This patch adds an example "sink" MSU buffer driver, which consumes trace data from MSC buffers.
Functionally, it acts similarly to "multi" mode with automatic window switching. Signed-off-by: Alexander Shishkin <[email protected]> --- drivers/hwtracing/intel_th/Makefile | 3 + drivers/hwtracing/intel_th/msu-sink.c | 137 ++++++++++++++++++++++++++ 2 files changed, 140 insertions(+) create mode 100644 drivers/hwtracing/intel_th/msu-sink.c diff --git a/drivers/hwtracing/intel_th/Makefile b/drivers/hwtracing/intel_th/Makefile index d9252fa8d9ca..b63eb8f309ad 100644 --- 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 index 000000000000..1a7949a282c3 --- /dev/null +++ b/drivers/hwtracing/intel_th/msu-sink.c @@ -0,0 +1,137 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * An example software sink buffer driver 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> + +static unsigned int block_order; + +module_param(block_order, int, 0600); + +#define MAX_SGTS 16 + +struct msu_sink_private { + struct device *dev; + struct sg_table **sgts; + unsigned int nr_sgts; + unsigned int block_order; +}; + +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 = kzalloc(sizeof(void *) * MAX_SGTS, GFP_KERNEL); + if (!priv->sgts) { + kfree(priv); + return NULL; + } + + priv->dev = dev; + priv->block_order = block_order; + *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 << priv->block_order); + + 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 << priv->block_order, + &sg_dma_address(sg_ptr), + GFP_KERNEL); + sg_set_buf(sg_ptr, block, PAGE_SIZE << priv->block_order); + if (priv->block_order) + split_page(virt_to_page(block), priv->block_order); + } + + 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 << priv->block_order, + 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_driver sink_bdrv = { + .name = "sink", + .owner = THIS_MODULE, + .assign = msu_sink_assign, + .unassign = msu_sink_unassign, + .alloc_window = msu_sink_alloc_window, + .free_window = msu_sink_free_window, + .ready = msu_sink_ready, +}; + +static int msu_sink_init(void) +{ + return intel_th_msu_buffer_register(&sink_bdrv); +} +module_init(msu_sink_init); + +static void msu_sink_exit(void) +{ + intel_th_msu_buffer_unregister(&sink_bdrv); +} +module_exit(msu_sink_exit); + +MODULE_LICENSE("GPL v2"); -- 2.20.1
