systimer: add helper functions to convert between tick and us

components/esp_hw_support/CMakeLists.txt

@@ -40,6 +40,10 @@ if(NOT BOOTLOADER_BUILD)
         list(APPEND srcs "esp_async_memcpy.c")
     endif()
 
+    if(CONFIG_SOC_SYSTIMER_SUPPORTED)
+        list(APPEND srcs "port/${target}/systimer.c")
+    endif()
+
 else()
     # Requires "_esp_error_check_failed()" function
     list(APPEND priv_requires "esp_system")

components/esp_hw_support/include/esp_private/systimer.h

@@ -0,0 +1,33 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Convert ticks to microseconds
+ *
+ * @param ticks ticks to convert
+ * @return microseconds
+ */
+uint64_t systimer_ticks_to_us(uint64_t ticks) __attribute__((const));
+
+/**
+ * @brief Convert microseconds to ticks
+ *
+ * @param us microseconds to convert
+ * @return ticks
+ */
+uint64_t systimer_us_to_ticks(uint64_t us) __attribute__((const));
+
+#ifdef __cplusplus
+}
+#endif

components/esp_hw_support/linker.lf

@@ -28,3 +28,5 @@ entries:
         gdma: gdma_stop (noflash)
         gdma: gdma_append (noflash)
         gdma: gdma_reset (noflash)
+    if SOC_SYSTIMER_SUPPORTED = y:
+        systimer (noflash)

components/esp_hw_support/port/esp32c2/systimer.c

@@ -0,0 +1,37 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "sdkconfig.h"
+#include "esp_private/systimer.h"
+
+/**
+ * @brief systimer's clock source is fixed to XTAL (40MHz/26MHz), and has a fixed fractional divider (2.5).
+ *        So the resolution of the systimer is 40MHz/2.5 = 16MHz, or 26MHz/2.5 = 10.4MHz.
+ */
+
+#if CONFIG_ESP32C2_XTAL_FREQ_40
+uint64_t systimer_ticks_to_us(uint64_t ticks)
+{
+    return ticks / 16;
+}
+
+uint64_t systimer_us_to_ticks(uint64_t us)
+{
+    return us * 16;
+}
+#elif CONFIG_ESP32C2_XTAL_FREQ_26
+uint64_t systimer_ticks_to_us(uint64_t ticks)
+{
+    return ticks * 5 / 52;
+}
+
+uint64_t systimer_us_to_ticks(uint64_t us)
+{
+    return us * 52 / 5;
+}
+#else
+#error "Unsupported XTAL frequency by systimer"
+#endif // CONFIG_ESP32C2_XTAL_FREQ_xx

components/esp_hw_support/port/esp32c3/systimer.c

@@ -0,0 +1,22 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "esp_private/systimer.h"
+
+/**
+ * @brief systimer's clock source is fixed to XTAL (40MHz), and has a fixed fractional divider (2.5).
+ *        So the resolution of the systimer is 40MHz/2.5 = 16MHz.
+ */
+
+uint64_t systimer_ticks_to_us(uint64_t ticks)
+{
+    return ticks / 16;
+}
+
+uint64_t systimer_us_to_ticks(uint64_t us)
+{
+    return us * 16;
+}

components/esp_hw_support/port/esp32h2/systimer.c

@@ -0,0 +1,22 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "esp_private/systimer.h"
+
+/**
+ * @brief systimer's clock source is fixed to XTAL (40MHz), and has a fixed fractional divider (2.5).
+ *        So the resolution of the systimer is 40MHz/2.5 = 16MHz.
+ */
+
+uint64_t systimer_ticks_to_us(uint64_t ticks)
+{
+    return ticks / 16;
+}
+
+uint64_t systimer_us_to_ticks(uint64_t us)
+{
+    return us * 16;
+}

components/esp_hw_support/port/esp32s2/systimer.c

@@ -0,0 +1,22 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "esp_private/systimer.h"
+
+/**
+ * @brief systimer's clock source can be switch between XTAL (40MHz) and APB (80MHz).
+ *        But the resolution of the systimer is configured to fix to 80MHz.
+ */
+
+uint64_t systimer_ticks_to_us(uint64_t ticks)
+{
+    return ticks / 80;
+}
+
+uint64_t systimer_us_to_ticks(uint64_t us)
+{
+    return us * 80;
+}

components/esp_hw_support/port/esp32s3/systimer.c

@@ -0,0 +1,22 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "esp_private/systimer.h"
+
+/**
+ * @brief systimer's clock source is fixed to XTAL (40MHz), and has a fixed fractional divider (2.5).
+ *        So the resolution of the systimer is 40MHz/2.5 = 16MHz.
+ */
+
+uint64_t systimer_ticks_to_us(uint64_t ticks)
+{
+    return ticks / 16;
+}
+
+uint64_t systimer_us_to_ticks(uint64_t us)
+{
+    return us * 16;
+}