// 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>
#include <video/nomodeset.h>

static int gpu_bind = -1;
module_param(gpu_bind, int, 0644);
MODULE_PARM_DESC(gpu_bind, "Whether to bind sound component to GPU "
                           "(1=always, 0=never, -1=on nomodeset(default))");

/**
 * 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") ||
                 !strcmp(dev->driver->name, "xe")) &&
            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)
{
        /* List of known platforms with no i915 support. */
        static const struct pci_device_id denylist[] = {
                /* CNL */
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a40), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a41), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a42), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a44), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a49), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a4a), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a4c), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a50), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a51), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a52), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a54), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a59), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a5a), 0x030000, 0xff0000 },
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x5a5c), 0x030000, 0xff0000 },
                /* LKF */
                { PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x9840), 0x030000, 0xff0000 },
                {}
        };
        struct pci_dev *display_dev = NULL;

        if (!gpu_bind || (gpu_bind < 0 && video_firmware_drivers_only()))
                return false;

        for_each_pci_dev(display_dev) {
                if (display_dev->vendor != PCI_VENDOR_ID_INTEL ||
                    !pci_is_display(display_dev))
                        continue;

                if (pci_match_id(denylist, display_dev))
                        continue;

                if (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) {
                snd_hdac_acomp_exit(bus);
                return dev_err_probe(bus->dev, -EPROBE_DEFER,
                                     "couldn't bind with audio component\n");
        }
        return 0;
}
EXPORT_SYMBOL_GPL(snd_hdac_i915_init);