From b8cc222e765d22dc2c2f3a4f361e4a0977fe93ee Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Date: Fri, 9 Dec 2022 19:13:10 +0100
Subject: [PATCH] cpu/stm32/periph_timer: implement timer_set()

The fallback implementation of timer_set() in `drivers/periph_common`
is known to fail on short relative sets. This adds a robust
implementation.
---
 cpu/stm32/include/periph/cpu_timer.h |  5 ++++
 cpu/stm32/periph/timer.c             | 41 ++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/cpu/stm32/include/periph/cpu_timer.h b/cpu/stm32/include/periph/cpu_timer.h
index 9d22a99969..83ed1c6821 100644
--- a/cpu/stm32/include/periph/cpu_timer.h
+++ b/cpu/stm32/include/periph/cpu_timer.h
@@ -34,6 +34,11 @@ extern "C" {
  */
 #define TIMER_CHANNEL_NUMOF (4U)
 
+/**
+ * @brief   The driver provides a relative set function
+ */
+#define PERIPH_TIMER_PROVIDES_SET
+
 /**
  * @brief   Define a macro for accessing a timer channel
  */
diff --git a/cpu/stm32/periph/timer.c b/cpu/stm32/periph/timer.c
index fdb45a217f..0118f51d2a 100644
--- a/cpu/stm32/periph/timer.c
+++ b/cpu/stm32/periph/timer.c
@@ -22,6 +22,7 @@
 
 #include "cpu.h"
 #include "periph/timer.h"
+#include <sys/_intsup.h>
 
 /**
  * @brief   Interrupt context for each configured timer
@@ -146,6 +147,46 @@ int timer_set_absolute(tim_t tim, int channel, unsigned int value)
     return 0;
 }
 
+int timer_set(tim_t tim, int channel, unsigned int timeout)
+{
+    if (channel >= (int)TIMER_CHANNEL_NUMOF) {
+        return -1;
+    }
+
+    unsigned irqstate = irq_disable();
+    set_oneshot(tim, channel);
+
+    /* clear spurious IRQs */
+    dev(tim)->SR &= ~(TIM_SR_CC1IF << channel);
+
+    unsigned value = (dev(tim)->CNT + timeout) & timer_config[tim].max;
+    TIM_CHAN(tim, channel) = value;
+
+    /* enable IRQ */
+    dev(tim)->DIER |= (TIM_DIER_CC1IE << channel);
+
+#ifdef MODULE_PERIPH_TIMER_PERIODIC
+    if (dev(tim)->ARR == TIM_CHAN(tim, channel)) {
+        dev(tim)->ARR = timer_config[tim].max;
+    }
+#endif
+
+    /* calculate time till timeout */
+    value = (value - dev(tim)->CNT) & timer_config[tim].max;
+
+    if (value > timeout) {
+        /* time till timeout is larger than requested --> timer already expired
+         * ==> let's make sure we have an IRQ pending :) */
+        dev(tim)->CR1 &= ~(TIM_CR1_CEN);
+        TIM_CHAN(tim, channel) = dev(tim)->CNT;
+        dev(tim)->CR1 |= TIM_CR1_CEN;
+    }
+
+    irq_restore(irqstate);
+
+    return 0;
+}
+
 #ifdef MODULE_PERIPH_TIMER_PERIODIC
 int timer_set_periodic(tim_t tim, int channel, unsigned int value, uint8_t flags)
 {