LXR linux/drivers/clk/tegra/cvb.c

   1/*
   2 * Utility functions for parsing Tegra CVB voltage tables
   3 *
   4 * Copyright (C) 2012-2014 NVIDIA Corporation.  All rights reserved.
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it will be useful, but WITHOUT
  11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13 * more details.
  14 *
  15 */
  16#include <linux/err.h>
  17#include <linux/kernel.h>
  18#include <linux/pm_opp.h>
  19
  20#include "cvb.h"
  21
  22/* cvb_mv = ((c2 * speedo / s_scale + c1) * speedo / s_scale + c0) */
  23static inline int get_cvb_voltage(int speedo, int s_scale,
  24                                  const struct cvb_coefficients *cvb)
  25{
  26        int mv;
  27
  28        /* apply only speedo scale: output mv = cvb_mv * v_scale */
  29        mv = DIV_ROUND_CLOSEST(cvb->c2 * speedo, s_scale);
  30        mv = DIV_ROUND_CLOSEST((mv + cvb->c1) * speedo, s_scale) + cvb->c0;
  31        return mv;
  32}
  33
  34static int round_cvb_voltage(int mv, int v_scale,
  35                             const struct rail_alignment *align)
  36{
  37        /* combined: apply voltage scale and round to cvb alignment step */
  38        int uv;
  39        int step = (align->step_uv ? : 1000) * v_scale;
  40        int offset = align->offset_uv * v_scale;
  41
  42        uv = max(mv * 1000, offset) - offset;
  43        uv = DIV_ROUND_UP(uv, step) * align->step_uv + align->offset_uv;
  44        return uv / 1000;
  45}
  46
  47enum {
  48        DOWN,
  49        UP
  50};
  51
  52static int round_voltage(int mv, const struct rail_alignment *align, int up)
  53{
  54        if (align->step_uv) {
  55                int uv;
  56
  57                uv = max(mv * 1000, align->offset_uv) - align->offset_uv;
  58                uv = (uv + (up ? align->step_uv - 1 : 0)) / align->step_uv;
  59                return (uv * align->step_uv + align->offset_uv) / 1000;
  60        }
  61        return mv;
  62}
  63
  64static int build_opp_table(struct device *dev, const struct cvb_table *table,
  65                           int speedo_value, unsigned long max_freq)
  66{
  67        const struct rail_alignment *align = &table->alignment;
  68        int i, ret, dfll_mv, min_mv, max_mv;
  69
  70        min_mv = round_voltage(table->min_millivolts, align, UP);
  71        max_mv = round_voltage(table->max_millivolts, align, DOWN);
  72
  73        for (i = 0; i < MAX_DVFS_FREQS; i++) {
  74                const struct cvb_table_freq_entry *entry = &table->entries[i];
  75
  76                if (!entry->freq || (entry->freq > max_freq))
  77                        break;
  78
  79                dfll_mv = get_cvb_voltage(speedo_value, table->speedo_scale,
  80                                          &entry->coefficients);
  81                dfll_mv = round_cvb_voltage(dfll_mv, table->voltage_scale,
  82                                            align);
  83                dfll_mv = clamp(dfll_mv, min_mv, max_mv);
  84
  85                ret = dev_pm_opp_add(dev, entry->freq, dfll_mv * 1000);
  86                if (ret)
  87                        return ret;
  88        }
  89
  90        return 0;
  91}
  92
  93/**
  94 * tegra_cvb_add_opp_table - build OPP table from Tegra CVB tables
  95 * @dev: the struct device * for which the OPP table is built
  96 * @tables: array of CVB tables
  97 * @count: size of the previously mentioned array
  98 * @process_id: process id of the HW module
  99 * @speedo_id: speedo id of the HW module
 100 * @speedo_value: speedo value of the HW module
 101 * @max_freq: highest safe clock rate
 102 *
 103 * On Tegra, a CVB table encodes the relationship between operating voltage
 104 * and safe maximal frequency for a given module (e.g. GPU or CPU). This
 105 * function calculates the optimal voltage-frequency operating points
 106 * for the given arguments and exports them via the OPP library for the
 107 * given @dev. Returns a pointer to the struct cvb_table that matched
 108 * or an ERR_PTR on failure.
 109 */
 110const struct cvb_table *
 111tegra_cvb_add_opp_table(struct device *dev, const struct cvb_table *tables,
 112                        size_t count, int process_id, int speedo_id,
 113                        int speedo_value, unsigned long max_freq)
 114{
 115        size_t i;
 116        int ret;
 117
 118        for (i = 0; i < count; i++) {
 119                const struct cvb_table *table = &tables[i];
 120
 121                if (table->speedo_id != -1 && table->speedo_id != speedo_id)
 122                        continue;
 123
 124                if (table->process_id != -1 && table->process_id != process_id)
 125                        continue;
 126
 127                ret = build_opp_table(dev, table, speedo_value, max_freq);
 128                return ret ? ERR_PTR(ret) : table;
 129        }
 130
 131        return ERR_PTR(-EINVAL);
 132}
 133
 134void tegra_cvb_remove_opp_table(struct device *dev,
 135                                const struct cvb_table *table,
 136                                unsigned long max_freq)
 137{
 138        unsigned int i;
 139
 140        for (i = 0; i < MAX_DVFS_FREQS; i++) {
 141                const struct cvb_table_freq_entry *entry = &table->entries[i];
 142
 143                if (!entry->freq || (entry->freq > max_freq))
 144                        break;
 145
 146                dev_pm_opp_remove(dev, entry->freq);
 147        }
 148}
 149