set fp seed command

This command can only be run once per reboot (I'm pretty sure) so it can be hard to debug. Luckily it worked 1st try for me.

crosec/src/commands/fp_set_seed.rs

@@ -0,0 +1,31 @@
+use std::ffi::c_int;
+
+use bytemuck::{Pod, Zeroable};
+
+use crate::{ec_command::ec_command_bytemuck, EcCmdResult};
+
+use super::CrosEcCmd;
+
+pub const FP_CONTEXT_TPM_BYTES: usize = 32;
+const FP_TEMPLATE_FORMAT_VERSION: u16 = 4;
+
+#[repr(C, align(4))]
+#[derive(Pod, Zeroable, Clone, Copy)]
+struct EcParamsFpSeed {
+    pub struct_version: u16,
+    pub reserved: u16,
+    pub seed: [u8; FP_CONTEXT_TPM_BYTES],
+}
+
+pub fn fp_set_seed(fd: c_int, seed: [u8; FP_CONTEXT_TPM_BYTES]) -> EcCmdResult<()> {
+    ec_command_bytemuck(
+        CrosEcCmd::FpSetSeed,
+        0,
+        &EcParamsFpSeed {
+            struct_version: FP_TEMPLATE_FORMAT_VERSION,
+            reserved: Default::default(),
+            seed,
+        },
+        fd,
+    )
+}

crosec/src/commands/mod.rs

@@ -18,12 +18,14 @@ pub enum CrosEcCmd {
     ConsoleRead = 0x0098,
     FpInfo = 0x0403,
     FpStats = 0x0407,
+    FpSetSeed = 0x0408,
     BatteryGetStatic = 0x0600,
 }
 
 pub mod board_version;
 pub mod charge_control;
 pub mod fp_info;
+pub mod fp_set_seed;
 pub mod fp_stats;
 pub mod get_chip_info;
 pub mod get_cmd_versions;

ectool/src/main.rs

@@ -4,6 +4,7 @@ use std::os::fd::AsRawFd;
 use clap::{Parser, Subcommand, ValueEnum};
 use color_eyre::eyre::Result;
 use crosec::commands::fp_info::fp_info;
+use crosec::commands::fp_set_seed::{fp_set_seed, FP_CONTEXT_TPM_BYTES};
 use crosec::commands::fp_stats::fp_stats;
 use crosec::commands::get_protocol_info::get_protocol_info;
 use num_traits::cast::FromPrimitive;
@@ -92,6 +93,9 @@ enum Commands {
     },
     FpInfo,
     FpStats,
+    FpSetSeed {
+        seed: String,
+    },
 }
 
 #[derive(Subcommand)]
@@ -280,6 +284,22 @@ fn main() -> Result<()> {
             let stats = fp_stats(fd)?;
             println!("{stats:#?}");
         }
+        Commands::FpSetSeed { seed } => {
+            match <Vec<u8> as TryInto<[u8; FP_CONTEXT_TPM_BYTES]>>::try_into(
+                seed.as_bytes().to_owned(),
+            ) {
+                Ok(seed) => {
+                    let file = File::open(CROS_FP_PATH).unwrap();
+                    let fd = file.as_raw_fd();
+                    fp_set_seed(fd, seed)?;
+                    println!("Set fp seed");
+                }
+                Err(seed) => {
+                    let seed_len = seed.len();
+                    println!("The seed must be {FP_CONTEXT_TPM_BYTES} bytes long. The seed you inputted is {seed_len} bytes long.");
+                }
+            }
+        }
     }
 
     Ok(())