From 36d8ffec3b22e065713f272f572e7c249b0fc11e Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Sun, 6 Sep 2020 00:11:19 +0800
Subject: [PATCH] expose i2c to kernels

---
 examples/device_db.py         |  7 +++++++
 src/runtime/src/i2c.rs        | 39 +++++++++++++++++++++++++++++++++++
 src/runtime/src/kernel/api.rs |  8 +++++++
 src/runtime/src/main.rs       |  4 ++++
 4 files changed, 58 insertions(+)
 create mode 100644 src/runtime/src/i2c.rs

diff --git a/examples/device_db.py b/examples/device_db.py
index 105d50f1..c24f5434 100644
--- a/examples/device_db.py
+++ b/examples/device_db.py
@@ -22,6 +22,13 @@ device_db = {
         "module": "artiq.coredevice.dma",
         "class": "CoreDMA"
     },
+
+    "i2c_switch": {
+        "type": "local",
+        "module": "artiq.coredevice.i2c",
+        "class": "PCA9548"
+    },
+
     # led? are common to all variants
     "led0": {
         "type": "local",
diff --git a/src/runtime/src/i2c.rs b/src/runtime/src/i2c.rs
new file mode 100644
index 00000000..fe585905
--- /dev/null
+++ b/src/runtime/src/i2c.rs
@@ -0,0 +1,39 @@
+use libboard_zynq;
+
+static mut I2C_BUS: Option<libboard_zynq::i2c::I2c> = None;
+
+pub extern fn start(_busno: i32) {
+    unsafe {
+        (&mut I2C_BUS).as_mut().unwrap().start().expect("I2C start failed")
+    }
+}
+
+pub extern fn restart(_busno: i32) {
+    unsafe {
+        (&mut I2C_BUS).as_mut().unwrap().restart().expect("I2C restart failed")
+    }
+}
+
+pub extern fn stop(_busno: i32) {
+    unsafe {
+        (&mut I2C_BUS).as_mut().unwrap().stop().expect("I2C stop failed")
+    }
+}
+
+pub extern fn write(_busno: i32, data: i32) -> bool {
+    unsafe {
+        (&mut I2C_BUS).as_mut().unwrap().write(data as u8).expect("I2C write failed")
+    }
+}
+
+pub extern fn read(_busno: i32, ack: bool) -> i32 {
+    unsafe {
+        (&mut I2C_BUS).as_mut().unwrap().read(ack).expect("I2C read failed") as i32
+    }
+}
+
+pub fn init() {
+    let mut i2c = libboard_zynq::i2c::I2c::i2c0();
+    i2c.init().expect("I2C bus initialization failed");
+    unsafe { I2C_BUS = Some(i2c) };
+}
diff --git a/src/runtime/src/kernel/api.rs b/src/runtime/src/kernel/api.rs
index 65e76cae..28ecef42 100644
--- a/src/runtime/src/kernel/api.rs
+++ b/src/runtime/src/kernel/api.rs
@@ -9,6 +9,7 @@ use alloc::vec;
 
 use crate::eh_artiq;
 use crate::rtio;
+use crate::i2c;
 use super::rpc::{rpc_send, rpc_send_async, rpc_recv};
 use super::dma;
 use super::cache;
@@ -100,6 +101,13 @@ pub fn resolve(required: &[u8]) -> Option<u32> {
         api!(cache_get = cache::get),
         api!(cache_put = cache::put),
 
+        // i2c
+        api!(i2c_start = i2c::start),
+        api!(i2c_restart = i2c::restart),
+        api!(i2c_stop = i2c::stop),
+        api!(i2c_write = i2c::write),
+        api!(i2c_read = i2c::read),
+
         // Double-precision floating-point arithmetic helper functions
         // RTABI chapter 4.1.2, Table 2
         api!(__aeabi_dadd),
diff --git a/src/runtime/src/main.rs b/src/runtime/src/main.rs
index dc118dc4..eca4b217 100644
--- a/src/runtime/src/main.rs
+++ b/src/runtime/src/main.rs
@@ -43,6 +43,7 @@ mod logger;
 mod mgmt;
 mod analyzer;
 mod irq;
+mod i2c;
 
 fn init_gateware() {
     // Set up PS->PL clocks
@@ -177,6 +178,9 @@ pub fn main_core0() {
 
     init_gateware();
     info!("detected gateware: {}", identifier_read(&mut [0; 64]));
+
+    i2c::init();
+
     let cfg = match Config::new() {
         Ok(cfg) => cfg,
         Err(err) => {