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, 137 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/common/posix/nvgpu.c b/drivers/gpu/nvgpu/common/posix/nvgpu.c
new file mode 100644
index 00000000..6f2a5fe9
--- /dev/null
+++ b/drivers/gpu/nvgpu/common/posix/nvgpu.c
@@ -0,0 +1,137 @@
+/*
+ * 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 <unistd.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+#include <nvgpu/bug.h>
+#include <nvgpu/types.h>
+#include <nvgpu/atomic.h>
+#include <nvgpu/nvgpu_common.h>
+#include <nvgpu/os_sched.h>
+
+#include <nvgpu/posix/probe.h>
+
+#include "os_posix.h"
+
+#include "gk20a/gk20a.h"
+
+void nvgpu_wait_for_deferred_interrupts(struct gk20a *g)
+{
+        /*
+         * No interrupts in userspace so nothing to wait for.
+         */
+}
+
+int nvgpu_current_pid(struct gk20a *g)
+{
+        /*
+         * In the kernel this gets us the PID of the calling process for IOCTLs.
+         * But since we are in userspace this doesn't quite mean the same thing.
+         * This simply returns the PID of the currently running process.
+         */
+        return (int)getpid();
+}
+
+int nvgpu_current_tid(struct gk20a *g)
+{
+        /*
+         * In POSIX thread ID is not the same as a process ID. In Linux threads
+         * and processes are represented by the same thing, but userspace can't
+         * really rely on that.
+         *
+         * We can, however, get a pthread_t for a given thread. But this
+         * pthread_t need not have any relation to the underlying system's
+         * representation of "threads".
+         */
+        return (int)pthread_self();
+}
+
+/*
+ * Somewhat meaningless in userspace...
+ */
+void nvgpu_kernel_restart(void *cmd)
+{
+        BUG();
+}
+
+/*
+ * We have no runtime PM stuff in userspace so these are really just noops.
+ */
+void gk20a_busy_noresume(struct gk20a *g)
+{
+}
+
+void gk20a_idle_nosuspend(struct gk20a *g)
+{
+}
+
+int gk20a_busy(struct gk20a *g)
+{
+        nvgpu_atomic_inc(&g->usage_count);
+
+        return 0;
+}
+
+void gk20a_idle(struct gk20a *g)
+{
+        nvgpu_atomic_dec(&g->usage_count);
+}
+
+/*
+ * This function aims to initialize enough stuff to make unit testing worth
+ * while. There are several interfaces and APIs that rely on the struct gk20a's
+ * state in order to function: logging, for example, but there are many other
+ * things, too.
+ *
+ * Initialize as much of that as possible here. This is meant to be equivalent
+ * to the kernel space driver's probe function.
+ */
+struct gk20a *nvgpu_posix_probe(void)
+{
+        struct gk20a *g;
+        struct nvgpu_os_posix *p;
+        int err;
+
+        p = malloc(sizeof(*p));
+        if (p == NULL)
+                return NULL;
+
+        g = &p->g;
+
+        err = nvgpu_kmem_init(g);
+        if (err != 0)
+                goto fail;
+
+        return g;
+
+fail:
+        free(p);
+
+        return NULL;
+}
+
+void nvgpu_posix_cleanup(struct gk20a *g)
+{
+        nvgpu_kmem_fini(g, 0);
+}