Add a configuration option (CONFIG_PULL_UPS in Makefile.common) for

building without GPIO pull-up support.  Applications can supply their own.

Makefile.common

@@ -43,6 +43,10 @@ CFLAGS		+= -O2 -Wall -Wextra -Wno-unused-parameter \
 			-Wno-unused-result -Wno-missing-field-initializers \
 			-Wno-sign-compare
 CFLAGS		+= -g
+# Add feature defines that are also used throughout.
+
+CFLAGS	+= -DCONFIG_PULL_UPS=1
+
 CORE_CFLAGS	= -DAVR_CORE=1
 
 ifeq (${shell uname}, Darwin)

simavr/sim/avr/avr_mcu_section.h

@@ -62,7 +62,9 @@ enum {
 	AVR_MMCU_TAG_VCD_TRACE,
 	AVR_MMCU_TAG_VCD_PORTPIN,
 	AVR_MMCU_TAG_VCD_IRQ,
+#ifdef CONFIG_PULL_UPS
 	AVR_MMCU_TAG_PORT_EXTERNAL_PULL,
+#endif
 };
 
 enum {
@@ -185,6 +187,7 @@ struct avr_mmcu_vcd_trace_t {
 		.len = sizeof(void *),\
 		.what = (void*)_register, \
 	}
+#ifdef CONFIG_PULL_UPS
 /*!
  * Allows the firmware to hint simavr as to wether there are external
  * pullups/down on PORT pins. It helps if the firmware uses "open drain"
@@ -198,6 +201,7 @@ struct avr_mmcu_vcd_trace_t {
 		(((unsigned long)((_port)&0xff) << 16) | \
 		((unsigned long)((_mask)&0xff) << 8) | \
 		((_val)&0xff)));
+#endif
 /*!
  * Add this port/pin to the VCD file. The syntax uses the name of the
  * port as a character, and not a pointer to a register.

simavr/sim/avr_ioport.c

@@ -70,13 +70,17 @@ avr_ioport_update_irqs(
 	for (int i = 0; i < 8; i++) {
 		if (ddr & (1 << i))
 			avr_raise_irq(p->io.irq + i, (avr->data[p->r_port] >> i) & 1);
+#ifdef CONFIG_PULL_UPS
 		else if (p->external.pull_mask & (1 << i))
 			avr_raise_irq(p->io.irq + i, (p->external.pull_value >> i) & 1);
 		else if ((avr->data[p->r_port] >> i) & 1)
 			avr_raise_irq(p->io.irq + i, 1);
+#endif
 	}
 	uint8_t pin = (avr->data[p->r_pin] & ~ddr) | (avr->data[p->r_port] & ddr);
+#ifdef CONFIG_PULL_UPS
 	pin = (pin & ~p->external.pull_mask) | p->external.pull_value;
+#endif
 	avr_raise_irq(p->io.irq + IOPORT_IRQ_PIN_ALL, pin);
 
 	// if IRQs are registered on the PORT register (for example, VCD dumps) send
@@ -270,6 +274,7 @@ avr_ioport_ioctl(
 					*((avr_ioport_state_t*)io_param) = state;
 				res = 0;
 			}
+#ifdef CONFIG_PULL_UPS
 			/*
 			 * Set the default IRQ values when pin is set as input
 			 */
@@ -279,6 +284,7 @@ avr_ioport_ioctl(
 				p->external.pull_value = m->value;
 				res = 0;
 			}
+#endif
 		}
 	}
 

simavr/sim/avr_ioport.h

@@ -72,6 +72,7 @@ typedef struct avr_ioport_state_t {
 // add port name (uppercase) to get the port state
 #define AVR_IOCTL_IOPORT_GETSTATE(_name) AVR_IOCTL_DEF('i','o','s',(_name))
 
+#ifdef CONFIG_PULL_UPS
 /*
  * ioctl used to set default port state when set as input.
  *
@@ -83,6 +84,7 @@ typedef struct avr_ioport_external_t {
 
 // add port name (uppercase) to set default input pin IRQ values
 #define AVR_IOCTL_IOPORT_SET_EXTERNAL(_name) AVR_IOCTL_DEF('i','o','p',(_name))
+#endif
 
 /**
  * pin structure
@@ -112,6 +114,7 @@ typedef struct avr_ioport_t {
 	uint8_t 	mask;
 	int8_t 		shift;
 
+#ifdef CONFIG_PULL_UPS
 	// This represent the default IRQ value when
 	// the port is set as input.
 	// If the mask is not set, no output value is sent
@@ -120,6 +123,7 @@ typedef struct avr_ioport_t {
 	struct {
 		uint8_t pull_mask, pull_value;
 	} external;
+#endif
 } avr_ioport_t;
 
 void avr_ioport_init(avr_t * avr, avr_ioport_t * port);

simavr/sim/sim_elf.c

@@ -170,6 +170,7 @@ avr_load_firmware(
 		memcpy(avr->fuse, firmware->fuse, firmware->fusesize);
 	if (firmware->lockbits)
 		avr->lockbits = firmware->lockbits[0];
+#ifdef CONFIG_PULL_UPS
 	// load the default pull up/down values for ports
 	for (int i = 0; i < 8 && firmware->external_state[i].port; i++) {
 		avr_ioport_external_t e = {
@@ -179,6 +180,7 @@ avr_load_firmware(
 		};
 		avr_ioctl(avr, AVR_IOCTL_IOPORT_SET_EXTERNAL(e.name), &e);
 	}
+#endif
 	avr_set_command_register(avr, firmware->command_register_addr);
 	avr_set_console_register(avr, firmware->console_register_addr);
 
@@ -299,6 +301,7 @@ elf_parse_mmcu_section(
 				firmware->aref =
 					src[0] | (src[1] << 8) | (src[2] << 16) | (src[3] << 24);
 				break;
+#ifdef CONFIG_PULL_UPS
 			case AVR_MMCU_TAG_PORT_EXTERNAL_PULL: {
 				for (int i = 0; i < 8; i++)
 					if (!firmware->external_state[i].port) {
@@ -315,6 +318,7 @@ elf_parse_mmcu_section(
 						break;
 					}
 			}	break;
+#endif
 			case AVR_MMCU_TAG_VCD_PORTPIN:
 			case AVR_MMCU_TAG_VCD_IRQ:
 			case AVR_MMCU_TAG_VCD_TRACE: {

simavr/sim/sim_elf.h

@@ -56,10 +56,12 @@ typedef struct elf_firmware_t {
 		char	name[64];
 	} trace[32];
 
+#ifdef CONFIG_PULL_UPS
 	struct {
 		char port;
 		uint8_t mask, value;
 	} external_state[8];
+#endif
 
 	// register to listen to for commands from the firmware
 	uint16_t	command_register_addr;

tests/atmega168_ioport.c

@@ -66,7 +66,7 @@ int main()
 
         /* This should say P<70 - pullups and direct output give 0xF0
          * but the caller sees that and turns off bit 7 input,
-         * overriding that pullup.
+         * overriding that pullup.  With pullups disabled: P<30.
          */
 
         printf("P<%02X ", PIND);

tests/test_atmega168_ioport.c

@@ -92,15 +92,25 @@ static void reg_read(struct avr_irq_t *irq, uint32_t value, void *param)
 /* This string should be sent by the firmware. */
 
 static const char *expected =
+#ifdef CONFIG_PULL_UPS
     "P<2A P<70 F<01 I<E0 P<E0 J<03 J<00 P<E8 | K | ";
+#else
+    "P<2A P<30 F<01 I<20 P<20 J<03 J<00 P<28 | K | ";
+#endif
 
 /* This string is expected in variable log. */
 
 static const char *log_expected =
-    "d-0F P-00 o-0A P-0A I-0A 5-01 o-09 P-29 d-3C 5-00 P-09 o-F0 5-01 P-F0 "
-    "I-70 "                                     // Interrupts off testing.
+    "d-0F P-00 o-0A P-0A I-0A 5-01 o-09 P-29 d-3C 5-00 P-09 o-F0 5-01 "
+#ifdef CONFIG_PULL_UPS
+    "P-F0 I-70 "                                // Interrupts off testing.
     "o-E0 P-E0 I-E0 I-E0 "                      // External interrupt test.
     "d-03 o-01 P-E1 o-03 P-E3 o-00 P-E8 I-E8 "; // Pin change interrupt test.
+#else
+    "P-30 I-30 "                                // Interrupts off testing.
+    "o-E0 P-20 I-20 I-20 "                      // External interrupt test.
+    "d-03 o-01 P-21 o-03 P-23 o-00 P-28 I-28 "; // Pin change interrupt test.
+#endif
 
 
 int main(int argc, char **argv) {