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ARM: OMAP4: VC: calculate ramp times

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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: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>
This commit is contained in:
Tero Kristo 2012-09-25 19:33:38 +03:00 committed by Kevin Hilman
parent 27c16b7026
commit 9a1729cbaa
1 changed files with 94 additions and 0 deletions
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94
arch/arm/mach-omap2/vc.c
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@ -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;