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Commit 9a1729cb authored by Tero Kristo's avatar Tero Kristo Committed by Kevin Hilman
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ARM: OMAP4: VC: calculate ramp times 



OMAP4 VC code now uses voltage deltas + slew rates for calculating
actual ramp times for voltage changes. Both retention / sleep +
off mode voltage ramp times are setup at the same time during
initialization.

Signed-off-by: default avatarTero Kristo <t-kristo@ti.com>
Signed-off-by: default avatarKevin Hilman <khilman@ti.com>
parent 27c16b70

arch/arm/mach-omap2/vc.c

+94 −0
Original line number Diff line number Diff line
@@ -308,12 +308,106 @@ static void __init omap3_vc_init_channel(struct voltagedomain *voltdm) 
	omap3_set_off_timings(voltdm);

}



/**

 * omap4_calc_volt_ramp - calculates voltage ramping delays on omap4

 * @voltdm: channel to calculate values for

 * @voltage_diff: voltage difference in microvolts

 *

 * Calculates voltage ramp prescaler + counter values for a voltage

 * difference on omap4. Returns a field value suitable for writing to

 * VOLTSETUP register for a channel in following format:

 * bits[8:9] prescaler ... bits[0:5] counter. See OMAP4 TRM for reference.

 */

static u32 omap4_calc_volt_ramp(struct voltagedomain *voltdm, u32 voltage_diff)

{

	u32 prescaler;

	u32 cycles;

	u32 time;



	time = voltage_diff / voltdm->pmic->slew_rate;



	cycles = voltdm->sys_clk.rate / 1000 * time / 1000;



	cycles /= 64;

	prescaler = 0;



	/* shift to next prescaler until no overflow */



	/* scale for div 256 = 64 * 4 */

	if (cycles > 63) {

		cycles /= 4;

		prescaler++;

	}



	/* scale for div 512 = 256 * 2 */

	if (cycles > 63) {

		cycles /= 2;

		prescaler++;

	}



	/* scale for div 2048 = 512 * 4 */

	if (cycles > 63) {

		cycles /= 4;

		prescaler++;

	}



	/* check for overflow => invalid ramp time */

	if (cycles > 63) {

		pr_warn("%s: invalid setuptime for vdd_%s\n", __func__,

			voltdm->name);

		return 0;

	}



	cycles++;



	return (prescaler << OMAP4430_RAMP_UP_PRESCAL_SHIFT) |

		(cycles << OMAP4430_RAMP_UP_COUNT_SHIFT);

}



/**

 * omap4_set_timings - set voltage ramp timings for a channel

 * @voltdm: channel to configure

 * @off_mode: whether off-mode values are used

 *

 * Calculates and sets the voltage ramp up / down values for a channel.

 */

static void omap4_set_timings(struct voltagedomain *voltdm, bool off_mode)

{

	u32 val;

	u32 ramp;

	int offset;



	if (off_mode) {

		ramp = omap4_calc_volt_ramp(voltdm,

			voltdm->vc_param->on - voltdm->vc_param->off);

		offset = voltdm->vfsm->voltsetup_off_reg;

	} else {

		ramp = omap4_calc_volt_ramp(voltdm,

			voltdm->vc_param->on - voltdm->vc_param->ret);

		offset = voltdm->vfsm->voltsetup_reg;

	}



	if (!ramp)

		return;



	val = voltdm->read(offset);



	val |= ramp << OMAP4430_RAMP_DOWN_COUNT_SHIFT;



	val |= ramp << OMAP4430_RAMP_UP_COUNT_SHIFT;



	voltdm->write(val, offset);

}



/* OMAP4 specific voltage init functions */

static void __init omap4_vc_init_channel(struct voltagedomain *voltdm)

{

	static bool is_initialized;

	u32 vc_val;



	omap4_set_timings(voltdm, true);

	omap4_set_timings(voltdm, false);



	if (is_initialized)

		return;