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) */
14static 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
25static 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
38enum {
39 DOWN,
40 UP
41};
42
43static 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
55static 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(mv: table->min_millivolts, align, up: UP);
62 max_mv = round_voltage(mv: table->max_millivolts, align, up: 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: speedo_value, s_scale: table->speedo_scale,
71 cvb: &entry->coefficients);
72 dfll_mv = round_cvb_voltage(mv: dfll_mv, v_scale: table->voltage_scale,
73 align);
74 dfll_mv = clamp(dfll_mv, min_mv, max_mv);
75
76 ret = dev_pm_opp_add(dev, freq: entry->freq, u_volt: 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 * @align: parameters of the regulator step and offset
90 * @process_id: process id of the HW module
91 * @speedo_id: speedo id of the HW module
92 * @speedo_value: speedo value of the HW module
93 * @max_freq: highest safe clock rate
94 *
95 * On Tegra, a CVB table encodes the relationship between operating voltage
96 * and safe maximal frequency for a given module (e.g. GPU or CPU). This
97 * function calculates the optimal voltage-frequency operating points
98 * for the given arguments and exports them via the OPP library for the
99 * given @dev. Returns a pointer to the struct cvb_table that matched
100 * or an ERR_PTR on failure.
101 */
102const struct cvb_table *
103tegra_cvb_add_opp_table(struct device *dev, const struct cvb_table *tables,
104 size_t count, struct rail_alignment *align,
105 int process_id, int speedo_id, int speedo_value,
106 unsigned long max_freq)
107{
108 size_t i;
109 int ret;
110
111 for (i = 0; i < count; i++) {
112 const struct cvb_table *table = &tables[i];
113
114 if (table->speedo_id != -1 && table->speedo_id != speedo_id)
115 continue;
116
117 if (table->process_id != -1 && table->process_id != process_id)
118 continue;
119
120 ret = build_opp_table(dev, table, align, speedo_value,
121 max_freq);
122 return ret ? ERR_PTR(error: ret) : table;
123 }
124
125 return ERR_PTR(error: -EINVAL);
126}
127
128void tegra_cvb_remove_opp_table(struct device *dev,
129 const struct cvb_table *table,
130 unsigned long max_freq)
131{
132 unsigned int i;
133
134 for (i = 0; i < MAX_DVFS_FREQS; i++) {
135 const struct cvb_table_freq_entry *entry = &table->entries[i];
136
137 if (!entry->freq || (entry->freq > max_freq))
138 break;
139
140 dev_pm_opp_remove(dev, freq: entry->freq);
141 }
142}
143

source code of linux/drivers/clk/tegra/cvb.c