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(const struct cvb_table *d, 65 int speedo_value, 66 unsigned long max_freq, 67 struct device *opp_dev) 68 { 69 int i, ret, dfll_mv, min_mv, max_mv; 70 const struct cvb_table_freq_entry *table = NULL; 71 const struct rail_alignment *align = &d->alignment; 72 73 min_mv = round_voltage(d->min_millivolts, align, UP); 74 max_mv = round_voltage(d->max_millivolts, align, DOWN); 75 76 for (i = 0; i < MAX_DVFS_FREQS; i++) { 77 table = &d->cvb_table[i]; 78 if (!table->freq || (table->freq > max_freq)) 79 break; 80 81 dfll_mv = get_cvb_voltage( 82 speedo_value, d->speedo_scale, &table->coefficients); 83 dfll_mv = round_cvb_voltage(dfll_mv, d->voltage_scale, align); 84 dfll_mv = clamp(dfll_mv, min_mv, max_mv); 85 86 ret = dev_pm_opp_add(opp_dev, table->freq, dfll_mv * 1000); 87 if (ret) 88 return ret; 89 } 90 91 return 0; 92 } 93 94 /** 95 * tegra_cvb_build_opp_table - build OPP table from Tegra CVB tables 96 * @cvb_tables: array of CVB tables 97 * @sz: 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_rate: highest safe clock rate 102 * @opp_dev: the struct device * for which the OPP table is built 103 * 104 * On Tegra, a CVB table encodes the relationship between operating voltage 105 * and safe maximal frequency for a given module (e.g. GPU or CPU). This 106 * function calculates the optimal voltage-frequency operating points 107 * for the given arguments and exports them via the OPP library for the 108 * given @opp_dev. Returns a pointer to the struct cvb_table that matched 109 * or an ERR_PTR on failure. 110 */ 111 const struct cvb_table *tegra_cvb_build_opp_table( 112 const struct cvb_table *cvb_tables, 113 size_t sz, int process_id, 114 int speedo_id, int speedo_value, 115 unsigned long max_rate, 116 struct device *opp_dev) 117 { 118 int i, ret; 119 120 for (i = 0; i < sz; i++) { 121 const struct cvb_table *d = &cvb_tables[i]; 122 123 if (d->speedo_id != -1 && d->speedo_id != speedo_id) 124 continue; 125 if (d->process_id != -1 && d->process_id != process_id) 126 continue; 127 128 ret = build_opp_table(d, speedo_value, max_rate, opp_dev); 129 return ret ? ERR_PTR(ret) : d; 130 } 131 132 return ERR_PTR(-EINVAL); 133 } 134