4x ports

Author: ArcaneNibble

main.c

@@ -4,6 +4,8 @@
 
 // Shared RAM (control input)
 
+#define NUM_I2C_CHANNELS    4
+
 #define I2C_CMD_QUIRK       0x02
 
 typedef struct i2c_command {
@@ -18,7 +20,7 @@ typedef struct i2c_command {
 typedef struct shared_ram {
     // Declare this as a u32 to force more-efficient codegen
     uint32_t pwms;
-    i2c_command i2c;
+    i2c_command i2c[NUM_I2C_CHANNELS];
     uint32_t profiling_test;
 } shared_ram;
 // XXX: The real address in use here is 0x80010000
@@ -79,7 +81,7 @@ typedef struct i2c_state_struct {
     uint8_t scl_bit;
     uint8_t sda_bit;
 } i2c_state_struct;
-i2c_state_struct i2c_states[1];
+i2c_state_struct i2c_states[NUM_I2C_CHANNELS];
 
 static inline __attribute__((always_inline)) void i2c_low(uint8_t gpio_bit) {
     uint32_t r = GPIO_BANK_01->dir;
@@ -99,7 +101,21 @@ static inline __attribute__((always_inline)) void i2c_hi(uint8_t gpio_bit) {
         :: handle_timeout                               \
     )
 
-static void handle_i2c(i2c_state_struct *i2c) {
+static inline __attribute__((always_inline)) uint32_t shared_i2c_get_flags(uint8_t cmd_offs) {
+    uint32_t x;
+    asm("lbco %0, 30, %1, 4" : "=r"(x) : "r"((uint8_t)(cmd_offs + __builtin_offsetof(i2c_command, flags))));
+    return x;
+}
+static inline __attribute__((always_inline)) void shared_i2c_set_flags(uint8_t cmd_offs, uint32_t x) {
+    asm("sbco %0, 30, %1, 4" :: "r"(x), "r"((uint8_t)(cmd_offs + __builtin_offsetof(i2c_command, flags))));
+}
+static inline __attribute__((always_inline)) uint8_t *shared_i2c_get_buffer(uint8_t cmd_offs) {
+    uint8_t *x;
+    asm("lbco %0, 30, %1, 4" : "=r"(x) : "r"((uint8_t)(cmd_offs + __builtin_offsetof(i2c_command, buffer))));
+    return x;
+}
+
+static void handle_i2c(uint8_t cmd_offs, i2c_state_struct *i2c) {
     uint8_t state = i2c->state;
     uint8_t phase = i2c->phase;
     uint8_t work_byte = i2c->work_byte;
@@ -110,12 +126,12 @@ static void handle_i2c(i2c_state_struct *i2c) {
 
     switch (state) {
         case I2C_STATE_IDLE: {
-            uint32_t flags = SHARED->i2c.flags;
+            uint32_t flags = shared_i2c_get_flags(cmd_offs);
             if ((flags & 0x81) != 0x01) {
                 break;
             }
 
-            i2c->buffer = SHARED->i2c.buffer;
+            i2c->buffer = shared_i2c_get_buffer(cmd_offs);
             i2c->addr = flags >> 24;
             i2c->rlen = flags >> 16;
             i2c->wlen = flags >> 8;
@@ -125,7 +141,7 @@ static void handle_i2c(i2c_state_struct *i2c) {
             phase = 0;
             i2c->timeout = I2C_TIMEOUT_LOOPS;
 
-            SHARED->i2c.flags = 0;
+            shared_i2c_set_flags(cmd_offs, 0);
 
             __attribute__((fallthrough));
         }
@@ -270,7 +286,7 @@ static void handle_i2c(i2c_state_struct *i2c) {
                     phase = 0;
                 } else {
                     state = I2C_STATE_IDLE;
-                    SHARED->i2c.flags = 0xaa80;
+                    shared_i2c_set_flags(cmd_offs, 0xaa80);
                 }
             }
             break;
@@ -353,14 +369,14 @@ static void handle_i2c(i2c_state_struct *i2c) {
 
     if (0) {
 handle_nak:
-        SHARED->i2c.flags = 0x4e80;
+        shared_i2c_set_flags(cmd_offs, 0x4e80);
         state = I2C_STATE_IDLE;
     }
 
     if (0) {
 handle_timeout:
         if (--i2c->timeout == 0) {
-            SHARED->i2c.flags = 0x5480;
+            shared_i2c_set_flags(cmd_offs, 0x5480);
             state = I2C_STATE_IDLE;
         }
     }
@@ -376,8 +392,14 @@ void main() {
     bool debug_profile_thing = false;
 
     // We initialize this in code to avoid having to copy a data ram binary
-    i2c_states[0].scl_bit = 12;
-    i2c_states[0].sda_bit = 14 + 16;
+    i2c_states[0].scl_bit = 2;
+    i2c_states[0].sda_bit = 15;
+    i2c_states[1].scl_bit = 14;
+    i2c_states[1].sda_bit = 13;
+    i2c_states[2].scl_bit = 12;
+    i2c_states[2].sda_bit = 14 + 16;
+    i2c_states[3].scl_bit = 1;
+    i2c_states[3].sda_bit = 15 + 16;
 
     while (1) {
         // 24 MHz / 256 ==> 93.75 kHz tick rate for this counter
@@ -399,7 +421,10 @@ void main() {
             *TIMER2_INTCTLSTAT = TIMER_INTCTLSTAT_PRDINTSTAT12;
 
             // This code runs at 20 kHz, which is 2x the I2C clock rate
-            handle_i2c(&i2c_states[0]);
+            handle_i2c(__builtin_offsetof(shared_ram, i2c[0]), &i2c_states[0]);
+            handle_i2c(__builtin_offsetof(shared_ram, i2c[1]), &i2c_states[1]);
+            handle_i2c(__builtin_offsetof(shared_ram, i2c[2]), &i2c_states[2]);
+            handle_i2c(__builtin_offsetof(shared_ram, i2c[3]), &i2c_states[3]);
 
             if (debug_profile_thing) {
                 uint32_t tim_profile = *TIMER2_TIM12;