add support for a small filesystem on the watch

2 files changed, 93 insertions, 0 deletions

diff --git a/watch-library/shared/watch/watch.h b/watch-library/shared/watch/watch.h
index ce85eed3..1dd8e7f7 100644
--- a/watch-library/shared/watch/watch.h
+++ b/watch-library/shared/watch/watch.h
@@ -64,6 +64,7 @@
 #include "watch_i2c.h"
 #include "watch_spi.h"
 #include "watch_uart.h"
+#include "watch_storage.h"
 #include "watch_deepsleep.h"
 
 #include "watch_private.h"
diff --git a/watch-library/shared/watch/watch_storage.h b/watch-library/shared/watch/watch_storage.h
new file mode 100644
index 00000000..6026cbcf
--- /dev/null
+++ b/watch-library/shared/watch/watch_storage.h
@@ -0,0 +1,92 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020 Joey Castillo
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef _WATCH_STORAGE_H_INCLUDED
+#define _WATCH_STORAGE_H_INCLUDED
+////< @file watch_storage.h
+
+#include "watch.h"
+
+#ifndef NVMCTRL_ROW_SIZE
+#define NVMCTRL_ROW_SIZE 256
+#endif
+#ifndef NVMCTRL_PAGE_SIZE
+#define NVMCTRL_PAGE_SIZE 64
+#endif
+#ifndef NVMCTRL_RWWEE_PAGES
+#define NVMCTRL_RWWEE_PAGES 128
+#endif
+
+/** @addtogroup storage Flash Storage
+  * @brief This section covers functions related to the SAM L22's 8 kilobyte EEPROM emulation area.
+  * @details The SAM L22 inside Sensor Watch has a 256 kilobyte Flash memory array that can be
+  *          programmed with whatever data we want. We use most of it to store the bootloader
+  *          and the application code that runs on your wrist. The bootloader region is read-only,
+  *          and the main application area is only writable by the bootloader (when you drag new
+  *          code onto the WATCHBOOT drive). However! there's also a special 8 kilobyte region
+  *          at the end of the Flash memory called the EEPROM Emulation Area. This EEPROM emulation
+  *          area can be written or erased while the main Flash array is being read. This makes it
+  *          super easy to work with, and useful for storing a small amount of non-volatile data that
+  *          persists across reboots, even when power is lost.
+  *          The functions in this section are very basic, and only cover reading and writing data
+  *          in this area. The region is laid out as 32 rows consisting of 4 pages of 64 bytes.
+  *          32*4*64 = 8192 bytes. The area can be written one page at a time, but it can only be
+  *          erased one row at a time. You can read at arbitrary word-aligned offsets within a row.
+  *
+  *                 ┌──────────────┬──────────────┬──────────────┬──────────────┐
+  *          Row 0  │   64 bytes   │   64 bytes   │   64 bytes   │   64 bytes   │
+  *                 ├──────────────┼──────────────┼──────────────┼──────────────┤
+  *          Row 1  │   64 bytes   │   64 bytes   │   64 bytes   │   64 bytes   │
+  *                 ├──────────────┼──────────────┼──────────────┼──────────────┤
+  *           ...   │              │              │              │              │
+  *                 ├──────────────┼──────────────┼──────────────┼──────────────┤
+  *          Row 31 │   64 bytes   │   64 bytes   │   64 bytes   │   64 bytes   │
+  *                 └──────────────┴──────────────┴──────────────┴──────────────┘
+  */
+/// @{
+/** @brief Reads a range of bytes from the storage area.
+  * @param row The row you want to read.
+  * @param offset The offset from the beginning of the row.
+  * @param buffer A buffer of at least `size` bytes.
+  * @param size The number of bytes you wish to read.
+  */
+bool watch_storage_read(uint32_t row, uint32_t offset, uint8_t *buffer, uint32_t size);
+
+/** @brief Writes bytes to a page in the storage area. Note that the row should already be erased before writing.
+  * @param row The row containing the page you want to write.
+  * @param offset The offset from the beginning of the row. Must be a multiple of 64.
+  * @param buffer The buffer containing the bytes you wish to set.
+  * @param size The number of bytes you wish to write.
+  */
+bool watch_storage_write(uint32_t row, uint32_t offset, const uint8_t *buffer, uint32_t size);
+
+/** @brief Erases a row in the storage area, setting all its bytes to 0xFF.
+  * @param row The row you want to erase.
+  */
+bool watch_storage_erase(uint32_t row);
+
+/** @brief Waits for any pending writes to complete.
+  */
+bool watch_storage_sync(void);
+/// @}
+#endif