rgb: add initial rgb code

It initializes the rgb driver, and can write to its registers.

Signed-off-by: Sean Cross <sean@xobs.io>

sw/include/rgb.h

@@ -0,0 +1,6 @@
+#ifndef _RGB_H_
+#define _RGB_H_
+
+void rgb_init(void);
+
+#endif /* _RGB_H_ */

sw/src/rgb.c

@@ -0,0 +1,46 @@
+#include <rgb.h>
+#include <generated/csr.h>
+
+enum led_registers {
+    LEDDCR0 = 8,
+    LEDDBR = 9,
+    LEDDONR = 10,
+    LEDDOFR = 11,
+    LEDDBCRR = 5,
+    LEDDBCFR = 6,
+    LEDDPWRR = 1,
+    LEDDPWRG = 2,
+    LEDDPWRB = 3,
+};
+
+#define BREATHE_ENABLE (1 << 7)
+#define BREATHE_EDGE_ON (0 << 6)
+#define BREATHE_EDGE_BOTH (1 << 6)
+#define BREATHE_MODE_MODULATE (1 << 5)
+#define BREATHE_RATE(x) ((x & 7) << 0)
+
+static void rgb_write(uint8_t value, uint8_t addr) {
+    rgb_addr_write(addr);
+    rgb_dat_write(value);
+}
+
+void rgb_init(void) {
+    // Turn on the RGB block and current enable, as well as enabling led control
+    rgb_ctrl_write((1 << 0) | (1 << 1) | (1 << 2));
+
+    rgb_write((1 << 7) | (1 << 6), LEDDCR0);
+
+    // Set clock register to 12 MHz / 64 kHz - 1
+    rgb_write((12000000/64000)-1, LEDDBR);
+
+    rgb_write(12, LEDDONR);
+    rgb_write(24, LEDDOFR);
+
+    rgb_write(BREATHE_ENABLE | BREATHE_EDGE_BOTH
+            | BREATHE_MODE_MODULATE | BREATHE_RATE(2), LEDDBCRR);
+    rgb_write(BREATHE_ENABLE | BREATHE_MODE_MODULATE | BREATHE_RATE(3), LEDDBCFR);
+
+    rgb_write(0x00/4, LEDDPWRG); // Red
+    rgb_write(0x4a/4, LEDDPWRB); // Green
+    rgb_write(0xe1/4, LEDDPWRR); // Blue
+}