From 8eb18dba4aed3431ecfe2a65ab63b25d7ed5e863 Mon Sep 17 00:00:00 2001
From: Alvaro Gomes Sobral Barcellos <alvaro.barcellos@cprm.gov.br>
Date: Wed, 20 Jul 2022 15:31:15 -0300
Subject: [PATCH] include bare bone spm routine

---
 optiboot/bootloaders/optiboot/Makefile   | 12 ++++---
 optiboot/bootloaders/optiboot/optiboot.c | 44 ++++++++++++++++++++----
 2 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/optiboot/bootloaders/optiboot/Makefile b/optiboot/bootloaders/optiboot/Makefile
index b1819468f..0f0de371c 100644
--- a/optiboot/bootloaders/optiboot/Makefile
+++ b/optiboot/bootloaders/optiboot/Makefile
@@ -259,6 +259,13 @@ APPSPM_CMD = -DAPP_NOSPM=1
 endif
 endif
 
+HELPTEXT += "Option APP_BBSPM=1          - allow call of bare bone spm\n"
+ifdef APP_BBSPM
+ifneq ($(APP_BBSPM),0)
+BBSPM_CMD = -DAPP_BBSPM=1
+endif
+endif
+
 HELPTEXT += "Option OSCCAL_VALUE=nnn      - set set OSCCAL_VALUE in bootloader\n"
 ifdef OSCCAL_VALUE
 OSCCAL_VALUE_CMD = -DOSCCAL_VALUE=$(OSCCAL_VALUE)
@@ -297,7 +304,7 @@ endif
 
 COMMON_OPTIONS = $(BAUD_RATE_CMD) $(LED_START_FLASHES_CMD) $(BIGBOOT_CMD)
 COMMON_OPTIONS += $(SOFT_UART_CMD) $(LED_DATA_FLASH_CMD) $(LED_CMD) $(SS_CMD)
-COMMON_OPTIONS += $(SUPPORT_EEPROM_CMD) $(LED_START_ON_CMD) $(APPSPM_CMD)
+COMMON_OPTIONS += $(SUPPORT_EEPROM_CMD) $(LED_START_ON_CMD) $(APPSPM_CMD) $(BBSPM_CMD)
 COMMON_OPTIONS += $(OSCCAL_VALUE_CMD) $(VERSION_CMD) $(TIMEOUT_CMD)
 COMMON_OPTIONS += $(POR_CMD) $(EXTR_CMD) $(RS485_CMD)
 
@@ -718,6 +725,3 @@ clean_asm:
 
 help:
 	@echo -e $(HELPTEXT)
-
-.DEFAULT:
-	@echo No target named \"$<\":  Maybe you need \"-f Makefile.mega0\"?
diff --git a/optiboot/bootloaders/optiboot/optiboot.c b/optiboot/bootloaders/optiboot/optiboot.c
index 6d9e0cc6f..30c304e4e 100644
--- a/optiboot/bootloaders/optiboot/optiboot.c
+++ b/optiboot/bootloaders/optiboot/optiboot.c
@@ -181,6 +181,9 @@
 #  define NO_START_APP_ON_POR 0
 #endif
 
+#if !defined(APP_BBSPM)
+#define APP_BBSPM 0
+#endif
 
 /* UART options */
 #if !defined(SOFT_UART)
@@ -699,6 +702,11 @@ void pre_main(void) {
     "  ret\n"   // if do_spm isn't include, return without doing anything
 #else
     "  rjmp    do_spm\n"
+#endif
+#if APP_BBSPM
+    "  rjmp    bb_spm\n"
+#else
+    "  ret\n"   // if do_spm isn't include, return without doing anything
 #endif
     "1:\n"
     );
@@ -1267,12 +1275,7 @@ static void inline toggle_led(void) {
   defined(__AVR_ATmega64__)   || defined(__AVR_ATmega128__)
   LED_PORT ^= _BV(LED);
 #else
-  // Newer AVRs can toggle by writing PINx.
-  if (&LED_PIN <= &_SFR_IO8(0x31)) {  // "if" code optimizes away.
-    LED_PIN |= _BV(LED); // becomes SBI on low ports (in theory: incorrectly)
-  } else {
-    LED_PIN = _BV(LED);  // high ports can't be sbi'ed (Issue #346)
-  }
+  LED_PIN |= _BV(LED);  // Newer AVRs can toggle by writing PINx
 #endif
 }
 
@@ -1605,7 +1608,35 @@ static void do_spm(uint16_t address, uint8_t command, uint16_t data) {
 }
 #endif
 
+#if APP_BBSPM
+
+/*
+    bare bone do_spm:
+    
+    r24 command and scratch, r25 SREG hold
+    r0:r1   defined by caller
+    r30:r31 defined by caller
 
+    SPMCR == 0x37
+    SPMEN == 0x00
+
+    only does spm and wait until ends. only.
+ */
+
+void bb_spm (void) {
+  asm volatile (
+    "       in r25, __SREG__\n"
+    "       cli\n"
+    "       sts 0x37, r24\n"
+    "       spm\n"
+    "10:\n"     
+    "       lds r24, 0x37\n"
+    "       sbrc r24, 0x00\n"
+    "       rjmp 10b\n"
+    "       out __SREG__, r25\n"
+    );
+}
+#endif
 
 #if BIGBOOT
 /*
@@ -1679,3 +1710,4 @@ OPT2FLASH(OPTIBOOT_CUSTOMVER);
 OPTFLASHSECT const char f_version[] = "Version=" xstr(OPTIBOOT_MAJVER) "." xstr(OPTIBOOT_MINVER);
 
 #endif
+