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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* hdac_i915.c - routines for sync between HD-A core and i915 display driver
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <sound/core.h>
#include <sound/hdaudio.h>
#include <sound/hda_i915.h>
#include <sound/hda_register.h>
/**
* snd_hdac_i915_set_bclk - Reprogram BCLK for HSW/BDW
* @bus: HDA core bus
*
* Intel HSW/BDW display HDA controller is in GPU. Both its power and link BCLK
* depends on GPU. Two Extended Mode registers EM4 (M value) and EM5 (N Value)
* are used to convert CDClk (Core Display Clock) to 24MHz BCLK:
* BCLK = CDCLK * M / N
* The values will be lost when the display power well is disabled and need to
* be restored to avoid abnormal playback speed.
*
* Call this function at initializing and changing power well, as well as
* at ELD notifier for the hotplug.
*/
void snd_hdac_i915_set_bclk(struct hdac_bus *bus)
{
struct drm_audio_component *acomp = bus->audio_component;
struct pci_dev *pci = to_pci_dev(bus->dev);
int cdclk_freq;
unsigned int bclk_m, bclk_n;
if (!acomp || !acomp->ops || !acomp->ops->get_cdclk_freq)
return; /* only for i915 binding */
if (!HDA_CONTROLLER_IS_HSW(pci))
return; /* only HSW/BDW */
cdclk_freq = acomp->ops->get_cdclk_freq(acomp->dev);
switch (cdclk_freq) {
case 337500:
bclk_m = 16;
bclk_n = 225;
break;
case 450000:
default: /* default CDCLK 450MHz */
bclk_m = 4;
bclk_n = 75;
break;
case 540000:
bclk_m = 4;
bclk_n = 90;
break;
case 675000:
bclk_m = 8;
bclk_n = 225;
break;
}
snd_hdac_chip_writew(bus, HSW_EM4, bclk_m);
snd_hdac_chip_writew(bus, HSW_EM5, bclk_n);
}
EXPORT_SYMBOL_GPL(snd_hdac_i915_set_bclk);
/* returns true if the devices can be connected for audio */
static bool connectivity_check(struct pci_dev *i915, struct pci_dev *hdac)
{
struct pci_bus *bus_a = i915->bus, *bus_b = hdac->bus;
/* directly connected on the same bus */
if (bus_a == bus_b)
return true;
bus_a = bus_a->parent;
bus_b = bus_b->parent;
/* connected via parent bus (may be NULL!) */
if (bus_a == bus_b)
return true;
if (!bus_a || !bus_b)
return false;
/*
* on i915 discrete GPUs with embedded HDA audio, the two
* devices are connected via 2nd level PCI bridge
*/
bus_a = bus_a->parent;
bus_b = bus_b->parent;
if (bus_a && bus_a == bus_b)
return true;
return false;
}
static int i915_component_master_match(struct device *dev, int subcomponent,
void *data)
{
struct pci_dev *hdac_pci, *i915_pci;
struct hdac_bus *bus = data;
if (!dev_is_pci(dev))
return 0;
hdac_pci = to_pci_dev(bus->dev);
i915_pci = to_pci_dev(dev);
if (!strcmp(dev->driver->name, "i915") &&
subcomponent == I915_COMPONENT_AUDIO &&
connectivity_check(i915_pci, hdac_pci))
return 1;
return 0;
}
/* check whether Intel graphics is present and reachable */
static int i915_gfx_present(struct pci_dev *hdac_pci)
{
struct pci_dev *display_dev = NULL;
for_each_pci_dev(display_dev) {
if (display_dev->vendor == PCI_VENDOR_ID_INTEL &&
(display_dev->class >> 16) == PCI_BASE_CLASS_DISPLAY &&
connectivity_check(display_dev, hdac_pci)) {
pci_dev_put(display_dev);
return true;
}
}
return false;
}
/**
* snd_hdac_i915_init - Initialize i915 audio component
* @bus: HDA core bus
*
* This function is supposed to be used only by a HD-audio controller
* driver that needs the interaction with i915 graphics.
*
* This function initializes and sets up the audio component to communicate
* with i915 graphics driver.
*
* Returns zero for success or a negative error code.
*/
int snd_hdac_i915_init(struct hdac_bus *bus)
{
struct drm_audio_component *acomp;
int err;
if (!i915_gfx_present(to_pci_dev(bus->dev)))
return -ENODEV;
err = snd_hdac_acomp_init(bus, NULL,
i915_component_master_match,
sizeof(struct i915_audio_component) - sizeof(*acomp));
if (err < 0)
return err;
acomp = bus->audio_component;
if (!acomp)
return -ENODEV;
if (!acomp->ops) {
if (!IS_ENABLED(CONFIG_MODULES) ||
!request_module("i915")) {
/* 60s timeout */
wait_for_completion_killable_timeout(&acomp->master_bind_complete,
msecs_to_jiffies(60 * 1000));
}
}
if (!acomp->ops) {
dev_info(bus->dev, "couldn't bind with audio component\n");
snd_hdac_acomp_exit(bus);
return -ENODEV;
}
return 0;
}
EXPORT_SYMBOL_GPL(snd_hdac_i915_init);
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