xref: /openbmc/linux/drivers/clk/tegra/cvb.c (revision b565eb81)
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  * @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  */
102 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)103 tegra_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 
tegra_cvb_remove_opp_table(struct device * dev,const struct cvb_table * table,unsigned long max_freq)128 void 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 }
143