Respond to I2C read request with an info structure.

Makefile

@@ -32,13 +32,14 @@ dist: all
 endif
 
 BAUD=921600
+DEV=/dev/ttyUSB1
 
 flash: all
 	sudo ~/stm32flash/stm32flash -b $(BAUD) \
-	-vw src/$(PROJ).hex /dev/ttyUSB0
+	-vw src/$(PROJ).hex $(DEV)
 
 start:
-	sudo ~/stm32flash/stm32flash -b $(BAUD) -g 0 /dev/ttyUSB0
+	sudo ~/stm32flash/stm32flash -b $(BAUD) -g 0 $(DEV)
 
 serial:
-	sudo miniterm.py /dev/ttyUSB0 115200
+	sudo miniterm.py $(DEV) 115200

inc/decls.h

@@ -14,10 +14,10 @@
 #include <stdarg.h>
 #include <stddef.h>
 
+#include "intrinsics.h"
 #include "util.h"
 #include "stm32f10x_regs.h"
 #include "stm32f10x.h"
-#include "intrinsics.h"
 
 #include "config.h"
 #include "cancellation.h"

inc/util.h

@@ -53,6 +53,9 @@ int strncmp(const char *s1, const char *s2, size_t n);
 char *strcpy(char *dest, const char *src);
 char *strrchr(const char *s, int c);
 int tolower(int c);
+int isspace(int c);
+
+long int strtol(const char *nptr, char **endptr, int base);
 
 uint16_t crc16_ccitt(const void *buf, size_t len, uint16_t crc);
 
@@ -114,7 +117,12 @@ void lcd_init(void);
 void lcd_process(void);
 extern struct display lcd_display;
 extern bool_t ff_osd_i2c_protocol;
-extern uint8_t ff_osd_buttons;
+extern uint8_t i2c_buttons_rx; /* Gotek -> FF_OSD */
+extern struct __packed i2c_osd_info {
+    uint8_t protocol_ver;
+    uint8_t fw_major, fw_minor;
+    uint8_t buttons;
+} i2c_osd_info;
 
 /* Build info. */
 extern const char fw_ver[];

src/lcd.c

@@ -47,11 +47,12 @@ static uint16_t t_cons, t_prod;
 static bool_t lcd_inc;
 static uint8_t lcd_ddraddr;
 struct display lcd_display;
-uint8_t ff_osd_buttons;
+uint8_t i2c_buttons_rx;
+struct i2c_osd_info i2c_osd_info;
 
-/* I2C Error ISR: As slave with clock stretc we can only receive:
+/* I2C Error ISR: As slave with clock stretch we can only receive:
  *  Bus error (BERR): Peripheral automatically recovers
- *  Arbitration lost (ARLO): Peripheral automatically recovers */
+ *  Acknowledge Failure (AF): Peripheral automatically recovers */
 static void IRQ_i2c_error(void)
 {
     /* Clear I2C errors. Nothing else needs to be done. */
@@ -60,12 +61,15 @@ static void IRQ_i2c_error(void)
 
 static void IRQ_i2c_event(void)
 {
+    static uint8_t rp;
     uint16_t sr1 = i2c->sr1;
 
     if (sr1 & I2C_SR1_ADDR) {
         /* Read SR2 clears SR1_ADDR. */
-        (void)i2c->sr2;
-        t_ring[MASK(t_ring, t_prod++)] = d_prod;
+        uint16_t sr2 = i2c->sr2;
+        if (!(sr2 & I2C_SR2_TRA))
+            t_ring[MASK(t_ring, t_prod++)] = d_prod;
+        rp = 0;
     }
 
     if (sr1 & I2C_SR1_STOPF) {
@@ -74,9 +78,15 @@ static void IRQ_i2c_event(void)
     }
 
     if (sr1 & I2C_SR1_RXNE) {
-        /* Read DR clear SR1_RXNE. */
+        /* Read DR clears SR1_RXNE. */
         d_ring[MASK(d_ring, d_prod++)] = i2c->dr;
     }
+
+    if (sr1 & I2C_SR1_TXE) {
+        /* Write DR clears SR1_TXE. */
+        uint8_t *info = (uint8_t *)&i2c_osd_info;
+        i2c->dr = (rp < sizeof(i2c_osd_info)) ? info[rp++] : 0;
+    }
 }
 
 static void process_cmd(uint8_t cmd)
@@ -190,7 +200,7 @@ static void ff_osd_process(void)
             } else {
                 switch (x & 0xf0) {
                 case OSD_BUTTONS:
-                    ff_osd_buttons = x & 0x0f;
+                    i2c_buttons_rx = x & 0x0f;
                     break;
                 case OSD_ROWS:
                     /* 0-3 */
@@ -256,6 +266,12 @@ void lcd_process(void)
 
 void lcd_init(void)
 {
+    char *p;
+
+    i2c_osd_info.protocol_ver = 0;
+    i2c_osd_info.fw_major = strtol(fw_ver, &p, 10);
+    i2c_osd_info.fw_minor = strtol(p+1, NULL, 10);
+
     rcc->apb1enr |= RCC_APB1ENR_I2C1EN;
 
     gpio_configure_pin(gpiob, SCL, AFO_opendrain(_2MHz));

src/main.c

@@ -491,6 +491,7 @@ struct gotek_button {
 } gl, gr, gs;
 
 static bool_t gotek_active;
+
 static void emulate_gotek_button(
     uint8_t keycode, struct gotek_button *button, int pin)
 {
@@ -509,13 +510,18 @@ static void emulate_gotek_button(
 
 static void emulate_gotek_buttons(void)
 {
+    uint8_t b = 0;
     if (config_active)
         gotek_active = FALSE;
     else if (!gotek_active && !keys)
         gotek_active = TRUE; /* only after keys are released */
     emulate_gotek_button(K_LEFT, &gl, 3);
     emulate_gotek_button(K_RIGHT, &gr, 4);
     emulate_gotek_button(K_SELECT, &gs, 5);
+    if (gl.pressed) b |= B_LEFT;
+    if (gr.pressed) b |= B_RIGHT;
+    if (gs.pressed) b |= B_SELECT;
+    *(volatile uint8_t *)&i2c_osd_info.buttons = b;
 }
 
 static struct display no_display;
@@ -783,7 +789,7 @@ int main(void)
                 if (keys & K_MENU) b |= B_SELECT;
             }
             /* Fold in button presses remoted via I2C. */
-            b |= ff_osd_buttons;
+            b |= i2c_buttons_rx;
             /* Pass button presses to config subsystem for processing. */
             config_process(b & ~B_PROCESSED);
         }

src/util.c

@@ -98,6 +98,68 @@ int tolower(int c)
     return c;
 }
 
+int isspace(int c)
+{
+    return (c == ' ') || (c == '\t') || (c == '\n') || (c == '\r')
+        || (c == '\f') || (c == '\v');
+}
+
+long int strtol(const char *nptr, char **endptr, int base)
+{
+    long int val = 0;
+    const char *p = nptr;
+    bool_t is_neg = FALSE;
+    int c;
+
+    /* Optional whitespace prefix. */
+    while (isspace(*p))
+        p++;
+    c = tolower(*p);
+
+    /* Optional sign prefix: +, -. */
+    if ((c == '+') || (c == '-')) {
+        is_neg = (c == '-');
+        c = tolower(*++p);
+    }
+
+    /* Optional base prefix: 0, 0x. */
+    if (c == '0') {
+        if (base == 0)
+            base = 8;
+        c = tolower(*++p);
+        if (c == 'x') {
+            if (base == 0)
+                base = 16;
+            if (base != 16)
+                goto out;
+            c = tolower(*++p);
+        }
+    }
+
+    if (base == 0)
+        base = 10;
+
+    /* Digits. */
+    for (;;) {
+        /* Convert c to a digit [0123456789abcdefghijklmnopqrstuvwxyz]. */
+        if ((c >= '0') && (c <= '9'))
+            c -= '0';
+        else if ((c >= 'a') && (c <= 'z'))
+            c -= 'a' - 10;
+        else
+            break;
+        if (c >= base)
+            break;
+        val = (val * base) + c;
+        c = tolower(*++p);
+    }
+
+out:
+    if (endptr)
+        *endptr = (char *)p;
+    return is_neg ? -val : val;
+}
+
 const static uint16_t crc16_ccitt_table[] = {
     0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
     0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,