1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Utility functions for parsing Tegra CVB voltage tables
4 *
5 * Copyright (C) 2012-2019 NVIDIA Corporation. All rights reserved.
6 */
7 #include <linux/err.h>
8 #include <linux/kernel.h>
9 #include <linux/pm_opp.h>
10
11 #include "cvb.h"
12
13 /* cvb_mv = ((c2 * speedo / s_scale + c1) * speedo / s_scale + c0) */
get_cvb_voltage(int speedo,int s_scale,const struct cvb_coefficients * cvb)14 static inline int get_cvb_voltage(int speedo, int s_scale,
15 const struct cvb_coefficients *cvb)
16 {
17 int mv;
18
19 /* apply only speedo scale: output mv = cvb_mv * v_scale */
20 mv = DIV_ROUND_CLOSEST(cvb->c2 * speedo, s_scale);
21 mv = DIV_ROUND_CLOSEST((mv + cvb->c1) * speedo, s_scale) + cvb->c0;
22 return mv;
23 }
24
round_cvb_voltage(int mv,int v_scale,const struct rail_alignment * align)25 static int round_cvb_voltage(int mv, int v_scale,
26 const struct rail_alignment *align)
27 {
28 /* combined: apply voltage scale and round to cvb alignment step */
29 int uv;
30 int step = (align->step_uv ? : 1000) * v_scale;
31 int offset = align->offset_uv * v_scale;
32
33 uv = max(mv * 1000, offset) - offset;
34 uv = DIV_ROUND_UP(uv, step) * align->step_uv + align->offset_uv;
35 return uv / 1000;
36 }
37
38 enum {
39 DOWN,
40 UP
41 };
42
round_voltage(int mv,const struct rail_alignment * align,int up)43 static int round_voltage(int mv, const struct rail_alignment *align, int up)
44 {
45 if (align->step_uv) {
46 int uv;
47
48 uv = max(mv * 1000, align->offset_uv) - align->offset_uv;
49 uv = (uv + (up ? align->step_uv - 1 : 0)) / align->step_uv;
50 return (uv * align->step_uv + align->offset_uv) / 1000;
51 }
52 return mv;
53 }
54
build_opp_table(struct device * dev,const struct cvb_table * table,struct rail_alignment * align,int speedo_value,unsigned long max_freq)55 static int build_opp_table(struct device *dev, const struct cvb_table *table,
56 struct rail_alignment *align,
57 int speedo_value, unsigned long max_freq)
58 {
59 int i, ret, dfll_mv, min_mv, max_mv;
60
61 min_mv = round_voltage(table->min_millivolts, align, UP);
62 max_mv = round_voltage(table->max_millivolts, align, DOWN);
63
64 for (i = 0; i < MAX_DVFS_FREQS; i++) {
65 const struct cvb_table_freq_entry *entry = &table->entries[i];
66
67 if (!entry->freq || (entry->freq > max_freq))
68 break;
69
70 dfll_mv = get_cvb_voltage(speedo_value, table->speedo_scale,
71 &entry->coefficients);
72 dfll_mv = round_cvb_voltage(dfll_mv, table->voltage_scale,
73 align);
74 dfll_mv = clamp(dfll_mv, min_mv, max_mv);
75
76 ret = dev_pm_opp_add(dev, entry->freq, dfll_mv * 1000);
77 if (ret)
78 return ret;
79 }
80
81 return 0;
82 }
83
84 /**
85 * tegra_cvb_add_opp_table - build OPP table from Tegra CVB tables
86 * @dev: the struct device * for which the OPP table is built
87 * @tables: array of CVB tables
88 * @count: size of the previously mentioned array
89 * @process_id: process id of the HW module
90 * @speedo_id: speedo id of the HW module
91 * @speedo_value: speedo value of the HW module
92 * @max_freq: highest safe clock rate
93 *
94 * On Tegra, a CVB table encodes the relationship between operating voltage
95 * and safe maximal frequency for a given module (e.g. GPU or CPU). This
96 * function calculates the optimal voltage-frequency operating points
97 * for the given arguments and exports them via the OPP library for the
98 * given @dev. Returns a pointer to the struct cvb_table that matched
99 * or an ERR_PTR on failure.
100 */
101 const struct cvb_table *
tegra_cvb_add_opp_table(struct device * dev,const struct cvb_table * tables,size_t count,struct rail_alignment * align,int process_id,int speedo_id,int speedo_value,unsigned long max_freq)102 tegra_cvb_add_opp_table(struct device *dev, const struct cvb_table *tables,
103 size_t count, struct rail_alignment *align,
104 int process_id, int speedo_id, int speedo_value,
105 unsigned long max_freq)
106 {
107 size_t i;
108 int ret;
109
110 for (i = 0; i < count; i++) {
111 const struct cvb_table *table = &tables[i];
112
113 if (table->speedo_id != -1 && table->speedo_id != speedo_id)
114 continue;
115
116 if (table->process_id != -1 && table->process_id != process_id)
117 continue;
118
119 ret = build_opp_table(dev, table, align, speedo_value,
120 max_freq);
121 return ret ? ERR_PTR(ret) : table;
122 }
123
124 return ERR_PTR(-EINVAL);
125 }
126
tegra_cvb_remove_opp_table(struct device * dev,const struct cvb_table * table,unsigned long max_freq)127 void tegra_cvb_remove_opp_table(struct device *dev,
128 const struct cvb_table *table,
129 unsigned long max_freq)
130 {
131 unsigned int i;
132
133 for (i = 0; i < MAX_DVFS_FREQS; i++) {
134 const struct cvb_table_freq_entry *entry = &table->entries[i];
135
136 if (!entry->freq || (entry->freq > max_freq))
137 break;
138
139 dev_pm_opp_remove(dev, entry->freq);
140 }
141 }
142
