Bitbang I2C

2020-12-02 10:52:08 -07:00
parent 2fea7dffde
commit 00c19d4295
3 changed files with 362 additions and 122 deletions
--- a/usb4/Cargo.lock
+++ b/usb4/Cargo.lock
@@ -1,29 +1,5 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-[[package]]
-name = "bitflags"
-version = "1.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
-
-[[package]]
-name = "byteorder"
-version = "1.3.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "08c48aae112d48ed9f069b33538ea9e3e90aa263cfa3d1c24309612b1f7472de"
-
-[[package]]
-name = "cc"
-version = "1.0.65"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "95752358c8f7552394baf48cd82695b345628ad3f170d607de3ca03b8dacca15"
-
-[[package]]
-name = "cfg-if"
-version = "0.1.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
-
 [[package]]
 name = "coreboot-collector"
 version = "0.1.0"
@@ -47,37 +23,12 @@ dependencies = [
 "synstructure",
 ]

-[[package]]
-name = "i2cdev"
-version = "0.4.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c0eb3d9b6b02dc2508ee23439170004e44344bab9d53a490eb1f64c885b5003"
-dependencies = [
- "bitflags",
- "byteorder",
- "libc",
- "nix",
-]
-
 [[package]]
 name = "libc"
 version = "0.2.80"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4d58d1b70b004888f764dfbf6a26a3b0342a1632d33968e4a179d8011c760614"

-[[package]]
-name = "nix"
-version = "0.14.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6c722bee1037d430d0f8e687bbdbf222f27cc6e4e68d5caf630857bb2b6dbdce"
-dependencies = [
- "bitflags",
- "cc",
- "cfg-if",
- "libc",
- "void",
-]
-
 [[package]]
 name = "numtoa"
 version = "0.2.3"
@@ -169,22 +120,15 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f7fe0bb3479651439c9112f72b6c505038574c9fbb575ed1bf3b797fa39dd564"

+[[package]]
+name = "usb4"
+version = "0.1.0"
+dependencies = [
+ "coreboot-collector",
+]
+
 [[package]]
 name = "version_check"
 version = "0.9.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b5a972e5669d67ba988ce3dc826706fb0a8b01471c088cb0b6110b805cc36aed"
-
-[[package]]
-name = "void"
-version = "1.0.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6a02e4885ed3bc0f2de90ea6dd45ebcbb66dacffe03547fadbb0eeae2770887d"
-
-[[package]]
-name = "you-ass-bee-see"
-version = "0.1.0"
-dependencies = [
- "coreboot-collector",
- "i2cdev",
-]
--- a/usb4/Cargo.toml
+++ b/usb4/Cargo.toml
@@ -1,5 +1,5 @@
 [package]
-name = "you-ass-bee-see"
+name = "usb4"
 version = "0.1.0"
 authors = ["Jeremy Soller <jeremy@system76.com>"]
 edition = "2018"
@@ -8,4 +8,3 @@ edition = "2018"

 [dependencies]
 coreboot-collector = { path = "../tools/coreboot-collector" }
-i2cdev = "0.4.4"
--- a/usb4/src/main.rs
+++ b/usb4/src/main.rs
@@ -1,7 +1,11 @@
 use coreboot_collector::sideband::Sideband;
-use i2cdev::core::I2CDevice;
-use i2cdev::linux::LinuxI2CDevice;
-use std::{fs, thread, time};
+use std::{
+    fs,
+    rc::Rc,
+    process,
+    thread,
+    time
+};

 const IECS_CMD: u8 = 8;
 const IECS_DATA: u8 = 9;
@@ -13,71 +17,319 @@ const CMD_BLKW: u32 = 0x574b4c42;
 const CMD_BOPS: u32 = 0x53504f42;
 const CMD_PCYC: u32 = 0x43594350;

-const GPIO_FORCE_POWER: (u8, u8) = (0x6E, 0x82); // GPP_A23

-fn read<I: I2CDevice>(dev: &mut I, reg: u8) -> Result<u32, I::Error> {
-    let bytes = dev.smbus_read_block_data(reg)?;
-    //TODO: return error on bytes.len() != 4
+#[repr(u64)]
+pub enum GpioPadMode {
+    Gpio = 0 << 10,
+    Nf1 = 1 << 10,
+    Nf2 = 2 << 10,
+    Nf3 = 3 << 10,
+    Nf4 = 4 << 10,
+    Nf5 = 5 << 10,
+    Nf6 = 6 << 10,
+    Nf7 = 7 << 10,
+}
+
+pub struct Gpio {
+    //TODO: this should probably be locked
+    sideband: Rc<Sideband>,
+    port: u8,
+    pad: u8,
+}
+
+impl Gpio {
+    const PAD_MODE: u64 = 0b111 << 10;
+    const RX_DIS: u64 = 1 << 9;
+    const TX_DIS: u64 = 1 << 8;
+    const RX: u64 = 1 << 1;
+    const TX: u64 = 1 << 0;
+
+    pub fn new(sideband: Rc<Sideband>, port: u8, pad: u8) -> Self {
+        Self { sideband, port, pad }
+    }
+
+    unsafe fn get_config(&self) -> u64 {
+        self.sideband.gpio(self.port, self.pad)
+    }
+
+    unsafe fn set_config(&mut self, config: u64) {
+        self.sideband.set_gpio(self.port, self.pad, config);
+    }
+
+    unsafe fn get_mask(&self, mask: u64) -> bool {
+        self.get_config() & mask == mask
+    }
+
+    unsafe fn set_mask(&mut self, mask: u64, value: bool) {
+        let mut config = self.get_config();
+        if value {
+            config |= mask;
+        } else {
+            config &= !mask;
+        }
+        self.set_config(config);
+    }
+
+    pub unsafe fn set_pad_mode(&mut self, mode: GpioPadMode) {
+        let mut config = self.get_config();
+        config &= !Self::PAD_MODE;
+        config |= mode as u64;
+        self.set_config(config);
+
+    }
+
+    pub unsafe fn enable_rx(&mut self, value: bool) {
+        self.set_mask(Self::RX_DIS, !value);
+    }
+
+    pub unsafe fn enable_tx(&mut self, value: bool) {
+        self.set_mask(Self::TX_DIS, !value);
+    }
+
+    pub unsafe fn get_rx(&self) -> bool {
+        self.get_mask(Self::RX)
+    }
+
+    pub unsafe fn get_tx(&self) -> bool {
+        self.get_mask(Self::TX)
+    }
+
+    pub unsafe fn set_tx(&mut self, value: bool) {
+        self.set_mask(Self::TX, value);
+    }
+}
+
+pub struct I2CBitbang {
+    scl: Gpio,
+    scl_config: u64,
+    sda: Gpio,
+    sda_config: u64,
+}
+
+impl I2CBitbang {
+    pub unsafe fn new(mut scl: Gpio, mut sda: Gpio) -> Self {
+        //TODO: will this transmit something invalid?
+
+        let scl_config = scl.get_config();
+        scl.enable_rx(true);
+        scl.enable_tx(false);
+        scl.set_tx(false);
+        scl.set_pad_mode(GpioPadMode::Gpio);
+
+        let sda_config = sda.get_config();
+        sda.enable_rx(true);
+        sda.enable_tx(false);
+        sda.set_tx(false);
+        sda.set_pad_mode(GpioPadMode::Gpio);
+
+        Self { scl, scl_config, sda, sda_config, }
+    }
+
+    // Delay half half of period
+    fn delay(&self) {
+        // Hard coded to 5 us, which is half of the period 10 us for a frequency of 100 KHz
+        thread::sleep(time::Duration::from_micros(5));
+    }
+
+    // Pull SCL low
+    unsafe fn clr_scl(&mut self) {
+        self.scl.enable_tx(true);
+    }
+
+    // Release SCL, bus pulls it high
+    unsafe fn set_scl(&mut self) {
+        self.scl.enable_tx(false);
+    }
+
+    // Pull SDA low
+    unsafe fn clr_sda(&mut self) {
+        self.sda.enable_tx(true);
+    }
+
+    // Release SDA, bus pulls it high
+    unsafe fn set_sda(&mut self) {
+        self.sda.enable_tx(false);
+    }
+
+    unsafe fn start(&mut self) {
+        self.set_scl();
+        self.set_sda();
+        self.delay();
+        self.clr_sda();
+        self.delay();
+        self.clr_scl();
+        self.delay();
+    }
+
+    unsafe fn stop(&mut self) {
+        self.clr_sda();
+        self.delay();
+        self.set_scl();
+        self.delay();
+        self.set_sda();
+        self.delay();
+    }
+
+    unsafe fn write_bit(&mut self, bit: bool) {
+        if bit {
+            self.set_sda();
+        } else {
+            self.clr_sda();
+        }
+        self.delay();
+        self.set_scl();
+        self.delay();
+        self.clr_scl();
+    }
+
+    unsafe fn read_bit(&mut self) -> bool {
+        self.set_sda();
+        self.delay();
+        self.set_scl();
+        self.delay();
+        let bit = self.sda.get_rx();
+        self.clr_scl();
+        bit
+    }
+
+    unsafe fn write_byte(&mut self, byte: u8, start: bool) -> bool {
+        if start {
+            self.start();
+        }
+        for i in (0..8).rev() {
+            self.write_bit(byte & (1 << i) != 0);
+        }
+        self.read_bit()
+    }
+
+    unsafe fn read_byte(&mut self, ack: bool) -> u8 {
+        let mut byte = 0;
+        for i in (0..8).rev() {
+            if self.read_bit() {
+                byte |= 1 << i;
+            }
+        }
+        self.write_bit(!ack);
+        byte
+    }
+
+    pub unsafe fn smbus_block_write(&mut self, address: u8, command: u8, bytes: &[u8]) -> usize {
+        // Only 32 bytes can be processed at a time
+        if bytes.len() > 32 {
+            return 0;
+        }
+
+        let mut count = 0;
+        if self.write_byte(address << 1, true) {
+            if self.write_byte(command, false) {
+                if self.write_byte(bytes.len() as u8, false) {
+                    for byte in bytes.iter() {
+                        if self.write_byte(*byte, false) {
+                            count += 1;
+                        } else {
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+        self.stop();
+        count
+    }
+
+    pub unsafe fn smbus_block_read(&mut self, address: u8, command: u8) -> Vec<u8> {
+        //TODO: use static buffer?
+        let mut bytes = Vec::new();
+        if self.write_byte(address << 1, true) {
+            if self.write_byte(command, false) {
+                if self.write_byte(address << 1 | 1, true) {
+                    let count = self.read_byte(true);
+                    for _i in 0..count {
+                        bytes.push(self.read_byte(true));
+                    }
+                }
+            }
+        }
+        self.stop();
+        bytes
+    }
+}
+
+impl Drop for I2CBitbang {
+    fn drop(&mut self) {
+        unsafe {
+            //TODO: will this transmit something invalid?
+            self.scl.set_config(self.scl_config);
+            self.sda.set_config(self.sda_config);
+        }
+    }
+}
+
+pub struct Retimer {
+    i2c: I2CBitbang,
+    address: u8,
+}
+
+impl Retimer {
+    pub fn new(i2c: I2CBitbang, address: u8) -> Self {
+        Self { i2c, address }
+    }
+
+    pub unsafe fn read(&mut self, reg: u8) -> Result<u32, String> {
+        let bytes = self.i2c.smbus_block_read(self.address, reg);
+        if bytes.len() == 4 {
            Ok(
                bytes[0] as u32 |
                (bytes[1] as u32) << 8 |
                (bytes[2] as u32) << 16 |
                (bytes[3] as u32) << 24
            )
+        } else {
+            Err(format!("Retimer::read: read {} bytes instead of 4", bytes.len()))
+        }
    }

-fn write<I: I2CDevice>(dev: &mut I, reg: u8, data: u32) -> Result<(), I::Error> {
+    pub unsafe fn write(&mut self, reg: u8, data: u32) -> Result<(), String> {
        let bytes = [
            data as u8,
            (data >> 8) as u8,
            (data >> 16) as u8,
            (data >> 24) as u8,
        ];
-    dev.smbus_write_block_data(reg, &bytes)
+        let count = self.i2c.smbus_block_write(self.address, reg, &bytes);
+        if count == 4 {
+            Ok(())
+        } else {
+            Err(format!("Retimer::write: wrote {} bytes instead of 4", count))
+        }
    }


-fn command<I: I2CDevice>(dev: &mut I, cmd: u32) -> Result<u32, I::Error> {
-    write(dev, IECS_CMD, cmd)?;
-    loop {
-        let status = read(dev, IECS_CMD)?;
+    pub unsafe fn command(&mut self, cmd: u32) -> Result<(), String> {
+        self.write(IECS_CMD, cmd)?;
+        //TODO: is this the right number of retries?
+        let retries = 1000;
+        for _i in 0..retries {
+            let status = self.read(IECS_CMD)?;
            if status != cmd {
-            //TODO: perform error checking here
-            return Ok(status);
+                if status == 0 {
+                    return Ok(());
+                } else {
+                    return Err(format!("Retimer::command: read 0x{:X} instead of 0", status));
                }
            }
        }
-
-fn main() {
-    //TODO: check model
-
-    let sideband = unsafe { Sideband::new(0xFD00_0000).unwrap() };
-
-    // Set FORCE_POWER high
-    unsafe {
-        let (port, pad) = GPIO_FORCE_POWER;
-        let mut value = sideband.gpio(port, pad);
-        value |= 1;
-        sideband.set_gpio(port, pad, value);
+        Err(format!("Retimer::command: timed out after {} retries", retries))
+    }
 }

-    // Sleep 40ms
-    thread::sleep(time::Duration::from_millis(40));
-
-    let mut dev = LinuxI2CDevice::new("/dev/i2c-11", 0x40).unwrap();
-    eprintln!("Vendor: {:X}", read(&mut dev, 0).unwrap());
-    eprintln!("Device: {:X}", read(&mut dev, 1).unwrap());
-
-    let image = fs::read("../models/galp5/usb4-retimer.rom").unwrap();
-
-    for i in 2..=32 {
-        println!("{}: {:X}", i, read(&mut dev, i).unwrap());
-    }
-
-    write(&mut dev, IECS_DATA, 0).unwrap();
-    println!("IECS_DATA: {:X}", read(&mut dev, IECS_DATA).unwrap());
+unsafe fn flash_retimer(retimer: &mut Retimer) -> Result<(), String> {
+    eprintln!("Vendor: {:X}", retimer.read(0)?);
+    eprintln!("Device: {:X}", retimer.read(1)?);

    /*
+    let image = fs::read("../models/galp5/usb4-retimer.rom").unwrap();
+
    eprintln!("Set offset to 0");
    write(&mut dev, IECS_DATA, 0).unwrap();
    let status = command(&mut dev, CMD_BOPS).unwrap();
@@ -125,11 +377,56 @@ fn main() {
    eprintln!("Successfully flashed retimer");
    */

-    // Set FORCE_POWER low
+    Ok(())
+}
+
+unsafe fn retimer_access(i2c: I2CBitbang) -> i32 {
+    let mut retimer = Retimer::new(i2c, 0x40);
+    match flash_retimer(&mut retimer) {
+        Ok(()) => 0,
+        Err(err) => {
+            eprintln!("Failed to flash retimer: {}", err);
+            1
+        }
+    }
+}
+
+unsafe fn i2c_access(sideband: Rc<Sideband>) -> i32 {
+    let scl = Gpio::new(sideband.clone(), 0x6A, 0x06); // GPP_C3
+    let sda = Gpio::new(sideband.clone(), 0x6A, 0x08); // GPP_C4
+    let i2c = I2CBitbang::new(scl, sda);
+    retimer_access(i2c)
+}
+
+unsafe fn force_power(sideband: Rc<Sideband>) -> i32 {
+    let mut force_power = Gpio::new(sideband.clone(), 0x6E, 0x82); // GPP_A23
+
+    println!("Set FORCE_POWER high");
+    force_power.set_tx(true);
+
+    println!("Sleep 40 ms");
+    thread::sleep(time::Duration::from_millis(40));
+
+    let exit_status = i2c_access(sideband);
+
+    eprintln!("Set FORCE_POWER low");
+    force_power.set_tx(false);
+
+    exit_status
+}
+
+fn main() {
+    //TODO: check model
+
    unsafe {
-        let (port, pad) = GPIO_FORCE_POWER;
-        let mut value = sideband.gpio(port, pad);
-        value &= !1;
-        sideband.set_gpio(port, pad, value);
+        let sideband = match Sideband::new(0xFD00_0000) {
+            Ok(ok) => Rc::new(ok),
+            Err(err) => {
+                eprintln!("Failed to access sideband: {}", err);
+                process::exit(1);
+            }
+        };
+
+        process::exit(force_power(sideband));
    }
 }