1// SPDX-License-Identifier: MIT
2/*
3 * Copyright © 2020 Intel Corporation
4 */
5
6#include "i915_drv.h"
7#include "i915_reg.h"
8#include "intel_gt.h"
9#include "intel_gt_clock_utils.h"
10#include "intel_gt_print.h"
11#include "intel_gt_regs.h"
12#include "soc/intel_dram.h"
13
14static u32 read_reference_ts_freq(struct intel_uncore *uncore)
15{
16 u32 ts_override = intel_uncore_read(uncore, GEN9_TIMESTAMP_OVERRIDE);
17 u32 base_freq, frac_freq;
18
19 base_freq = ((ts_override & GEN9_TIMESTAMP_OVERRIDE_US_COUNTER_DIVIDER_MASK) >>
20 GEN9_TIMESTAMP_OVERRIDE_US_COUNTER_DIVIDER_SHIFT) + 1;
21 base_freq *= 1000000;
22
23 frac_freq = ((ts_override &
24 GEN9_TIMESTAMP_OVERRIDE_US_COUNTER_DENOMINATOR_MASK) >>
25 GEN9_TIMESTAMP_OVERRIDE_US_COUNTER_DENOMINATOR_SHIFT);
26 frac_freq = 1000000 / (frac_freq + 1);
27
28 return base_freq + frac_freq;
29}
30
31static u32 gen11_get_crystal_clock_freq(struct intel_uncore *uncore,
32 u32 rpm_config_reg)
33{
34 u32 f19_2_mhz = 19200000;
35 u32 f24_mhz = 24000000;
36 u32 f25_mhz = 25000000;
37 u32 f38_4_mhz = 38400000;
38 u32 crystal_clock = rpm_config_reg & GEN11_RPM_CONFIG0_CRYSTAL_CLOCK_FREQ_MASK;
39
40 switch (crystal_clock) {
41 case GEN11_RPM_CONFIG0_CRYSTAL_CLOCK_FREQ_24_MHZ:
42 return f24_mhz;
43 case GEN11_RPM_CONFIG0_CRYSTAL_CLOCK_FREQ_19_2_MHZ:
44 return f19_2_mhz;
45 case GEN11_RPM_CONFIG0_CRYSTAL_CLOCK_FREQ_38_4_MHZ:
46 return f38_4_mhz;
47 case GEN11_RPM_CONFIG0_CRYSTAL_CLOCK_FREQ_25_MHZ:
48 return f25_mhz;
49 default:
50 MISSING_CASE(crystal_clock);
51 return 0;
52 }
53}
54
55static u32 gen11_read_clock_frequency(struct intel_uncore *uncore)
56{
57 u32 ctc_reg = intel_uncore_read(uncore, CTC_MODE);
58 u32 freq = 0;
59
60 /*
61 * Note that on gen11+, the clock frequency may be reconfigured.
62 * We do not, and we assume nobody else does.
63 *
64 * First figure out the reference frequency. There are 2 ways
65 * we can compute the frequency, either through the
66 * TIMESTAMP_OVERRIDE register or through RPM_CONFIG. CTC_MODE
67 * tells us which one we should use.
68 */
69 if ((ctc_reg & CTC_SOURCE_PARAMETER_MASK) == CTC_SOURCE_DIVIDE_LOGIC) {
70 freq = read_reference_ts_freq(uncore);
71 } else {
72 u32 c0 = intel_uncore_read(uncore, RPM_CONFIG0);
73
74 freq = gen11_get_crystal_clock_freq(uncore, rpm_config_reg: c0);
75
76 /*
77 * Now figure out how the command stream's timestamp
78 * register increments from this frequency (it might
79 * increment only every few clock cycle).
80 */
81 freq >>= 3 - REG_FIELD_GET(GEN10_RPM_CONFIG0_CTC_SHIFT_PARAMETER_MASK, c0);
82 }
83
84 return freq;
85}
86
87static u32 gen9_read_clock_frequency(struct intel_uncore *uncore)
88{
89 u32 ctc_reg = intel_uncore_read(uncore, CTC_MODE);
90 u32 freq = 0;
91
92 if ((ctc_reg & CTC_SOURCE_PARAMETER_MASK) == CTC_SOURCE_DIVIDE_LOGIC) {
93 freq = read_reference_ts_freq(uncore);
94 } else {
95 freq = IS_GEN9_LP(uncore->i915) ? 19200000 : 24000000;
96
97 /*
98 * Now figure out how the command stream's timestamp
99 * register increments from this frequency (it might
100 * increment only every few clock cycle).
101 */
102 freq >>= 3 - REG_FIELD_GET(CTC_SHIFT_PARAMETER_MASK, ctc_reg);
103 }
104
105 return freq;
106}
107
108static u32 gen6_read_clock_frequency(struct intel_uncore *uncore)
109{
110 /*
111 * PRMs say:
112 *
113 * "The PCU TSC counts 10ns increments; this timestamp
114 * reflects bits 38:3 of the TSC (i.e. 80ns granularity,
115 * rolling over every 1.5 hours).
116 */
117 return 12500000;
118}
119
120static u32 gen5_read_clock_frequency(struct intel_uncore *uncore)
121{
122 /*
123 * 63:32 increments every 1000 ns
124 * 31:0 mbz
125 */
126 return 1000000000 / 1000;
127}
128
129static u32 g4x_read_clock_frequency(struct intel_uncore *uncore)
130{
131 /*
132 * 63:20 increments every 1/4 ns
133 * 19:0 mbz
134 *
135 * -> 63:32 increments every 1024 ns
136 */
137 return 1000000000 / 1024;
138}
139
140static u32 gen4_read_clock_frequency(struct intel_uncore *uncore)
141{
142 /*
143 * PRMs say:
144 *
145 * "The value in this register increments once every 16
146 * hclks." (through the “Clocking Configuration”
147 * (“CLKCFG”) MCHBAR register)
148 *
149 * Testing on actual hardware has shown there is no /16.
150 */
151 return DIV_ROUND_CLOSEST(intel_fsb_freq(uncore->i915), 4) * 1000;
152}
153
154static u32 read_clock_frequency(struct intel_uncore *uncore)
155{
156 if (GRAPHICS_VER(uncore->i915) >= 11)
157 return gen11_read_clock_frequency(uncore);
158 else if (GRAPHICS_VER(uncore->i915) >= 9)
159 return gen9_read_clock_frequency(uncore);
160 else if (GRAPHICS_VER(uncore->i915) >= 6)
161 return gen6_read_clock_frequency(uncore);
162 else if (GRAPHICS_VER(uncore->i915) == 5)
163 return gen5_read_clock_frequency(uncore);
164 else if (IS_G4X(uncore->i915))
165 return g4x_read_clock_frequency(uncore);
166 else if (GRAPHICS_VER(uncore->i915) == 4)
167 return gen4_read_clock_frequency(uncore);
168 else
169 return 0;
170}
171
172void intel_gt_init_clock_frequency(struct intel_gt *gt)
173{
174 gt->clock_frequency = read_clock_frequency(uncore: gt->uncore);
175
176 /* Icelake appears to use another fixed frequency for CTX_TIMESTAMP */
177 if (GRAPHICS_VER(gt->i915) == 11)
178 gt->clock_period_ns = NSEC_PER_SEC / 13750000;
179 else if (gt->clock_frequency)
180 gt->clock_period_ns = intel_gt_clock_interval_to_ns(gt, count: 1);
181
182 GT_TRACE(gt,
183 "Using clock frequency: %dkHz, period: %dns, wrap: %lldms\n",
184 gt->clock_frequency / 1000,
185 gt->clock_period_ns,
186 div_u64(mul_u32_u32(gt->clock_period_ns, S32_MAX),
187 USEC_PER_SEC));
188}
189
190#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)
191void intel_gt_check_clock_frequency(const struct intel_gt *gt)
192{
193 if (gt->clock_frequency != read_clock_frequency(gt->uncore)) {
194 gt_err(gt, "GT clock frequency changed, was %uHz, now %uHz!\n",
195 gt->clock_frequency,
196 read_clock_frequency(gt->uncore));
197 }
198}
199#endif
200
201static u64 div_u64_roundup(u64 nom, u32 den)
202{
203 return div_u64(dividend: nom + den - 1, divisor: den);
204}
205
206u64 intel_gt_clock_interval_to_ns(const struct intel_gt *gt, u64 count)
207{
208 return mul_u64_u32_div(a: count, NSEC_PER_SEC, div: gt->clock_frequency);
209}
210
211u64 intel_gt_pm_interval_to_ns(const struct intel_gt *gt, u64 count)
212{
213 return intel_gt_clock_interval_to_ns(gt, count: 16 * count);
214}
215
216u64 intel_gt_ns_to_clock_interval(const struct intel_gt *gt, u64 ns)
217{
218 return mul_u64_u32_div(a: ns, mul: gt->clock_frequency, NSEC_PER_SEC);
219}
220
221u64 intel_gt_ns_to_pm_interval(const struct intel_gt *gt, u64 ns)
222{
223 u64 val;
224
225 /*
226 * Make these a multiple of magic 25 to avoid SNB (eg. Dell XPS
227 * 8300) freezing up around GPU hangs. Looks as if even
228 * scheduling/timer interrupts start misbehaving if the RPS
229 * EI/thresholds are "bad", leading to a very sluggish or even
230 * frozen machine.
231 */
232 val = div_u64_roundup(nom: intel_gt_ns_to_clock_interval(gt, ns), den: 16);
233 if (GRAPHICS_VER(gt->i915) == 6)
234 val = div_u64_roundup(nom: val, den: 25) * 25;
235
236 return val;
237}
238

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