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/*
* 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;
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);
}
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