diff --git a/firmware/ice40-riscv/icE1usb/e1.c b/firmware/ice40-riscv/icE1usb/e1.c
index 59be063..6a4c73c 100644
--- a/firmware/ice40-riscv/icE1usb/e1.c
+++ b/firmware/ice40-riscv/icE1usb/e1.c
@@ -18,9 +18,16 @@
 #include "led.h" // FIXME
 
 
+// HW access
+// ---------
+
 static volatile struct e1_core * const e1_regs = (void *)(E1_CORE_BASE);
 static volatile uint8_t * const e1_data = (void *)(E1_DATA_BASE);
 
+
+// Helpers
+// -------
+
 static unsigned int
 e1_data_ofs(int mf, int frame, int ts)
 {
@@ -33,6 +40,7 @@
 	return &e1_data[e1_data_ofs(mf, frame, ts)];
 }
 
+
 // FIFOs
 // -----
 /* Note: FIFO works at 'frame' level (i.e. 32 bytes) */
@@ -98,7 +106,6 @@
 	return (ofs >> 4);
 }
 
-
 	/* Debug */
 static void
 e1f_debug(struct e1_fifo *fifo, const char *name)
@@ -207,7 +214,6 @@
 }
 
 
-
 // Main logic
 // ----------
 
@@ -232,12 +238,11 @@
 		int in_flight;
 		enum e1_pipe_state state;
 	} tx;
+
 	struct e1_error_count errors;
 } g_e1;
 
 
-
-
 void
 e1_init(uint16_t rx_cr, uint16_t tx_cr)
 {
@@ -285,8 +290,6 @@
 	e1_regs->rx.csr = g_e1.rx.cr;
 }
 
-#include "dma.h"
-
 unsigned int
 e1_rx_need_data(unsigned int usb_addr, unsigned int max_frames, unsigned int *pos)
 {
diff --git a/firmware/ice40-riscv/icE1usb/e1.h b/firmware/ice40-riscv/icE1usb/e1.h
index 4cbb6e5..9ceffdd 100644
--- a/firmware/ice40-riscv/icE1usb/e1.h
+++ b/firmware/ice40-riscv/icE1usb/e1.h
@@ -7,6 +7,9 @@
 
 #pragma once
 
+
+/* control */
+
 void e1_init(uint16_t rx_cr, uint16_t tx_cr);
 void e1_poll(void);
 void e1_debug_print(bool data);
@@ -14,6 +17,17 @@
 void e1_tx_config(uint16_t cr);
 void e1_rx_config(uint16_t cr);
 
+
+/* data flow */
+
+unsigned int e1_rx_need_data(unsigned int usb_addr, unsigned int max_len, unsigned int *pos);
+unsigned int e1_tx_feed_data(unsigned int usb_addr, unsigned int len);
+unsigned int e1_tx_level(void);
+unsigned int e1_rx_level(void);
+
+
+/* error reporting */
+
 #define E1_ERR_F_ALIGN_ERR	0x01
 #define E1_ERR_F_LOS		0x02
 #define E1_ERR_F_RAI		0x04
@@ -28,6 +42,9 @@
 
 const struct e1_error_count *e1_get_error_count(void);
 
+
+/* external function provided by the platform; used by E1 driver to control LEDs */
+
 enum e1_platform_led {
 	E1P_LED_GREEN		= 0,
 	E1P_LED_YELLOW		= 1,
@@ -40,6 +57,5 @@
 	E1P_LED_ST_BLINK_FAST	= 3
 };
 
-/* external function provided by the platform; used by E1 driver to control LEDs */
 extern void e1_platform_led_set(uint8_t port, enum e1_platform_led led,
 				enum e1_platform_led_state state);
diff --git a/firmware/ice40-riscv/icE1usb/usb_e1.c b/firmware/ice40-riscv/icE1usb/usb_e1.c
index b4d8839..34ade71 100644
--- a/firmware/ice40-riscv/icE1usb/usb_e1.c
+++ b/firmware/ice40-riscv/icE1usb/usb_e1.c
@@ -15,7 +15,6 @@
 #include "console.h"
 #include "misc.h"
 #include "e1.h"
-#include "e1_hw.h"
 
 #include "ice1usb_proto.h"
 
@@ -41,13 +40,6 @@
 };
 
 
-/* Hack */
-unsigned int e1_rx_need_data(unsigned int usb_addr, unsigned int max_len, unsigned int *pos);
-unsigned int e1_tx_feed_data(unsigned int usb_addr, unsigned int len);
-unsigned int e1_tx_level(void);
-unsigned int e1_rx_level(void);
-/* ---- */
-
 static void
 _usb_fill_feedback_ep(void)
 {