Hello Mike,
On Fri, Apr 16, 2010 at 11:33:22PM +0200, ext Mike Turquette wrote:
> Introduces voltscale_adaptive_body_bias function to voltage.c.
> voltscale_adaptive_body_bias is called by omap_voltage_scale after a
> voltage transition has occured. Currently voltscale_adaptive_body_bias
> only implements Forward Body-Bias (FBB) for OMAP3630 when MPU runs at
> 1GHz or higher. In the future Reverse Body-Bias might be included.
>
> FBB is an Adaptive Body-Bias technique to boost performance for weak
> process devices at high OPPs. This results in voltage boost on the VDD1
> PMOS back gates when running at maximum OPP. Current recommendations
> are to enable FBB on all 3630 regardless of silicon characteristics and
> EFUSE values.
>
> ABB applies to all OMAP silicon based on 45nm process, which includes
> OMAP4. OMAP4 recommendations for ABB are not complete and will be added
> to voltscale_adaptive_body_bias in the future.
Nice !
>
> Signed-off-by: Mike Turquette <mturquette@xxxxxx>
> ---
> arch/arm/mach-omap2/voltage.c | 129 ++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 127 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/voltage.c b/arch/arm/mach-omap2/voltage.c
> index c2c8192..98d8bb3 100644
> --- a/arch/arm/mach-omap2/voltage.c
> +++ b/arch/arm/mach-omap2/voltage.c
> @@ -37,6 +37,11 @@
> #define VP_IDLE_TIMEOUT 200
> #define VP_TRANXDONE_TIMEOUT 300
>
> +#define ABB_MAX_SETTLING_TIME 30
> +#define ABB_FAST_OPP 1
> +#define ABB_NOMINAL_OPP 2
> +#define ABB_SLOW_OPP 3
> +
> /**
> * OMAP3 Voltage controller SR parameters. TODO: Pass this info as part of
> * board data or PMIC data
> @@ -635,6 +640,118 @@ static int vp_forceupdate_scale_voltage(u32 vdd, unsigned long target_volt,
> }
>
> /**
> + * voltscale_adaptive_body_bias - controls ABB ldo during voltage scaling
> + * @target_volt: target voltage determines if ABB ldo is active or bypassed
> + *
> + * Adaptive Body-Bias is a technique in all OMAP silicon that uses the 45nm
> + * process. ABB can boost voltage in high OPPs for silicon with weak
> + * characteristics (forward Body-Bias) as well as lower voltage in low OPPs
> + * for silicon with strong characteristics (Reverse Body-Bias).
> + *
> + * Only Foward Body-Bias for operating at high OPPs is implemented below, per
> + * recommendations from silicon team.
> + * Reverse Body-Bias for saving power in active cases and sleep cases is not
> + * yet implemented.
> + * OMAP4 hardward also supports ABB ldo, but no recommendations have been made
> + * to implement it yet.
> + */
> +int voltscale_adaptive_body_bias(unsigned long target_volt)
> +{
> + u32 sr2en_enabled;
> + int timeout;
> + int sr2_wtcnt_value;
> +
> + /* calculate SR2_WTCNT_VALUE settling time */
> + sr2_wtcnt_value = (ABB_MAX_SETTLING_TIME *
> + (clk_get_rate("sys_ck") / 1000000) / 8);
> +
> + /* has SR2EN been enabled previously? */
> + sr2en_enabled = (prm_read_mod_reg(OMAP3430_GR_MOD,
> + OMAP3_PRM_LDO_ABB_CTRL_OFFSET) &
> + OMAP3630_SR2EN);
> +
> + /* select fast, nominal or slow OPP for ABB ldo */
> + /* FIXME: include OMAP4 once recommendations are complete */
> + if (cpu_is_omap3630() && (target_volt >= 1350000)) {
You are creating two steps to decide if you apply or not FBB.
Here and also bellow (omap voltage scale). Would it make sense to bind it
per opp? I mean just a flag on opp dat then you apply or not based on that flag.
Same for RBB.
> + /* program for fast opp - enable FBB */
> + prm_rmw_mod_reg_bits(OMAP3630_OPP_SEL_MASK,
> + (ABB_FAST_OPP << OMAP3630_OPP_SEL_SHIFT),
> + OMAP3430_GR_MOD,
> + OMAP3_PRM_LDO_ABB_SETUP_OFFSET);
> +
> + /* enable the ABB ldo if not done already */
> + if (!sr2en_enabled)
> + prm_set_mod_reg_bits(OMAP3630_SR2EN,
> + OMAP3430_GR_MOD,
> + OMAP3_PRM_LDO_ABB_CTRL_OFFSET);
> + } else if (sr2en_enabled) {
> + /* program for nominal opp - bypass ABB ldo */
> + prm_rmw_mod_reg_bits(OMAP3630_OPP_SEL_MASK,
> + (ABB_NOMINAL_OPP << OMAP3630_OPP_SEL_SHIFT),
> + OMAP3430_GR_MOD,
> + OMAP3_PRM_LDO_ABB_SETUP_OFFSET);
> + } else {
> + /* nothing to do here yet... might enable RBB here someday */
> + return 0;
> + }
> +
> + /* set ACTIVE_FBB_SEL for all 45nm silicon */
> + prm_set_mod_reg_bits(OMAP3630_ACTIVE_FBB_SEL,
> + OMAP3430_GR_MOD,
> + OMAP3_PRM_LDO_ABB_CTRL_OFFSET);
> +
> + /* program settling time of 30us for ABB ldo transition */
> + prm_rmw_mod_reg_bits(OMAP3630_SR2_WTCNT_VALUE_MASK,
> + (sr2_wtcnt_value << OMAP3630_SR2_WTCNT_VALUE_SHIFT),
> + OMAP3430_GR_MOD,
> + OMAP3_PRM_LDO_ABB_CTRL_OFFSET);
> +
> + /* clear ABB ldo interrupt status */
> + prm_write_mod_reg(OMAP3630_ABB_LDO_TRANXDONE_ST,
> + OCP_MOD,
> + OMAP2_PRCM_IRQSTATUS_MPU_OFFSET);
> +
> + /* enable ABB LDO OPP change */
> + prm_set_mod_reg_bits(OMAP3630_OPP_CHANGE,
> + OMAP3430_GR_MOD,
> + OMAP3_PRM_LDO_ABB_SETUP_OFFSET);
> +
> + timeout = 0;
> +
> + /* wait until OPP change completes */
> + while ((timeout < ABB_MAX_SETTLING_TIME ) &&
> + (!(prm_read_mod_reg(OCP_MOD,
> + OMAP2_PRCM_IRQSTATUS_MPU_OFFSET) &
> + OMAP3630_ABB_LDO_TRANXDONE_ST))) {
> + udelay(1);
> + timeout++;
> + }
> +
> + if (timeout == ABB_MAX_SETTLING_TIME)
> + pr_debug("ABB: TRANXDONE timed out waiting for OPP change\n");
> +
> + timeout = 0;
> +
> + /* Clear all pending TRANXDONE interrupts/status */
> + while (timeout < ABB_MAX_SETTLING_TIME) {
> + prm_write_mod_reg(OMAP3630_ABB_LDO_TRANXDONE_ST,
> + OCP_MOD,
> + OMAP2_PRCM_IRQSTATUS_MPU_OFFSET);
> + if (!(prm_read_mod_reg(OCP_MOD,
> + OMAP2_PRCM_IRQSTATUS_MPU_OFFSET)
> + & OMAP3630_ABB_LDO_TRANXDONE_ST))
> + break;
> +
> + udelay(1);
> + timeout++;
> + }
Is there any other way of implementing the above instead of busy loop / udelay?
> + if (timeout == ABB_MAX_SETTLING_TIME)
> + pr_debug("ABB: TRANXDONE timed out trying to clear status\n");
> +
> + return 0;
> +}
> +
> +/**
> * get_curr_vdd1_voltage : Gets the current non-auto-compensated vdd1 voltage
> *
> * This is a temporary placeholder for this API. This should ideally belong
> @@ -758,11 +875,19 @@ void omap_voltageprocessor_disable(int vp_id)
> int omap_voltage_scale(int vdd, unsigned long target_volt,
> unsigned long current_volt)
> {
> + int ret;
> +
> if (voltscale_vpforceupdate)
> - return vp_forceupdate_scale_voltage(vdd, target_volt,
> + ret = vp_forceupdate_scale_voltage(vdd, target_volt,
> current_volt);
> else
> - return vc_bypass_scale_voltage(vdd, target_volt, current_volt);
> + ret = vc_bypass_scale_voltage(vdd, target_volt, current_volt);
> +
> + /* FIXME OMAP4 needs ABB too; recommendations not yet complete */
> + if (ret && (cpu_is_omap3630() && vdd == VDD1))
I meant here. I guess would be better to have just one place to check if you apply or not.
> + ret = voltscale_adaptive_body_bias(target_volt);
> +
> + return ret;
> }
>
> /**
> --
> 1.6.3.2
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-omap" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
