--- /dev/null
+#
+/*
+ * Raspberry Pi support library for the ACK
+ * © 2013 David Given
+ * This file is redistributable under the terms of the 3-clause BSD license.
+ * See the file 'Copying' in the root of the distribution for the full text.
+ */
+
+#include "libsysasm.h"
+
+.sect .text
+
+#define PASSWD 0x5a000000
+#define PLLC 5
+#define OSC 1
+
+#define A2W 0x7e102000
+#define A2W_PLLC_MULT 0x7e102020
+#define A2W_PLLC_MULT2 0x7e102120
+#define A2W_PLLC_MULT_FRACT 0x7e102220
+#define A2W_PLLx_DIV 0x7e102620
+
+#define CM 0x7e101000
+#define CM_VPU_CTL 0x7e101008
+#define CM_VPU_DIV 0x7e10100c
+#define CM_TIME_DIV 0x7e1010ec
+#define CM_TIME_CTL 0x7e1010e8
+
+#define hash #
+#define copy(A) A
+#define poke(A, V) \
+ mov r0, copy(hash) V; mov r1, copy(hash) A; st r0, (r1)
+
+! Changes the clock speed to 250MHz.
+
+.define _pi_fast_mode
+_pi_fast_mode:
+ poke(A2W + 0x190, 0x5a000001)
+ poke(A2W_PLLC_MULT_FRACT, PASSWD | 87380)
+ poke(A2W_PLLC_MULT2, PASSWD | 52 | 0x1000)
+ poke(A2W + 0x3c, 0x5a000100)
+ poke(A2W + 0x38, 0x5a000000)
+ poke(A2W + 0x34, 0x5a144000)
+ poke(A2W + 0x30, 0x5a000000)
+ poke(CM + 0x108, 0x5a000200)
+ poke(CM + 0x108, 0x5a0002aa)
+ poke(A2W + 0x2c, 0x5a000000)
+ poke(A2W + 0x28, 0x5a400000)
+ poke(A2W + 0x24, 0x5a000005)
+ poke(A2W_PLLC_MULT, PASSWD | 52 | 0x555000)
+ poke(A2W_PLLC_MULT2, PASSWD | 52 | 0x21000)
+ poke(A2W + 0x2c, 0x5a000042)
+ poke(A2W + 0x28, 0x5a500401)
+ poke(A2W + 0x24, 0x5a004005)
+ poke(A2W_PLLC_MULT, PASSWD | 52 | 0x555000)
+ poke(A2W_PLLx_DIV, PASSWD | 2)
+ poke(CM + 0x108, 0x5a0002ab)
+ poke(CM + 0x108, 0x5a0002aa)
+ poke(CM + 0x108, 0x5a0002a8)
+ poke(CM_VPU_CTL, PASSWD | 0x200 | OSC | 0x40)
+ poke(CM_VPU_DIV, PASSWD | [4 << 12])
+ poke(CM_VPU_CTL, PASSWD | PLLC | 0x40)
+ poke(CM_VPU_CTL, PASSWD | PLLC | 0x50)
+ poke(CM_TIME_DIV, PASSWD | [19 << 12] | 819)
+ poke(CM_TIME_CTL, PASSWD | OSC | 0x10)
+
+ mov r0, #250000000
+ st r0, _pi_clock_speed
+ b lr
+