From 81152cfee2121e16931a146771fefa0495f6ba82 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Wed, 21 Jul 2021 23:33:22 +0200
Subject: [PATCH] eeprom_blockprog: add EEPROM block programing library

---
 eeprom_blockprog.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++
 eeprom_blockprog.h | 14 ++++++++++
 2 files changed, 83 insertions(+)
 create mode 100644 eeprom_blockprog.c
 create mode 100644 eeprom_blockprog.h

diff --git a/eeprom_blockprog.c b/eeprom_blockprog.c
new file mode 100644
index 0000000..f9fea72
--- /dev/null
+++ b/eeprom_blockprog.c
@@ -0,0 +1,69 @@
+/** library to program EEPROM using block programming
+ *  @file
+ *  @author King Kévin <kingkevin@cuvoodoo.info>
+ *  @copyright SPDX-License-Identifier: GPL-3.0-or-later
+ *  @date 2021
+ *  @warning functions need to be put in and run from RAM (because block programming is used)
+ */
+
+// RAM code-putting from https://lujji.github.io/blog/executing-code-from-ram-on-stm8/
+
+/* standard libraries */
+#include <stdint.h> // standard integer types
+#include <stdbool.h> // boolean types
+
+#include "stm8s.h" // STM8S definitions
+#include "eeprom_blockprog.h" // own definitions
+
+// start address of EEPROM
+#define EEPROM_ADDR 0x4000
+// block size from low-density devices (including STM8S103)
+#define DATA_BLOCK_SIZE 64U
+
+#pragma codeseg RAM_SEG
+bool eeprom_blockprog(const uint8_t* data, uint16_t length)
+{
+	if (0 == length) {
+		return true; // nothing to do
+	}
+	if (!data) {
+		return false; // data missing
+	}
+	if (0 != (length % DATA_BLOCK_SIZE)) {
+		return false; // we can only program whole blocks
+	}
+
+	// disable DATA (e.g. EEPROM) write protection
+	// don't check if it is locked this it does not save that much time and uses memory)
+	FLASH_DUKR = FLASH_DUKR_KEY1;
+	FLASH_DUKR = FLASH_DUKR_KEY2;
+// don't verify if unlock succeeded to save memory
+//	if (!(FLASH_IAPSR & FLASH_IAPSR_DUL)) { // un-protecting failed
+//		return false;
+//	}
+
+
+	// program data
+	uint8_t* eeprom = (uint8_t*)(EEPROM_ADDR);
+	while (length) {
+		// enable standard block programming
+		FLASH_CR2 |= FLASH_CR2_PRG;
+		FLASH_NCR2 &= ~FLASH_NCR2_NPRG;
+		// program block
+		for (uint8_t i = 0; i < DATA_BLOCK_SIZE; i++) {
+			*(eeprom++) = *(data++);
+		}
+		length -= DATA_BLOCK_SIZE;
+		// wait until program completed
+		while (FLASH_CR2 & FLASH_CR2_PRG);
+		// check if programming failed
+		// we don't check for WR_PG_DIS (while checking EOP) because EEPROM isn't (and can't be) write protected
+		if (!(FLASH_IAPSR & FLASH_IAPSR_EOP)) {
+			FLASH_IAPSR &= ~FLASH_IAPSR_DUL; // re-enable write protection
+			return false;
+		}
+	}
+
+	FLASH_IAPSR &= ~FLASH_IAPSR_DUL; // re-enable write protection
+	return true;
+}
diff --git a/eeprom_blockprog.h b/eeprom_blockprog.h
new file mode 100644
index 0000000..8b0c3d4
--- /dev/null
+++ b/eeprom_blockprog.h
@@ -0,0 +1,14 @@
+/** library to program EEPROM using block programming
+ *  @file
+ *  @author King Kévin <kingkevin@cuvoodoo.info>
+ *  @copyright SPDX-License-Identifier: GPL-3.0-or-later
+ *  @date 2021
+ *  @warning functions need to be put in and run from RAM (because block programming is used)
+ */
+
+/** program EEPROM using block programming
+ *  @param[in] data data to be programmed
+ *  @param[in] length length of data to be programmed (must be a multiple of the block length)
+ *  @return if program succeeded
+ */
+bool eeprom_blockprog(const uint8_t* data, uint16_t length);