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/*
* Aug 2016 Karl Palsson <karlp@tweak.net.au>
*/
#include <stdlib.h>
#include <libopencm3/stm32/flash.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/pwr.h>
#include <libopencm3/stm32/rcc.h>
/* Disco board is b6 */
#define LEDPORT GPIOB
#define LEDPIN GPIO6
#ifndef ARRAY_LENGTH
#define ARRAY_LENGTH(array) (sizeof((array))/sizeof((array)[0]))
#endif
/*
* A set of valid clock configurations with HSI as the source.
* thankfully, L1 allows apb1/apb2 to reach full ahb speed in all cases.
*/
struct rcc_clock_scale valid_hsi_clocks[] = {
{
/* 8Mhz, hsi/div2, max perf for range 2 with 0 ws */
.hpre = RCC_CFGR_HPRE_SYSCLK_DIV2,
.ppre1 = RCC_CFGR_PPRE1_HCLK_NODIV,
.ppre2 = RCC_CFGR_PPRE2_HCLK_NODIV,
.voltage_scale = PWR_SCALE2,
.flash_config = FLASH_ACR_LATENCY_0WS,
.ahb_frequency = 8e6,
.apb1_frequency = 8e6,
.apb2_frequency = 8e6,
},
{
/* Slowest hsi possible */
.hpre = RCC_CFGR_HPRE_SYSCLK_DIV512,
.ppre1 = RCC_CFGR_PPRE1_HCLK_NODIV,
.ppre2 = RCC_CFGR_PPRE1_HCLK_NODIV,
.voltage_scale = PWR_SCALE3,
.flash_config = FLASH_ACR_LATENCY_0WS,
.ahb_frequency = 31250,
.apb1_frequency = 31250,
.apb2_frequency = 31250,
},
{
/* Fastest HSI possible, range 1, 0ws */
.hpre = RCC_CFGR_HPRE_SYSCLK_NODIV,
.ppre1 = RCC_CFGR_PPRE1_HCLK_NODIV,
.ppre2 = RCC_CFGR_PPRE1_HCLK_NODIV,
.voltage_scale = PWR_SCALE1,
.flash_config = FLASH_ACR_LATENCY_0WS,
.ahb_frequency = 16e6,
.apb1_frequency = 16e6,
.apb2_frequency = 16e6,
},
{
/* highest perf for range 3 with 0 wait states */
.hpre = RCC_CFGR_HPRE_SYSCLK_DIV8,
.ppre1 = RCC_CFGR_PPRE1_HCLK_NODIV,
.ppre2 = RCC_CFGR_PPRE1_HCLK_NODIV,
.voltage_scale = PWR_SCALE3,
.flash_config = FLASH_ACR_LATENCY_0WS,
.ahb_frequency = 2e6,
.apb1_frequency = 2e6,
.apb2_frequency = 2e6,
},
{
/* Fastest HSI for range 2, 0ws */
.hpre = RCC_CFGR_HPRE_SYSCLK_NODIV,
.ppre1 = RCC_CFGR_PPRE1_HCLK_NODIV,
.ppre2 = RCC_CFGR_PPRE1_HCLK_NODIV,
.voltage_scale = PWR_SCALE1,
.flash_config = FLASH_ACR_LATENCY_0WS,
.ahb_frequency = 16e6,
.apb1_frequency = 16e6,
.apb2_frequency = 16e6,
},
{
/* highest perf for range 3 */
.hpre = RCC_CFGR_HPRE_SYSCLK_DIV4,
.ppre1 = RCC_CFGR_PPRE1_HCLK_NODIV,
.ppre2 = RCC_CFGR_PPRE1_HCLK_NODIV,
.voltage_scale = PWR_SCALE3,
.flash_config = FLASH_ACR_LATENCY_1WS,
.ahb_frequency = 4e6,
.apb1_frequency = 4e6,
.apb2_frequency = 4e6,
},
};
int shuffled[ARRAY_LENGTH(valid_hsi_clocks)];
/**
* blink led count times, with vile hack * 1000 asm nops
*/
static void hack_blink(int count, int hack)
{
for (int i = 0; i < count; i++) {
gpio_toggle(LEDPORT, LEDPIN);
for (int k = 0; k < hack * 1000; k++) {
__asm__("nop");
}
}
}
/* Stack overflow, wiki, whathaveyou */
/* FIXME oh yeah, did I mention that rand() is always zero? */
static void shuffle_fisher_yates(int *array, size_t n)
{
if (n > 1) {
size_t i;
for (i = 0; i < n - 1; i++) {
size_t j = i + rand() / (RAND_MAX / (n - i) + 1);
int t = array[j];
array[j] = array[i];
array[i] = t;
}
}
}
static void run_clock_set(void)
{
shuffle_fisher_yates(shuffled, ARRAY_LENGTH(shuffled));
struct rcc_clock_scale *clock;
for (size_t i = 0; i < ARRAY_LENGTH(shuffled); i++) {
clock = &valid_hsi_clocks[i];
rcc_clock_setup_hsi(clock);
/** blink quickly/slowly as we run through these */
hack_blink(10, clock->ahb_frequency / (500 * 1000));
hack_blink(4, clock->ahb_frequency / (200 * 1000));
}
}
int main(void)
{
/* Allow leds on any port */
RCC_AHBENR |= 0xff;
gpio_mode_setup(LEDPORT, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, LEDPIN);
/* blink twice with slow msi reset clock */
hack_blink(4, 60);
/* ok, now, "randomly" sort the list of clocks to try them out */
for (size_t i = 0; i < ARRAY_LENGTH(shuffled); i++) {
shuffled[i] = i;
}
while (1) {
run_clock_set();
}
return 0;
}
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