uart: fix esp32h2, esp32c6, and esp32 initialization for the early stages

Author: antmak

src/esp32/src/uart.c

@@ -4,16 +4,66 @@
  * SPDX-License-Identifier: Apache-2.0 OR MIT
  */
 
+
 #include <stdint.h>
+#include <stddef.h>
 
 #include <rtc_clk.h>
+#include <reg_base.h>
 
 // These functions are defined in the ROM
 extern void uartAttach(void);
-extern void uart_div_modify(uint8_t uart_no, uint32_t DivLatchValue);
+void Uart_Init(uint8_t uart_no, uint32_t clock);
+extern void ets_install_putc1(void (*p)(char c));
+extern void ets_install_putc2(void (*p)(char c));
+extern uint32_t ets_get_detected_xtal_freq(void);
+
+#define RTC_STORE5 (DR_REG_RTCCNTL_BASE + 0xb4)
+
+#define REG_WRITE(_r, _v)    (*(volatile uint32_t *)(_r)) = (_v)
+#define REG_READ(_r) (*(volatile uint32_t *)(_r))
+
+/* The symbol
+
+PROVIDE ( ets_get_detected_xtal_freq_patch = 40065c18 );
+
+exists in the ROM rev.3, but not in earlier revisions.
+I don't think it affects the stub size much.
+ */
+static uint32_t ets_get_detected_xtal_freq_patch()
+{
+    // Original detection function, reads from RTC_STORE5
+    // or CK8 detected frequency otherwise
+    uint32_t clock = ets_get_detected_xtal_freq();
+
+    // Quantize the detected clock to either 40MHz or 26MHz
+    // mid-point is 30.5MHz based on data from ATE team about
+    // 8M clock error rates
+    if (clock < 30500 * 1000) {
+        clock = 26 * 1000 * 1000;
+    } else {
+        clock = 40 * 1000 * 1000;
+    }
+
+    do {
+        uint32_t high, low;
+        high = REG_READ(RTC_STORE5) >> 16;
+        low = REG_READ(RTC_STORE5) & 0xffff;
+        if(high == low && high != 0 && high != 0xffff) {
+            clock = high << 12;
+        } else {
+            REG_WRITE(RTC_STORE5, (clock >> 12) | ((clock >> 12) <<16));
+        }
+    } while(0);
+    return clock;
+}
 
 void stub_target_uart_init(uint8_t uart_num, uint32_t baudrate)
 {
+    (void)baudrate;
     uartAttach();
-    uart_div_modify(uart_num, (stub_lib_rtc_clk_apb_freq_get() << 4) / baudrate);
+    Uart_Init(uart_num, ets_get_detected_xtal_freq_patch());
+
+    ets_install_putc1(NULL);
+    ets_install_putc2(NULL);
 }

src/esp32c6/src/uart.c

@@ -10,17 +10,21 @@
 
 // These functions are defined in the ROM
 extern void uartAttach(void *rxBuffer);
-extern void Uart_Init(uint8_t uart_no, uint32_t clock);
+extern void Uart_Init(uint8_t uart_no);
 extern uint32_t ets_clk_get_xtal_freq(void);
 extern void ets_update_cpu_frequency(uint32_t ticks_per_us);
 
-#define  APB_CLK_FREQ_ROM       (40 * 1000000)
+extern void ets_install_putc1(void (*p)(char c));
+extern void ets_install_putc2(void (*p)(char c));
 
 void stub_target_uart_init(uint8_t uart_num, uint32_t baudrate)
 {
     (void)baudrate;
     uartAttach(NULL);
     uint32_t clock = ets_clk_get_xtal_freq();
     ets_update_cpu_frequency(clock / 1000000);
-    Uart_Init(uart_num, APB_CLK_FREQ_ROM);
+    Uart_Init(uart_num);
+
+    ets_install_putc1(NULL);
+    ets_install_putc2(NULL);
 }

src/esp32h2/src/uart.c

@@ -10,17 +10,21 @@
 
 // These functions are defined in the ROM
 extern void uartAttach(void *rxBuffer);
-extern void Uart_Init(uint8_t uart_no, uint32_t clock);
+extern void Uart_Init(uint8_t uart_no);
 extern uint32_t ets_clk_get_xtal_freq(void);
 extern void ets_update_cpu_frequency(uint32_t ticks_per_us);
 
-#define  APB_CLK_FREQ_ROM       (32 * 1000000)
+extern void ets_install_putc1(void (*p)(char c));
+extern void ets_install_putc2(void (*p)(char c));
 
 void stub_target_uart_init(uint8_t uart_num, uint32_t baudrate)
 {
     (void)baudrate;
     uartAttach(NULL);
     uint32_t clock = ets_clk_get_xtal_freq();
     ets_update_cpu_frequency(clock / 1000000);
-    Uart_Init(uart_num, APB_CLK_FREQ_ROM);
+    Uart_Init(uart_num);
+
+    ets_install_putc1(NULL);
+    ets_install_putc2(NULL);
 }