Re: [PATCH 6/7] ARM: omap: abb: init & transition functions

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Oct 3, 2012 at 6:26 PM, Mike Turquette <mturquette@xxxxxx> wrote:
> The Adaptive Body-Bias ldo can be set to bypass, Forward Body-Bias or
> Reverse Body-Bias during a voltage transition.  The ABB programming
> sequence depends on whether voltage is scaling up or down.
>
> This patch implements the Adaptive Body-Bias ldo initialization routine
> and the transition sequence which is needed after any voltage scaling
> operation.
>
> Note that this sequence will need to be revisited someday when the
> various SmartReflex AVS features, fixes and improvements are upstreamed
> and enabled for OMAP2+ kernels.
>
> Signed-off-by: Mike Turquette <mturquette@xxxxxx>
> Signed-off-by: Mike Turquette <mturquette@xxxxxxxxxx>
> ---
>  arch/arm/mach-omap2/Makefile |    2 +-
>  arch/arm/mach-omap2/abb.c    |  322 ++++++++++++++++++++++++++++++++++++++++++
>  arch/arm/mach-omap2/abb.h    |    9 ++
>  3 files changed, 332 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm/mach-omap2/abb.c
>
> diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
> index 57e053e..a262aaa 100644
> --- a/arch/arm/mach-omap2/Makefile
> +++ b/arch/arm/mach-omap2/Makefile
> @@ -107,7 +107,7 @@ obj-$(CONFIG_ARCH_OMAP4)            += $(omap-prcm-4-5-common) prm44xx.o
>  obj-$(CONFIG_SOC_OMAP5)                        += $(omap-prcm-4-5-common)
>
>  # OMAP voltage domains
> -voltagedomain-common                   := voltage.o vc.o vp.o
> +voltagedomain-common                   := voltage.o vc.o vp.o abb.o
>  obj-$(CONFIG_ARCH_OMAP2)               += $(voltagedomain-common)
>  obj-$(CONFIG_ARCH_OMAP2)               += voltagedomains2xxx_data.o
>  obj-$(CONFIG_ARCH_OMAP3)               += $(voltagedomain-common)
> diff --git a/arch/arm/mach-omap2/abb.c b/arch/arm/mach-omap2/abb.c
> new file mode 100644
> index 0000000..e8a3ae0
> --- /dev/null
> +++ b/arch/arm/mach-omap2/abb.c
> @@ -0,0 +1,322 @@
> +/*
> + * OMAP Adaptive Body-Bias core
> + *
> + * Copyright (C) 2011 Texas Instruments, Inc.
> + * Mike Turquette <mturquette@xxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/delay.h>
> +
> +#include "abb.h"
> +#include "voltage.h"
> +
> +/**
> + * omap_abb_set_opp - program ABB ldo based on new voltage
> + *
> + * @voltdm - voltage domain that just finished scaling voltage
> + * @opp_sel - target ABB ldo operating mode
> + *
> + * Program the ABB ldo to the new state (if necessary), clearing the
> + * PRM_IRQSTATUS bit before and after the transition.  Returns 0 on
> + * success, -ETIMEDOUT otherwise.
> + */
> +int omap_abb_set_opp(struct voltagedomain *voltdm, u8 opp_sel)
> +{
> +       struct omap_abb_instance *abb = voltdm->abb;
> +       int ret, timeout;
> +
> +       /* bail early if no transition is necessary */
> +       if (opp_sel == abb->_opp_sel)
> +               return 0;
> +
> +       /* clear interrupt status */
> +       timeout = 0;
> +       while (timeout++ < ABB_TRANXDONE_TIMEOUT) {
> +               abb->common->ops->clear_tranxdone(abb->prm_irq_id);
> +
> +               ret = abb->common->ops->check_tranxdone(abb->prm_irq_id);
> +               if (!ret)
> +                       break;
> +
> +               udelay(1);
> +       }
> +
> +       if (timeout >= ABB_TRANXDONE_TIMEOUT) {
> +               pr_warn("%s: vdd_%s ABB TRANXDONE timeout\n",
> +                               __func__, voltdm->name);
> +               return -ETIMEDOUT;
> +       }
> +
> +       /* program the setup register */
> +       switch (opp_sel) {
> +       case OMAP_ABB_NOMINAL_OPP:
> +               voltdm->rmw(abb->common->active_fbb_sel_mask,
> +                               0x0,
> +                               abb->setup_offs);
> +               break;
> +       case OMAP_ABB_FAST_OPP:
> +               voltdm->rmw(abb->common->active_fbb_sel_mask,
> +                               abb->common->active_fbb_sel_mask,
> +                               abb->setup_offs);
> +               break;
> +       }
> +
> +       /* program next state of ABB ldo */
> +       voltdm->rmw(abb->common->opp_sel_mask,
> +                       opp_sel << __ffs(abb->common->opp_sel_mask),
> +                       abb->ctrl_offs);
> +
> +       /* initiate ABB ldo change */
> +       voltdm->rmw(abb->common->opp_change_mask,
> +                       abb->common->opp_change_mask,
> +                       abb->ctrl_offs);
> +
> +       /* clear interrupt status */
> +       timeout = 0;
> +       while (timeout++ < ABB_TRANXDONE_TIMEOUT) {
> +               abb->common->ops->clear_tranxdone(abb->prm_irq_id);
> +
> +               ret = abb->common->ops->check_tranxdone(abb->prm_irq_id);
> +               if (!ret)
> +                       break;
> +
> +               udelay(1);
> +       }
> +
> +       if (timeout >= ABB_TRANXDONE_TIMEOUT) {
> +               pr_warn("%s: vdd_%s ABB TRANXDONE timeout\n",
> +                               __func__, voltdm->name);
> +               return -ETIMEDOUT;
> +       }
> +
> +       /* track internal state */
> +       abb->_opp_sel = opp_sel;
> +
> +       return 0;
> +}
> +
> +/**
> + * omap_abb_pre_scale - ABB transition pre-voltage scale, if needed
> + *
> + * @voltdm - voltage domain that is about to scale
> + * @target_volt - voltage that voltdm is scaling towards
> + *
> + * Changes the ABB ldo mode prior to scaling the voltage domain.
> + * Returns 0 on success, otherwise an error code.
> + */
> +int omap_abb_pre_scale(struct voltagedomain *voltdm,
> +               unsigned long target_volt)
> +{
> +       struct omap_abb_instance *abb = voltdm->abb;
> +       struct omap_volt_data *cur_volt_data;
> +       struct omap_volt_data *target_volt_data;
> +       u8 opp_sel;
> +
> +       /* sanity */
> +       if (!voltdm)
> +               return -EINVAL;
> +
> +       if (!abb)
> +               return 0;
> +
> +       /*
> +        * XXX boot-time corner case: voltdm->nominal volt might be zero
> +        *
> +        * This implies that we're running at the default PMIC voltage,
> +        * since voltdm->nominal_volt should have been populated in
> +        * omap_voltage_late_init if the voltage had been scaled
> +        * previously.  The best way to fix this is for DT data to pass
> +        * in PMIC boot voltage.
> +        *
> +        * For now, handle this by returning success (0) to not block
> +        * the rest of the transition.
> +        */
> +       if (!voltdm->nominal_volt)
> +               return 0;
> +
> +       cur_volt_data = omap_voltage_get_voltdata(voltdm, voltdm->nominal_volt);
> +       target_volt_data = omap_voltage_get_voltdata(voltdm, target_volt);
> +
> +       if (IS_ERR(cur_volt_data))
> +               return PTR_ERR(cur_volt_data);
> +
> +       if (IS_ERR(target_volt_data))
> +               return PTR_ERR(target_volt_data);
> +
> +       /* bail if the sequence is wrong */
> +       if (target_volt_data->volt_nominal > cur_volt_data->volt_nominal)
> +               return 0;
> +
> +       opp_sel = target_volt_data->opp_sel;
> +
> +       /* bail early if no transition is necessary */
> +       if (opp_sel == abb->_opp_sel)
> +               return 0;
> +
> +       return omap_abb_set_opp(voltdm, opp_sel);
> +}
> +
> +/**
> + * omap_abb_post_scale - ABB transition post-voltage scale, if needed
> + * @voltdm - voltage domain that just finished scaling
> + * @target_volt - voltage that voltdm is scaling towards
> + *
> + * Changes the ABB ldo mode prior to scaling the voltage domain.
> + * Returns 0 on success, otherwise an error code.
> + */
> +int omap_abb_post_scale(struct voltagedomain *voltdm,
> +               unsigned long target_volt)
> +{
> +       struct omap_abb_instance *abb = voltdm->abb;
> +       struct omap_volt_data *cur_volt_data;
> +       struct omap_volt_data *target_volt_data;
> +       u8 opp_sel;
> +
> +       /* sanity */
> +       if (!voltdm)
> +               return -EINVAL;
> +
> +       if (!abb)
> +               return 0;
> +
> +       cur_volt_data = omap_voltage_get_voltdata(voltdm, voltdm->nominal_volt);
> +       if (IS_ERR(cur_volt_data))
> +               return PTR_ERR(cur_volt_data);
> +
> +       target_volt_data = omap_voltage_get_voltdata(voltdm, target_volt);
> +       if (IS_ERR(target_volt_data))
> +               return PTR_ERR(target_volt_data);
> +
> +       /* bail if the sequence is wrong */
> +       if (target_volt_data->volt_nominal < cur_volt_data->volt_nominal)
> +               return 0;
> +
> +       opp_sel = target_volt_data->opp_sel;
> +
> +       /* bail early if no transition is necessary */
> +       if (opp_sel == abb->_opp_sel)
> +               return 0;
> +
> +       return omap_abb_set_opp(voltdm, opp_sel);
> +}
> +
> +/*
> + * omap_abb_enable - enable ABB ldo on a particular voltage domain
> + *
> + * @voltdm - pointer to particular voltage domain
> + */
> +void omap_abb_enable(struct voltagedomain *voltdm)
> +{
> +       struct omap_abb_instance *abb = voltdm->abb;
> +
> +       if (abb->enabled)
> +               return;
> +
> +       abb->enabled = true;
> +
> +       voltdm->rmw(abb->common->sr2en_mask, abb->common->sr2en_mask,
> +                       abb->setup_offs);
> +}
> +
> +/*
> + * omap_abb_disable - disable ABB ldo on a particular voltage domain
> + *
> + * @voltdm - pointer to particular voltage domain
> + *
> + * Included for completeness.  Not currently used but will be needed in the
> + * future if ABB is converted to a loadable module.
> + */
> +void omap_abb_disable(struct voltagedomain *voltdm)
> +{
> +       struct omap_abb_instance *abb = voltdm->abb;
> +
> +       if (!abb->enabled)
> +               return;
> +
> +       abb->enabled = false;
> +
> +       voltdm->rmw(abb->common->sr2en_mask,
> +                       (0 << __ffs(abb->common->sr2en_mask)),
> +                       abb->setup_offs);
> +}
> +
> +/*
> + * omap_abb_init - Initialize an ABB ldo instance
> + *
> + * @voltdm: voltage domain upon which ABB ldo resides
> + *
> + * Initializes an individual ABB ldo for Forward Body-Bias.  FBB is used to
> + * insure stability at higher voltages.  Note that some older OMAP chips have a
> + * Reverse Body-Bias mode meant to save power at low voltage, but that mode is
> + * unsupported and phased out on newer chips.
> + */
> +void __init omap_abb_init(struct voltagedomain *voltdm)
> +{
> +       struct omap_abb_instance *abb = voltdm->abb;
> +       u32 sys_clk_rate;
> +       u32 sr2_wt_cnt_val;
> +       u32 clock_cycles;
> +       u32 settling_time;
> +       u32 val;
> +
> +       if (IS_ERR_OR_NULL(abb))
> +               return;
> +
> +       /*
> +        * SR2_WTCNT_VALUE is the settling time for the ABB ldo after a
> +        * transition and must be programmed with the correct time at boot.
> +        * The value programmed into the register is the number of SYS_CLK
> +        * clock cycles that match a given wall time profiled for the ldo.
> +        * This value depends on:
> +        * settling time of ldo in micro-seconds (varies per OMAP family)
> +        * # of clock cycles per SYS_CLK period (varies per OMAP family)
> +        * the SYS_CLK frequency in MHz (varies per board)
> +        * The formula is:
> +        *
> +        *                      ldo settling time (in micro-seconds)
> +        * SR2_WTCNT_VALUE = ------------------------------------------
> +        *                   (# system clock cycles) * (sys_clk period)
> +        *
> +        * Put another way:
> +        *
> +        * SR2_WTCNT_VALUE = settling time / (# SYS_CLK cycles / SYS_CLK rate))
> +        *
> +        * To avoid dividing by zero multiply both "# clock cycles" and
> +        * "settling time" by 10 such that the final result is the one we want.
> +        */
> +
> +       /* convert SYS_CLK rate to MHz & prevent divide by zero */
> +       sys_clk_rate = DIV_ROUND_CLOSEST(voltdm->sys_clk.rate, 1000000);
There is a possible small rounding error here. Depending on
SYS_CLK_rate value, you might loose significant digits when converting
from Hz to MHz.

Also, wouldn't it be safer to do all multiplications first and then
divisions, like:
SR2_WTCNT_VALUE = ((settling time * SYS_CLK_rate_kHz) / # SYS_CLK
cycles  ) / 1000

> +       clock_cycles = abb->common->clock_cycles * 10;
> +       settling_time = abb->common->settling_time * 10;
> +
> +       /* calculate cycle rate */
> +       clock_cycles = DIV_ROUND_CLOSEST(clock_cycles, sys_clk_rate);
> +
> +       /* calulate SR2_WTCNT_VALUE */
> +       sr2_wt_cnt_val = DIV_ROUND_CLOSEST(settling_time, clock_cycles);
> +
> +       voltdm->rmw(abb->common->sr2_wtcnt_value_mask,
> +                       (sr2_wt_cnt_val << __ffs(abb->common->sr2_wtcnt_value_mask)),
> +                       abb->setup_offs);
> +
> +       /* did bootloader set OPP_SEL? */
> +       val = voltdm->read(abb->ctrl_offs);
> +       val &= abb->common->opp_sel_mask;
> +       abb->_opp_sel = val >> __ffs(abb->common->opp_sel_mask);
> +
> +       /* enable the ldo if not done by bootloader */
> +       val = voltdm->read(abb->setup_offs);
> +       val &= abb->common->sr2en_mask;
> +       if (val)
> +               abb->enabled = true;
> +       else
> +               omap_abb_enable(voltdm);
> +
> +       return;
> +}
> diff --git a/arch/arm/mach-omap2/abb.h b/arch/arm/mach-omap2/abb.h
> index 2acc187..b18305f 100644
> --- a/arch/arm/mach-omap2/abb.h
> +++ b/arch/arm/mach-omap2/abb.h
> @@ -82,4 +82,13 @@ extern struct omap_abb_instance omap36xx_abb_mpu;
>  extern struct omap_abb_instance omap4_abb_mpu;
>  extern struct omap_abb_instance omap4_abb_iva;
>
> +void omap_abb_init(struct voltagedomain *voltdm);
> +void omap_abb_enable(struct voltagedomain *voltdm);
> +void omap_abb_disble(struct voltagedomain *voltdm);
> +int omap_abb_set_opp(struct voltagedomain *voltdm, u8 opp_sel);
> +int omap_abb_pre_scale(struct voltagedomain *voltdm,
> +               unsigned long target_volt);
> +int omap_abb_post_scale(struct voltagedomain *voltdm,
> +               unsigned long target_volt);
> +
>  #endif
> --
> 1.7.9.5
>
> --
> 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


[Index of Archives]     [Linux Arm (vger)]     [ARM Kernel]     [ARM MSM]     [Linux Tegra]     [Linux WPAN Networking]     [Linux Wireless Networking]     [Maemo Users]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Trails]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux