freertos: deprecate XT_CLOCK_FREQ

- freertos: add deprecated definition for XT_CLOCK_FREQ
- flash_ops: don't use XT_CLOCK_FREQ
- unity: don't use XT_CLOCK_FREQ
- hw_random: don't use XT_CLOCK_FREQ
- core_dump: don't use XT_CLOCK_FREQ
- app_trace: don't use XT_CLOCK_FREQ
- xtensa_init: init xt_tick_divisor

components/esp32/hw_random.c

@@ -17,6 +17,7 @@
 #include <stddef.h>
 #include <string.h>
 #include "esp_attr.h"
+#include "esp_clk.h"
 #include "soc/wdev_reg.h"
 #include "freertos/FreeRTOSConfig.h"
 #include "xtensa/core-macros.h"
@@ -35,13 +36,21 @@ uint32_t IRAM_ATTR esp_random(void)
      * WDEV_RND_REG reads while waiting.
      */
 
+    /* This code does not run in a critical section, so CPU frequency switch may
+     * happens while this code runs (this will not happen in the current
+     * implementation, but possible in the future). However if that happens,
+     * the number of cycles spent on frequency switching will certainly be more
+     * than the number of cycles we need to wait here.
+     */
+    uint32_t cpu_to_apb_freq_ratio = esp_clk_cpu_freq() / esp_clk_apb_freq();
+
     static uint32_t last_ccount = 0;
     uint32_t ccount;
     uint32_t result = 0;
     do {
         ccount = XTHAL_GET_CCOUNT();
         result ^= REG_READ(WDEV_RND_REG);
-    } while (ccount - last_ccount < XT_CLOCK_FREQ / APB_CLK_FREQ * 16);
+    } while (ccount - last_ccount < cpu_to_apb_freq_ratio * 16);
     last_ccount = ccount;
     return result ^ REG_READ(WDEV_RND_REG);
 }