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authorTero Kristo <t-kristo@ti.com>2012-09-25 20:33:38 +0400
committerKevin Hilman <khilman@ti.com>2012-11-06 03:11:32 +0400
commit9a1729cbaaf1a9d1fd27f80cd488ef182fe033a0 (patch)
treed5d91e6c8f3830da955ac9bf7e690f4ba4dce295 /arch/arm/mach-omap2/vc.c
parent27c16b7026a9ca6455dd319fb00a28c5bb2023b6 (diff)
downloadlinux-9a1729cbaaf1a9d1fd27f80cd488ef182fe033a0.tar.xz
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: Tero Kristo <t-kristo@ti.com> Signed-off-by: Kevin Hilman <khilman@ti.com>
Diffstat (limited to 'arch/arm/mach-omap2/vc.c')
-rw-r--r--arch/arm/mach-omap2/vc.c94
1 files changed, 94 insertions, 0 deletions
diff --git a/arch/arm/mach-omap2/vc.c b/arch/arm/mach-omap2/vc.c
index 73b4bcd67023..07e2090d7119 100644
--- a/arch/arm/mach-omap2/vc.c
+++ b/arch/arm/mach-omap2/vc.c
@@ -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;