[RFC PATCH v7 7/8] WIP macio/cuda: Attempt to add i2c support

[BALATON Zoltan]

This is not a final, RFC patch attempt to implement i2c bus in CUDA
needed for firmware to access SPD data of installed RAM. The skeleton
is there but actual implementation of I2C commands need to be refined
because I don't know how this is supposed to work. In my understanding
after an I2C command (at least for combined transfer) CUDA should
enter a mode where reading subsequent values from VIA[SR] should
return bytes received from the i2C device but not sure what ends this
mode or how to model it correctly. So this patch just returns fixed
amount of bytes expected by reading SPD eeproms just to make testing
the firmware ROM possible. Help fixing and finishing this is welcome,
I don't plan to spend more time with this so just submitted it for
whoever picks this up.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
---
 hw/misc/macio/cuda.c         | 76 +++++++++++++++++++++++++++++++++++-
 include/hw/misc/macio/cuda.h |  1 +
 2 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/hw/misc/macio/cuda.c b/hw/misc/macio/cuda.c
index 5bbc7770fa..3fc9773717 100644
--- a/hw/misc/macio/cuda.c
+++ b/hw/misc/macio/cuda.c
@@ -28,6 +28,7 @@
 #include "hw/ppc/mac.h"
 #include "hw/qdev-properties.h"
 #include "migration/vmstate.h"
+#include "hw/i2c/i2c.h"
 #include "hw/input/adb.h"
 #include "hw/misc/mos6522.h"
 #include "hw/misc/macio/cuda.h"
@@ -370,6 +371,75 @@ static bool cuda_cmd_set_time(CUDAState *s,
     return true;
 }
 
+static bool cuda_cmd_get_set_iic(CUDAState *s,
+                                 const uint8_t *in_data, int in_len,
+                                 uint8_t *out_data, int *out_len)
+{
+    int i;
+
+    qemu_log_mask(LOG_UNIMP, "CUDA: unimplemented GET_SET_IIC %s 0x%x %d\n",
+                  (in_data[0] & 1 ? "read" : "write"), in_data[0] >> 1,
+                  in_len);
+    if (i2c_start_transfer(s->i2c_bus, in_data[0] >> 1, in_data[0] & 1)) {
+        return false;
+    }
+    for (i = 0; i < in_len - 3; i++) {
+        if (i2c_send(s->i2c_bus, in_data[i])) {
+            i2c_end_transfer(s->i2c_bus);
+            return false;
+        }
+    }
+    return true;
+}
+
+static bool cuda_cmd_combined_iic(CUDAState *s,
+                                  const uint8_t *in_data, int in_len,
+                                  uint8_t *out_data, int *out_len)
+{
+    int i;
+
+    if (in_len < 3) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "CUDA: COMBINED_FORMAT_IIC too few input bytes\n");
+        return false;
+    }
+    if ((in_data[0] & 0xfe) != (in_data[2] & 0xfe)) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                      "CUDA: COMBINED_FORMAT_IIC address mismatch\n");
+        return false;
+    }
+
+    uint8_t data = in_data[1];
+    if (i2c_start_transfer(s->i2c_bus, in_data[0] >> 1, in_data[0] & 1) ||
+        i2c_send_recv(s->i2c_bus, &data, in_data[0] & 1)) {
+        return false;
+    }
+    i2c_end_transfer(s->i2c_bus);
+    if (in_data[2] & 1) {
+        if (i2c_start_transfer(s->i2c_bus, in_data[2] >> 1, in_data[2] & 1)) {
+            i2c_end_transfer(s->i2c_bus);
+            return false;
+        }
+        for (i = 0; i < 5; i++) {
+            if (i2c_send_recv(s->i2c_bus, &out_data[i], in_data[2] & 1)) {
+                i2c_end_transfer(s->i2c_bus);
+                return false;
+            }
+        }
+        *out_len = i;
+        i2c_end_transfer(s->i2c_bus);
+    } else {
+        for (i = 0; i < in_len - 3; i++) {
+            data = in_data[3 + i];
+            if (i2c_send_recv(s->i2c_bus, &data, in_data[2] & 1)) {
+                i2c_end_transfer(s->i2c_bus);
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
 static const CudaCommand handlers[] = {
     { CUDA_AUTOPOLL, "AUTOPOLL", cuda_cmd_autopoll },
     { CUDA_SET_AUTO_RATE, "SET_AUTO_RATE",  cuda_cmd_set_autorate },
@@ -382,6 +452,8 @@ static const CudaCommand handlers[] = {
       cuda_cmd_set_power_message },
     { CUDA_GET_TIME, "GET_TIME", cuda_cmd_get_time },
     { CUDA_SET_TIME, "SET_TIME", cuda_cmd_set_time },
+    { CUDA_GET_SET_IIC, "GET_SET_IIC", cuda_cmd_get_set_iic },
+    { CUDA_COMBINED_FORMAT_IIC, "COMBINED_FORMAT_IIC", cuda_cmd_combined_iic },
 };
 
 static void cuda_receive_packet(CUDAState *s,
@@ -549,6 +621,7 @@ static void cuda_init(Object *obj)
 {
     CUDAState *s = CUDA(obj);
     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
+    DeviceState *dev = DEVICE(obj);
 
     object_initialize_child(obj, "mos6522-cuda", &s->mos6522_cuda,
                             TYPE_MOS6522_CUDA);
@@ -557,7 +630,8 @@ static void cuda_init(Object *obj)
     sysbus_init_mmio(sbd, &s->mem);
 
     qbus_create_inplace(&s->adb_bus, sizeof(s->adb_bus), TYPE_ADB_BUS,
-                        DEVICE(obj), "adb.0");
+                        dev, "adb.0");
+    s->i2c_bus = i2c_init_bus(dev, "i2c");
 }
 
 static Property cuda_properties[] = {
diff --git a/include/hw/misc/macio/cuda.h b/include/hw/misc/macio/cuda.h
index a8cf0be1ec..6856ed7704 100644
--- a/include/hw/misc/macio/cuda.h
+++ b/include/hw/misc/macio/cuda.h
@@ -79,6 +79,7 @@ typedef struct CUDAState {
 
     ADBBusState adb_bus;
     MOS6522CUDAState mos6522_cuda;
+    I2CBus *i2c_bus;
 
     uint32_t tick_offset;
     uint64_t tb_frequency;
-- 
2.21.3