Kernel: Allow higher audio sample rates than 65kHZ (u16)

Executing `asctl set r 96000` no longer results in weird sample rates
being set on the audio devices. SB16 checks for a sample rate between 1
and 44100 Hz, while AC97 implements double-rate support which allows
sample rates between 8kHz and 96kHZ.

Kernel/Devices/Audio/AC97.cpp

@@ -13,6 +13,10 @@ namespace Kernel {
 
 static constexpr int buffer_descriptor_list_max_entries = 32;
 
+// Valid output range - with double-rate enabled, sample rate can go up to 96kHZ
+static constexpr u16 pcm_sample_rate_minimum = 8000;
+static constexpr u16 pcm_sample_rate_maximum = 48000;
+
 static ErrorOr<OwnPtr<Memory::Region>> allocate_physical_buffer(size_t size, StringView name)
 {
     auto vmobject = TRY(Memory::AnonymousVMObject::try_create_physically_contiguous_with_size(Memory::page_round_up(size)));
@@ -92,22 +96,31 @@ UNMAP_AFTER_INIT void AC97::initialize()
     auto control = m_io_bus_base.offset(NativeAudioBusRegister::GlobalControl).in<u32>();
     control |= GlobalControlFlag::GPIInterruptEnable;
     control |= GlobalControlFlag::AC97ColdReset;
-    m_io_bus_base.offset(NativeAudioBusRegister::GlobalControl).out<u32>(control);
+    m_io_bus_base.offset(NativeAudioBusRegister::GlobalControl).out(control);
 
     // Reset mixer
     m_io_mixer_base.offset(NativeAudioMixerRegister::Reset).out<u16>(1);
 
     // Verify extended capabilities
     auto extended_audio_id = m_io_mixer_base.offset(NativeAudioMixerRegister::ExtendedAudioID).in<u16>();
-    VERIFY((extended_audio_id & ExtendedAudioMask::VariableRatePCMAudio) == 1);
+    VERIFY((extended_audio_id & ExtendedAudioMask::VariableRatePCMAudio) > 0);
     VERIFY((extended_audio_id & ExtendedAudioMask::Revision) >> 10 == AC97Revision::Revision23);
 
+    // Enable double rate PCM audio if supported
+    if ((extended_audio_id & ExtendedAudioMask::DoubleRatePCMAudio) > 0) {
+        auto extended_audio_status_control_register = m_io_mixer_base.offset(NativeAudioMixerRegister::ExtendedAudioStatusControl);
+        auto extended_audio_status = extended_audio_status_control_register.in<u16>();
+        extended_audio_status |= ExtendedAudioStatusControlFlag::DoubleRateAudio;
+        extended_audio_status_control_register.out(extended_audio_status);
+        m_double_rate_pcm_enabled = true;
+    }
+
+    MUST(set_pcm_output_sample_rate(m_sample_rate));
+
     // Left and right volume of 0 means attenuation of 0 dB
     set_master_output_volume(0, 0, Muted::No);
     set_pcm_output_volume(0, 0, Muted::No);
 
-    set_pcm_output_sample_rate(m_sample_rate);
-
     reset_pcm_out();
     enable_irq();
 }
@@ -116,15 +129,14 @@ ErrorOr<void> AC97::ioctl(OpenFileDescription&, unsigned request, Userspace<void
 {
     switch (request) {
     case SOUNDCARD_IOCTL_GET_SAMPLE_RATE: {
-        auto output = static_ptr_cast<u16*>(arg);
+        auto output = static_ptr_cast<u32*>(arg);
         return copy_to_user(output, &m_sample_rate);
     }
     case SOUNDCARD_IOCTL_SET_SAMPLE_RATE: {
-        auto sample_rate_value = static_cast<u16>(arg.ptr());
+        auto sample_rate = static_cast<u32>(arg.ptr());
-        if (sample_rate_value == 0)
+        if (sample_rate == m_sample_rate)
-            return EINVAL;
+            return {};
-        if (m_sample_rate != sample_rate_value)
+        TRY(set_pcm_output_sample_rate(sample_rate));
-            set_pcm_output_sample_rate(sample_rate_value);
         return {};
     }
     default:
@@ -151,12 +163,20 @@ void AC97::set_master_output_volume(u8 left_channel, u8 right_channel, Muted mut
     m_io_mixer_base.offset(NativeAudioMixerRegister::SetMasterOutputVolume).out(volume_value);
 }
 
-void AC97::set_pcm_output_sample_rate(u16 sample_rate)
+ErrorOr<void> AC97::set_pcm_output_sample_rate(u32 sample_rate)
 {
+    auto const double_rate_shift = m_double_rate_pcm_enabled ? 1 : 0;
+    auto shifted_sample_rate = sample_rate >> double_rate_shift;
+    if (shifted_sample_rate < pcm_sample_rate_minimum || shifted_sample_rate > pcm_sample_rate_maximum)
+        return ENOTSUP;
+
     auto pcm_front_dac_rate_register = m_io_mixer_base.offset(NativeAudioMixerRegister::PCMFrontDACRate);
-    pcm_front_dac_rate_register.out(sample_rate);
+    pcm_front_dac_rate_register.out<u16>(shifted_sample_rate);
-    m_sample_rate = pcm_front_dac_rate_register.in<u16>();
+    m_sample_rate = static_cast<u32>(pcm_front_dac_rate_register.in<u16>()) << double_rate_shift;
+
     dbgln("AC97 @ {}: PCM front DAC rate set to {} Hz", pci_address(), m_sample_rate);
+
+    return {};
 }
 
 void AC97::set_pcm_output_volume(u8 left_channel, u8 right_channel, Muted mute)

Kernel/Devices/Audio/AC97.h

@@ -43,14 +43,20 @@ private:
         SetMasterOutputVolume = 0x02,
         SetPCMOutputVolume = 0x18,
         ExtendedAudioID = 0x28,
+        ExtendedAudioStatusControl = 0x2a,
         PCMFrontDACRate = 0x2c,
     };
 
     enum ExtendedAudioMask : u16 {
         VariableRatePCMAudio = 1 << 0,
+        DoubleRatePCMAudio = 1 << 1,
         Revision = 3 << 10,
     };
 
+    enum ExtendedAudioStatusControlFlag : u16 {
+        DoubleRateAudio = 1 << 1,
+    };
+
     enum AC97Revision : u8 {
         Revision21OrEarlier = 0b00,
         Revision22 = 0b01,
@@ -150,12 +156,13 @@ private:
     void initialize();
     void reset_pcm_out();
     void set_master_output_volume(u8, u8, Muted);
-    void set_pcm_output_sample_rate(u16);
+    ErrorOr<void> set_pcm_output_sample_rate(u32);
     void set_pcm_output_volume(u8, u8, Muted);
     ErrorOr<void> write_single_buffer(UserOrKernelBuffer const&, size_t, size_t);
 
     OwnPtr<Memory::Region> m_buffer_descriptor_list;
     u8 m_buffer_descriptor_list_index = 0;
+    bool m_double_rate_pcm_enabled = false;
     IOAddress m_io_mixer_base;
     IOAddress m_io_bus_base;
     WaitQueue m_irq_queue;
@@ -163,7 +170,7 @@ private:
     u8 m_output_buffer_page_count = 4;
     u8 m_output_buffer_page_index = 0;
     AC97Channel m_pcm_out_channel;
-    u16 m_sample_rate = 44100;
+    u32 m_sample_rate = 44100;
 };
 
 }

Kernel/Devices/Audio/SB16.cpp

@@ -123,9 +123,10 @@ ErrorOr<void> SB16::ioctl(OpenFileDescription&, unsigned request, Userspace<void
         return copy_to_user(output, &m_sample_rate);
     }
     case SOUNDCARD_IOCTL_SET_SAMPLE_RATE: {
-        auto sample_rate_value = static_cast<u16>(arg.ptr());
+        auto sample_rate_input = static_cast<u32>(arg.ptr());
-        if (sample_rate_value == 0)
+        if (sample_rate_input == 0 || sample_rate_input > 44100)
-            return EINVAL;
+            return ENOTSUP;
+        auto sample_rate_value = static_cast<u16>(sample_rate_input);
         if (m_sample_rate != sample_rate_value)
             set_sample_rate(sample_rate_value);
         return {};

Userland/Services/AudioServer/AudioServer.ipc

@@ -11,8 +11,8 @@ endpoint AudioServer
     set_self_volume(double volume) => ()
 
     // Audio device
-    set_sample_rate(u16 sample_rate) => ()
+    set_sample_rate(u32 sample_rate) => ()
-    get_sample_rate() => (u16 sample_rate)
+    get_sample_rate() => (u32 sample_rate)
 
     // Buffer playback
     enqueue_buffer(Core::AnonymousBuffer buffer, i32 buffer_id, int sample_count) => (bool success)

Userland/Services/AudioServer/ClientConnection.cpp

@@ -73,7 +73,7 @@ Messages::AudioServer::GetSampleRateResponse ClientConnection::get_sample_rate()
     return { m_mixer.audiodevice_get_sample_rate() };
 }
 
-void ClientConnection::set_sample_rate(u16 sample_rate)
+void ClientConnection::set_sample_rate(u32 sample_rate)
 {
     m_mixer.audiodevice_set_sample_rate(sample_rate);
 }

Userland/Services/AudioServer/ClientConnection.h

@@ -49,7 +49,7 @@ private:
     virtual Messages::AudioServer::GetPlayingBufferResponse get_playing_buffer() override;
     virtual Messages::AudioServer::GetMutedResponse get_muted() override;
     virtual void set_muted(bool) override;
-    virtual void set_sample_rate(u16 sample_rate) override;
+    virtual void set_sample_rate(u32 sample_rate) override;
     virtual Messages::AudioServer::GetSampleRateResponse get_sample_rate() override;
 
     Mixer& m_mixer;

Userland/Services/AudioServer/Mixer.cpp

@@ -165,7 +165,7 @@ void Mixer::set_muted(bool muted)
     });
 }
 
-int Mixer::audiodevice_set_sample_rate(u16 sample_rate)
+int Mixer::audiodevice_set_sample_rate(u32 sample_rate)
 {
     int code = ioctl(m_device->fd(), SOUNDCARD_IOCTL_SET_SAMPLE_RATE, sample_rate);
     if (code != 0)
@@ -173,9 +173,9 @@ int Mixer::audiodevice_set_sample_rate(u16 sample_rate)
     return code;
 }
 
-u16 Mixer::audiodevice_get_sample_rate() const
+u32 Mixer::audiodevice_get_sample_rate() const
 {
-    u16 sample_rate = 0;
+    u32 sample_rate = 0;
     int code = ioctl(m_device->fd(), SOUNDCARD_IOCTL_GET_SAMPLE_RATE, &sample_rate);
     if (code != 0)
         dbgln("Error while getting sample rate: ioctl error: {}", strerror(errno));

Userland/Services/AudioServer/Mixer.h

@@ -119,8 +119,8 @@ public:
     bool is_muted() const { return m_muted; }
     void set_muted(bool);
 
-    int audiodevice_set_sample_rate(u16 sample_rate);
+    int audiodevice_set_sample_rate(u32 sample_rate);
-    u16 audiodevice_get_sample_rate() const;
+    u32 audiodevice_get_sample_rate() const;
 
 private:
     Mixer(NonnullRefPtr<Core::ConfigFile> config);

Userland/Utilities/asctl.cpp

@@ -81,7 +81,7 @@ int main(int argc, char** argv)
                 break;
             }
             case AudioVariable::SampleRate: {
-                u16 sample_rate = audio_client->get_sample_rate();
+                u32 sample_rate = audio_client->get_sample_rate();
                 if (human_mode)
                     outln("Sample rate: {:5d} Hz", sample_rate);
                 else