Print GPIO pin configuration for humility gpio --input --with-config

Cargo.toml

@@ -257,7 +257,8 @@ thiserror = "1.0"
 toml = "0.5"
 trycmd = "0.13.2"
 winapi = "0.3.9"
-zerocopy = "0.6.1"
+zerocopy = "0.6.6"
+zerocopy-derive = "0.6.6"
 zip = "0.6.4"
 
 [profile.release]

cmd/gpio/Cargo.toml

@@ -9,6 +9,7 @@ hif.workspace = true
 clap.workspace = true
 anyhow.workspace = true
 parse_int.workspace = true
+zerocopy.workspace = true
 
 humility-cli.workspace = true
 humility-cmd.workspace = true

cmd/gpio/src/config_cache.rs

@@ -0,0 +1,63 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+//! Generic cache for GPIO configuration register blocks.
+//!
+//! This module provides a chip-independent way to cache raw GPIO register
+//! block data from device memory. The cache stores raw bytes indexed by
+//! GPIO group identifiers, avoiding repeated memory reads for the same
+//! GPIO port.
+
+use anyhow::Result;
+use humility_cli::ExecutionContext;
+use std::collections::BTreeMap;
+
+/// A generic cache for GPIO configuration register blocks.
+///
+/// This cache stores raw byte data for GPIO register blocks, indexed by
+/// a group identifier (typically a character like 'A', 'B', etc.). The
+/// cache is chip-independent and works with any architecture that organizes
+/// GPIO pins into groups/ports with contiguous register blocks.
+pub struct ConfigCache {
+    cache: BTreeMap<char, Vec<u8>>,
+}
+
+impl ConfigCache {
+    /// Creates a new empty configuration cache.
+    pub fn new() -> ConfigCache {
+        ConfigCache { cache: BTreeMap::new() }
+    }
+
+    /// Gets or fetches the raw register block data for a GPIO group.
+    ///
+    /// If the data for the specified group is already cached, returns it
+    /// directly. Otherwise, calls the provided `fetch_fn` to read the data
+    /// from device memory, caches it, and returns it.
+    ///
+    /// # Arguments
+    ///
+    /// * `context` - Execution context with access to the device core
+    /// * `group` - GPIO group identifier (e.g., 'A', 'B', 'C')
+    /// * `fetch_fn` - Function that fetches the register block from device memory
+    ///
+    /// # Returns
+    ///
+    /// A reference to the cached raw register block data
+    pub fn get_or_fetch<F>(
+        &mut self,
+        context: &mut ExecutionContext,
+        group: char,
+        fetch_fn: F,
+    ) -> Result<&[u8]>
+    where
+        F: FnOnce(&mut ExecutionContext, char) -> Result<Vec<u8>>,
+    {
+        use std::collections::btree_map::Entry;
+        if let Entry::Vacant(e) = self.cache.entry(group) {
+            let data = fetch_fn(context, group)?;
+            e.insert(data);
+        }
+        Ok(self.cache.get(&group).unwrap().as_slice())
+    }
+}