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(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 * @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(ret) : table;
123	}
124
125	return ERR_PTR(-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, entry->freq);
141	}
142}