[PATCH 1/2] drivers/gpio: Add support for selecting real-time clock timestamps

[Jan Kiszka via Xenomai]

From: Jan Kiszka <jan.kis...@siemens.com>

This allows to compare timestamps of GPIO pins against other devices and
ensures that the stamps are synchronized cross-systems in case PTP is in
use (dovetail-based kernels). Keep default to monotonic for now.

Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
---
 include/cobalt/kernel/rtdm/gpio.h |  1 +
 include/rtdm/uapi/gpio.h          |  4 +++-
 kernel/drivers/gpio/gpio-core.c   | 14 +++++++++++---
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/include/cobalt/kernel/rtdm/gpio.h 
b/include/cobalt/kernel/rtdm/gpio.h
index 00055ec0a9..72cc3a0356 100644
--- a/include/cobalt/kernel/rtdm/gpio.h
+++ b/include/cobalt/kernel/rtdm/gpio.h
@@ -34,6 +34,7 @@ struct rtdm_gpio_pin {
        char *name;
        struct gpio_desc *desc;
        nanosecs_abs_t timestamp;
+       bool monotonic_timestamp;
 };
 
 struct rtdm_gpio_chip {
diff --git a/include/rtdm/uapi/gpio.h b/include/rtdm/uapi/gpio.h
index 2839f7d51c..fb84274453 100644
--- a/include/rtdm/uapi/gpio.h
+++ b/include/rtdm/uapi/gpio.h
@@ -29,7 +29,9 @@ struct rtdm_gpio_readout {
 #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)
-#define GPIO_RTIOC_TS          _IOR(RTDM_CLASS_GPIO, 7, int)
+#define GPIO_RTIOC_TS_MONO     _IOR(RTDM_CLASS_GPIO, 7, int)
+#define GPIO_RTIOC_TS          GPIO_RTIOC_TS_MONO
+#define GPIO_RTIOC_TS_REAL     _IOR(RTDM_CLASS_GPIO, 8, int)
 
 #define GPIO_TRIGGER_NONE              0x0 /* unspecified */
 #define GPIO_TRIGGER_EDGE_RISING       0x1
diff --git a/kernel/drivers/gpio/gpio-core.c b/kernel/drivers/gpio/gpio-core.c
index 600ef9789a..06a19b33a9 100644
--- a/kernel/drivers/gpio/gpio-core.c
+++ b/kernel/drivers/gpio/gpio-core.c
@@ -189,11 +189,13 @@ static int gpio_pin_ioctl_nrt(struct rtdm_fd *fd,
                gpio_free(gpio);
                chan->requested = false;
                break;
-       case GPIO_RTIOC_TS:
+       case GPIO_RTIOC_TS_MONO:
+       case GPIO_RTIOC_TS_REAL:
                ret = rtdm_safe_copy_from_user(fd, &val, arg, sizeof(val));
                if (ret)
                        return ret;
                chan->want_timestamp = !!val;
+               pin->monotonic_timestamp = request == GPIO_RTIOC_TS_MONO;
                break;
        default:
                return -EINVAL;
@@ -228,8 +230,11 @@ static ssize_t gpio_pin_read_rt(struct rtdm_fd *fd,
                        if (ret)
                                return ret;
                        rdo.timestamp = pin->timestamp;
-               } else
+               } else if (pin->monotonic_timestamp) {
                        rdo.timestamp = rtdm_clock_read_monotonic();
+               } else {
+                       rdo.timestamp = rtdm_clock_read();
+               }
 
                len = sizeof(rdo);
                rdo.value = gpiod_get_raw_value(pin->desc);
@@ -489,7 +494,10 @@ int rtdm_gpiochip_post_event(struct rtdm_gpio_chip *rgc,
                return -EINVAL;
 
        pin = rgc->pins + offset;
-       pin->timestamp = rtdm_clock_read_monotonic();
+       if (pin->monotonic_timestamp)
+               pin->timestamp = rtdm_clock_read_monotonic();
+       else
+               pin->timestamp = rtdm_clock_read();
        rtdm_event_signal(&pin->event);
        
        return 0;
-- 
2.31.1