1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * hdac_i915.c - routines for sync between HD-A core and i915 display driver |
4 | */ |
5 | |
6 | #include <linux/init.h> |
7 | #include <linux/module.h> |
8 | #include <linux/pci.h> |
9 | #include <sound/core.h> |
10 | #include <sound/hdaudio.h> |
11 | #include <sound/hda_i915.h> |
12 | #include <sound/hda_register.h> |
13 | #include <video/nomodeset.h> |
14 | |
15 | static int gpu_bind = -1; |
16 | module_param(gpu_bind, int, 0644); |
17 | MODULE_PARM_DESC(gpu_bind, "Whether to bind sound component to GPU " |
18 | "(1=always, 0=never, -1=on nomodeset(default))" ); |
19 | |
20 | /** |
21 | * snd_hdac_i915_set_bclk - Reprogram BCLK for HSW/BDW |
22 | * @bus: HDA core bus |
23 | * |
24 | * Intel HSW/BDW display HDA controller is in GPU. Both its power and link BCLK |
25 | * depends on GPU. Two Extended Mode registers EM4 (M value) and EM5 (N Value) |
26 | * are used to convert CDClk (Core Display Clock) to 24MHz BCLK: |
27 | * BCLK = CDCLK * M / N |
28 | * The values will be lost when the display power well is disabled and need to |
29 | * be restored to avoid abnormal playback speed. |
30 | * |
31 | * Call this function at initializing and changing power well, as well as |
32 | * at ELD notifier for the hotplug. |
33 | */ |
34 | void snd_hdac_i915_set_bclk(struct hdac_bus *bus) |
35 | { |
36 | struct drm_audio_component *acomp = bus->audio_component; |
37 | struct pci_dev *pci = to_pci_dev(bus->dev); |
38 | int cdclk_freq; |
39 | unsigned int bclk_m, bclk_n; |
40 | |
41 | if (!acomp || !acomp->ops || !acomp->ops->get_cdclk_freq) |
42 | return; /* only for i915 binding */ |
43 | if (!HDA_CONTROLLER_IS_HSW(pci)) |
44 | return; /* only HSW/BDW */ |
45 | |
46 | cdclk_freq = acomp->ops->get_cdclk_freq(acomp->dev); |
47 | switch (cdclk_freq) { |
48 | case 337500: |
49 | bclk_m = 16; |
50 | bclk_n = 225; |
51 | break; |
52 | |
53 | case 450000: |
54 | default: /* default CDCLK 450MHz */ |
55 | bclk_m = 4; |
56 | bclk_n = 75; |
57 | break; |
58 | |
59 | case 540000: |
60 | bclk_m = 4; |
61 | bclk_n = 90; |
62 | break; |
63 | |
64 | case 675000: |
65 | bclk_m = 8; |
66 | bclk_n = 225; |
67 | break; |
68 | } |
69 | |
70 | snd_hdac_chip_writew(bus, HSW_EM4, bclk_m); |
71 | snd_hdac_chip_writew(bus, HSW_EM5, bclk_n); |
72 | } |
73 | EXPORT_SYMBOL_GPL(snd_hdac_i915_set_bclk); |
74 | |
75 | /* returns true if the devices can be connected for audio */ |
76 | static bool connectivity_check(struct pci_dev *i915, struct pci_dev *hdac) |
77 | { |
78 | struct pci_bus *bus_a = i915->bus, *bus_b = hdac->bus; |
79 | |
80 | /* directly connected on the same bus */ |
81 | if (bus_a == bus_b) |
82 | return true; |
83 | |
84 | bus_a = bus_a->parent; |
85 | bus_b = bus_b->parent; |
86 | |
87 | /* connected via parent bus (may be NULL!) */ |
88 | if (bus_a == bus_b) |
89 | return true; |
90 | |
91 | if (!bus_a || !bus_b) |
92 | return false; |
93 | |
94 | /* |
95 | * on i915 discrete GPUs with embedded HDA audio, the two |
96 | * devices are connected via 2nd level PCI bridge |
97 | */ |
98 | bus_a = bus_a->parent; |
99 | bus_b = bus_b->parent; |
100 | if (bus_a && bus_a == bus_b) |
101 | return true; |
102 | |
103 | return false; |
104 | } |
105 | |
106 | static int i915_component_master_match(struct device *dev, int subcomponent, |
107 | void *data) |
108 | { |
109 | struct pci_dev *hdac_pci, *i915_pci; |
110 | struct hdac_bus *bus = data; |
111 | |
112 | if (!dev_is_pci(dev)) |
113 | return 0; |
114 | |
115 | hdac_pci = to_pci_dev(bus->dev); |
116 | i915_pci = to_pci_dev(dev); |
117 | |
118 | if ((!strcmp(dev->driver->name, "i915" ) || |
119 | !strcmp(dev->driver->name, "xe" )) && |
120 | subcomponent == I915_COMPONENT_AUDIO && |
121 | connectivity_check(i915: i915_pci, hdac: hdac_pci)) |
122 | return 1; |
123 | |
124 | return 0; |
125 | } |
126 | |
127 | /* check whether Intel graphics is present and reachable */ |
128 | static int i915_gfx_present(struct pci_dev *hdac_pci) |
129 | { |
130 | struct pci_dev *display_dev = NULL; |
131 | |
132 | if (!gpu_bind || (gpu_bind < 0 && video_firmware_drivers_only())) |
133 | return false; |
134 | |
135 | for_each_pci_dev(display_dev) { |
136 | if (display_dev->vendor == PCI_VENDOR_ID_INTEL && |
137 | (display_dev->class >> 16) == PCI_BASE_CLASS_DISPLAY && |
138 | connectivity_check(i915: display_dev, hdac: hdac_pci)) { |
139 | pci_dev_put(dev: display_dev); |
140 | return true; |
141 | } |
142 | } |
143 | |
144 | return false; |
145 | } |
146 | |
147 | /** |
148 | * snd_hdac_i915_init - Initialize i915 audio component |
149 | * @bus: HDA core bus |
150 | * |
151 | * This function is supposed to be used only by a HD-audio controller |
152 | * driver that needs the interaction with i915 graphics. |
153 | * |
154 | * This function initializes and sets up the audio component to communicate |
155 | * with i915 graphics driver. |
156 | * |
157 | * Returns zero for success or a negative error code. |
158 | */ |
159 | int snd_hdac_i915_init(struct hdac_bus *bus) |
160 | { |
161 | struct drm_audio_component *acomp; |
162 | int err; |
163 | |
164 | if (!i915_gfx_present(to_pci_dev(bus->dev))) |
165 | return -ENODEV; |
166 | |
167 | err = snd_hdac_acomp_init(bus, NULL, |
168 | match_master: i915_component_master_match, |
169 | extra_size: sizeof(struct i915_audio_component) - sizeof(*acomp)); |
170 | if (err < 0) |
171 | return err; |
172 | acomp = bus->audio_component; |
173 | if (!acomp) |
174 | return -ENODEV; |
175 | if (!acomp->ops) { |
176 | snd_hdac_acomp_exit(bus); |
177 | return dev_err_probe(dev: bus->dev, err: -EPROBE_DEFER, |
178 | fmt: "couldn't bind with audio component\n" ); |
179 | } |
180 | return 0; |
181 | } |
182 | EXPORT_SYMBOL_GPL(snd_hdac_i915_init); |
183 | |