1 files changed, 262 insertions, 0 deletions
diff --git a/drivers/block/rnull/configfs.rs b/drivers/block/rnull/configfs.rs
new file mode 100644
index 000000000000..8498e9bae6fd
--- /dev/null
+++ b/drivers/block/rnull/configfs.rs
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use super::{NullBlkDevice, THIS_MODULE};
+use core::fmt::{Display, Write};
+use kernel::{
+    block::mq::gen_disk::{GenDisk, GenDiskBuilder},
+    c_str,
+    configfs::{self, AttributeOperations},
+    configfs_attrs, new_mutex,
+    page::PAGE_SIZE,
+    prelude::*,
+    str::{kstrtobool_bytes, CString},
+    sync::Mutex,
+};
+use pin_init::PinInit;
+
+pub(crate) fn subsystem() -> impl PinInit<kernel::configfs::Subsystem<Config>, Error> {
+    let item_type = configfs_attrs! {
+        container: configfs::Subsystem<Config>,
+        data: Config,
+        child: DeviceConfig,
+        attributes: [
+            features: 0,
+        ],
+    };
+
+    kernel::configfs::Subsystem::new(c_str!("rnull"), item_type, try_pin_init!(Config {}))
+}
+
+#[pin_data]
+pub(crate) struct Config {}
+
+#[vtable]
+impl AttributeOperations<0> for Config {
+    type Data = Config;
+
+    fn show(_this: &Config, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+        let mut writer = kernel::str::Formatter::new(page);
+        writer.write_str("blocksize,size,rotational,irqmode\n")?;
+        Ok(writer.bytes_written())
+    }
+}
+
+#[vtable]
+impl configfs::GroupOperations for Config {
+    type Child = DeviceConfig;
+
+    fn make_group(
+        &self,
+        name: &CStr,
+    ) -> Result<impl PinInit<configfs::Group<DeviceConfig>, Error>> {
+        let item_type = configfs_attrs! {
+            container: configfs::Group<DeviceConfig>,
+            data: DeviceConfig,
+            attributes: [
+                // Named for compatibility with C null_blk
+                power: 0,
+                blocksize: 1,
+                rotational: 2,
+                size: 3,
+                irqmode: 4,
+            ],
+        };
+
+        Ok(configfs::Group::new(
+            name.try_into()?,
+            item_type,
+            // TODO: cannot coerce new_mutex!() to impl PinInit<_, Error>, so put mutex inside
+            try_pin_init!( DeviceConfig {
+                data <- new_mutex!(DeviceConfigInner {
+                    powered: false,
+                    block_size: 4096,
+                    rotational: false,
+                    disk: None,
+                    capacity_mib: 4096,
+                    irq_mode: IRQMode::None,
+                    name: name.try_into()?,
+                }),
+            }),
+        ))
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub(crate) enum IRQMode {
+    None,
+    Soft,
+}
+
+impl TryFrom<u8> for IRQMode {
+    type Error = kernel::error::Error;
+
+    fn try_from(value: u8) -> Result<Self> {
+        match value {
+            0 => Ok(Self::None),
+            1 => Ok(Self::Soft),
+            _ => Err(EINVAL),
+        }
+    }
+}
+
+impl Display for IRQMode {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        match self {
+            Self::None => f.write_str("0")?,
+            Self::Soft => f.write_str("1")?,
+        }
+        Ok(())
+    }
+}
+
+#[pin_data]
+pub(crate) struct DeviceConfig {
+    #[pin]
+    data: Mutex<DeviceConfigInner>,
+}
+
+#[pin_data]
+struct DeviceConfigInner {
+    powered: bool,
+    name: CString,
+    block_size: u32,
+    rotational: bool,
+    capacity_mib: u64,
+    irq_mode: IRQMode,
+    disk: Option<GenDisk<NullBlkDevice>>,
+}
+
+#[vtable]
+impl configfs::AttributeOperations<0> for DeviceConfig {
+    type Data = DeviceConfig;
+
+    fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+        let mut writer = kernel::str::Formatter::new(page);
+
+        if this.data.lock().powered {
+            writer.write_str("1\n")?;
+        } else {
+            writer.write_str("0\n")?;
+        }
+
+        Ok(writer.bytes_written())
+    }
+
+    fn store(this: &DeviceConfig, page: &[u8]) -> Result {
+        let power_op = kstrtobool_bytes(page)?;
+        let mut guard = this.data.lock();
+
+        if !guard.powered && power_op {
+            guard.disk = Some(NullBlkDevice::new(
+                &guard.name,
+                guard.block_size,
+                guard.rotational,
+                guard.capacity_mib,
+                guard.irq_mode,
+            )?);
+            guard.powered = true;
+        } else if guard.powered && !power_op {
+            drop(guard.disk.take());
+            guard.powered = false;
+        }
+
+        Ok(())
+    }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<1> for DeviceConfig {
+    type Data = DeviceConfig;
+
+    fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+        let mut writer = kernel::str::Formatter::new(page);
+        writer.write_fmt(fmt!("{}\n", this.data.lock().block_size))?;
+        Ok(writer.bytes_written())
+    }
+
+    fn store(this: &DeviceConfig, page: &[u8]) -> Result {
+        if this.data.lock().powered {
+            return Err(EBUSY);
+        }
+
+        let text = core::str::from_utf8(page)?.trim();
+        let value = text.parse::<u32>().map_err(|_| EINVAL)?;
+
+        GenDiskBuilder::validate_block_size(value)?;
+        this.data.lock().block_size = value;
+        Ok(())
+    }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<2> for DeviceConfig {
+    type Data = DeviceConfig;
+
+    fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+        let mut writer = kernel::str::Formatter::new(page);
+
+        if this.data.lock().rotational {
+            writer.write_str("1\n")?;
+        } else {
+            writer.write_str("0\n")?;
+        }
+
+        Ok(writer.bytes_written())
+    }
+
+    fn store(this: &DeviceConfig, page: &[u8]) -> Result {
+        if this.data.lock().powered {
+            return Err(EBUSY);
+        }
+
+        this.data.lock().rotational = kstrtobool_bytes(page)?;
+
+        Ok(())
+    }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<3> for DeviceConfig {
+    type Data = DeviceConfig;
+
+    fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+        let mut writer = kernel::str::Formatter::new(page);
+        writer.write_fmt(fmt!("{}\n", this.data.lock().capacity_mib))?;
+        Ok(writer.bytes_written())
+    }
+
+    fn store(this: &DeviceConfig, page: &[u8]) -> Result {
+        if this.data.lock().powered {
+            return Err(EBUSY);
+        }
+
+        let text = core::str::from_utf8(page)?.trim();
+        let value = text.parse::<u64>().map_err(|_| EINVAL)?;
+
+        this.data.lock().capacity_mib = value;
+        Ok(())
+    }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<4> for DeviceConfig {
+    type Data = DeviceConfig;
+
+    fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+        let mut writer = kernel::str::Formatter::new(page);
+        writer.write_fmt(fmt!("{}\n", this.data.lock().irq_mode))?;
+        Ok(writer.bytes_written())
+    }
+
+    fn store(this: &DeviceConfig, page: &[u8]) -> Result {
+        if this.data.lock().powered {
+            return Err(EBUSY);
+        }
+
+        let text = core::str::from_utf8(page)?.trim();
+        let value = text.parse::<u8>().map_err(|_| EINVAL)?;
+
+        this.data.lock().irq_mode = IRQMode::try_from(value)?;
+        Ok(())
+    }
+}