coresight: Add generic TMC sg table framework

This patch introduces a generic sg table data structure and
associated operations. An SG table can be used to map a set
of Data pages where the trace data could be stored by the TMC
ETR. The information about the data pages could be stored in
different formats, depending on the type of the underlying
SG mechanism (e.g, TMC ETR SG vs Coresight CATU). The generic
structure provides book keeping of the pages used for the data
as well as the table contents. The table should be filled by
the user of the infrastructure.

A table can be created by specifying the number of data pages
as well as the number of table pages required to hold the
pointers, where the latter could be different for different
types of tables. The pages are mapped in the appropriate dma
data direction mode (i.e, DMA_TO_DEVICE for table pages
and DMA_FROM_DEVICE for data pages).  The framework can optionally
accept a set of allocated data pages (e.g, perf ring buffer) and
map them accordingly. The table and data pages are vmap'ed to allow
easier access by the drivers. The framework also provides helpers to
sync the data written to the pages with appropriate directions.

This will be later used by the TMC ETR SG unit and CATU.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 50 insertions, 0 deletions

diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index 1d7cd582919b..cdb668b4441d 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -7,6 +7,7 @@
 #ifndef _CORESIGHT_TMC_H
 #define _CORESIGHT_TMC_H
 
+#include <linux/dma-mapping.h>
 #include <linux/miscdevice.h>
 
 #define TMC_RSZ			0x004
@@ -160,6 +161,38 @@ struct tmc_drvdata {
 	u32			etr_caps;
 };
 
+/**
+ * struct tmc_pages - Collection of pages used for SG.
+ * @nr_pages:		Number of pages in the list.
+ * @daddrs:		Array of DMA'able page address.
+ * @pages:		Array pages for the buffer.
+ */
+struct tmc_pages {
+	int nr_pages;
+	dma_addr_t	*daddrs;
+	struct page	**pages;
+};
+
+/*
+ * struct tmc_sg_table - Generic SG table for TMC
+ * @dev:		Device for DMA allocations
+ * @table_vaddr:	Contiguous Virtual address for PageTable
+ * @data_vaddr:		Contiguous Virtual address for Data Buffer
+ * @table_daddr:	DMA address of the PageTable base
+ * @node:		Node for Page allocations
+ * @table_pages:	List of pages & dma address for Table
+ * @data_pages:		List of pages & dma address for Data
+ */
+struct tmc_sg_table {
+	struct device *dev;
+	void *table_vaddr;
+	void *data_vaddr;
+	dma_addr_t table_daddr;
+	int node;
+	struct tmc_pages table_pages;
+	struct tmc_pages data_pages;
+};
+
 /* Generic functions */
 void tmc_wait_for_tmcready(struct tmc_drvdata *drvdata);
 void tmc_flush_and_stop(struct tmc_drvdata *drvdata);
@@ -215,4 +248,21 @@ static inline bool tmc_etr_has_cap(struct tmc_drvdata *drvdata, u32 cap)
 	return !!(drvdata->etr_caps & cap);
 }
 
+struct tmc_sg_table *tmc_alloc_sg_table(struct device *dev,
+					int node,
+					int nr_tpages,
+					int nr_dpages,
+					void **pages);
+void tmc_free_sg_table(struct tmc_sg_table *sg_table);
+void tmc_sg_table_sync_table(struct tmc_sg_table *sg_table);
+void tmc_sg_table_sync_data_range(struct tmc_sg_table *table,
+				  u64 offset, u64 size);
+ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table,
+			      u64 offset, size_t len, char **bufpp);
+static inline unsigned long
+tmc_sg_table_buf_size(struct tmc_sg_table *sg_table)
+{
+	return sg_table->data_pages.nr_pages << PAGE_SHIFT;
+}
+
 #endif