup); int i2c_handle_smbus_alert(struct i2c_client *ara); +/* Interface to poll smbus alert */ +int i2c_smbus_ara_poll(const struct i2c_client *client); + #endif /* _LINUX_I2C_SMBUS_H */ -- Jean Delvare SUSE L3 Support -- To unsubscribe from this list: send the line unsubscribe linux-i2c in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [RFC Patch v0 1/3] i2c-smbus: Add poll interface for smbus alert
On March 27, 2014 7:44:56 AM GMT+00:00, Jean Delvare jdelv...@suse.de wrote: On Wed, 26 Mar 2014 17:42:10 -0700, Srinivas Pandruvada wrote: The current i2c smbus alert module depends on smbus alert mechanism supported by underlying bus drivers. By specifications, these alerts can be polled if there is no hardware support. Currently multiple drivers who needs smbus alerts are creating a new i2c dummy device with address 0x0C (ARA register), by luck they don't co-exist. Otherwise i2c device creation will fail. Added a poll interface, so that all these driver can call a common interface to poll. Even if they polli, all drivers bound to an adapater will be notified by their alert callback if ARA register read is successful. Signed-off-by: Srinivas Pandruvada srinivas.pandruv...@linux.intel.com --- drivers/i2c/i2c-smbus.c | 23 +++ include/linux/i2c-smbus.h | 3 +++ 2 files changed, 26 insertions(+) diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c index fc99f0d..e274f20 100644 --- a/drivers/i2c/i2c-smbus.c +++ b/drivers/i2c/i2c-smbus.c @@ -72,6 +72,29 @@ static int smbus_do_alert(struct device *dev, void *addrp) return -EBUSY; } +int i2c_smbus_ara_poll(const struct i2c_client *client) +{ +union i2c_smbus_data data; +int status; +struct alert_data alert_data; + +status = i2c_smbus_xfer(client-adapter, 0x0C, 0, +I2C_SMBUS_READ, 0, +I2C_SMBUS_BYTE, data); +if (status 0) +return status; + +alert_data.flag = data.byte 1; +alert_data.addr = data.byte 1; + +/* Notify driver for the device which issued the alert */ +device_for_each_child(client-adapter-dev, alert_data, +smbus_do_alert); + +return data.byte; +} This is essentially duplicating code from smbus_alert(), but in a hackish way, as the ARA is never properly reserved. Your bus driver should really register the ARA with i2c_setup_smbus_alert(). I see that the code may not properly deal with the polled case everywhere but it should be pretty trivial to deal with. For example, check for alert-irq 0 before re-enabling the irq in smbus_alert(). I don't immediately see any other change needed. If SMBus alert polling is done from the i2c device driver, we'll have to find a standard way for i2c device drivers to retrieve the ara client associated with an i2c_adapter. However I still need to be convinced that this makes any sense at all. Ultimately the alert will call the i2c device drivers's alert() callback. If the i2c device driver needs to do that, there's no need to go through ARA, it might as well just call the callback by itself. So can you please explain what problem exactly you are trying to solve? As I understand it the issue is that some parts will not clear their internal interrupt status unless an at a read occurs and presumably the read has to get the correct address? To my mind we should have polling inside the core and it should ensure all devices that want to have replied. Have I miss understood how Ara is supposed to work but should we not know which device to call the callback on? +EXPORT_SYMBOL_GPL(i2c_smbus_ara_poll); + /* * 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. diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h index 8f1b086..f70755d 100644 --- a/include/linux/i2c-smbus.h +++ b/include/linux/i2c-smbus.h @@ -48,4 +48,7 @@ struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter, struct i2c_smbus_alert_setup *setup); int i2c_handle_smbus_alert(struct i2c_client *ara); +/* Interface to poll smbus alert */ +int i2c_smbus_ara_poll(const struct i2c_client *client); + #endif /* _LINUX_I2C_SMBUS_H */ -- Sent from my Android phone with K-9 Mail. Please excuse my brevity. -- To unsubscribe from this list: send the line unsubscribe linux-i2c in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[RFC Patch v0 1/3] i2c-smbus: Add poll interface for smbus alert
The current i2c smbus alert module depends on smbus alert mechanism supported by underlying bus drivers. By specifications, these alerts can be polled if there is no hardware support. Currently multiple drivers who needs smbus alerts are creating a new i2c dummy device with address 0x0C (ARA register), by luck they don't co-exist. Otherwise i2c device creation will fail. Added a poll interface, so that all these driver can call a common interface to poll. Even if they polli, all drivers bound to an adapater will be notified by their alert callback if ARA register read is successful. Signed-off-by: Srinivas Pandruvada srinivas.pandruv...@linux.intel.com --- drivers/i2c/i2c-smbus.c | 23 +++ include/linux/i2c-smbus.h | 3 +++ 2 files changed, 26 insertions(+) diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c index fc99f0d..e274f20 100644 --- a/drivers/i2c/i2c-smbus.c +++ b/drivers/i2c/i2c-smbus.c @@ -72,6 +72,29 @@ static int smbus_do_alert(struct device *dev, void *addrp) return -EBUSY; } +int i2c_smbus_ara_poll(const struct i2c_client *client) +{ + union i2c_smbus_data data; + int status; + struct alert_data alert_data; + + status = i2c_smbus_xfer(client-adapter, 0x0C, 0, + I2C_SMBUS_READ, 0, + I2C_SMBUS_BYTE, data); + if (status 0) + return status; + + alert_data.flag = data.byte 1; + alert_data.addr = data.byte 1; + + /* Notify driver for the device which issued the alert */ + device_for_each_child(client-adapter-dev, alert_data, + smbus_do_alert); + + return data.byte; +} +EXPORT_SYMBOL_GPL(i2c_smbus_ara_poll); + /* * 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. diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h index 8f1b086..f70755d 100644 --- a/include/linux/i2c-smbus.h +++ b/include/linux/i2c-smbus.h @@ -48,4 +48,7 @@ struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter, struct i2c_smbus_alert_setup *setup); int i2c_handle_smbus_alert(struct i2c_client *ara); +/* Interface to poll smbus alert */ +int i2c_smbus_ara_poll(const struct i2c_client *client); + #endif /* _LINUX_I2C_SMBUS_H */ -- 1.8.3.2 -- To unsubscribe from this list: send the line unsubscribe linux-i2c in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html