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    Subject[PATCH v9 04/17] clk: tegra: Add functions for parsing CVB tables
    Date
    From: Tuomas Tynkkynen <ttynkkynen@nvidia.com>

    Tegra CVB tables encode the relationship between operating voltage
    and optimal frequency as a function of the so-called speedo value.
    The speedo value is written to the on-chip fuses at the factory,
    which allows the voltage-frequency operating points to be calculated
    on an per-chip basis.

    Add utility functions to parse the Tegra-specific tables and export the
    voltage-frequency pairs to the generic OPP framework for other drivers
    to use.

    Signed-off-by: Tuomas Tynkkynen <ttynkkynen@nvidia.com>
    Signed-off-by: Mikko Perttunen <mikko.perttunen@kapsi.fi>
    Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
    Acked-by: Michael Turquette <mturquette@linaro.org>
    ---
    arch/arm/mach-tegra/Kconfig | 1 +
    drivers/clk/tegra/cvb.c | 140 ++++++++++++++++++++++++++++++++++++++++++++
    drivers/clk/tegra/cvb.h | 67 +++++++++++++++++++++
    3 files changed, 208 insertions(+)
    create mode 100644 drivers/clk/tegra/cvb.c
    create mode 100644 drivers/clk/tegra/cvb.h

    diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
    index 5d1a318..0fa4c5f 100644
    --- a/arch/arm/mach-tegra/Kconfig
    +++ b/arch/arm/mach-tegra/Kconfig
    @@ -8,6 +8,7 @@ menuconfig ARCH_TEGRA
    select HAVE_ARM_SCU if SMP
    select HAVE_ARM_TWD if SMP
    select PINCTRL
    + select PM_OPP
    select ARCH_HAS_RESET_CONTROLLER
    select RESET_CONTROLLER
    select SOC_BUS
    diff --git a/drivers/clk/tegra/cvb.c b/drivers/clk/tegra/cvb.c
    new file mode 100644
    index 0000000..0204e08
    --- /dev/null
    +++ b/drivers/clk/tegra/cvb.c
    @@ -0,0 +1,140 @@
    +/*
    + * Utility functions for parsing Tegra CVB voltage tables
    + *
    + * Copyright (C) 2012-2014 NVIDIA Corporation. All rights reserved.
    + *
    + * 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.
    + *
    + * This program is distributed in the hope that it will be useful, but WITHOUT
    + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
    + * more details.
    + *
    + */
    +#include <linux/err.h>
    +#include <linux/kernel.h>
    +#include <linux/pm_opp.h>
    +
    +#include "cvb.h"
    +
    +/* cvb_mv = ((c2 * speedo / s_scale + c1) * speedo / s_scale + c0) */
    +static inline int get_cvb_voltage(int speedo, int s_scale,
    + const struct cvb_coefficients *cvb)
    +{
    + int mv;
    +
    + /* apply only speedo scale: output mv = cvb_mv * v_scale */
    + mv = DIV_ROUND_CLOSEST(cvb->c2 * speedo, s_scale);
    + mv = DIV_ROUND_CLOSEST((mv + cvb->c1) * speedo, s_scale) + cvb->c0;
    + return mv;
    +}
    +
    +static int round_cvb_voltage(int mv, int v_scale,
    + const struct rail_alignment *align)
    +{
    + /* combined: apply voltage scale and round to cvb alignment step */
    + int uv;
    + int step = (align->step_uv ? : 1000) * v_scale;
    + int offset = align->offset_uv * v_scale;
    +
    + uv = max(mv * 1000, offset) - offset;
    + uv = DIV_ROUND_UP(uv, step) * align->step_uv + align->offset_uv;
    + return uv / 1000;
    +}
    +
    +enum {
    + DOWN,
    + UP
    +};
    +
    +static int round_voltage(int mv, const struct rail_alignment *align, int up)
    +{
    + if (align->step_uv) {
    + int uv;
    +
    + uv = max(mv * 1000, align->offset_uv) - align->offset_uv;
    + uv = (uv + (up ? align->step_uv - 1 : 0)) / align->step_uv;
    + return (uv * align->step_uv + align->offset_uv) / 1000;
    + }
    + return mv;
    +}
    +
    +static int build_opp_table(const struct cvb_table *d,
    + int speedo_value,
    + unsigned long max_freq,
    + struct device *opp_dev)
    +{
    + int i, ret, dfll_mv, min_mv, max_mv;
    + const struct cvb_table_freq_entry *table = NULL;
    + const struct rail_alignment *align = &d->alignment;
    +
    + min_mv = round_voltage(d->min_millivolts, align, UP);
    + max_mv = round_voltage(d->max_millivolts, align, DOWN);
    +
    + for (i = 0; i < MAX_DVFS_FREQS; i++) {
    + table = &d->cvb_table[i];
    + if (!table->freq || (table->freq > max_freq))
    + break;
    +
    + /*
    + * FIXME after clk_round_rate/clk_determine_rate prototypes
    + * have been updated
    + */
    + if (table->freq & (1<<31))
    + continue;
    +
    + dfll_mv = get_cvb_voltage(
    + speedo_value, d->speedo_scale, &table->coefficients);
    + dfll_mv = round_cvb_voltage(dfll_mv, d->voltage_scale, align);
    + dfll_mv = clamp(dfll_mv, min_mv, max_mv);
    +
    + ret = dev_pm_opp_add(opp_dev, table->freq, dfll_mv * 1000);
    + if (ret)
    + return ret;
    + }
    +
    + return 0;
    +}
    +
    +/**
    + * tegra_cvb_build_opp_table - build OPP table from Tegra CVB tables
    + * @cvb_tables: array of CVB tables
    + * @sz: size of the previously mentioned array
    + * @process_id: process id of the HW module
    + * @speedo_id: speedo id of the HW module
    + * @speedo_value: speedo value of the HW module
    + * @max_rate: highest safe clock rate
    + * @opp_dev: the struct device * for which the OPP table is built
    + *
    + * On Tegra, a CVB table encodes the relationship between operating voltage
    + * and safe maximal frequency for a given module (e.g. GPU or CPU). This
    + * function calculates the optimal voltage-frequency operating points
    + * for the given arguments and exports them via the OPP library for the
    + * given @opp_dev. Returns a pointer to the struct cvb_table that matched
    + * or an ERR_PTR on failure.
    + */
    +const struct cvb_table *tegra_cvb_build_opp_table(
    + const struct cvb_table *cvb_tables,
    + size_t sz, int process_id,
    + int speedo_id, int speedo_value,
    + unsigned long max_rate,
    + struct device *opp_dev)
    +{
    + int i, ret;
    +
    + for (i = 0; i < sz; i++) {
    + const struct cvb_table *d = &cvb_tables[i];
    +
    + if (d->speedo_id != -1 && d->speedo_id != speedo_id)
    + continue;
    + if (d->process_id != -1 && d->process_id != process_id)
    + continue;
    +
    + ret = build_opp_table(d, speedo_value, max_rate, opp_dev);
    + return ret ? ERR_PTR(ret) : d;
    + }
    +
    + return ERR_PTR(-EINVAL);
    +}
    diff --git a/drivers/clk/tegra/cvb.h b/drivers/clk/tegra/cvb.h
    new file mode 100644
    index 0000000..f62cdc4
    --- /dev/null
    +++ b/drivers/clk/tegra/cvb.h
    @@ -0,0 +1,67 @@
    +/*
    + * Utility functions for parsing Tegra CVB voltage tables
    + *
    + * 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.
    + *
    + * This program is distributed in the hope that it will be useful, but WITHOUT
    + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
    + * more details.
    + *
    + */
    +
    +#ifndef __DRIVERS_CLK_TEGRA_CVB_H
    +#define __DRIVERS_CLK_TEGRA_CVB_H
    +
    +#include <linux/types.h>
    +
    +struct device;
    +
    +#define MAX_DVFS_FREQS 40
    +
    +struct rail_alignment {
    + int offset_uv;
    + int step_uv;
    +};
    +
    +struct cvb_coefficients {
    + int c0;
    + int c1;
    + int c2;
    +};
    +
    +struct cvb_table_freq_entry {
    + unsigned long freq;
    + struct cvb_coefficients coefficients;
    +};
    +
    +struct cvb_cpu_dfll_data {
    + u32 tune0_low;
    + u32 tune0_high;
    + u32 tune1;
    +};
    +
    +struct cvb_table {
    + int speedo_id;
    + int process_id;
    +
    + int min_millivolts;
    + int max_millivolts;
    + struct rail_alignment alignment;
    +
    + int speedo_scale;
    + int voltage_scale;
    + struct cvb_table_freq_entry cvb_table[MAX_DVFS_FREQS];
    + struct cvb_cpu_dfll_data cpu_dfll_data;
    +};
    +
    +const struct cvb_table *tegra_cvb_build_opp_table(
    + const struct cvb_table *cvb_tables,
    + size_t sz, int process_id,
    + int speedo_id, int speedo_value,
    + unsigned long max_rate,
    + struct device *opp_dev);
    +
    +#endif
    --
    2.3.0


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