From 437e0e645984da937b9071a6c67c260919761740 Mon Sep 17 00:00:00 2001
From: Peter Barker <pbarker@barker.dropbear.id.au>
Date: Tue, 13 Jul 2021 11:37:14 +1000
Subject: [PATCH] SITL: add simulated SPI devices

---
 libraries/SITL/SIM_SPI.cpp     | 93 ++++++++++++++++++++++++++++++++++
 libraries/SITL/SIM_SPI.h       | 61 ++++++++++++++++++++++
 libraries/SITL/SIM_SPIDevice.h | 18 +++++++
 libraries/SITL/SITL.h          |  7 ++-
 4 files changed, 178 insertions(+), 1 deletion(-)
 create mode 100644 libraries/SITL/SIM_SPI.cpp
 create mode 100644 libraries/SITL/SIM_SPI.h
 create mode 100644 libraries/SITL/SIM_SPIDevice.h

diff --git a/libraries/SITL/SIM_SPI.cpp b/libraries/SITL/SIM_SPI.cpp
new file mode 100644
index 0000000000..c49201f678
--- /dev/null
+++ b/libraries/SITL/SIM_SPI.cpp
@@ -0,0 +1,93 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+/*
+  Simulated spi buses and devices
+*/
+
+
+#include <GCS_MAVLink/GCS.h>
+#include <SITL/SITL.h>
+
+#include "SIM_SPI.h"
+
+#include <signal.h>
+
+using namespace SITL;
+
+struct spi_device_at_cs_pin {
+    uint8_t bus;
+    uint8_t cs_pin;
+    SPIDevice &device;
+} spi_devices[] {
+};
+
+void SPI::init()
+{
+    for (auto &i : spi_devices) {
+        i.device.init();
+    }
+
+    // sanity check the spi_devices structure to ensure we don't have
+    // two devices at the same address on the same bus:
+    for (uint8_t i=0; i<ARRAY_SIZE(spi_devices)-1; i++) {
+        const auto &dev_i = spi_devices[i];
+        for (uint8_t j=i+1; j<ARRAY_SIZE(spi_devices); j++) {
+            const auto &dev_j = spi_devices[j];
+            if (dev_i.bus == dev_j.bus &&
+                dev_i.cs_pin == dev_j.cs_pin) {
+                AP_HAL::panic("Two devices on the same cs_pin on the same bus");
+            }
+        }
+    }
+}
+
+void SPI::update(const class Aircraft &aircraft)
+{
+    for (auto daa : spi_devices) {
+        daa.device.update(aircraft);
+    }
+}
+
+int SPI::ioctl_transaction(uint8_t bus, uint8_t cs_pin, uint8_t count, spi_ioc_transfer *data)
+{
+    for (auto &dev_at_cs_pin : spi_devices) {
+        if (dev_at_cs_pin.cs_pin != cs_pin) {
+            continue;
+        }
+        if (dev_at_cs_pin.bus != bus) {
+            continue;
+        }
+        return dev_at_cs_pin.device.rdwr(count, data);
+    }
+    ::fprintf(stderr, "Unhandled spi message: bus=%u cs_pin=%u\n", bus, cs_pin);
+    return -1;
+}
+
+int SPI::ioctl(uint8_t bus, uint8_t cs_pin, uint8_t ioctl_type, void *data)
+{
+    uint8_t count;
+    switch (ioctl_type) {
+    case SPI_TRANSACTION_1LONG:
+        count = 1;
+        break;
+    case SPI_TRANSACTION_2LONG:
+        count = 2;
+        break;
+    default:
+        AP_HAL::panic("Bad transaction type");
+    }
+
+    return ioctl_transaction(bus, cs_pin, count, (spi_ioc_transfer*)data);
+}
diff --git a/libraries/SITL/SIM_SPI.h b/libraries/SITL/SIM_SPI.h
new file mode 100644
index 0000000000..47daace425
--- /dev/null
+++ b/libraries/SITL/SIM_SPI.h
@@ -0,0 +1,61 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+  Simulated spi buses and devices
+*/
+
+#pragma once
+
+#include <AP_Param/AP_Param.h>
+
+#include "stdint.h"
+
+namespace SITL {
+
+class SPI {
+public:
+    SPI() {}
+
+    void init();
+
+    // update spi state
+    void update(const class Aircraft &aircraft);
+
+    int ioctl(uint8_t bus, uint8_t cs_pin, uint8_t ioctl_type, void *data);
+
+    // the following must be identical to AP_HAL_SITL/SPIDevice.h
+    struct spi_ioc_transfer {
+        uint64_t tx_buf;
+        uint64_t rx_buf;
+
+        uint32_t len;
+        // uint32_t speed_hz;
+
+        // uint16_t delay_usecs;
+        // uint8_t bits_per_word;
+        // uint8_t cs_change;
+    };
+
+#define SPI_TRANSACTION_1LONG 17
+#define SPI_TRANSACTION_2LONG 18
+    // end "the following"
+
+private:
+    int ioctl_transaction(uint8_t bus, uint8_t cs_pin, uint8_t count, spi_ioc_transfer *data);
+
+};
+
+}
diff --git a/libraries/SITL/SIM_SPIDevice.h b/libraries/SITL/SIM_SPIDevice.h
new file mode 100644
index 0000000000..5a0e8fdf82
--- /dev/null
+++ b/libraries/SITL/SIM_SPIDevice.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include "SIM_SPI.h"
+
+#include <SITL/SIM_Aircraft.h>
+
+namespace SITL {
+
+class SPIDevice {
+public:
+    virtual void init() {}
+
+    virtual void update(const class Aircraft &aircraft) { }
+
+    virtual int rdwr(uint8_t count, SPI::spi_ioc_transfer *&data) = 0;
+};
+
+} // namespace SITL
diff --git a/libraries/SITL/SITL.h b/libraries/SITL/SITL.h
index 53715b5eee..03aa762da5 100644
--- a/libraries/SITL/SITL.h
+++ b/libraries/SITL/SITL.h
@@ -14,6 +14,7 @@
 #include "SIM_Gripper_EPM.h"
 #include "SIM_Gripper_Servo.h"
 #include "SIM_I2C.h"
+#include "SIM_SPI.h"
 #include "SIM_Parachute.h"
 #include "SIM_Precland.h"
 #include "SIM_Sprayer.h"
@@ -404,6 +405,10 @@ public:
         return i2c_sim.ioctl(i2c_operation, data);
     }
 
+    int spi_ioctl(uint8_t bus, uint8_t cs_pin, uint8_t spi_operation, void *data) {
+        return spi_sim.ioctl(bus, cs_pin, spi_operation, data);
+    }
+
     Sprayer sprayer_sim;
 
     // simulated ship takeoffs
@@ -415,6 +420,7 @@ public:
     Parachute parachute_sim;
     Buzzer buzzer_sim;
     I2C i2c_sim;
+    SPI spi_sim;
     ToneAlarm tonealarm_sim;
     SIM_Precland precland_sim;
     RichenPower richenpower_sim;
@@ -476,7 +482,6 @@ public:
 
     // Master instance to use servos from with slave instances
     AP_Int8 ride_along_master;
-
 };
 
 } // namespace SITL