Re: [PATCH v2 2/3] hwmon: (lm90) add support to handle IRQ.

[Wei Ni <wni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

On 07/11/2013 02:12 AM, Guenter Roeck wrote:
> On Wed, Jul 10, 2013 at 10:05:53AM -0700, Thierry Reding wrote:
>> On Wed, Jul 10, 2013 at 07:25:38PM +0800, Wei Ni wrote:
>>> When the temperature exceed the limit range value,
>>> the driver can handle the interrupt.
>>>
>>> Signed-off-by: Wei Ni <wni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>> ---
>>>  drivers/hwmon/lm90.c |   77 +++++++++++++++++++++++++++++++++++++++++---------
>>>  1 file changed, 64 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/drivers/hwmon/lm90.c b/drivers/hwmon/lm90.c
>>> index 2cb7f8e..88ff362 100644
>>> --- a/drivers/hwmon/lm90.c
>>> +++ b/drivers/hwmon/lm90.c
>>> @@ -89,6 +89,7 @@
>>>  #include <linux/err.h>
>>>  #include <linux/mutex.h>
>>>  #include <linux/sysfs.h>
>>> +#include <linux/interrupt.h>
>>>  
>>>  /*
>>>   * Addresses to scan
>>> @@ -179,6 +180,19 @@ enum chips { lm90, adm1032, lm99, lm86, max6657, max6659, adt7461, max6680,
>>>  #define LM90_HAVE_TEMP3		(1 << 6) /* 3rd temperature sensor	*/
>>>  #define LM90_HAVE_BROKEN_ALERT	(1 << 7) /* Broken alert		*/
>>>  
>>> +/* LM90 status */
>>> +#define LM90_LTHRM	(1 << 0)	/* local THERM limit tripped */
>>> +#define LM90_RTHRM	(1 << 1)	/* remote THERM limit tripped */
>>> +#define LM90_OPEN	(1 << 2)	/* remote is an open circuit */
>>> +#define LM90_RLOW	(1 << 3)	/* remote low temp limit tripped */
>>> +#define LM90_RHIGH	(1 << 4)	/* remote high temp limit tripped */
>>> +#define LM90_LLOW	(1 << 5)	/* local low temp limit tripped */
>>> +#define LM90_LHIGH	(1 << 6)	/* local high temp limit tripped */
>>> +#define LM90_BUSY	(1 << 7)	/* ADC is converting */
>>> +
>>> +#define MAX6696_RLOW	(1 << 3)	/* remote2 low temp limit tripped */
>>> +#define MAX6696_RHIGH	(1 << 4)	/* remote2 high temp limit tripped */
>>
>> I think this is a nice cleanup, but I'll leave it up to Guenter or Jean
>> to decide if they want to have this. One problem with the above is that
>> it's not immediately clear which register contains these bits. That's
>> often solved by using the register name as prefix but that will in turn
>> make the names for these bits rather long:
>>
>> 	#define LM90_REG_R_STATUS_LTHRM	(1 << 0)
>> 	...
>>
>> Perhaps something like
>>
>> 	#define LM90_STATUS_LTHRM	(1 << 0)
>>
>> would be a good compromise?
>>
> Something like that, yes.

Ok, I will change it.

> 
>> Also if Guenter and Jean agree that this is a nice cleanup, it should
>> probably go into a separate patch since it isn't directly related to the
>> IRQ support.
>>
> Correct.

Yes, it should be a separate patch, I will do it.

> 
>>>  /*
>>>   * Driver data (common to all clients)
>>>   */
>>> @@ -1423,6 +1437,43 @@ static void lm90_init_client(struct i2c_client *client)
>>>  		i2c_smbus_write_byte_data(client, LM90_REG_W_CONFIG1, config);
>>>  }
>>>  
>>> +static void lm90_alarm_status(struct i2c_client *client,
>>> +			      u8 alarms, u8 alarms_max6696)
>>> +{
>>> +	if (alarms & (LM90_LLOW | LM90_LHIGH | LM90_LTHRM))
>>> +		dev_warn(&client->dev,
>>> +			 "temp%d out of range, please check!\n", 1);
>>> +	if (alarms & (LM90_RLOW | LM90_RHIGH | LM90_RTHRM))
>>> +		dev_warn(&client->dev,
>>> +			 "temp%d out of range, please check!\n", 2);
>>> +	if (alarms & LM90_OPEN)
>>> +		dev_warn(&client->dev,
>>> +			 "temp%d diode open, please check!\n", 2);
>>> +
>>> +	if (alarms_max6696 & (MAX6696_RLOW | MAX6696_RHIGH))
>>> +		dev_warn(&client->dev,
>>> +			 "temp%d out of range, please check!\n", 3);
>>> +}
>>> +
>>> +static irqreturn_t lm90_irq_thread(int irq, void *dev_id)
>>> +{
>>> +	struct lm90_data *data = dev_id;
>>> +	struct i2c_client *client = to_i2c_client(data->hwmon_dev->parent);
>>> +	u8 alarms, alarms_max6696 = 0;
>>> +
>>> +	lm90_read_reg(client, LM90_REG_R_STATUS, &alarms);
>>> +
>>> +	if (data->kind == max6696)
>>> +		lm90_read_reg(client, MAX6696_REG_R_STATUS2, &alarms_max6696);
>>> +
>>> +	if ((alarms & 0x7f) == 0 && (alarms_max6696 & 0xfe) == 0) {
>>> +		return IRQ_NONE;
>>
>> For non-MAX6696 chips this will evaluate to:
>>
>> 	if ((alarms & 0x7f) == 0 && (0 & 0xfe) == 0)
>>
>> and therefore be true for any value of "alarms" and therefore always
>> result in IRQ_NONE being returned.
>>
> Not really. If
> 	(alarms & 0xfe) == 0
> returns false (ie thee is an alarm) the expression is false and the
> if statement won't be executed. Or maybe I didn't get enough sleep
> last night ;).
> 
>> One other thing that slightly bugs me about this is that it's a little
>> tedious to pass alarms_max6696 around like this. Suppose yet another
>> slightly different variant is supported by this chip in the future,
>> it's possible it will require another alarms_XYZ variable that has to be
>> passed around. I don't have a better suggestion though, so maybe it can
>> remain like this and be rewritten at some point should the need arise.
>>
> The driver has tables to separate chips, so masks for status and status2 can
> be made generic and configurable if needed. But, yes, it would be better to
> select a generic name for the variable from the beginning (status and status2
> would do quite nicely).
> 
>> Thierry
> 
>