Make ecrt_master_reset available in RT context

It takes the master_sem, so calling it from RT context is not an option.
The reset is done by a workqueue now, which is triggered in a NMI-safe way.

Fixes #103

master/ioctl.c

@@ -2282,9 +2282,12 @@ static ATTRIBUTES int ec_ioctl_reset(
         ec_ioctl_context_t *ctx /**< Private data structure of file handle. */
         )
 {
-    down(&master->master_sem);
-    ecrt_master_reset(master);
-    up(&master->master_sem);
+#ifdef EC_IOCTL_RTDM
+    /* Xenomai/LXRT is like NMI context, so we do a two-stage schedule. */
+    irq_work_queue(&master->sc_reset_work_kicker);
+#else
+    schedule_work(&master->sc_reset_work);
+#endif
     return 0;
 }
 
@@ -4720,6 +4723,13 @@ static long ec_ioctl_both(
         case EC_IOCTL_MASTER_LINK_STATE:
             ret = ec_ioctl_master_link_state(master, arg, ctx);
             break;
+        case EC_IOCTL_RESET:
+            if (!ctx->writable) {
+                ret = -EPERM;
+                break;
+            }
+            ret = ec_ioctl_reset(master, arg, ctx);
+            break;
         case EC_IOCTL_REF_CLOCK_TIME:
             if (!ctx->writable) {
                 ret = -EPERM;
@@ -5204,13 +5214,6 @@ static long ec_ioctl_nrt
             }
             ret = ec_ioctl_deactivate(master, arg, ctx);
             break;
-        case EC_IOCTL_RESET:
-            if (!ctx->writable) {
-                ret = -EPERM;
-                break;
-            }
-            ret = ec_ioctl_reset(master, arg, ctx);
-            break;
         case EC_IOCTL_SC_SYNC:
             if (!ctx->writable) {
                 ret = -EPERM;

master/master.c

@@ -107,6 +107,8 @@ static int ec_master_eoe_thread(void *);
 void ec_master_find_dc_ref_clock(ec_master_t *);
 void ec_master_clear_device_stats(ec_master_t *);
 void ec_master_update_device_stats(ec_master_t *);
+static void sc_reset_task_kicker(struct irq_work *work);
+static void sc_reset_task(struct work_struct *work);
 
 /****************************************************************************/
 
@@ -316,6 +318,9 @@ int ec_master_init(ec_master_t *master, /**< EtherCAT master */
     master->dc_ref_config = NULL;
     master->dc_ref_clock = NULL;
 
+    INIT_WORK(&master->sc_reset_work, sc_reset_task);
+    init_irq_work(&master->sc_reset_work_kicker, sc_reset_task_kicker);
+
     // init character device
     ret = ec_cdev_init(&master->cdev, master, device_number);
     if (ret)
@@ -383,6 +388,9 @@ void ec_master_clear(
 
     ec_cdev_clear(&master->cdev);
 
+    irq_work_sync(&master->sc_reset_work_kicker);
+    cancel_work_sync(&master->sc_reset_work);
+
 #ifdef EC_EOE
     ec_master_clear_eoe_handlers(master);
 #endif
@@ -3257,6 +3265,27 @@ void ecrt_master_reset(ec_master_t *master)
 
 /****************************************************************************/
 
+static void sc_reset_task_kicker(struct irq_work *work)
+{
+    struct ec_master *master =
+        container_of(work, struct ec_master, sc_reset_work_kicker);
+    schedule_work(&master->sc_reset_work);
+}
+
+/****************************************************************************/
+
+static void sc_reset_task(struct work_struct *work)
+{
+    struct ec_master *master =
+        container_of(work, struct ec_master, sc_reset_work);
+
+    down(&master->master_sem);
+    ecrt_master_reset(master);
+    up(&master->master_sem);
+}
+
+/****************************************************************************/
+
 /** \cond */
 
 EXPORT_SYMBOL(ecrt_master_create_domain);

master/master.h

@@ -30,11 +30,13 @@
 #define __EC_MASTER_H__
 
 #include <linux/version.h>
+#include <linux/irq_work.h>
 #include <linux/list.h>
 #include <linux/timer.h>
 #include <linux/wait.h>
 #include <linux/kthread.h>
 #include <linux/rtmutex.h>
+#include <linux/workqueue.h>
 
 #include "device.h"
 #include "domain.h"
@@ -294,6 +296,9 @@ struct ec_master {
 
     wait_queue_head_t request_queue; /**< Wait queue for external requests
                                        from user space. */
+    struct work_struct sc_reset_work; /**< Task to reset slave configuration. */
+    struct irq_work sc_reset_work_kicker; /**< NMI-Safe kicker to trigger
+                                            reset task above. */
 };
 
 /****************************************************************************/