intel_th: msu-sink: An example msu buffer "sink"

This patch adds an example MSU buffer "sink", which consumes trace
data from MSC buffers.

Functionally, it acts similarly to "multi" mode with automatic window
switching.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20190705141425.19894-3-alexander.shishkin@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/intel_th/Makefile b/drivers/hwtracing/intel_th/Makefile
index d9252fa8d9ca19142bb72e808636de10006457fd..b63eb8f309ad116068b9f6ac1cf10d277a2cfed2 100644 (file)
--- a/drivers/hwtracing/intel_th/Makefile
+++ b/drivers/hwtracing/intel_th/Makefile
@@ -20,3 +20,6 @@ intel_th_msu-y                        := msu.o
 
 obj-$(CONFIG_INTEL_TH_PTI)     += intel_th_pti.o
 intel_th_pti-y                 := pti.o
+
+obj-$(CONFIG_INTEL_TH_MSU)     += intel_th_msu_sink.o
+intel_th_msu_sink-y            := msu-sink.o

diff --git a/drivers/hwtracing/intel_th/msu-sink.c b/drivers/hwtracing/intel_th/msu-sink.c
new file mode 100644 (file)
index 0000000..2c7f511
--- /dev/null
+++ b/drivers/hwtracing/intel_th/msu-sink.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * An example software sink buffer for Intel TH MSU.
+ *
+ * Copyright (C) 2019 Intel Corporation.
+ */
+
+#include <linux/intel_th.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+
+#define MAX_SGTS 16
+
+struct msu_sink_private {
+       struct device   *dev;
+       struct sg_table **sgts;
+       unsigned int    nr_sgts;
+};
+
+static void *msu_sink_assign(struct device *dev, int *mode)
+{
+       struct msu_sink_private *priv;
+
+       priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+       if (!priv)
+               return NULL;
+
+       priv->sgts = kcalloc(MAX_SGTS, sizeof(void *), GFP_KERNEL);
+       if (!priv->sgts) {
+               kfree(priv);
+               return NULL;
+       }
+
+       priv->dev = dev;
+       *mode = MSC_MODE_MULTI;
+
+       return priv;
+}
+
+static void msu_sink_unassign(void *data)
+{
+       struct msu_sink_private *priv = data;
+
+       kfree(priv->sgts);
+       kfree(priv);
+}
+
+/* See also: msc.c: __msc_buffer_win_alloc() */
+static int msu_sink_alloc_window(void *data, struct sg_table **sgt, size_t size)
+{
+       struct msu_sink_private *priv = data;
+       unsigned int nents;
+       struct scatterlist *sg_ptr;
+       void *block;
+       int ret, i;
+
+       if (priv->nr_sgts == MAX_SGTS)
+               return -ENOMEM;
+
+       nents = DIV_ROUND_UP(size, PAGE_SIZE);
+
+       ret = sg_alloc_table(*sgt, nents, GFP_KERNEL);
+       if (ret)
+               return -ENOMEM;
+
+       priv->sgts[priv->nr_sgts++] = *sgt;
+
+       for_each_sg((*sgt)->sgl, sg_ptr, nents, i) {
+               block = dma_alloc_coherent(priv->dev->parent->parent,
+                                          PAGE_SIZE, &sg_dma_address(sg_ptr),
+                                          GFP_KERNEL);
+               sg_set_buf(sg_ptr, block, PAGE_SIZE);
+       }
+
+       return nents;
+}
+
+/* See also: msc.c: __msc_buffer_win_free() */
+static void msu_sink_free_window(void *data, struct sg_table *sgt)
+{
+       struct msu_sink_private *priv = data;
+       struct scatterlist *sg_ptr;
+       int i;
+
+       for_each_sg(sgt->sgl, sg_ptr, sgt->nents, i) {
+               dma_free_coherent(priv->dev->parent->parent, PAGE_SIZE,
+                                 sg_virt(sg_ptr), sg_dma_address(sg_ptr));
+       }
+
+       sg_free_table(sgt);
+       priv->nr_sgts--;
+}
+
+static int msu_sink_ready(void *data, struct sg_table *sgt, size_t bytes)
+{
+       struct msu_sink_private *priv = data;
+
+       intel_th_msc_window_unlock(priv->dev, sgt);
+
+       return 0;
+}
+
+static const struct msu_buffer sink_mbuf = {
+       .name           = "sink",
+       .assign         = msu_sink_assign,
+       .unassign       = msu_sink_unassign,
+       .alloc_window   = msu_sink_alloc_window,
+       .free_window    = msu_sink_free_window,
+       .ready          = msu_sink_ready,
+};
+
+module_intel_th_msu_buffer(sink_mbuf);
+
+MODULE_LICENSE("GPL v2");