diff --git a/firmware/ice40-riscv/common/spi.h b/firmware/ice40-riscv/common/spi.h
new file mode 100644
index 0000000..3a95358
--- /dev/null
+++ b/firmware/ice40-riscv/common/spi.h
@@ -0,0 +1,36 @@
+/*
+ * spi.h
+ *
+ * Copyright (C) 2019-2020  Sylvain Munaut <tnt@246tNt.com>
+ * SPDX-License-Identifier: LGPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <stdbool.h>
+
+struct spi_xfer_chunk {
+	uint8_t *data;
+	unsigned len;
+	bool write;
+	bool read;
+};
+
+#define SPI_CS_FLASH	0
+#define SPI_CS_LIU(n)	(4+(n))
+
+void spi_init(void);
+void spi_xfer(unsigned cs, const struct spi_xfer_chunk *xfer, unsigned n);
+
+void flash_cmd(uint8_t cmd);
+void flash_deep_power_down(void);
+void flash_wake_up(void);
+void flash_write_enable(void);
+void flash_write_disable(void);
+void flash_manuf_id(void *manuf);
+void flash_unique_id(void *id);
+uint8_t flash_read_sr(void);
+void flash_write_sr(uint8_t sr);
+void flash_read(void *dst, uint32_t addr, unsigned len);
+void flash_page_program(void *src, uint32_t addr, unsigned len);
+void flash_sector_erase(uint32_t addr);