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>

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);
+}