gint/src/clock/freq.c

//---
//	gint:clock:freq - Clock frequency management
//---

#include <gint/drivers.h>
#include <gint/clock.h>
#include <core/std.h>

#include <gint/mpu.h>
#include <gint/mpu/cpg.h>

//---
//	Driver storage
//---

/* Local copy of the CPG settings */
GBSS static clock_frequency_t freq;

/* clock_freq() - get the frequency of the main clocks */
const clock_frequency_t *clock_freq(void)
{
	return &freq;
}

//---
//	SH7705 Clock signals
//---

#ifdef FX9860G
#define CPG SH7705_CPG

static void sh7705_probe(void)
{
	/* According to Sentaro21 in the sources of Ftune 1.0.1, the clock mode
	   is thought to be 5, which means that:
	   - CPG input is XTAL         (14.745'600 MHz)
	   - PLL2 is active and *2     (29.491'200 MHz)
	   - CKIO is output from PLL2  (29.491'200 MHz) */
	int xtal = 14745600;
	int pll2 = 2;
	int ckio = xtal * pll2;

	/* This signal is multiplied by the PLL1 circuit */
	int pll1 = CPG.FRQCR.STC + 1;

	/* Iphi and Pphi have dividers (Bphi is always equal to CKIO) */
	int idiv = CPG.FRQCR.IFC;
	int pdiv = CPG.FRQCR.PFC;

	/* Fill in the setting structure */
	freq.PLL1 = pll1;
	freq.PLL2 = pll2;
	freq.Bphi_div = 1;
	freq.Iphi_div = idiv + 1;
	freq.Pphi_div = pdiv + 1;

	/* Deduce the frequency of the main clocks. This value is ckio/3 */
	int ckio_3 = 9830400;

	/* Exchange the setting values 2 and 3 */
	idiv = idiv ^ (idiv >> 1);
	pdiv = pdiv ^ (pdiv >> 1);

	freq.CKIO_f = ckio;
	freq.Bphi_f = ckio;
	freq.Iphi_f = (idiv == 3) ? ckio_3 : ckio >> idiv;
	freq.Pphi_f = (pdiv == 3) ? ckio_3 : ckio >> pdiv;
}

#undef CPG
#endif /* FX9860G */

//---
//	SH7305 clock signals
//---

#define CPG SH7305_CPG

static void sh7305_probe(void)
{
	/* The meaning of the PLL setting on SH7305 differs from the
	   documentation of SH7224; the value must not be doubled. */
	int pll = CPG.FRQCRA.STC + 1;
	freq.PLL = pll;

	/* The FLL ratio is the value of the setting, halved if SELXM=1 */
	int fll = CPG.FLLFRQ.FLF;
	if(CPG.FLLFRQ.SELXM == 1) fll >>= 1;
	freq.FLL = fll;

	/* On SH7724, the divider ratio is given by 1 / (setting + 1), but
	   SH7305 behaves as 1 / (2^setting + 1). */

	int divb = CPG.FRQCRA.BFC;
	int divi = CPG.FRQCRA.IFC;
	int divp = CPG.FRQCRA.P1FC;

	freq.Bphi_div = 1 << (divb + 1);
	freq.Iphi_div = 1 << (divi + 1);
	freq.Pphi_div = 1 << (divp + 1);

	/* Deduce the input frequency of divider 1 */
	int base = 32768;
	if(CPG.PLLCR.FLLE) base *= fll;
	if(CPG.PLLCR.PLLE) base *= pll;

	/* And the frequency of all other input clocks */
	freq.RTCCLK_f = 32768;
	freq.Bphi_f   = base >> (divb + 1);
	freq.Iphi_f   = base >> (divi + 1);
	freq.Pphi_f   = base >> (divp + 1);
}

#undef CPG

//---
//	Other driver stuff
//---

#ifdef GINT_BOOT_LOG

static const char *cpg_status(void)
{
	static char status[18];
	sprintf(status, "I%3d B%3d P%3d C%c",
		freq.Iphi_f / 1000000,
		freq.Bphi_f / 1000000,
		freq.Pphi_f / 1000000,
		isSH3() ? 'e' : 'E'
	);
	return status;
}

#endif /* GINT_BOOT_LOG */

static void init(void)
{
	/* This avoids warnings about sh7705() not being defined on fxcg50 */
	#ifdef FX9860G
	isSH3() ? sh7705_probe() :
	#endif

	sh7305_probe();
}

gint_driver_t drv_cpg = {
	.name		= "CPG",
	.init		= init,
	.status		= GINT_DRIVER_STATUS(cpg_status),
	.ctx_size	= 0,
	.sys_ctx	= NULL,
	.ctx_save	= NULL,
	.ctx_restore	= NULL,
};

GINT_DECLARE_DRIVER(1, drv_cpg);