rt-thread/bsp/at91sam9260/platform/system_clock.c

291 lines
6.6 KiB
C

/*
* Copyright (c) 2006-2021, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2011-01-13 weety first version
*/
#include <rtthread.h>
#include "at91sam926x.h"
static rt_list_t clocks;
struct clk {
char name[32];
rt_uint32_t rate_hz;
struct clk *parent;
rt_list_t node;
};
static struct clk clk32k = {
"clk32k",
AT91_SLOW_CLOCK,
RT_NULL,
{RT_NULL, RT_NULL},
};
static struct clk main_clk = {
"main",
0,
RT_NULL,
{RT_NULL, RT_NULL},
};
static struct clk plla = {
"plla",
0,
RT_NULL,
{RT_NULL, RT_NULL},
};
static struct clk mck = {
"mck",
0,
RT_NULL,
{RT_NULL, RT_NULL},
};
static struct clk uhpck = {
"uhpck",
0,
RT_NULL,
{RT_NULL, RT_NULL},
};
static struct clk pllb = {
"pllb",
0,
&main_clk,
{RT_NULL, RT_NULL},
};
static struct clk udpck = {
"udpck",
0,
&pllb,
{RT_NULL, RT_NULL},
};
static struct clk *const standard_pmc_clocks[] = {
/* four primary clocks */
&clk32k,
&main_clk,
&plla,
/* MCK */
&mck
};
/* clocks cannot be de-registered no refcounting necessary */
struct clk *clk_get(const char *id)
{
struct clk *clk;
rt_list_t *list;
for (list = (&clocks)->next; list != &clocks; list = list->next)
{
clk = (struct clk *)rt_list_entry(list, struct clk, node);
if (rt_strcmp(id, clk->name) == 0)
return clk;
}
return RT_NULL;
}
rt_uint32_t clk_get_rate(struct clk *clk)
{
rt_uint32_t flags;
rt_uint32_t rate;
for (;;) {
rate = clk->rate_hz;
if (rate || !clk->parent)
break;
clk = clk->parent;
}
return rate;
}
static rt_uint32_t at91_pll_rate(struct clk *pll, rt_uint32_t freq, rt_uint32_t reg)
{
unsigned mul, div;
div = reg & 0xff;
mul = (reg >> 16) & 0x7ff;
if (div && mul) {
freq /= div;
freq *= mul + 1;
} else
freq = 0;
return freq;
}
static unsigned at91_pll_calc(unsigned main_freq, unsigned out_freq)
{
unsigned i, div = 0, mul = 0, diff = 1 << 30;
unsigned ret = (out_freq > 155000000) ? 0xbe00 : 0x3e00;
/* PLL output max 240 MHz (or 180 MHz per errata) */
if (out_freq > 240000000)
goto fail;
for (i = 1; i < 256; i++) {
int diff1;
unsigned input, mul1;
/*
* PLL input between 1MHz and 32MHz per spec, but lower
* frequences seem necessary in some cases so allow 100K.
* Warning: some newer products need 2MHz min.
*/
input = main_freq / i;
if (input < 100000)
continue;
if (input > 32000000)
continue;
mul1 = out_freq / input;
if (mul1 > 2048)
continue;
if (mul1 < 2)
goto fail;
diff1 = out_freq - input * mul1;
if (diff1 < 0)
diff1 = -diff1;
if (diff > diff1) {
diff = diff1;
div = i;
mul = mul1;
if (diff == 0)
break;
}
}
if (i == 256 && diff > (out_freq >> 5))
goto fail;
return ret | ((mul - 1) << 16) | div;
fail:
return 0;
}
static rt_uint32_t at91_usb_rate(struct clk *pll, rt_uint32_t freq, rt_uint32_t reg)
{
if (pll == &pllb && (reg & AT91_PMC_USB96M))
return freq / 2;
else
return freq;
}
/* PLLB generated USB full speed clock init */
static void at91_pllb_usbfs_clock_init(rt_uint32_t main_clock)
{
rt_uint32_t at91_pllb_usb_init;
/*
* USB clock init: choose 48 MHz PLLB value,
* disable 48MHz clock during usb peripheral suspend.
*
* REVISIT: assumes MCK doesn't derive from PLLB!
*/
uhpck.parent = &pllb;
at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) | AT91_PMC_USB96M;
pllb.rate_hz = at91_pll_rate(&pllb, main_clock, at91_pllb_usb_init);
at91_sys_write(AT91_CKGR_PLLBR, 0);
udpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
uhpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
}
static struct clk *at91_css_to_clk(unsigned long css)
{
switch (css) {
case AT91_PMC_CSS_SLOW:
return &clk32k;
case AT91_PMC_CSS_MAIN:
return &main_clk;
case AT91_PMC_CSS_PLLA:
return &plla;
case AT91_PMC_CSS_PLLB:
return &pllb;
}
return RT_NULL;
}
#define false 0
#define true 1
int at91_clock_init(rt_uint32_t main_clock)
{
unsigned tmp, freq, mckr;
int i;
int pll_overclock = false;
/*
* When the bootloader initialized the main oscillator correctly,
* there's no problem using the cycle counter. But if it didn't,
* or when using oscillator bypass mode, we must be told the speed
* of the main clock.
*/
if (!main_clock) {
do {
tmp = at91_sys_read(AT91_CKGR_MCFR);
} while (!(tmp & AT91_PMC_MAINRDY));
main_clock = (tmp & AT91_PMC_MAINF) * (AT91_SLOW_CLOCK / 16);
}
main_clk.rate_hz = main_clock;
/* report if PLLA is more than mildly overclocked */
plla.rate_hz = at91_pll_rate(&plla, main_clock, at91_sys_read(AT91_CKGR_PLLAR));
if (plla.rate_hz > 209000000)
pll_overclock = true;
if (pll_overclock)
;//rt_kprintf("Clocks: PLLA overclocked, %ld MHz\n", plla.rate_hz / 1000000);
at91_pllb_usbfs_clock_init(main_clock);
/*
* MCK and CPU derive from one of those primary clocks.
* For now, assume this parentage won't change.
*/
mckr = at91_sys_read(AT91_PMC_MCKR);
mck.parent = at91_css_to_clk(mckr & AT91_PMC_CSS);
freq = mck.parent->rate_hz;
freq /= (1 << ((mckr & AT91_PMC_PRES) >> 2)); /* prescale */
mck.rate_hz = freq / (1 << ((mckr & AT91_PMC_MDIV) >> 8)); /* mdiv */
/* Register the PMC's standard clocks */
rt_list_init(&clocks);
for (i = 0; i < ARRAY_SIZE(standard_pmc_clocks); i++)
rt_list_insert_after(&clocks, &standard_pmc_clocks[i]->node);
rt_list_insert_after(&clocks, &pllb.node);
rt_list_insert_after(&clocks, &uhpck.node);
rt_list_insert_after(&clocks, &udpck.node);
/* MCK and CPU clock are "always on" */
//clk_enable(&mck);
/*rt_kprintf("Clocks: CPU %u MHz, master %u MHz, main %u.%03u MHz\n",
freq / 1000000, (unsigned) mck.rate_hz / 1000000,
(unsigned) main_clock / 1000000,
((unsigned) main_clock % 1000000) / 1000);*///cause blocked
return 0;
}
/**
* @brief System Clock Configuration
*/
void rt_hw_clock_init(void)
{
at91_clock_init(18432000);
}