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) */
get_cvb_voltage(int speedo,int s_scale,const struct cvb_coefficients * cvb)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 
round_cvb_voltage(int mv,int v_scale,const struct rail_alignment * align)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 
round_voltage(int mv,const struct rail_alignment * align,int up)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 
build_opp_table(struct device * dev,const struct cvb_table * table,int speedo_value,unsigned long max_freq)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 *
tegra_cvb_add_opp_table(struct device * dev,const struct cvb_table * tables,size_t count,int process_id,int speedo_id,int speedo_value,unsigned long max_freq)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 
tegra_cvb_remove_opp_table(struct device * dev,const struct cvb_table * table,unsigned long max_freq)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 }
149