1// SPDX-License-Identifier: MIT
2/*
3 * Copyright © 2019 Intel Corporation
4 */
5
6#include <asm/tsc.h>
7#include <linux/cpufreq.h>
8
9#include "i915_drv.h"
10#include "i915_reg.h"
11#include "intel_gt.h"
12#include "intel_llc.h"
13#include "intel_mchbar_regs.h"
14#include "intel_pcode.h"
15#include "intel_rps.h"
16
17struct ia_constants {
18 unsigned int min_gpu_freq;
19 unsigned int max_gpu_freq;
20
21 unsigned int min_ring_freq;
22 unsigned int max_ia_freq;
23};
24
25static struct intel_gt *llc_to_gt(struct intel_llc *llc)
26{
27 return container_of(llc, struct intel_gt, llc);
28}
29
30static unsigned int cpu_max_MHz(void)
31{
32 struct cpufreq_policy *policy;
33 unsigned int max_khz;
34
35 policy = cpufreq_cpu_get(cpu: 0);
36 if (policy) {
37 max_khz = policy->cpuinfo.max_freq;
38 cpufreq_cpu_put(policy);
39 } else {
40 /*
41 * Default to measured freq if none found, PCU will ensure we
42 * don't go over
43 */
44 max_khz = tsc_khz;
45 }
46
47 return max_khz / 1000;
48}
49
50static bool get_ia_constants(struct intel_llc *llc,
51 struct ia_constants *consts)
52{
53 struct drm_i915_private *i915 = llc_to_gt(llc)->i915;
54 struct intel_rps *rps = &llc_to_gt(llc)->rps;
55
56 if (!HAS_LLC(i915) || IS_DGFX(i915))
57 return false;
58
59 consts->max_ia_freq = cpu_max_MHz();
60
61 consts->min_ring_freq =
62 intel_uncore_read(uncore: llc_to_gt(llc)->uncore, DCLK) & 0xf;
63 /* convert DDR frequency from units of 266.6MHz to bandwidth */
64 consts->min_ring_freq = mult_frac(consts->min_ring_freq, 8, 3);
65
66 consts->min_gpu_freq = intel_rps_get_min_raw_freq(rps);
67 consts->max_gpu_freq = intel_rps_get_max_raw_freq(rps);
68
69 return true;
70}
71
72static void calc_ia_freq(struct intel_llc *llc,
73 unsigned int gpu_freq,
74 const struct ia_constants *consts,
75 unsigned int *out_ia_freq,
76 unsigned int *out_ring_freq)
77{
78 struct drm_i915_private *i915 = llc_to_gt(llc)->i915;
79 const int diff = consts->max_gpu_freq - gpu_freq;
80 unsigned int ia_freq = 0, ring_freq = 0;
81
82 if (GRAPHICS_VER(i915) >= 9) {
83 /*
84 * ring_freq = 2 * GT. ring_freq is in 100MHz units
85 * No floor required for ring frequency on SKL.
86 */
87 ring_freq = gpu_freq;
88 } else if (GRAPHICS_VER(i915) >= 8) {
89 /* max(2 * GT, DDR). NB: GT is 50MHz units */
90 ring_freq = max(consts->min_ring_freq, gpu_freq);
91 } else if (IS_HASWELL(i915)) {
92 ring_freq = mult_frac(gpu_freq, 5, 4);
93 ring_freq = max(consts->min_ring_freq, ring_freq);
94 /* leave ia_freq as the default, chosen by cpufreq */
95 } else {
96 const int min_freq = 15;
97 const int scale = 180;
98
99 /*
100 * On older processors, there is no separate ring
101 * clock domain, so in order to boost the bandwidth
102 * of the ring, we need to upclock the CPU (ia_freq).
103 *
104 * For GPU frequencies less than 750MHz,
105 * just use the lowest ring freq.
106 */
107 if (gpu_freq < min_freq)
108 ia_freq = 800;
109 else
110 ia_freq = consts->max_ia_freq - diff * scale / 2;
111 ia_freq = DIV_ROUND_CLOSEST(ia_freq, 100);
112 }
113
114 *out_ia_freq = ia_freq;
115 *out_ring_freq = ring_freq;
116}
117
118static void gen6_update_ring_freq(struct intel_llc *llc)
119{
120 struct ia_constants consts;
121 unsigned int gpu_freq;
122
123 if (!get_ia_constants(llc, consts: &consts))
124 return;
125
126 /*
127 * Although this is unlikely on any platform during initialization,
128 * let's ensure we don't get accidentally into infinite loop
129 */
130 if (consts.max_gpu_freq <= consts.min_gpu_freq)
131 return;
132 /*
133 * For each potential GPU frequency, load a ring frequency we'd like
134 * to use for memory access. We do this by specifying the IA frequency
135 * the PCU should use as a reference to determine the ring frequency.
136 */
137 for (gpu_freq = consts.max_gpu_freq;
138 gpu_freq >= consts.min_gpu_freq;
139 gpu_freq--) {
140 unsigned int ia_freq, ring_freq;
141
142 calc_ia_freq(llc, gpu_freq, consts: &consts, out_ia_freq: &ia_freq, out_ring_freq: &ring_freq);
143 snb_pcode_write(llc_to_gt(llc)->uncore, GEN6_PCODE_WRITE_MIN_FREQ_TABLE,
144 ia_freq << GEN6_PCODE_FREQ_IA_RATIO_SHIFT |
145 ring_freq << GEN6_PCODE_FREQ_RING_RATIO_SHIFT |
146 gpu_freq);
147 }
148}
149
150void intel_llc_enable(struct intel_llc *llc)
151{
152 gen6_update_ring_freq(llc);
153}
154
155void intel_llc_disable(struct intel_llc *llc)
156{
157 /* Currently there is no HW configuration to be done to disable. */
158}
159
160#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
161#include "selftest_llc.c"
162#endif
163

source code of linux/drivers/gpu/drm/i915/gt/intel_llc.c