Large reorganization.

What was in core/ is now moved to arch/stm34l4xxx/peripherals.  This new
directory is *supposed to* to contain raw header files defining just the
pertinent register structures for the various peripherals.  Peripheral
management belongs somewhere in the new `kern/..` directories. This is
not completely the case at the moment, so more refactoring needs to be
done.

What was sitting in the root has now been moved into the kern/
directory. The kern/ directory is to contain everything else
other than raw device register definitions. The root of the kern/
tree is reserved for standard library-esque headers.

The kern/<peripheral> directory contains management systems for that
peripheral. (At the moment DMA is the only peripheral with a decent
management system.) Preferably these peripheral systems should only
include their correlating header in arch/stm34l4xxx/peripherals, and
use other management systems for handling other peripherals rather
than manipulating their raw registers directly. (Though this ideal
will require much more critical mass of management systems.)

1 files changed, 126 insertions, 0 deletions

diff --git a/02-usart/include/arch/stm32l4xxx/peripherals/clock.h b/02-usart/include/arch/stm32l4xxx/peripherals/clock.h
new file mode 100644
index 0000000..6e461de
--- /dev/null
+++ b/02-usart/include/arch/stm32l4xxx/peripherals/clock.h
@@ -0,0 +1,126 @@
+#ifndef CORE_CLOCK_H__
+#define CORE_CLOCK_H__
+
+#include <stdint.h>
+#include "arch/stm32l4xxx/peripherals/rcc.h"
+
+#define PERIPH_BASE ((uint32_t)0x40000000)
+#define AHBPERIPH_BASE (PERIPH_BASE + 0x00020000)
+#define FLASH_R_BASE (AHBPERIPH_BASE + 0x00003C00)
+#define PWR_BASE (PERIPH_BASE + 0x7000)
+#define PWR_CSR_VOSF ((uint16_t)0x0010) /*!< Voltage Scaling select flag */
+
+#ifndef __IO
+#define __IO volatile
+#endif
+
+typedef struct {
+  __IO uint32_t cr;
+  __IO uint32_t csr;
+} pwr_t;
+
+// typedef struct {
+//   __IO uint32_t acr;
+//   __IO uint32_t pecr;
+//   __IO uint32_t pdkeyr;
+//   __IO uint32_t pekeyr;
+//   __IO uint32_t prgkeyr;
+//   __IO uint32_t optkeyr;
+//   __IO uint32_t sr;
+//   __IO uint32_t obr;
+//   __IO uint32_t wrpr;
+// } flash_t;
+
+// #define FLASH (*(flash_t*) (FLASH_R_BASE))
+#define PWR (*(pwr_t*)(PWR_BASE))
+
+/* Valid values for the PLLR/PLLQ bits of the PLLCFG register. */
+typedef enum {
+  PLL_DIVISOR_2 = 1,
+  PLL_DIVISOR_4 = 3,
+  PLL_DIVISOR_6 = 5,
+  PLL_DIVISOR_8 = 7,
+  PLL_DIVISOR_OFF = 0,
+} pll_divisor_t;
+
+/* Valid values for the PLLP bits off the PLLCFG register. */
+typedef enum {
+  PLLP_DIVISOR_7 = 1,
+  PLLP_DIVISOR_17 = 3,
+  PLLP_DIVISOR_OFF = 0,
+} pllp_divisor_t;
+
+/* Valid values for the PLLM bits of the PLLCFG register. */
+typedef enum {
+  PLLM_DIVISOR_1 = 0,
+  PLLM_DIVISOR_2 = 1,
+  PLLM_DIVISOR_3 = 2,
+  PLLM_DIVISOR_4 = 3,
+  PLLM_DIVISOR_5 = 4,
+  PLLM_DIVISOR_6 = 5,
+  PLLM_DIVISOR_7 = 6,
+  PLLM_DIVISOR_8 = 7,
+} pllm_divisor_t;
+
+/* Possible sources for the input clock. */
+typedef enum {
+  PLL_SRC_NONE = 0,
+  PLL_SRC_MSI = 1,
+  PLL_SRC_HSI = 2,
+  PLL_SRC_HSE = 3,
+} pll_src_t;
+
+/* Valid sources for the system clock. */
+typedef enum {
+  SYSTEM_CLOCK_SRC_MSI = 0,
+  SYSTEM_CLOCK_SRC_HSI = 1,
+  SYSTEM_CLOCK_SRC_HSE = 2,
+  SYSTEM_CLOCK_SRC_PLL = 3,
+} system_clock_src_t;
+
+#define E_BADPLLN (-2)
+#define E_BADPLLP_DIV (-1)
+#define E_TIMEOUT (-3)
+#define E_NOT_OFF (-4)
+#define E_BAD_ARG (-5)
+
+#define enable_hsi(rcc, enabled) do { \
+  if (enabled) { \
+    (rcc)->c_r |= BIT(8); \
+  } else { \
+    (rcc)->c_r &= ~BIT(8); \
+  } \
+} while(0)
+
+/*
+ * Sets the system clock to a full 80Mhz.
+ */
+int set_system_clock_MHz(uint8_t mhz);
+
+/*
+ * Set the PLL on.
+ */
+int pll_on();
+
+/*
+ * Set the PLL off.
+ */
+int pll_off();
+
+/*
+ * Sets the source of the system clock.
+ */
+int set_system_clock_src(system_clock_src_t src);
+
+/*
+ * Configure the PLL.
+ */
+int configure_pll(
+    uint8_t pllp_div_factor, pll_divisor_t pllr, /* System clock divisor. */
+    pll_divisor_t pllq,  /* Divison factor for PLL48M1CLK. */
+    pllp_divisor_t pllp, /* Divison factor for PLLSAI2CLK. */
+    uint8_t plln,        /* PLL numerator. */
+    pllm_divisor_t pllm, /* PLL denominator. */
+    pll_src_t pllsrc /* PLL source */);
+
+#endif /* CORE_CLOCK_H__ */