On 1/25/19 10:48 AM, Jan Kiszka wrote: > On 25.01.19 10:38, Philippe Gerum wrote: >> On 1/25/19 10:33 AM, Jan Kiszka wrote: >>> On 25.01.19 10:31, Philippe Gerum wrote: >>>> On 1/25/19 10:23 AM, Jan Kiszka wrote: >>>>> On 25.01.19 10:15, Philippe Gerum wrote: >>>>>> On 1/24/19 7:17 PM, Jan Kiszka wrote: >>>>>>> On 24.01.19 16:34, Philippe Gerum wrote: >>>>>>>> In timestamping mode, read() returns the timestamp of the latest >>>>>>>> event >>>>>>>> receipt on the pin based on CLOCK_MONOTONIC, along with the pin >>>>>>>> state. This is an optional pin readout mode controlled by the >>>>>>>> GPIO_RTIOC_TS request, e.g.: >>>>>>>> >>>>>>>> struct rtdm_gpio_readout rdo; >>>>>>>> int ret, on, val; >>>>>>>> >>>>>>>> on = 1; >>>>>>>> ret = ioctl(pinfd, GPIO_RTIOC_TS, &on); >>>>>>>> ret = read(pinfd, &rdo, sizeof(rdo)); >>>>>>>> /* pin state changed to rdo.value at time rdo.timestamp */ >>>>>>>> >>>>>>>> on = 0; >>>>>>>> ret = ioctl(pinfd, GPIO_RTIOC_TS, &on); >>>>>>>> ret = read(pinfd, &val, sizeof(val)); >>>>>>>> /* pin state changed to value (time of change unspecified) */ >>>>>>>> >>>>>>>> By default, timestamping mode is disabled, which corresponds to the >>>>>>>> original behavior. >>>>>>>> >>>>>>>> Signed-off-by: Philippe Gerum <[email protected]> >>>>>>>> --- >>>>>>>> include/cobalt/kernel/rtdm/gpio.h | 1 + >>>>>>>> include/rtdm/uapi/gpio.h | 18 +++++++---- >>>>>>>> kernel/drivers/gpio/gpio-core.c | 54 >>>>>>>> +++++++++++++++++++++++-------- >>>>>>>> 3 files changed, 54 insertions(+), 19 deletions(-) >>>>>>>> >>>>>>>> diff --git a/include/cobalt/kernel/rtdm/gpio.h >>>>>>>> b/include/cobalt/kernel/rtdm/gpio.h >>>>>>>> index cdb472f8a..00055ec0a 100644 >>>>>>>> --- a/include/cobalt/kernel/rtdm/gpio.h >>>>>>>> +++ b/include/cobalt/kernel/rtdm/gpio.h >>>>>>>> @@ -33,6 +33,7 @@ struct rtdm_gpio_pin { >>>>>>>> rtdm_event_t event; >>>>>>>> char *name; >>>>>>>> struct gpio_desc *desc; >>>>>>>> + nanosecs_abs_t timestamp; >>>>>>>> }; >>>>>>>> struct rtdm_gpio_chip { >>>>>>>> diff --git a/include/rtdm/uapi/gpio.h b/include/rtdm/uapi/gpio.h >>>>>>>> index b745f156c..ac14be66c 100644 >>>>>>>> --- a/include/rtdm/uapi/gpio.h >>>>>>>> +++ b/include/rtdm/uapi/gpio.h >>>>>>>> @@ -18,12 +18,18 @@ >>>>>>>> #ifndef _RTDM_UAPI_GPIO_H >>>>>>>> #define _RTDM_UAPI_GPIO_H >>>>>>>> -#define GPIO_RTIOC_DIR_OUT _IOW(RTDM_CLASS_GPIO, 0, >>>>>>>> int) >>>>>>>> -#define GPIO_RTIOC_DIR_IN _IO(RTDM_CLASS_GPIO, 1) >>>>>>>> -#define GPIO_RTIOC_IRQEN _IOW(RTDM_CLASS_GPIO, 2, int) /* >>>>>>>> GPIO >>>>>>>> trigger */ >>>>>>>> -#define GPIO_RTIOC_IRQDIS _IO(RTDM_CLASS_GPIO, 3) >>>>>>>> -#define GPIO_RTIOC_REQS _IO(RTDM_CLASS_GPIO, 4) >>>>>>>> -#define GPIO_RTIOC_RELS _IO(RTDM_CLASS_GPIO, 5) >>>>>>>> +struct rtdm_gpio_readout { >>>>>>>> + __u64 timestamp; >>>>>>> >>>>>>> nanosecs_abs_t - we use this type also in to userspace interface. >>>>>>> >>>>>> >>>>>> Nope. This is ABI stuff, nanosecs_abs_t is not guaranteed to have the >>>>>> same size regardless of the ABI models, which is unsafe in mixed >>>>>> 32/64 >>>>>> model configurations. OTOH, __u64 is safe. >>>>> >>>>> If nanosecs_abs_t is alread an ABI, and it is used as such for a long >>>>> time (see include/rtdm/uapi/serial.h). If you see a bug in its >>>>> definition, that needs to be fixed. We should not resolve that by >>>>> choosing open-coded local workarounds. >>>>> >>>> >>>> nanosecs_t is not defined in the Xenomai ABI, never has been. Using >>>> nanosecs_t in structs actually abuses such ABI. So we may either keep >>>> adding even more nanosecs, or fix the spots where it should be replaced >>>> with __u64. >>> >>> Xenomai ABI includes the driver ABI - so your assumption might have been >>> it's not while it was de facto. >>> >>> Again, let's address the issue, not work around it. >>> >> >> __u64 is the fix, using nanosecs*_t in uapi/ is wrong. So please merge >> this fix, and we'll see how we can progress fixing other abuses. > > Nope: Adjust nanosecs_*_t if it has a problem ([u]int64_t vs. __u/s64 - > what's the problem exactly?), and use that. That will both address > existing users and future ones. No special solution for the GPIO driver > here. >
I'm not pushing for a GPIO-specific solution, I'm pushing for using ABI-specific types which state their size explicitly in uapi/ data as much as possible, which is safer with mixed ABI models and would have spared me a lot of trouble back when I implemented the 32/64 ABI support for Xenomai. nanosecs_* is originally a kernel-side type which slipped in uapi/ structs, which does not state its size. The fact that nanosecs_* is defined as uint64_t but the kernel today does not address the issue at stake: there would be no obvious way to detect that a discrepancy might exist with what userland expects once such definition is modified for a different with if ever (which might be highly unlikely for nanosecs, but could happen for other types). -- Philippe.
