gpu: nvgpu: Add timeout API

Add a timeout API to nvgpu since this is a common operation done all
across the nvgpu driver.

Also add two new directories for this common code:

  drivers/gpu/nvgpu/common
  drivers/gpu/nvgpu/include/nvgpu

The common directory is for common C code. The include directory is for
common include files.

Bug 1799159

Change-Id: I8b710eecaa75c0707df83f859fb28484525185a6
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: http://git-master/r/1255864
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

3 files changed, 275 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/Makefile.nvgpu b/drivers/gpu/nvgpu/Makefile.nvgpu
index 96cdfb0a..71077386 100644
--- a/drivers/gpu/nvgpu/Makefile.nvgpu
+++ b/drivers/gpu/nvgpu/Makefile.nvgpu
@@ -1,10 +1,11 @@
 GCOV_PROFILE := y
 
-ccflags-y += -Idrivers/gpu/nvgpu
+ccflags-y += -Idrivers/gpu/nvgpu/include
 ccflags-y += -Idrivers/video/tegra/host
 ccflags-y += -Idrivers/devfreq
 ccflags-y += -I../nvgpu/include
 ccflags-y += -I../nvgpu/include/uapi
+ccflags-y += -I../nvgpu/drivers/gpu/nvgpu/include
 ccflags-y += -Wno-multichar
 ccflags-y += -Werror
 ccflags-y += -Wno-error=cpp
@@ -25,8 +26,9 @@ endif
 obj-$(CONFIG_GK20A) := nvgpu.o
 
 nvgpu-y := \
-        gk20a/gk20a.o \
+        common/linux/timers.o \
         nvgpu_common.o \
+        gk20a/gk20a.o \
         gk20a/sched_gk20a.o \
         gk20a/as_gk20a.o \
         gk20a/ctrl_gk20a.o \
diff --git a/drivers/gpu/nvgpu/common/linux/timers.c b/drivers/gpu/nvgpu/common/linux/timers.c
new file mode 100644
index 00000000..e1e08f82
--- /dev/null
+++ b/drivers/gpu/nvgpu/common/linux/timers.c
@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/>.
+ */
+
+#include <linux/jiffies.h>
+
+#include <nvgpu/timers.h>
+
+#include "gk20a/gk20a.h"
+
+/*
+ * Returns 1 if the platform is pre-Si and should ignore the timeout checking.
+ * Setting %NVGPU_TIMER_NO_PRE_SI will make this always return 0 (i.e do the
+ * timeout check regardless of platform).
+ */
+static int nvgpu_timeout_is_pre_silicon(struct nvgpu_timeout *timeout)
+{
+        if (timeout->flags & NVGPU_TIMER_NO_PRE_SI)
+                return 0;
+
+        return !tegra_platform_is_silicon();
+}
+
+/**
+ * nvgpu_timeout_init - Init timer.
+ *
+ * @g        - nvgpu device.
+ * @timeout  - The timer.
+ * @duration - Timeout in milliseconds or number of retries.
+ * @flags    - Flags for timer.
+ *
+ * This configures the timeout to start the timeout duration now, i.e: when this
+ * function is called. Available flags to pass to @flags:
+ *
+ *   %NVGPU_TIMER_CPU_TIMER
+ *   %NVGPU_TIMER_RETRY_TIMER
+ *   %NVGPU_TIMER_NO_PRE_SI
+ *   %NVGPU_TIMER_SILENT_TIMEOUT
+ *
+ * If neither %NVGPU_TIMER_CPU_TIMER or %NVGPU_TIMER_RETRY_TIMER is passed then
+ * a CPU timer is used by default.
+ */
+int nvgpu_timeout_init(struct gk20a *g, struct nvgpu_timeout *timeout,
+                       int duration, unsigned long flags)
+{
+        if (flags & ~NVGPU_TIMER_FLAG_MASK)
+                return -EINVAL;
+
+        memset(timeout, 0, sizeof(*timeout));
+
+        timeout->g = g;
+        timeout->flags = flags;
+
+        if (flags & NVGPU_TIMER_RETRY_TIMER)
+                timeout->retries.max = duration;
+        else
+                timeout->time = jiffies + msecs_to_jiffies(duration);
+
+        return 0;
+}
+
+static int __nvgpu_timeout_check_msg_cpu(struct nvgpu_timeout *timeout,
+                                         void *caller,
+                                         const char *fmt, va_list args)
+{
+        struct gk20a *g = timeout->g;
+        unsigned long now = jiffies;
+
+        if (nvgpu_timeout_is_pre_silicon(timeout))
+                return 0;
+
+        if (time_after(now, (unsigned long)timeout->time)) {
+                if (!(timeout->flags & NVGPU_TIMER_SILENT_TIMEOUT)) {
+                        char buf[128];
+
+                        vsnprintf(buf, sizeof(buf), fmt, args);
+
+                        dev_err(dev_from_gk20a(g),
+                                "Timeout detected @ 0x%pF %s\n", caller, buf);
+                }
+
+                return -ETIMEDOUT;
+        }
+
+        return 0;
+}
+
+static int __nvgpu_timeout_check_msg_retry(struct nvgpu_timeout *timeout,
+                                           void *caller,
+                                           const char *fmt, va_list args)
+{
+        struct gk20a *g = timeout->g;
+
+        if (nvgpu_timeout_is_pre_silicon(timeout))
+                return 0;
+
+        if (timeout->retries.attempted >= timeout->retries.max) {
+                if (!(timeout->flags & NVGPU_TIMER_SILENT_TIMEOUT)) {
+                        char buf[128];
+
+                        vsnprintf(buf, sizeof(buf), fmt, args);
+
+                        dev_err(dev_from_gk20a(g),
+                                "No more retries @ 0x%pF %s\n", caller, buf);
+                }
+
+                return -ETIMEDOUT;
+        }
+
+        timeout->retries.attempted++;
+
+        return 0;
+}
+
+/**
+ * __nvgpu_timeout_check_msg - Check if a timeout has expired.
+ *
+ * @timeout - The timeout to check.
+ * @caller  - Address of the caller of this function.
+ * @fmt     - The fmt string.
+ *
+ * Returns -ETIMEDOUT if the timeout has expired, 0 otherwise.
+ *
+ * If a timeout occurs and %NVGPU_TIMER_SILENT_TIMEOUT is not set in the timeout
+ * then a message is printed based on %fmt.
+ */
+int __nvgpu_timeout_check_msg(struct nvgpu_timeout *timeout,
+                              void *caller, const char *fmt, ...)
+{
+        int ret;
+        va_list args;
+
+        va_start(args, fmt);
+        if (timeout->flags & NVGPU_TIMER_RETRY_TIMER)
+                ret = __nvgpu_timeout_check_msg_retry(timeout, caller, fmt,
+                                                      args);
+        else
+                ret = __nvgpu_timeout_check_msg_cpu(timeout, caller, fmt,
+                                                    args);
+        va_end(args);
+
+        return ret;
+}
+
+/**
+ * nvgpu_timeout_peek - Check the status of a timeout.
+ *
+ * @timeout - The timeout to check.
+ *
+ * Returns non-zero if the timeout is expired, zero otherwise. In the case of
+ * retry timers this will not increment the underlying retry count. Also if the
+ * timer has expired no messages will be printed.
+ *
+ * This function honors the pre-Si check as well.
+ */
+int nvgpu_timeout_peek(struct nvgpu_timeout *timeout)
+{
+        if (nvgpu_timeout_is_pre_silicon(timeout))
+                return 0;
+
+        if (timeout->flags & NVGPU_TIMER_RETRY_TIMER)
+                return timeout->retries.attempted >= timeout->retries.max;
+        else
+                return time_after(jiffies, (unsigned long)timeout->time);
+}
diff --git a/drivers/gpu/nvgpu/include/nvgpu/timers.h b/drivers/gpu/nvgpu/include/nvgpu/timers.h
new file mode 100644
index 00000000..e46982c9
--- /dev/null
+++ b/drivers/gpu/nvgpu/include/nvgpu/timers.h
@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/>.
+ */
+
+#ifndef __NVGPU_TIMERS_H__
+#define __NVGPU_TIMERS_H__
+
+struct gk20a;
+
+/*
+ * struct nvgpu_timeout - define a timeout.
+ *
+ * There are two types of timer suported:
+ *
+ *   o  NVGPU_TIMER_CPU_TIMER
+ *        Timer uses the CPU to measure the timeout.
+ *
+ *   o  NVGPU_TIMER_RETRY_TIMER
+ *        Instead of measuring a time limit keep track of the number of times
+ *        something has been attempted. After said limit, "expire" the timer.
+ *
+ * Available flags:
+ *
+ *   o  NVGPU_TIMER_NO_PRE_SI
+ *        By default when the system is not running on silicon the timeout
+ *        code will ignore the requested timeout. Specifying this flag will
+ *        override that behavior and honor the timeout regardless of platform.
+ *
+ *   o  NVGPU_TIMER_SILENT_TIMEOUT
+ *        Do not print any messages on timeout. Normally a simple message is
+ *        printed that specifies where the timeout occurred.
+ */
+struct nvgpu_timeout {
+        struct gk20a            *g;
+
+        unsigned int             flags;
+
+        union {
+                unsigned long    time;
+                struct {
+                        int      max;
+                        int      attempted;
+                } retries;
+        };
+};
+
+/*
+ * Bit 0 specifies the type of timer: CPU or retry.
+ */
+#define NVGPU_TIMER_CPU_TIMER           (0x0)
+#define NVGPU_TIMER_RETRY_TIMER         (0x1)
+
+/*
+ * Bits 1 through 7 are reserved; bits 8 and up are flags:
+ */
+#define NVGPU_TIMER_NO_PRE_SI           (0x1 << 8)
+#define NVGPU_TIMER_SILENT_TIMEOUT      (0x1 << 9)
+
+#define NVGPU_TIMER_FLAG_MASK           (NVGPU_TIMER_RETRY_TIMER |      \
+                                         NVGPU_TIMER_NO_PRE_SI |        \
+                                         NVGPU_TIMER_SILENT_TIMEOUT)
+
+int nvgpu_timeout_init(struct gk20a *g, struct nvgpu_timeout *timeout,
+                       int duration, unsigned long flags);
+int nvgpu_timeout_peek(struct nvgpu_timeout *timeout);
+
+#define nvgpu_timeout_check(__timeout)                                  \
+        __nvgpu_timeout_check_msg(__timeout,                            \
+                                  __builtin_return_address(0), "")
+
+#define nvgpu_timeout_check_msg(__timeout, fmt, args...)                \
+        __nvgpu_timeout_check_msg(__timeout,                            \
+                                  __builtin_return_address(0),          \
+                                  fmt, ##args)
+
+/*
+ * Don't use this directly.
+ */
+int __nvgpu_timeout_check_msg(struct nvgpu_timeout *timeout,
+                              void *caller, const char *fmt, ...);
+
+#endif