soc: apple: Add SEP driver.

This is a co-processor in charge of various security-related
features on Apple SoCs. This driver only boots the firmware,
which is needed to unlock the mic secure disable on certain
laptop models.

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>

Author: WhatAmISupposedToPutHere

drivers/soc/apple/Kconfig

@@ -58,6 +58,18 @@ config APPLE_AOP
 
 	  Say 'y' here if you have an Apple laptop.
 
+config APPLE_SEP
+	tristate "Apple Secure Element Processor"
+	depends on ARCH_APPLE || COMPILE_TEST
+	depends on RUST
+	select RUST_APPLE_RTKIT
+	default y if ARCH_APPLE
+	help
+	  A security co-processor persent on Apple SoCs, controlling transparent
+	  disk encryption, secure boot, HDCP, biometric auth and probably more.
+
+	  Say 'y' here if you have an Apple SoC.
+
 endmenu
 
 endif

drivers/soc/apple/Makefile

@@ -10,3 +10,5 @@ obj-$(CONFIG_APPLE_SART) += apple-sart.o
 apple-sart-y = sart.o
 
 obj-$(CONFIG_APPLE_AOP) += aop.o
+
+obj-$(CONFIG_APPLE_SEP) += sep.o

drivers/soc/apple/sep.rs

@@ -0,0 +1,344 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+#![recursion_limit = "2048"]
+
+//! Apple SEP driver
+//!
+//! Copyright (C) The Asahi Linux Contributors
+
+use core::sync::atomic::{AtomicBool, Ordering};
+
+use kernel::{
+    bindings, c_str, device, dma, module_platform_driver, new_mutex, of, platform,
+    prelude::*,
+    soc::apple::mailbox::{MailCallback, Mailbox, Message},
+    sync::{Arc, Mutex},
+    types::{ARef, ForeignOwnable},
+    workqueue::{self, impl_has_work, new_work, Work, WorkItem},
+};
+
+const SHMEM_SIZE: usize = 0x30000;
+const MSG_BOOT_TZ0: u64 = 0x5;
+const MSG_BOOT_IMG4: u64 = 0x6;
+const MSG_SET_SHMEM: u64 = 0x18;
+const MSG_BOOT_TZ0_ACK1: u64 = 0x69;
+const MSG_BOOT_TZ0_ACK2: u64 = 0xD2;
+const MSG_BOOT_IMG4_ACK: u64 = 0x6A;
+const MSG_ADVERTISE_EP: u64 = 0;
+const EP_DISCOVER: u64 = 0xFD;
+const EP_SHMEM: u64 = 0xFE;
+const EP_BOOT: u64 = 0xFF;
+
+const MSG_TYPE_SHIFT: u32 = 16;
+const MSG_TYPE_MASK: u64 = 0xFF;
+//const MSG_PARAM_SHIFT: u32 = 24;
+//const MSG_PARAM_MASK: u64 = 0xFF;
+
+const MSG_EP_MASK: u64 = 0xFF;
+const MSG_DATA_SHIFT: u32 = 32;
+
+const IOVA_SHIFT: u32 = 0xC;
+
+type ShMem = dma::CoherentAllocation<u8>;
+
+fn align_up(v: usize, a: usize) -> usize {
+    (v + a - 1) & !(a - 1)
+}
+
+fn memcpy_to_iomem(iomem: &ShMem, off: usize, src: &[u8]) -> Result<()> {
+    // SAFETY:
+    // as_slice_mut() checks that off and src.len() are whithin iomem's limits.
+    // memcpy_to_iomem is only called from within probe() ansuring there are no
+    // concurrent read and write accesses to the same region while the slice is
+    // alive per as_slice_mut()'s requiremnts.
+    unsafe {
+        let target = iomem.as_slice_mut(off, src.len())?;
+        target.copy_from_slice(src);
+    }
+    Ok(())
+}
+
+fn build_shmem(dev: &platform::Device) -> Result<ShMem> {
+    let of = dev.as_ref().of_node().ok_or(EIO)?;
+    let iomem = dma::CoherentAllocation::<u8>::alloc_coherent(dev, SHMEM_SIZE, GFP_KERNEL)?;
+
+    let panic_offset = 0x4000;
+    let panic_size = 0x8000;
+    memcpy_to_iomem(&iomem, panic_offset, &1u32.to_le_bytes())?;
+
+    let lpol_offset = panic_offset + panic_size;
+    let lpol = of
+        .find_property(c_str!("local-policy-manifest"))
+        .ok_or(EIO)?;
+    memcpy_to_iomem(
+        &iomem,
+        lpol_offset,
+        &(lpol.value().len() as u32).to_le_bytes(),
+    )?;
+    memcpy_to_iomem(&iomem, lpol_offset + 4, lpol.value())?;
+    let lpol_size = align_up(lpol.value().len() + 4, 0x4000);
+
+    let ibot_offset = lpol_offset + lpol_size;
+    let ibot = of.find_property(c_str!("iboot-manifest")).ok_or(EIO)?;
+    memcpy_to_iomem(
+        &iomem,
+        ibot_offset,
+        &(ibot.value().len() as u32).to_le_bytes(),
+    )?;
+    memcpy_to_iomem(&iomem, ibot_offset + 4, ibot.value())?;
+    let ibot_size = align_up(ibot.value().len() + 4, 0x4000);
+
+    memcpy_to_iomem(&iomem, 0, b"CNIP")?;
+    memcpy_to_iomem(&iomem, 4, &(panic_size as u32).to_le_bytes())?;
+    memcpy_to_iomem(&iomem, 8, &(panic_offset as u32).to_le_bytes())?;
+
+    memcpy_to_iomem(&iomem, 16, b"OPLA")?;
+    memcpy_to_iomem(&iomem, 16 + 4, &(lpol_size as u32).to_le_bytes())?;
+    memcpy_to_iomem(&iomem, 16 + 8, &(lpol_offset as u32).to_le_bytes())?;
+
+    memcpy_to_iomem(&iomem, 32, b"IPIS")?;
+    memcpy_to_iomem(&iomem, 32 + 4, &(ibot_size as u32).to_le_bytes())?;
+    memcpy_to_iomem(&iomem, 32 + 8, &(ibot_offset as u32).to_le_bytes())?;
+
+    memcpy_to_iomem(&iomem, 48, b"llun")?;
+    Ok(iomem)
+}
+
+#[pin_data]
+struct SepReceiveWork {
+    data: Arc<SepData>,
+    msg: Message,
+    #[pin]
+    work: Work<SepReceiveWork>,
+}
+
+impl_has_work! {
+    impl HasWork<Self, 0> for SepReceiveWork { self.work }
+}
+
+impl SepReceiveWork {
+    fn new(data: Arc<SepData>, msg: Message) -> Result<Arc<Self>> {
+        Arc::pin_init(
+            pin_init!(SepReceiveWork {
+                data,
+                msg,
+                work <- new_work!("SepReceiveWork::work"),
+            }),
+            GFP_ATOMIC,
+        )
+    }
+}
+
+impl WorkItem for SepReceiveWork {
+    type Pointer = Arc<SepReceiveWork>;
+
+    fn run(this: Arc<SepReceiveWork>) {
+        this.data.process_message(this.msg);
+    }
+}
+
+struct FwRegionParams {
+    addr: u64,
+    size: usize,
+}
+
+#[pin_data]
+struct SepData {
+    dev: ARef<device::Device>,
+    #[pin]
+    mbox: Mutex<Option<Mailbox<SepData>>>,
+    shmem: ShMem,
+    region_params: FwRegionParams,
+    fw_mapped: AtomicBool,
+}
+
+impl SepData {
+    fn new(dev: &platform::Device, region_params: FwRegionParams) -> Result<Arc<SepData>> {
+        Arc::pin_init(
+            try_pin_init!(SepData {
+                shmem: build_shmem(dev)?,
+                dev: ARef::<device::Device>::from(dev.as_ref()),
+                mbox <- new_mutex!(None),
+                region_params,
+                fw_mapped: AtomicBool::new(false),
+            }),
+            GFP_KERNEL,
+        )
+    }
+    fn start(&self) -> Result<()> {
+        self.mbox.lock().as_ref().unwrap().send(
+            Message {
+                msg0: EP_BOOT | (MSG_BOOT_TZ0 << MSG_TYPE_SHIFT),
+                msg1: 0,
+            },
+            false,
+        )
+    }
+    fn load_fw_and_shmem(&self) -> Result<()> {
+        let fw_addr = unsafe {
+            let res = bindings::dma_map_resource(
+                self.dev.as_raw(),
+                self.region_params.addr,
+                self.region_params.size,
+                bindings::dma_data_direction_DMA_TO_DEVICE,
+                0,
+            );
+            if bindings::dma_mapping_error(self.dev.as_raw(), res) != 0 {
+                dev_err!(self.dev, "Failed to map firmware");
+                return Err(ENOMEM);
+            }
+            self.fw_mapped.store(true, Ordering::Relaxed);
+            res >> IOVA_SHIFT
+        };
+        let guard = self.mbox.lock();
+        let mbox = guard.as_ref().unwrap();
+        mbox.send(
+            Message {
+                msg0: EP_BOOT | (MSG_BOOT_IMG4 << MSG_TYPE_SHIFT) | (fw_addr << MSG_DATA_SHIFT),
+                msg1: 0,
+            },
+            false,
+        )?;
+        let shm_addr = self.shmem.dma_handle() >> IOVA_SHIFT;
+        mbox.send(
+            Message {
+                msg0: EP_SHMEM | (MSG_SET_SHMEM << MSG_TYPE_SHIFT) | (shm_addr << MSG_DATA_SHIFT),
+                msg1: 0,
+            },
+            false,
+        )?;
+        Ok(())
+    }
+    fn process_boot_msg(&self, msg: Message) {
+        let ty = (msg.msg0 >> MSG_TYPE_SHIFT) & MSG_TYPE_MASK;
+        match ty {
+            MSG_BOOT_TZ0_ACK1 => {}
+            MSG_BOOT_TZ0_ACK2 => {
+                let res = self.load_fw_and_shmem();
+                if let Err(e) = res {
+                    dev_err!(self.dev, "Unable to load firmware: {:?}", e);
+                }
+            }
+            MSG_BOOT_IMG4_ACK => {}
+            _ => {
+                dev_err!(self.dev, "Unknown boot message type: {}", ty);
+            }
+        }
+    }
+    fn process_discover_msg(&self, msg: Message) {
+        let ty = (msg.msg0 >> MSG_TYPE_SHIFT) & MSG_TYPE_MASK;
+        //let data = (msg.msg0 >> MSG_DATA_SHIFT) as u32;
+        //let param = (msg.msg0 >> MSG_PARAM_SHIFT) & MSG_PARAM_MASK;
+        match ty {
+            MSG_ADVERTISE_EP => {
+                /*dev_info!(
+                    self.dev,
+                    "Got endpoint {:?} at {}",
+                    core::str::from_utf8(&data.to_be_bytes()),
+                    param
+                );*/
+            }
+            _ => {
+                //dev_warn!(self.dev, "Unknown discovery message type: {}", ty);
+            }
+        }
+    }
+    fn process_message(&self, msg: Message) {
+        let ep = msg.msg0 & MSG_EP_MASK;
+        match ep {
+            EP_BOOT => self.process_boot_msg(msg),
+            EP_DISCOVER => self.process_discover_msg(msg),
+            _ => {} // dev_warn!(self.dev, "Message from unknown endpoint: {}", ep),
+        }
+    }
+    fn remove(&self) {
+        *self.mbox.lock() = None;
+        if self.fw_mapped.load(Ordering::Relaxed) {
+            unsafe {
+                bindings::dma_unmap_resource(
+                    self.dev.as_raw(),
+                    self.region_params.addr,
+                    self.region_params.size,
+                    bindings::dma_data_direction_DMA_TO_DEVICE,
+                    0,
+                );
+            }
+        }
+    }
+}
+
+impl MailCallback for SepData {
+    type Data = Arc<SepData>;
+    fn recv_message(data: <Self::Data as ForeignOwnable>::Borrowed<'_>, msg: Message) {
+        let work = SepReceiveWork::new(data.into(), msg);
+        if let Ok(work) = work {
+            let res = workqueue::system().enqueue(work);
+            if res.is_err() {
+                dev_err!(
+                    data.dev,
+                    "Unable to schedule work item for message {}",
+                    msg.msg0
+                );
+            }
+        } else {
+            dev_err!(
+                data.dev,
+                "Unable to allocate work item for message {}",
+                msg.msg0
+            );
+        }
+    }
+}
+
+unsafe impl Send for SepData {}
+unsafe impl Sync for SepData {}
+
+struct SepDriver(Arc<SepData>);
+
+kernel::of_device_table!(
+    OF_TABLE,
+    MODULE_OF_TABLE,
+    (),
+    [(of::DeviceId::new(c_str!("apple,sep")), ())]
+);
+
+impl platform::Driver for SepDriver {
+    type IdInfo = ();
+
+    const OF_ID_TABLE: Option<of::IdTable<()>> = Some(&OF_TABLE);
+
+    fn probe(pdev: &mut platform::Device, _info: Option<&()>) -> Result<Pin<KBox<SepDriver>>> {
+        let of = pdev.as_ref().of_node().ok_or(EIO)?;
+        let fw_node = of.parse_phandle(c_str!("memory-region"), 0).ok_or(EIO)?;
+        let mut reg = [0u64, 0u64];
+        fw_node
+            .find_property(c_str!("reg"))
+            .ok_or(EIO)?
+            .copy_to_slice(&mut reg)?;
+        let data = SepData::new(
+            pdev,
+            FwRegionParams {
+                addr: reg[0],
+                size: reg[1] as usize,
+            },
+        )?;
+        *data.mbox.lock() = Some(Mailbox::new_byname(
+            pdev.as_ref(),
+            c_str!("mbox"),
+            data.clone(),
+        )?);
+        data.start()?;
+        Ok(KBox::pin(SepDriver(data), GFP_KERNEL)?)
+    }
+}
+
+impl Drop for SepDriver {
+    fn drop(&mut self) {
+        self.0.remove();
+    }
+}
+
+module_platform_driver! {
+    type: SepDriver,
+    name: "apple_sep",
+    license: "Dual MIT/GPL",
+}