Completed the basic counter firmware. Now it just has to work ...

- cntr/fw/cntr/Makefile, cntr/fw/cntr/descr.c, cntr/fw/cntr/ep0.c: enabled
  the usual USB stack
- cntr/fw/cntr/cntr.c: initialize and poll USB
- cntr/fw/cntr/cntr.c, cntr/fw/cntr/ep0.c: added counter application
- cntr/fw/common/config.h (PLATFORM_SETUP): enable the crossbar

cntr/fw/cntr/Makefile

@@ -12,7 +12,7 @@
 
 
 MAIN = cntr
-OBJS = $(MAIN) # usb descr version ep0
+OBJS = $(MAIN) usb descr version ep0
 
 F32XBASE = ../../../../f32xbase
 

cntr/fw/cntr/cntr.c

@@ -11,6 +11,8 @@
  */
 
 
+#include <stdint.h>
+
 #include "regs.h"
 #include "io.h"
 #include "usb.h"
@@ -18,6 +20,16 @@
 #include "version.h"
 
 
+/*
+ * Free-running 32 bit counter. The lower two bytes are from hardware Timer 0.
+ * The upper two bytes are maintained by software. At the maximum input clock
+ * frequency of 6 MHz, it wraps around every 11.9 minutes, leaving the host
+ * plenty of time to read it.
+ */
+
+uint8_t cntr[4];
+
+
 static void init_io(void)
 {
 	/*
@@ -46,14 +58,47 @@ static void init_io(void)
 }
 
 
+static void setup_counter(void)
+{
+	TCON = TR0;		/* enable Timer 0 */
+	TMOD = C_T0 | T0M0;	/* clock from T0, mode 1: 16 bit counter */
+
+	XBR1 |= T0E;		/* route T0 to port */
+
+	P0SKIP = 0x7f;		/* assign T0 to P0_7 */
+}
+
+
+static void read_counter(void)
+{
+	uint8_t th;
+
+	th = TH0;
+	while (1) {
+		cntr[0] = TL0;
+		if (th == TH0)
+			break;
+		th = TH0;
+	}
+	if (th < cntr[1]) {
+		cntr[2]++;
+		if (!cntr[2])
+			cntr[3]++;
+	}
+	cntr[1] = th;
+}
+
+
 void main(void)
 {
 	init_io();
+	setup_counter();
 
-//	usb_init();
+	usb_init();
-//	ep0_init();
+	ep0_init();
 
 	while (1) {
-//		usb_poll();
+		read_counter();
+		usb_poll();
 	}
 }

cntr/fw/cntr/descr.c

@@ -0,0 +1,68 @@
+/*
+ * atspi/descr.c - USB descriptors
+ *
+ * Written 2008-2010 by Werner Almesberger
+ * Copyright 2008-2010 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include "usb.h"
+
+#include "config.h"
+
+
+/*
+ * Device descriptor
+ */
+
+const uint8_t device_descriptor[18] = {
+	18,			/* bLength */
+	USB_DT_DEVICE,		/* bDescriptorType */
+	LE(0x200),		/* bcdUSB */
+	USB_CLASS_VENDOR_SPEC,	/* bDeviceClass */
+	0x00,			/* bDeviceSubClass */
+	0x00,			/* bDeviceProtocol */
+	EP0_SIZE,		/* bMaxPacketSize */
+	LE(USB_VENDOR),		/* idVendor */
+	LE(USB_PRODUCT),	/* idProduct */
+	LE(0x0001),		/* bcdDevice */
+	0,			/* iManufacturer */
+	0,			/* iProduct */
+	0,			/* iSerialNumber */
+	1			/* bNumConfigurations */
+};
+
+
+/*
+ * Our configuration
+ *
+ * We're always bus-powered.
+ */
+
+const uint8_t config_descriptor[] = {
+	9,			/* bLength */
+	USB_DT_CONFIG,		/* bDescriptorType */
+	LE(9+9),		/* wTotalLength */
+	1,			/* bNumInterfaces */
+	1,			/* bConfigurationValue (> 0 !) */
+	0,			/* iConfiguration */
+	USB_ATTR_BUS_POWERED,	/* bmAttributes */
+	15,			/* bMaxPower */
+
+	/* Interface #0 */
+
+	9,			/* bLength */
+	USB_DT_INTERFACE,	/* bDescriptorType */
+	0,			/* bInterfaceNumber */
+	0,			/* bAlternateSetting */
+	0,			/* bNumEndpoints */
+	USB_CLASS_VENDOR_SPEC,	/* bInterfaceClass */
+	0,			/* bInterfaceSubClass */
+	0,			/* bInterfaceProtocol */
+	0,			/* iInterface */
+};

cntr/fw/cntr/ep0.c

@@ -0,0 +1,119 @@
+/*
+ * cntr/ep0.c - EP0 extension protocol
+ *
+ * Written 2008-2010 by Werner Almesberger
+ * Copyright 2008-2010 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <stdint.h>
+
+#ifndef NULL
+#define NULL 0
+#endif
+
+#include "regs.h"
+#include "usb.h"
+#include "cntr/ep0.h"
+#include "version.h"
+
+
+#define debug(...)
+#define error(...)
+
+
+/*
+ * SDCC 2.8.0 had a number of code generation bugs that appeared in the big
+ * switch statement of my_setup. SDCC_FORCE_UPDATE forced the value of the
+ * "size" variable to be written to memory. This work-around doesn't seem
+ * to be necessary with 2.9.0, but we keep it around, just in case.
+ *
+ * Unfortunately, the setup->bRequest garbling bug is still with us. Without
+ * the evaluation forced with SDCC_FORCE_EVAL, sdcc gets confused about the
+ * value of setup->bRequest and then rejects all SETUP requests.
+ */
+
+#define	SDCC_FORCE_EVAL(type, value)	\
+    do {				\
+	static volatile type foo;	\
+	foo = value;			\
+    } while (0)
+
+#define	SDCC_FORCE_UPDATE(type, var)	\
+    do {				\
+	volatile type foo;		\
+	foo = var;			\
+	var = foo;			\
+    } while (0)
+
+
+extern uint8_t cntr[8];
+
+static const uint8_t id[] = { EP0CNTR_MAJOR, EP0CNTR_MINOR, HW_TYPE };
+static __xdata uint8_t buf[128];
+
+
+#define	BUILD_OFFSET	7	/* '#' plus "65535" plus ' ' */
+
+
+static __bit my_setup(struct setup_request *setup) __reentrant
+{
+	unsigned tmp;
+	uint8_t size, i;
+
+	switch (setup->bmRequestType | setup->bRequest << 8) {
+	case CNTR_FROM_DEV(CNTR_ID):
+		debug("CNTR_ID\n");
+		if (setup->wLength > 3)
+			return 0;
+		usb_send(&ep0, id, setup->wLength, NULL, NULL);
+		return 1;
+	case CNTR_FROM_DEV(CNTR_BUILD):
+		debug("CNTR_BUILD\n");
+		tmp = build_number;
+		for (i = BUILD_OFFSET-2; tmp; i--) {
+			buf[i] = (tmp % 10)+'0';
+			tmp /= 10;
+		}
+		buf[i] = '#';
+		buf[BUILD_OFFSET-1] = ' ';
+		for (size = 0; build_date[size]; size++)
+			buf[BUILD_OFFSET+size] = build_date[size];
+		size += BUILD_OFFSET-i+1;
+		SDCC_FORCE_EVAL(uint8_t, setup->bRequest);
+		if (size > setup->wLength)
+			return 0;
+		usb_send(&ep0, buf+i, size, NULL, NULL);
+		return 1;
+
+	case CNTR_TO_DEV(CNTR_RESET):
+		debug("CNTR_RESET\n");
+		RSTSRC = SWRSF;
+		while (1);
+
+	case CNTR_FROM_DEV(CNTR_READ):
+		debug("CNTR_READ\n");
+		buf[0] = cntr[0];
+		buf[1] = cntr[1];
+		buf[2] = cntr[2];
+		buf[3] = cntr[3];
+		usb_send(&ep0, buf, 4, NULL, NULL);
+		return 1;
+
+	default:
+		error("Unrecognized SETUP: 0x%02x 0x%02x ...\n",
+		    setup->bmRequestType, setup->bRequest);
+		return 0;
+	}
+}
+
+
+void ep0_init(void)
+{
+	user_setup = my_setup;
+}

cntr/fw/common/config.h

@@ -25,8 +25,9 @@
  * This turns on the LED, to indicate that we're in the boot loader.
  */
 
-#define PLATFORM_SETUP \
+#define PLATFORM_SETUP			\
-	LED_MODE |= 1 << LED_BIT;
+	LED_MODE |= 1 << LED_BIT;	\
+	XBR1 = XBARE;
 
 
 /*