gpu: nvgpu: Userspace POSIX support

Add support for compiling nvgpu in a POSIX compliant userspace.
This code adds all of the necessary abstraction interfaces (mostly
stubbed) to enabled extremely limited and basic functionality in
nvgpu.

The goal of this code is to facilitate unit testing of the nvgpu
common core. By doing this in userspace it is much easier to write
tests that rely on very particular states within nvgpu since a user
can very precisely control the state of nvgpu.

JIRA NVGPU-525

Change-Id: I30e95016df14997d951075777e0585f912dc5960
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1683914
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/common/posix/thread.c b/drivers/gpu/nvgpu/common/posix/thread.c
new file mode 100644
index 00000000..d9476523
--- /dev/null
+++ b/drivers/gpu/nvgpu/common/posix/thread.c
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2018, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <nvgpu/bug.h>
+#include <nvgpu/thread.h>
+
+#include <nvgpu/posix/thread.h>
+
+/**
+ * Use pthreads to mostly emulate the Linux kernel APIs. There are some things
+ * that are quite different - especially the stop/should_stop notions. In user
+ * space threads can send signals to one another but of course within the kernel
+ * that is not as simple.
+ *
+ * This could use some nice debugging some day as well.
+ */
+
+/*
+ * nvgpu thread functions return int. POSIX threads return void *. This little
+ * wrapper takes the int returning nvgpu thread and instead passes that int back
+ * through the void * pointer.
+ */
+static void *__nvgpu_posix_thread_wrapper(void *data)
+{
+        struct nvgpu_posix_thread_data *nvgpu = data;
+
+        return ERR_PTR(nvgpu->fn(nvgpu->data));
+}
+
+int nvgpu_thread_create(struct nvgpu_thread *thread,
+                        void *data,
+                        int (*threadfn)(void *data), const char *name)
+{
+        int ret;
+
+        BUG_ON(thread->running);
+
+        memset(thread, 0, sizeof(*thread));
+
+        /*
+         * By subtracting 1 the above memset ensures that we have a zero
+         * terminated string.
+         */
+        strncpy(thread->tname, name, NVGPU_THREAD_POSIX_MAX_NAMELEN - 1);
+
+        thread->nvgpu.data = data;
+        thread->nvgpu.fn = threadfn;
+
+        ret = pthread_create(&thread->thread, NULL,
+                             __nvgpu_posix_thread_wrapper,
+                             &thread->nvgpu);
+        if (ret != 0)
+                return ret;
+
+#ifdef _GNU_SOURCE
+        pthread_setname_np(thread->thread, thread->tname);
+#endif
+
+        thread->running = true;
+
+        return 0;
+}
+
+void nvgpu_thread_stop(struct nvgpu_thread *thread)
+{
+        thread->should_stop = true;
+}
+
+bool nvgpu_thread_should_stop(struct nvgpu_thread *thread)
+{
+        return thread->should_stop;
+}
+
+bool nvgpu_thread_is_running(struct nvgpu_thread *thread)
+{
+        return thread->running;
+}