cpu/sam0_common: flashpage: introduce functions to write to user page

cpu/sam0_common/include/periph_cpu_common.h

@@ -1095,6 +1095,78 @@ int rtc_tamper_register(gpio_t pin, gpio_flank_t flank);
 void rtc_tamper_enable(void);
 /** @} */
 
+/**
+ * @name sam0 User Configuration
+ *
+ *      The MCUs of this family contain a region of memory that is used to store
+ *      CPU configuration & calibration data.
+ *      It can be used to set persistent settings and has some additional space
+ *      to store user configuration data.
+ * @{
+ */
+
+/**
+ * @brief MCU configuration applied on start. The contents of this struct differ
+ *        between families.
+ */
+typedef struct sam0_aux_cfg_mapping nvm_user_page_t;
+
+/**
+ * @brief   Size of the free to use auxiliary area in the user page
+ */
+#ifdef FLASH_USER_PAGE_SIZE
+#define FLASH_USER_PAGE_AUX_SIZE (FLASH_USER_PAGE_SIZE - sizeof(nvm_user_page_t))
+#else
+#define FLASH_USER_PAGE_AUX_SIZE (AUX_PAGE_SIZE * AUX_NB_OF_PAGES - sizeof(nvm_user_page_t))
+#endif
+
+/**
+ * @brief   Reset the configuration area, apply a new configuration.
+ *
+ *
+ * @param   cfg     New MCU configuration, may be NULL.
+ *                  If cfg is NULL, this will clear the configuration area
+ *                  and apply the current configuration again.
+ */
+void sam0_flashpage_aux_reset(const nvm_user_page_t *cfg);
+
+/**
+ * @brief   Write data to the user configuration area.
+ *          This will write data to the remaining space after @see nvm_user_page_t
+ *          The size of this area depends on the MCU family used.
+ *
+ *          Will only write bits 1 -> 0. To reset bits to 1, call @see sam0_flashpage_aux_reset
+ *          This will reset the whole user area configuration.
+ *
+ *          Arbitrary data lengths and offsets are supported.
+ *
+ * @param   offset  Byte offset after @see nvm_user_page_t
+ *                  must be less than `FLASH_USER_PAGE_AUX_SIZE`
+ * @param   data    The data to write
+ * @param   len     Size of the data
+ */
+void sam0_flashpage_aux_write_raw(uint32_t offset, const void *data, size_t len);
+
+/**
+ * @brief   Get pointer to data in the user configuration area.
+ *
+ * @param   offset  Byte offset after @see nvm_user_page_t
+ *                  must be less than `FLASH_USER_PAGE_AUX_SIZE`
+ * @return  Pointer to the data in the User Page
+ */
+#define sam0_flashpage_aux_get(offset)  \
+    (const void*)((uint8_t*)NVMCTRL_USER + sizeof(nvm_user_page_t) + (offset))
+
+/**
+ * @brief   Get pointer to data in the CPU configuration struct
+ *
+ * @return  Pointer to the @ref nvm_user_page_t structure
+ */
+#define sam0_flashpage_aux_cfg() \
+    ((const nvm_user_page_t*)NVMCTRL_USER)
+
+/** @} */
+
 #ifdef __cplusplus
 }
 #endif

cpu/sam0_common/periph/flashpage.c

@@ -27,6 +27,7 @@
  */
 
 #include <assert.h>
+#include <string.h>
 
 #include "cpu.h"
 #include "periph/flashpage.h"
@@ -36,6 +37,15 @@
 
 #define MIN(x, y) (((x) < (y)) ? (x) : (y))
 
+/* Write Quad Word is the only allowed operation on AUX pages */
+#if defined(NVMCTRL_CTRLB_CMD_WQW)
+#define AUX_CHUNK_SIZE  (4 * sizeof(uint32_t))
+#elif defined(AUX_PAGE_SIZE)
+#define AUX_CHUNK_SIZE AUX_PAGE_SIZE
+#else
+#define AUX_CHUNK_SIZE FLASH_USER_PAGE_SIZE
+#endif
+
 /**
  * @brief   NVMCTRL selection macros
  */
@@ -87,6 +97,21 @@ static void _cmd_clear_page_buffer(void)
 #endif
 }
 
+static void _cmd_erase_aux(void)
+{
+    wait_nvm_is_ready();
+
+    /* send Erase Page/Auxiliary Row command */
+#if defined(NVMCTRL_CTRLB_CMD_EP)
+    _NVMCTRL->CTRLB.reg = (NVMCTRL_CTRLB_CMDEX_KEY | NVMCTRL_CTRLB_CMD_EP);
+#elif defined(NVMCTRL_CTRLA_CMD_EAR)
+    _NVMCTRL->CTRLA.reg = (NVMCTRL_CTRLA_CMDEX_KEY | NVMCTRL_CTRLA_CMD_EAR);
+#else
+    /* SAML1x uses same command for all areas */
+    _NVMCTRL->CTRLA.reg = (NVMCTRL_CTRLA_CMDEX_KEY | NVMCTRL_CTRLA_CMD_ER);
+#endif
+}
+
 static void _cmd_erase_row(void)
 {
     wait_nvm_is_ready();
@@ -99,6 +124,21 @@ static void _cmd_erase_row(void)
 #endif
 }
 
+static void _cmd_write_aux(void)
+{
+    wait_nvm_is_ready();
+
+    /* write auxiliary page */
+#if defined(NVMCTRL_CTRLA_CMD_WAP)
+    _NVMCTRL->CTRLA.reg = (NVMCTRL_CTRLA_CMDEX_KEY | NVMCTRL_CTRLA_CMD_WAP);
+#elif defined(NVMCTRL_CTRLB_CMD_WQW)
+    _NVMCTRL->CTRLB.reg = (NVMCTRL_CTRLB_CMDEX_KEY | NVMCTRL_CTRLB_CMD_WQW);
+#else
+    /* SAML1x uses same command for all areas */
+    _NVMCTRL->CTRLA.reg = (NVMCTRL_CTRLA_CMDEX_KEY | NVMCTRL_CTRLA_CMD_WP);
+#endif
+}
+
 static void _cmd_write_page(void)
 {
     wait_nvm_is_ready();
@@ -202,7 +242,32 @@ void flashpage_write_raw(void *target_addr, const void *data, size_t len)
            (CPU_FLASH_BASE + (FLASHPAGE_SIZE * FLASHPAGE_NUMOF)));
 
     _write_page(target_addr, data, len, _cmd_write_page);
+}
 
+void sam0_flashpage_aux_write_raw(uint32_t offset, const void *data, size_t len)
+{
+    uintptr_t dst = NVMCTRL_USER + sizeof(nvm_user_page_t) + offset;
+
+#ifdef FLASH_USER_PAGE_SIZE
+    assert(dst + len <= NVMCTRL_USER + FLASH_USER_PAGE_SIZE);
+#else
+    assert(dst + len <= NVMCTRL_USER + AUX_PAGE_SIZE * AUX_NB_OF_PAGES);
+#endif
+
+    _write_row((void*)dst, data, len, AUX_CHUNK_SIZE, _cmd_write_aux);
+}
+
+void sam0_flashpage_aux_reset(const nvm_user_page_t *cfg)
+{
+    nvm_user_page_t old_cfg;
+
+    if (cfg == NULL) {
+        cfg = &old_cfg;
+        memcpy(&old_cfg, (void*)NVMCTRL_USER, sizeof(*cfg));
+    }
+
+    _erase_page((void*)NVMCTRL_USER, _cmd_erase_aux);
+    _write_row((void*)NVMCTRL_USER, cfg, sizeof(*cfg), AUX_CHUNK_SIZE, _cmd_write_aux);
 }
 
 #ifdef FLASHPAGE_RWWEE_NUMOF