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 14 #define IS_HSW_CONTROLLER(pci) (((pci)->device == 0x0a0c) || \ 15 ((pci)->device == 0x0c0c) || \ 16 ((pci)->device == 0x0d0c) || \ 17 ((pci)->device == 0x160c)) 18 19 /** 20 * snd_hdac_i915_set_bclk - Reprogram BCLK for HSW/BDW 21 * @bus: HDA core bus 22 * 23 * Intel HSW/BDW display HDA controller is in GPU. Both its power and link BCLK 24 * depends on GPU. Two Extended Mode registers EM4 (M value) and EM5 (N Value) 25 * are used to convert CDClk (Core Display Clock) to 24MHz BCLK: 26 * BCLK = CDCLK * M / N 27 * The values will be lost when the display power well is disabled and need to 28 * be restored to avoid abnormal playback speed. 29 * 30 * Call this function at initializing and changing power well, as well as 31 * at ELD notifier for the hotplug. 32 */ 33 void snd_hdac_i915_set_bclk(struct hdac_bus *bus) 34 { 35 struct drm_audio_component *acomp = bus->audio_component; 36 struct pci_dev *pci = to_pci_dev(bus->dev); 37 int cdclk_freq; 38 unsigned int bclk_m, bclk_n; 39 40 if (!acomp || !acomp->ops || !acomp->ops->get_cdclk_freq) 41 return; /* only for i915 binding */ 42 if (!IS_HSW_CONTROLLER(pci)) 43 return; /* only HSW/BDW */ 44 45 cdclk_freq = acomp->ops->get_cdclk_freq(acomp->dev); 46 switch (cdclk_freq) { 47 case 337500: 48 bclk_m = 16; 49 bclk_n = 225; 50 break; 51 52 case 450000: 53 default: /* default CDCLK 450MHz */ 54 bclk_m = 4; 55 bclk_n = 75; 56 break; 57 58 case 540000: 59 bclk_m = 4; 60 bclk_n = 90; 61 break; 62 63 case 675000: 64 bclk_m = 8; 65 bclk_n = 225; 66 break; 67 } 68 69 snd_hdac_chip_writew(bus, HSW_EM4, bclk_m); 70 snd_hdac_chip_writew(bus, HSW_EM5, bclk_n); 71 } 72 EXPORT_SYMBOL_GPL(snd_hdac_i915_set_bclk); 73 74 /* returns true if the devices can be connected for audio */ 75 static bool connectivity_check(struct pci_dev *i915, struct pci_dev *hdac) 76 { 77 struct pci_bus *bus_a = i915->bus, *bus_b = hdac->bus; 78 79 /* directly connected on the same bus */ 80 if (bus_a == bus_b) 81 return true; 82 83 /* 84 * on i915 discrete GPUs with embedded HDA audio, the two 85 * devices are connected via 2nd level PCI bridge 86 */ 87 bus_a = bus_a->parent; 88 bus_b = bus_b->parent; 89 if (!bus_a || !bus_b) 90 return false; 91 bus_a = bus_a->parent; 92 bus_b = bus_b->parent; 93 if (bus_a && bus_a == bus_b) 94 return true; 95 96 return false; 97 } 98 99 static int i915_component_master_match(struct device *dev, int subcomponent, 100 void *data) 101 { 102 struct pci_dev *hdac_pci, *i915_pci; 103 struct hdac_bus *bus = data; 104 105 if (!dev_is_pci(dev)) 106 return 0; 107 108 hdac_pci = to_pci_dev(bus->dev); 109 i915_pci = to_pci_dev(dev); 110 111 if (!strcmp(dev->driver->name, "i915") && 112 subcomponent == I915_COMPONENT_AUDIO && 113 connectivity_check(i915_pci, hdac_pci)) 114 return 1; 115 116 return 0; 117 } 118 119 /* check whether Intel graphics is present and reachable */ 120 static int i915_gfx_present(struct pci_dev *hdac_pci) 121 { 122 struct pci_dev *display_dev = NULL; 123 124 for_each_pci_dev(display_dev) { 125 if (display_dev->vendor == PCI_VENDOR_ID_INTEL && 126 (display_dev->class >> 16) == PCI_BASE_CLASS_DISPLAY && 127 connectivity_check(display_dev, hdac_pci)) { 128 pci_dev_put(display_dev); 129 return true; 130 } 131 } 132 133 return false; 134 } 135 136 /** 137 * snd_hdac_i915_init - Initialize i915 audio component 138 * @bus: HDA core bus 139 * 140 * This function is supposed to be used only by a HD-audio controller 141 * driver that needs the interaction with i915 graphics. 142 * 143 * This function initializes and sets up the audio component to communicate 144 * with i915 graphics driver. 145 * 146 * Returns zero for success or a negative error code. 147 */ 148 int snd_hdac_i915_init(struct hdac_bus *bus) 149 { 150 struct drm_audio_component *acomp; 151 int err; 152 153 if (!i915_gfx_present(to_pci_dev(bus->dev))) 154 return -ENODEV; 155 156 err = snd_hdac_acomp_init(bus, NULL, 157 i915_component_master_match, 158 sizeof(struct i915_audio_component) - sizeof(*acomp)); 159 if (err < 0) 160 return err; 161 acomp = bus->audio_component; 162 if (!acomp) 163 return -ENODEV; 164 if (!acomp->ops) { 165 if (!IS_ENABLED(CONFIG_MODULES) || 166 !request_module("i915")) { 167 /* 60s timeout */ 168 wait_for_completion_killable_timeout(&acomp->master_bind_complete, 169 msecs_to_jiffies(60 * 1000)); 170 } 171 } 172 if (!acomp->ops) { 173 dev_info(bus->dev, "couldn't bind with audio component\n"); 174 snd_hdac_acomp_exit(bus); 175 return -ENODEV; 176 } 177 return 0; 178 } 179 EXPORT_SYMBOL_GPL(snd_hdac_i915_init); 180