sam3n kdebug: fix bug, enable correctly UART PMC.

[bertos.git] / bertos / cpu / cortex-m3 / drv / clock_sam3.c

diff --git a/bertos/cpu/cortex-m3/drv/clock_sam3.c b/bertos/cpu/cortex-m3/drv/clock_sam3.c
index 967e3798b6613429ef293e4675b8ed78286f9601..b0486c51d992ef94edcf16a7e60e4e382ee09a53 100644 (file)
--- a/bertos/cpu/cortex-m3/drv/clock_sam3.c
+++ b/bertos/cpu/cortex-m3/drv/clock_sam3.c
@@ -30,13 +30,100 @@
  *
  * -->
  *
- * \brief AT91SAM3 clocking driver.
+ * \brief ATSAM3 clock setup.
  *
  * \author Stefano Fedrigo <aleph@develer.com>
  */
 
 #include "clock_sam3.h"
+#include <io/sam3_pmc.h>
+#include <io/sam3_sysctl.h>
+#include <cfg/compiler.h>
+#include <cfg/macros.h>
+
+
+/* Frequency of board main oscillator */
+#define BOARDOSC_FREQ  12000000
+
+/* Main crystal oscillator startup time, optimal value for CPU_FREQ == 48 MHz */
+#define BOARD_OSC_COUNT  (CKGR_MOR_MOSCXTST(0x8))
+
+/* Timer countdown timeout for clock initialization operations */
+#define CLOCK_TIMEOUT    0xFFFFFFFF
+
+
+/*
+ * Try to evaluate the correct divider and multiplier value depending
+ * on the desired CPU frequency.
+ *
+ * We try all combinations in a certain range of divider and multiplier
+ * values.  The range can change, with better match with "strange"
+ * frequencies, but boot time will be longer.
+ *
+ * Limits for SAM3N: divider [1,255], multiplier [1,2047].
+ */
+INLINE uint32_t evaluate_pll(void)
+{
+       int mul, div, best_mul, best_div;
+       int best_delta = CPU_FREQ;
+       int freq = 0;
+
+       for (mul = 1; mul <= 8; mul++)
+       {
+               for (div = 1; div <= 24; div++)
+               {
+                       freq = BOARDOSC_FREQ / div * (1 + mul);
+                       if (ABS((int)CPU_FREQ - freq) < best_delta) {
+                               best_delta = ABS((int)CPU_FREQ - freq);
+                               best_mul = mul;
+                               best_div = div;
+                       }
+               }
+       }
+
+       // Bit 29 must always be set to 1
+       return CKGR_PLLR_DIV(best_div) | CKGR_PLLR_MUL(best_mul) | BV(29);
+}
+
 
 void clock_init(void)
 {
+       uint32_t timeout;
+
+       // Select external slow clock
+       if (!(SUPC_SR_R & SUPC_SR_OSCSEL))
+       {
+               SUPC_CR_R = SUPC_CR_XTALSEL | SUPC_CR_KEY(0xA5);
+               while (!(SUPC_SR_R & SUPC_SR_OSCSEL));
+       }
+
+       // Initialize main oscillator
+       if (!(CKGR_MOR_R & CKGR_MOR_MOSCSEL))
+       {
+               CKGR_MOR_R = CKGR_MOR_KEY(0x37) | BOARD_OSC_COUNT | CKGR_MOR_MOSCRCEN | CKGR_MOR_MOSCXTEN;
+               timeout = CLOCK_TIMEOUT;
+               while (!(PMC_SR_R & PMC_SR_MOSCXTS) && --timeout);
+       }
+
+       // Switch to external oscillator
+       CKGR_MOR_R = CKGR_MOR_KEY(0x37) | BOARD_OSC_COUNT | CKGR_MOR_MOSCRCEN | CKGR_MOR_MOSCXTEN | CKGR_MOR_MOSCSEL;
+       timeout = CLOCK_TIMEOUT;
+       while (!(PMC_SR_R & PMC_SR_MOSCSELS) && --timeout);
+
+       PMC_MCKR_R = (PMC_MCKR_R & ~(uint32_t)PMC_MCKR_CSS_M) | PMC_MCKR_CSS_MAIN_CLK;
+       timeout = CLOCK_TIMEOUT;
+       while (!(PMC_SR_R & PMC_SR_MCKRDY) && --timeout);
+
+       // Initialize and enable PLL clock
+       CKGR_PLLR_R = evaluate_pll() | CKGR_PLLR_STUCKTO1 | CKGR_PLLR_PLLCOUNT(0x1);
+       timeout = CLOCK_TIMEOUT;
+       while (!(PMC_SR_R & PMC_SR_LOCK) && --timeout);
+
+       PMC_MCKR_R = PMC_MCKR_CSS_MAIN_CLK;
+       timeout = CLOCK_TIMEOUT;
+       while (!(PMC_SR_R & PMC_SR_MCKRDY) && --timeout);
+
+       PMC_MCKR_R = PMC_MCKR_CSS_PLL_CLK;
+       timeout = CLOCK_TIMEOUT;
+       while (!(PMC_SR_R & PMC_SR_MCKRDY) && --timeout);
 }