cpu/stm32: add rtc_mem

cpu/stm32/Makefile.dep

@@ -35,4 +35,9 @@ ifneq (,$(filter periph_eth periph_ptp,$(USEMODULE)))
   USEMODULE += periph_eth_common
 endif
 
+# periph_rtc_mem is currently tied to the peripg_rtc
+ifneq (,$(filter periph_rtc_mem,$(USEMODULE)))
+  FEATURES_REQUIRED += periph_rtc
+endif
+
 include $(RIOTCPU)/cortexm_common/Makefile.dep

cpu/stm32/Makefile.features

@@ -17,6 +17,13 @@ ifneq (,$(filter $(CPU_FAM),f0 f1 f3 g0 g4 l0 l1 l4 l5 wb wl))
   FEATURES_PROVIDED += periph_flashpage_pagewise
 endif
 
+ifneq (,$(filter $(CPU_FAM),f0 f2 f3 f4 f7 l0 l1 l4 l5 wb wl))
+  CPU_MODELS_WITHOUT_RTC_BKPR += stm32f030% stm32f070%
+  ifeq (,$(filter $(CPU_MODELS_WITHOUT_RTC_BKPR),$(CPU_MODEL)))
+    FEATURES_PROVIDED += periph_rtc_mem
+  endif
+endif
+
 # The f2, f4 and f7 do not support the pagewise api
 ifneq (,$(filter $(CPU_FAM),f2 f4 f7))
   FEATURES_PROVIDED += periph_flashpage

cpu/stm32/kconfigs/f0/Kconfig.lines

@@ -26,28 +26,34 @@ config CPU_LINE_STM32F030XC
 config CPU_LINE_STM32F031X6
     bool
     select CPU_FAM_F0
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F038XX
     bool
     select CPU_FAM_F0
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F042X6
     bool
     select CPU_FAM_F0
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F048XX
     bool
     select CPU_FAM_F0
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F051X8
     bool
     select CPU_FAM_F0
     select CLOCK_HAS_NO_MCO_PRE
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F058XX
     bool
     select CPU_FAM_F0
     select CLOCK_HAS_NO_MCO_PRE
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F070X6
     bool
@@ -60,19 +66,24 @@ config CPU_LINE_STM32F070XB
 config CPU_LINE_STM32F071XB
     bool
     select CPU_FAM_F0
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F072XB
     bool
     select CPU_FAM_F0
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F078XX
     bool
     select CPU_FAM_F0
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F091XC
     bool
     select CPU_FAM_F0
+    select HAS_PERIPH_RTC_MEM
 
 config CPU_LINE_STM32F098XX
     bool
     select CPU_FAM_F0
+    select HAS_PERIPH_RTC_MEM

cpu/stm32/kconfigs/f2/Kconfig

@@ -13,6 +13,7 @@ config CPU_FAM_F2
     select HAS_CORTEXM_MPU
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_HWRNG
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/kconfigs/f3/Kconfig

@@ -13,6 +13,7 @@ config CPU_FAM_F3
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_FLASHPAGE_PAGEWISE
     select HAS_PERIPH_FLASHPAGE_RAW
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/kconfigs/f4/Kconfig

@@ -12,6 +12,7 @@ config CPU_FAM_F4
     select HAS_CPU_STM32F4
     select HAS_CORTEXM_MPU
     select HAS_PERIPH_FLASHPAGE
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/kconfigs/f7/Kconfig

@@ -13,6 +13,7 @@ config CPU_FAM_F7
     select HAS_CORTEXM_MPU
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_HWRNG
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/kconfigs/l0/Kconfig

@@ -13,6 +13,7 @@ config CPU_FAM_L0
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_FLASHPAGE_PAGEWISE
     select HAS_PERIPH_EEPROM
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/kconfigs/l1/Kconfig

@@ -14,6 +14,7 @@ config CPU_FAM_L1
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_FLASHPAGE_PAGEWISE
     select HAS_PERIPH_EEPROM
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/kconfigs/l4/Kconfig

@@ -14,6 +14,7 @@ config CPU_FAM_L4
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_FLASHPAGE_PAGEWISE
     select HAS_PERIPH_HWRNG
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/kconfigs/l5/Kconfig

@@ -13,6 +13,7 @@ config CPU_FAM_L5
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_FLASHPAGE_PAGEWISE
     select HAS_PERIPH_HWRNG
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/kconfigs/wb/Kconfig

@@ -13,6 +13,7 @@ config CPU_FAM_WB
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_FLASHPAGE_PAGEWISE
     select HAS_PERIPH_HWRNG
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/kconfigs/wl/Kconfig

@@ -13,6 +13,7 @@ config CPU_FAM_WL
     select HAS_CPU_STM32WL
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_FLASHPAGE_PAGEWISE
+    select HAS_PERIPH_RTC_MEM
     select HAS_PERIPH_WDT
     select HAS_BOOTLOADER_STM32
 

cpu/stm32/periph/rtc_all.c

@@ -209,7 +209,7 @@ static int bcd2val(uint32_t val, int shift, uint32_t mask)
     return (((tmp >> 4) * 10) + (tmp & 0x0f));
 }
 
-static inline void rtc_unlock(void)
+void rtc_unlock(void)
 {
     /* enable backup clock domain */
     stmclk_dbp_unlock();
@@ -221,7 +221,7 @@ static inline void rtc_unlock(void)
     while (!(RTC_REG_ISR & RTC_ISR_INITF)) {}
 }
 
-static inline void rtc_lock(void)
+void rtc_lock(void)
 {
     /* exit RTC init mode */
     RTC_REG_ISR &= ~RTC_ISR_INIT;

cpu/stm32/periph/rtc_mem.c

@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2021 Inria
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     cpu_stm32
+ * @{
+ * @file
+ * @brief       Low-level RTC backup memory implementation
+ *
+ * @author      Kaspar Schleiser <kaspar@schleiser.de>
+ * @author      Francisco Molina <francois-xavier.molina@inria.fr>
+ * @}
+ */
+
+#include <string.h>
+
+#include "cpu.h"
+#include "periph/rtc_mem.h"
+
+#if defined(RTC_BKP31R)
+#define RTC_MEM_SIZE    32
+#elif defined(RTC_BKP30R)
+#define RTC_MEM_SIZE    31
+#elif defined(RTC_BKP29R)
+#define RTC_MEM_SIZE    30
+#elif defined(RTC_BKP28R)
+#define RTC_MEM_SIZE    29
+#elif defined(RTC_BKP27R)
+#define RTC_MEM_SIZE    28
+#elif defined(RTC_BKP26R)
+#define RTC_MEM_SIZE    27
+#elif defined(RTC_BKP25R)
+#define RTC_MEM_SIZE    26
+#elif defined(RTC_BKP24R)
+#define RTC_MEM_SIZE    25
+#elif defined(RTC_BKP23R)
+#define RTC_MEM_SIZE    24
+#elif defined(RTC_BKP22R)
+#define RTC_MEM_SIZE    23
+#elif defined(RTC_BKP21R)
+#define RTC_MEM_SIZE    22
+#elif defined(RTC_BKP20R)
+#define RTC_MEM_SIZE    21
+#elif defined(RTC_BKP19R)
+#define RTC_MEM_SIZE    20
+#elif defined(RTC_BKP18R)
+#define RTC_MEM_SIZE    19
+#elif defined(RTC_BKP17R)
+#define RTC_MEM_SIZE    18
+#elif defined(RTC_BKP16R)
+#define RTC_MEM_SIZE    17
+#elif defined(RTC_BKP15R)
+#define RTC_MEM_SIZE    16
+#elif defined(RTC_BKP14R)
+#define RTC_MEM_SIZE    15
+#elif defined(RTC_BKP13R)
+#define RTC_MEM_SIZE    14
+#elif defined(RTC_BKP12R)
+#define RTC_MEM_SIZE    13
+#elif defined(RTC_BKP11R)
+#define RTC_MEM_SIZE    12
+#elif defined(RTC_BKP10R)
+#define RTC_MEM_SIZE    11
+#elif defined(RTC_BKP9R)
+#define RTC_MEM_SIZE    10
+#elif defined(RTC_BKP8R)
+#define RTC_MEM_SIZE    9
+#elif defined(RTC_BKP7R)
+#define RTC_MEM_SIZE    8
+#elif defined(RTC_BKP6R)
+#define RTC_MEM_SIZE    8
+#elif defined(RTC_BKP5R)
+#define RTC_MEM_SIZE    6
+#elif defined(RTC_BKP4R)
+#define RTC_MEM_SIZE    5
+#elif defined(RTC_BKP3R)
+#define RTC_MEM_SIZE    4
+#elif defined(RTC_BKP2R)
+#define RTC_MEM_SIZE    3
+#elif defined(RTC_BKP1R)
+#define RTC_MEM_SIZE    2
+#elif defined(RTC_BKP0R)
+#define RTC_MEM_SIZE    1
+#else
+#define RTC_MEM_SIZE    0
+#endif
+
+extern void rtc_lock(void);
+extern void rtc_unlock(void);
+
+size_t rtc_mem_size(void)
+{
+    return RTC_MEM_SIZE * __SIZEOF_POINTER__;
+}
+
+void rtc_mem_write(unsigned offset, const void *data, size_t len)
+{
+    if (offset + len > rtc_mem_size()) {
+        return;
+    }
+
+    const uint8_t *in = data;
+
+    volatile uint32_t *rtc_regs = &RTC->BKP0R + (offset / __SIZEOF_POINTER__);
+    offset %= __SIZEOF_POINTER__;
+
+    rtc_unlock();
+
+    while (len) {
+        unsigned to_copy = (len >= __SIZEOF_POINTER__) ?
+                           __SIZEOF_POINTER__ - offset : len;
+        uint32_t tmp = *rtc_regs;
+        memcpy(((uint8_t *)&tmp) + offset, in, to_copy);
+        offset = 0;
+        *rtc_regs++ = tmp;
+        len -= to_copy;
+        in += to_copy;
+    }
+
+    rtc_lock();
+}
+
+void rtc_mem_read(unsigned offset, void *data, size_t len)
+{
+    if (offset + len > rtc_mem_size()) {
+        return;
+    }
+
+    uint8_t *out = (uint8_t *)data;
+
+    volatile uint32_t *rtc_regs = &RTC->BKP0R + (offset / __SIZEOF_POINTER__);
+    offset %= __SIZEOF_POINTER__;
+
+    while (len) {
+        unsigned to_copy = (len >= __SIZEOF_POINTER__) ?
+                           __SIZEOF_POINTER__ - offset : len;
+        uint32_t tmp = *rtc_regs++;
+        memcpy(out, ((uint8_t *)&tmp) + offset, to_copy);
+        offset = 0;
+        len -= to_copy;
+        out += to_copy;
+    }
+}