lantiq: ltq-tapi: add kernel 5.10 compatiblity

Due to SCHED_FIFO being a broken scheduler model, all users of
sched_setscheduler() are converted to sched_set_fifo_low() upstream and
sched_setscheduler() is no longer exported.

The callback handling of the tasklet API was redesigned and the macros
using the old syntax renamed to _OLD.

Signed-off-by: Mathias Kresin <dev@kresin.me>
(cherry picked from commit 31f3f79700)
[Add DECLARE_TASKLET handling for kernel 5.4.235 too]
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

package/kernel/lantiq/ltq-tapi/patches/500-linux-509.patch

@@ -0,0 +1,51 @@
+--- a/src/drv_tapi_linux.c
++++ b/src/drv_tapi_linux.c
+@@ -3287,10 +3287,13 @@ static IFX_void_t proc_EntriesRemove(IFX
+ */
+ static IFX_void_t tapi_wq_setscheduler (IFX_int32_t foo)
+ {
++#if LINUX_VERSION_CODE < KERNEL_VERSION(5,9,0)
+    struct sched_param sched_params;
+-
+    sched_params.sched_priority = TAPI_OS_THREAD_PRIO_HIGH;
+    sched_setscheduler(current, SCHED_FIFO, &sched_params);
++#else
++   sched_set_fifo_low(current);
++#endif
+ }
+ #endif /* LINUX_2_6 */
+ 
+@@ -3727,6 +3730,7 @@ static IFX_int32_t TAPI_SelectCh (TAPI_F
+ */
+ IFX_int32_t TAPI_OS_ThreadPriorityModify(IFX_uint32_t newPriority)
+ {
++#if (LINUX_VERSION_CODE < KERNEL_VERSION(5,9,0))
+    struct sched_param sched_params;
+    IFX_int32_t ret;
+ 
+@@ -3744,6 +3748,10 @@ IFX_int32_t TAPI_OS_ThreadPriorityModify
+    }
+ 
+    return (ret < 0) ? IFX_ERROR : IFX_SUCCESS;
++#else
++   sched_set_fifo_low(current);
++   return IFX_SUCCESS;
++#endif
+ }
+ 
+ 
+--- a/src/drv_tapi_kpi.c
++++ b/src/drv_tapi_kpi.c
+@@ -134,7 +134,12 @@ extern IFX_int32_t           block_ingre
+ /* ========================================================================== */
+ static IFX_void_t ifx_tapi_KPI_IngressHandler (IFX_ulong_t foo);
+ #ifdef KPI_TASKLET
++#if LINUX_VERSION_CODE < KERNEL_VERSION(5,9,0) && \
++    !(LINUX_VERSION_CODE < KERNEL_VERSION(5,5,0) && LINUX_VERSION_CODE > KERNEL_VERSION(5,4,235))
+ DECLARE_TASKLET(tl_kpi_ingress, ifx_tapi_KPI_IngressHandler, 0L);
++#else
++DECLARE_TASKLET_OLD(tl_kpi_ingress, ifx_tapi_KPI_IngressHandler);
++#endif
+ #endif /* KPI_TASKLET */
+ static IFX_int32_t ifx_tapi_KPI_IngressThread (IFXOS_ThreadParams_t *pThread);
+ static IFX_return_t ifx_tapi_KPI_GroupInit(IFX_uint32_t nKpiGroup);