pic32cz fixes: better reset clock and uart restoration

arch.mk

@@ -288,10 +288,7 @@ ifeq ($(ARCH),ARM)
     OBJS+=hal/pic32c.o
 
     ifeq ($(WOLFHSM_CLIENT),1)
-      ifeq ($(WOLFHSM_MICROCHIP_PIC32CZ),)
-        $(error WOLFHSM_MICROCHIP_PIC32CZ is not set: point it at the wolfHSM \
-                PIC32CZ client port directory (the one containing port/))
-      endif
+      WOLFHSM_MICROCHIP_PIC32CZ ?= ..
 
       CFLAGS+=-I$(WOLFHSM_MICROCHIP_PIC32CZ) \
               -DWOLFHSM_CFG_NO_SYS_TIME \

hal/pic32cz.c

@@ -27,6 +27,7 @@
 
 #ifdef DEBUG_UART
 #include "uart_drv.h"
+void uart_deinit(void);
 #endif
 
 #if defined(WOLFBOOT_ENABLE_WOLFHSM_CLIENT)
@@ -60,6 +61,9 @@
 
 #endif /* WOLFBOOT_ENABLE_WOLFHSM_CLIENT */
 
+/* if the SUPC PLL regulator was already on at reset */
+static int pic32_vreg_pll_was_enabled = 0;
+
 #define SUPC_BASE (0x44020000U)
 #define SUPC_VREGCTRL (*(volatile uint32_t *)(SUPC_BASE + 0x1CU))
 #define SUPC_STATUS (*(volatile uint32_t *)(SUPC_BASE + 0x0CU))
@@ -69,14 +73,34 @@
 #define SUPC_STATUS_ADDVREGRDY_PLL (4)
 #define SUPC_STATUS_ADDVREGRDY_SHIFT (8)
 
+static void pic32_delay_cnt(uint32_t ticks)
+{
+    uint32_t i = 0;
+    for (i = 0; i < ticks; i++) {
+        __asm__ __volatile__("nop");
+    }
+}
+
+#define PLL_VREG_SETTLE_TICKS (4000)
+
 static void pic32_supc_vreg_pll_enable(void)
 {
+    pic32_vreg_pll_was_enabled =
+        ((SUPC_VREGCTRL >> SUPC_VREGCTRL_AVREGEN_SHIFT)
+         & SUPC_VREGCTRL_AVREGEN_PLLREG_EN) != 0;
+
+    if (pic32_vreg_pll_was_enabled) {
+        return;
+    }
+
     SUPC_VREGCTRL |= SUPC_VREGCTRL_AVREGEN_PLLREG_EN
         << SUPC_VREGCTRL_AVREGEN_SHIFT;
 
     /* wait for the vreg to be ready */
     while (!(SUPC_STATUS &
              (SUPC_STATUS_ADDVREGRDY_PLL << SUPC_STATUS_ADDVREGRDY_SHIFT))) {}
+
+    pic32_delay_cnt(PLL_VREG_SETTLE_TICKS);
 }
 
 #ifdef DUALBANK_SWAP
@@ -106,14 +130,6 @@ int hal_flash_erase(uint32_t addr, int len)
     return pic32_flash_erase(addr, len);
 }
 
-static void pic32_delay_cnt(uint32_t ticks)
-{
-    uint32_t i = 0;
-    for (i = 0; i < ticks; i++) {
-        __asm__("nop");
-    }
-}
-
 void hal_init(void)
 {
 #if defined(TEST_CLOCK)
@@ -143,8 +159,17 @@ void hal_init(void)
 
 void hal_prepare_boot(void)
 {
+#ifdef DEBUG_UART
+    uart_deinit();
+#endif
+
 #ifdef WOLFBOOT_RESTORE_CLOCK
     pic32_clock_reset();
+
+    if (!pic32_vreg_pll_was_enabled) {
+        SUPC_VREGCTRL &= ~((uint32_t)SUPC_VREGCTRL_AVREGEN_PLLREG_EN
+                           << SUPC_VREGCTRL_AVREGEN_SHIFT);
+    }
 #endif
 }
 

hal/uart/uart_drv_pic32cz.c

@@ -49,6 +49,7 @@
 #define SERCOM_SYNCBUSY (*(volatile uint32_t*)(SERCOM1 + 0x1CU))
 #define SERCOM_DATA    (*(volatile uint32_t*)(SERCOM1 + 0x28U))
 
+#define CTRLA_SWRST          (0x1U << 0)
 #define CTRLA_MODE_USART_INT (0x1U << 2)  /* USART with internal clock */
 #define CTRLA_ENABLE         (0x1U << 1)
 #define CTRLA_IBON           (0x1U << 8)
@@ -59,6 +60,7 @@
 #define CTRLB_TXEN           (0x1U << 16)
 
 #define INTFLAG_DRE          (0x1U << 0)  /* Data Register Empty */
+#define INTFLAG_TXC          (0x1U << 1)  /* Transmit Complete */
 
 /* GCLK: generator 1 sources SERCOM1 */
 #define GCLK_GENCTRL1 (*(volatile uint32_t*)(GCLK_BASE + 0x20U + (1 * 4)))
@@ -139,6 +141,35 @@ int uart_init(uint32_t bitrate, uint8_t data, char parity, uint8_t stop)
     return 0;
 }
 
+#define TXC_WAIT_MAX (200000U)
+
+void uart_deinit(void)
+{
+    uint32_t spin;
+
+    /* drain tx */
+    for (spin = 0U; spin < TXC_WAIT_MAX; spin++) {
+        if ((SERCOM_INTFLAG & INTFLAG_TXC) != 0U) {
+            break;
+        }
+    }
+
+    SERCOM_CTRLA &= ~(uint32_t)CTRLA_ENABLE;
+    while (SERCOM_SYNCBUSY != 0U) {
+        /* wait sync */
+    }
+
+    SERCOM_CTRLA = CTRLA_SWRST;
+    while (SERCOM_SYNCBUSY != 0U) {
+        /* wait sync */
+    }
+
+    PORTC_PMUX(2)   = 0x0U;
+    PORTC_PMUX(3)   = 0x0U;
+    PORTC_PINCFG(4) = 0x0U;
+    PORTC_PINCFG(7) = 0x0U;
+}
+
 int uart_tx(const uint8_t c)
 {
     while ((SERCOM_INTFLAG & INTFLAG_DRE) == 0U) {