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) */
  23 static 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
  34 static 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
  47 enum {
  48         DOWN,
  49         UP
  50 };
  51
  52 static 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
  64 static 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  */
 110 const struct cvb_table *
 111 tegra_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
 134 void 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 }