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, 268 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/common/posix/bitmap.c b/drivers/gpu/nvgpu/common/posix/bitmap.c
new file mode 100644
index 00000000..51361777
--- /dev/null
+++ b/drivers/gpu/nvgpu/common/posix/bitmap.c
@@ -0,0 +1,268 @@
+/*
+ * 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 <stdio.h>
+#include <stdlib.h>
+
+#include <nvgpu/posix/bitops.h>
+#include <nvgpu/posix/atomic.h>
+
+#define BIT_MASK(nr)    (1UL << ((nr) % BITS_PER_LONG))
+#define BIT_WORD(nr)    ((nr) / BITS_PER_LONG)
+
+unsigned long __nvgpu_posix_fls(unsigned long word)
+{
+        int num = BITS_PER_LONG - 1;
+
+#if BITS_PER_LONG == 64
+        if (!(word & (~0ul << 32))) {
+                num -= 32;
+                word <<= 32;
+        }
+#endif
+        if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
+                num -= 16;
+                word <<= 16;
+        }
+        if (!(word & (~0ul << (BITS_PER_LONG-8)))) {
+                num -= 8;
+                word <<= 8;
+        }
+        if (!(word & (~0ul << (BITS_PER_LONG-4)))) {
+                num -= 4;
+                word <<= 4;
+        }
+        if (!(word & (~0ul << (BITS_PER_LONG-2)))) {
+                num -= 2;
+                word <<= 2;
+        }
+        if (!(word & (~0ul << (BITS_PER_LONG-1))))
+                num -= 1;
+        return num;
+}
+
+unsigned long __nvgpu_posix_ffs(unsigned long word)
+{
+        int num = 0;
+
+#if BITS_PER_LONG == 64
+        if ((word & 0xffffffff) == 0) {
+                num += 32;
+                word >>= 32;
+        }
+#endif
+        if ((word & 0xffff) == 0) {
+                num += 16;
+                word >>= 16;
+        }
+        if ((word & 0xff) == 0) {
+                num += 8;
+                word >>= 8;
+        }
+        if ((word & 0xf) == 0) {
+                num += 4;
+                word >>= 4;
+        }
+        if ((word & 0x3) == 0) {
+                num += 2;
+                word >>= 2;
+        }
+        if ((word & 0x1) == 0)
+                num += 1;
+
+        return num;
+}
+
+static unsigned long __find_next_bit(const unsigned long *addr,
+                                     unsigned long n,
+                                     unsigned long start,
+                                     bool invert)
+{
+        unsigned long idx;
+        unsigned long w;
+        unsigned long start_mask;
+
+        /*
+         * We make a mask we can XOR into the word so that we can invert the
+         * word without requiring a branch. I.e instead of doing:
+         *
+         *   w = invert ? ~addr[idx] : addr[idx]
+         *
+         * We can do:
+         *
+         *   w = addr[idx] ^= invert_mask
+         *
+         * This saves us a branch every iteration through the loop. Now we can
+         * always just look for 1s.
+         */
+        unsigned long invert_mask = invert ? ~0UL : 0UL;
+
+        if (start >= n)
+                return n;
+
+        start_mask = ~0UL << (start & (BITS_PER_LONG - 1));
+
+        idx = start / BITS_PER_LONG;
+        w = (addr[idx] ^ invert_mask) & start_mask;
+
+        start = round_up(start, BITS_PER_LONG);
+
+        /*
+         * Find the first non-zero word taking into account start and
+         * invert.
+         */
+        while (!w) {
+                idx++;
+                start += BITS_PER_LONG;
+
+                w = addr[idx] ^ invert_mask;
+        }
+
+        return min(n, ffs(w) + idx * BITS_PER_LONG);
+}
+
+unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+{
+        return __find_next_bit(addr, size, 0, false);
+}
+
+unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)
+{
+        return __find_next_bit(addr, size, 0, true);
+}
+
+unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
+                            unsigned long offset)
+{
+        return __find_next_bit(addr, size, offset, false);
+}
+
+static unsigned long find_next_zero_bit(const unsigned long *addr,
+                                        unsigned long size,
+                                        unsigned long offset)
+{
+        return __find_next_bit(addr, size, offset, true);
+}
+
+void bitmap_set(unsigned long *map, unsigned int start, int len)
+{
+        unsigned int end = start + len;
+
+        /*
+         * Super slow naive implementation. But speed isn't what matters here.
+         */
+        while (start < end)
+                set_bit(start++, map);
+}
+
+void bitmap_clear(unsigned long *map, unsigned int start, int len)
+{
+        unsigned int end = start + len;
+
+        while (start < end)
+                clear_bit(start++, map);
+}
+
+/*
+ * This is essentially a find-first-fit allocator: this searches a bitmap for
+ * the first space that is large enough to satisfy the requested size of bits.
+ * That means that this is not a vary smart allocator. But it is fast relative
+ * to an allocator that goes looking for an optimal location.
+ */
+unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
+                                             unsigned long size,
+                                             unsigned long start,
+                                             unsigned int nr,
+                                             unsigned long align_mask,
+                                             unsigned long align_offset)
+{
+        unsigned long offs;
+
+        while (start + nr <= size) {
+                start = find_next_zero_bit(map, size, start);
+
+                start = ALIGN_MASK(start + align_offset, align_mask) -
+                        align_offset;
+
+                /*
+                 * Not enough space left to satisfy the requested area.
+                 */
+                if ((start + nr) > size)
+                        return size;
+
+                offs = find_next_bit(map, size, start);
+
+                if ((offs - start) >= nr)
+                        return start;
+
+                start = offs + 1;
+        }
+
+        return size;
+}
+
+unsigned long bitmap_find_next_zero_area(unsigned long *map,
+                                         unsigned long size,
+                                         unsigned long start,
+                                         unsigned int nr,
+                                         unsigned long align_mask)
+{
+        return bitmap_find_next_zero_area_off(map, size, start, nr,
+                                              align_mask, 0);
+}
+
+bool test_bit(int nr, const volatile unsigned long *addr)
+{
+        return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
+}
+
+bool test_and_set_bit(int nr, volatile unsigned long *addr)
+{
+        unsigned long mask = BIT_MASK(nr);
+        volatile unsigned long *p = addr + BIT_WORD(nr);
+
+        return !!(__sync_fetch_and_or(p, mask) & mask);
+}
+
+bool test_and_clear_bit(int nr, volatile unsigned long *addr)
+{
+        unsigned long mask = BIT_MASK(nr);
+        unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+        return !!(__sync_fetch_and_and(p, ~mask) & mask);
+}
+
+void set_bit(int nr, volatile unsigned long *addr)
+{
+        unsigned long mask = BIT_MASK(nr);
+        unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+        __atomic_or(p, mask);
+}
+
+void clear_bit(int nr, volatile unsigned long *addr)
+{
+        unsigned long mask = BIT_MASK(nr);
+        unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+        __atomic_and(p, ~mask);
+}