firmware: Add support for hardware revision detection

firmware/Makefile

@@ -19,9 +19,14 @@ ifeq ($(APOLLO_BOARD), luna)
 endif
 
 ifeq ($(BOARD), cynthion_d11)
-	# These should default to the latest revision but can be set on the command line.
-	BOARD_REVISION_MAJOR ?= 1
-	BOARD_REVISION_MINOR ?= 4
+	# Enable revision autodetection by default if no revision is provided.
+	ifeq ($(BOARD_REVISION_MAJOR),)
+		ifeq ($(BOARD_REVISION_MINOR),)
+			BOARD_REVISION_DETECT := 1
+			BOARD_REVISION_MAJOR := 255
+			BOARD_REVISION_MINOR := 255
+		endif
+	endif
 
 	# On r0.1 or r0.2 boards, we target the SAMD21 configuration.
 	ifeq ($(BOARD_REVISION_MAJOR), 0)
@@ -36,6 +41,8 @@ else
 	BOARD := $(APOLLO_BOARD)
 endif
 
+# This should be set to 1 at this point if autodetection is enabled.
+BOARD_REVISION_DETECT ?= 0
 
 # Default to using a maximum possible HW version, which means "generic Apollo board".
 BOARD_REVISION_MAJOR ?= 255
@@ -61,6 +68,7 @@ CFLAGS += \
 	-Wno-unused-parameter \
 	-Wno-cast-qual \
 	-fstrict-volatile-bitfields \
+	-D_BOARD_REVISION_DETECT_=$(BOARD_REVISION_DETECT) \
 	-D_BOARD_REVISION_MAJOR_=$(BOARD_REVISION_MAJOR) \
 	-D_BOARD_REVISION_MINOR_=$(BOARD_REVISION_MINOR) \
 	-D VERSION_STRING=\"$(VERSION_STRING)\" \

firmware/src/board_rev.c

@@ -0,0 +1,25 @@
+/*
+ * Board revision detection.
+ *
+ * This file is part of Apollo.
+ *
+ * Copyright (c) 2024 Great Scott Gadgets <[email protected]>
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "board_rev.h"
+
+/**
+ * Detect hardware revision using a board-specific method.
+ */
+__attribute__((weak)) void detect_hardware_revision(void)
+{
+}
+
+/**
+ * Returns the board revision in bcdDevice format.
+ */
+__attribute__((weak)) uint16_t get_board_revision(void)
+{
+    return (_BOARD_REVISION_MAJOR_ << 8) | _BOARD_REVISION_MINOR_;
+}

firmware/src/board_rev.h

@@ -0,0 +1,26 @@
+/*
+ * Board revision detection.
+ *
+ * This file is part of Apollo.
+ *
+ * Copyright (c) 2024 Great Scott Gadgets <[email protected]>
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdint.h>
+
+#ifndef __BOARD_REV_H__
+#define __BOARD_REV_H__
+
+/**
+ * Detect hardware revision using a board-specific method.
+ */
+void detect_hardware_revision(void);
+
+/**
+ * Returns the board revision in bcdDevice format.
+ */
+uint16_t get_board_revision(void);
+
+
+#endif

firmware/src/boards/cynthion_d11/apollo_board.h

@@ -52,18 +52,32 @@ enum {
  */
 enum {
 	FPGA_PROGRAM   = PIN_PA08,
-#if ((_BOARD_REVISION_MAJOR_ == 0) && (_BOARD_REVISION_MINOR_ < 6))
+#ifdef BOARD_HAS_SHARED_BUTTON
 	PROGRAM_BUTTON = PIN_PA16,
 	PHY_RESET      = PIN_PA09,
 #else
 	PROGRAM_BUTTON = PIN_PA02,
 	USB_SWITCH     = PIN_PA06,
 	FPGA_ADV       = PIN_PA09,
 #endif
-#if ((_BOARD_REVISION_MAJOR_ == 1) && (_BOARD_REVISION_MINOR_ > 2))
+	// FPGA sysCFG pins only in revs >= 1.3.
 	FPGA_INITN     = PIN_PA03,
 	FPGA_DONE      = PIN_PA04,
-#endif
+};
+
+
+/**
+ * Cynthion board revisions as bcdDevice values.
+ */
+enum {
+    CYNTHION_REV_UNKNOWN = 0,
+    CYNTHION_REV_0_6     = (0 << 8) | 6,
+    CYNTHION_REV_0_7     = (0 << 8) | 7,
+    CYNTHION_REV_1_0     = (1 << 8) | 0,
+    CYNTHION_REV_1_1     = (1 << 8) | 1,
+    CYNTHION_REV_1_2     = (1 << 8) | 2,
+    CYNTHION_REV_1_3     = (1 << 8) | 3,
+    CYNTHION_REV_1_4     = (1 << 8) | 4,
 };
 
 

firmware/src/boards/cynthion_d11/board_rev.c

@@ -0,0 +1,108 @@
+/*
+ * Board revision detection for Cynthion.
+ *
+ * This file is part of Apollo.
+ *
+ * Copyright (c) 2024 Great Scott Gadgets <[email protected]>
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdint.h>
+
+#include "apollo_board.h"
+#include "board_rev.h"
+
+#include <hpl_pm_config.h>
+#include <hpl/pm/hpl_pm_base.h>
+#include <hpl/gclk/hpl_gclk_base.h>
+
+
+#if (_BOARD_REVISION_DETECT_ == 1)
+
+static uint16_t revision = CYNTHION_REV_UNKNOWN;
+static bool gsg_production = false;
+
+/**
+ * Detect hardware revision using Cynthion pin straps.
+ */
+void detect_hardware_revision(void)
+{
+    _pm_enable_bus_clock(PM_BUS_APBC, ADC);
+    _gclk_enable_channel(ADC_GCLK_ID, CONF_GCLK_ADC_SRC);
+
+    // Initialize ADC device registers.
+    uint16_t calib_reg = ADC_CALIB_BIAS_CAL((*(uint32_t *)ADC_FUSES_BIASCAL_ADDR >> ADC_FUSES_BIASCAL_Pos))
+                | ADC_CALIB_LINEARITY_CAL((*(uint64_t *)ADC_FUSES_LINEARITY_0_ADDR >> ADC_FUSES_LINEARITY_0_Pos));
+
+    hri_adc_wait_for_sync(ADC);
+    hri_adc_write_CTRLA_reg(ADC, ADC_CTRLA_SWRST);
+    hri_adc_wait_for_sync(ADC);
+
+    hri_adc_write_CALIB_reg(ADC, calib_reg);
+    hri_adc_write_REFCTRL_reg(ADC, ADC_REFCTRL_REFCOMP | ADC_REFCTRL_REFSEL_INTVCC1);
+    hri_adc_write_CTRLB_reg(ADC, ADC_CTRLB_PRESCALER_DIV512 | ADC_CTRLB_RESSEL_12BIT);
+    hri_adc_write_INPUTCTRL_reg(ADC, ADC_INPUTCTRL_GAIN_DIV2 | ADC_INPUTCTRL_MUXPOS_PIN5 | ADC_INPUTCTRL_MUXNEG_GND);
+    hri_adc_write_CTRLA_reg(ADC, ADC_CTRLA_ENABLE);
+
+    // Configure relevant GPIO to function as an ADC input.
+    gpio_set_pin_function(PIN_PA07, PINMUX_PA07B_ADC_AIN5);
+
+    // Retrieve a single ADC reading.
+    hri_adc_set_SWTRIG_START_bit(ADC);
+	while (!hri_adc_get_interrupt_RESRDY_bit(ADC));
+	uint16_t reading = hri_adc_read_RESULT_reg(ADC);
+
+    // Convert ADC measurement to a percentage of the reference voltage.
+    uint32_t percentage = (((uint32_t)reading * 100) + 2048) >> 12;
+    if (percentage > 51) {
+        percentage = 100 - percentage;
+        gsg_production = true;
+    }
+
+    /*
+    hardware version  |  percent of +3V3
+    ___________________________________________
+    0.6               |  0-1
+    future versions   |  2-20
+    1.4               |  21-22
+    1.3               |  23-24
+    1.2               |  25-26
+    1.0               |  27-28
+    1.1               |  29-31
+    reserved          |  32-48
+    0.7               |  49-51
+    reserved          |  52-68
+    1.1-production    |  69-71
+    future-production |  72-100
+    */
+
+    // Identify the board revision by comparing against expected thresholds.
+    struct {
+        uint16_t version;
+        uint8_t threshold;
+    } revisions[] = {
+        { CYNTHION_REV_0_6,         1 },
+        { CYNTHION_REV_UNKNOWN,    20 },
+        { CYNTHION_REV_1_4,        22 },
+        { CYNTHION_REV_1_3,        24 },
+        { CYNTHION_REV_1_2,        26 },
+        { CYNTHION_REV_1_0,        28 },
+        { CYNTHION_REV_1_1,        31 },
+        { CYNTHION_REV_UNKNOWN,    48 },
+        { CYNTHION_REV_0_7,        51 },
+    };
+
+    int i = 0;
+    while (percentage > revisions[i].threshold) { ++i; }
+    revision = revisions[i].version;
+}
+
+/**
+ * Returns the board revision in bcdDevice format.
+ */
+uint16_t get_board_revision(void)
+{
+    return revision;
+}
+
+#endif

firmware/src/boards/cynthion_d11/fpga.c

@@ -11,6 +11,7 @@
 #include "apollo_board.h"
 #include "jtag.h"
 #include "fpga.h"
+#include "board_rev.h"
 
 
 /*
@@ -20,17 +21,17 @@
  */
 void permit_fpga_configuration(bool enable)
 {
-#if ((_BOARD_REVISION_MAJOR_ == 1) && (_BOARD_REVISION_MINOR_ > 2))
-	gpio_set_pin_level(FPGA_INITN, enable);
-	gpio_set_pin_direction(FPGA_INITN, GPIO_DIRECTION_OUT);
+    if (get_board_revision() < CYNTHION_REV_1_3) return;
 
-	/*
-	 * Delay a bit (in case the FPGA is already initializing) because
-	 * TN-02039 says that PROGRAMN should not have a falling edge during
-	 * initialization.
-	 */
-	board_delay(1);
-#endif
+    gpio_set_pin_level(FPGA_INITN, enable);
+    gpio_set_pin_direction(FPGA_INITN, GPIO_DIRECTION_OUT);
+
+    /*
+    * Delay a bit (in case the FPGA is already initializing) because
+    * TN-02039 says that PROGRAMN should not have a falling edge during
+    * initialization.
+    */
+    board_delay(1);
 }
 
 

firmware/src/main.c

@@ -32,6 +32,7 @@
 #include <bsp/board_api.h>
 #include <apollo_board.h>
 
+#include "board_rev.h"
 #include "led.h"
 #include "jtag.h"
 #include "fpga.h"
@@ -49,6 +50,7 @@
 int main(void)
 {
 	board_init();
+	detect_hardware_revision();
 	tusb_init();
 
 	fpga_io_init();

firmware/src/mcu/samd11/usb_descriptors.c

@@ -26,13 +26,14 @@
  */
 
 #include "tusb.h"
+#include "board_rev.h"
 
 #define SERIAL_NUMBER_STRING_INDEX 3
 
 //--------------------------------------------------------------------+
 // Device Descriptors
 //--------------------------------------------------------------------+
-tusb_desc_device_t const desc_device =
+tusb_desc_device_t desc_device =
 {
 	.bLength            = sizeof(tusb_desc_device_t),
 	.bDescriptorType    = TUSB_DESC_DEVICE,
@@ -50,7 +51,6 @@ tusb_desc_device_t const desc_device =
 	// These are a unique VID/PID for development LUNA boards.
 	.idVendor           = 0x1d50,
 	.idProduct          = 0x615c,
-	.bcdDevice          = (_BOARD_REVISION_MAJOR_ << 8) | _BOARD_REVISION_MINOR_,
 
 	.iManufacturer      = 0x01,
 	.iProduct           = 0x02,
@@ -63,6 +63,7 @@ tusb_desc_device_t const desc_device =
 // Application return pointer to descriptor
 uint8_t const * tud_descriptor_device_cb(void)
 {
+	desc_device.bcdDevice = get_board_revision();
 	return (uint8_t const *) &desc_device;
 }