esp32/uart: Preserve console UART clock, fix UART console with DFS.

In commit 7c929d44 the console UART was changed to use the UART HAL.
Starting the UART HAL will change the UART clock from whatever it was
already configured at to UART_SCLK_DEFAULT.  There is no "initialize at
existing settings" option.

This clock doesn't work with DFS.

The ESP-IDF code already takes this into account, and when DFS is enabled
it will configure the console UART to use the correct platform-specific
clock that will work with DFS.

The UART HAL init undoes this and sets it back to default.

This change will query the clock before the HAL init, then use the HAL
function to restore it back.  Thus keeping the clock at the "correct"
value, which depends on platform, DFS status, and so on.

The clock frequency will be found using the UART driver function ESP-IDF
code uses for this.  The existing code hard-coded a path that worked if the
clock was the APB clock and would fail otherwise.

The UART_NUM_0 define is removed because driver/uart.h already provides
this same macro.

Signed-off-by: Trent Piepho <tpiepho@gmail.com>

1 files changed, 5 insertions, 10 deletions

diff --git a/ports/esp32/uart.c b/ports/esp32/uart.c
index fc69e279e..e0c8141a8 100644
--- a/ports/esp32/uart.c
+++ b/ports/esp32/uart.c
@@ -34,12 +34,9 @@
 #if MICROPY_HW_ENABLE_UART_REPL
 
 #include <stdio.h>
+#include "driver/uart.h" // For uart_get_sclk_freq()
 #include "hal/uart_hal.h"
 
-// Backwards compatibility for when MICROPY_HW_UART_REPL was a ESP-IDF UART
-// driver enum. Only UART_NUM_0 was supported with that version of the driver.
-#define UART_NUM_0 0
-
 STATIC void uart_irq_handler(void *arg);
 
 // Declaring the HAL structure on the stack saves a tiny amount of static RAM
@@ -53,16 +50,14 @@ STATIC void uart_irq_handler(void *arg);
 
 void uart_stdout_init(void) {
     uart_hal_context_t repl_hal = REPL_HAL_DEFN();
+    uart_sclk_t sclk;
     uint32_t sclk_freq;
 
-    #if UART_SCLK_DEFAULT == SOC_MOD_CLK_APB
-    sclk_freq = APB_CLK_FREQ; // Assumes no frequency scaling
-    #else
-    // ESP32-H2 and ESP32-C2, I think
-    #error "This SoC uses a different default UART SCLK source, code needs updating."
-    #endif
+    uart_hal_get_sclk(&repl_hal, &sclk); // To restore SCLK after uart_hal_init() resets it
+    ESP_ERROR_CHECK(uart_get_sclk_freq(sclk, &sclk_freq));
 
     uart_hal_init(&repl_hal, MICROPY_HW_UART_REPL); // Sets defaults: 8n1, no flow control
+    uart_hal_set_sclk(&repl_hal, sclk);
     uart_hal_set_baudrate(&repl_hal, MICROPY_HW_UART_REPL_BAUD, sclk_freq);
     uart_hal_rxfifo_rst(&repl_hal);
     uart_hal_txfifo_rst(&repl_hal);