coresight: tmc-etr buf: Add TMC scatter gather mode backend

Add the support for Scatter-Gather mode to the etr-buf layer.
Since we now have two different modes, we choose the backend
based on a set of conditions, documented in the code.

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>

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index fba659d..6164eed 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -516,7 +516,7 @@ static void tmc_etr_sg_table_populate(struct etr_sg_table *etr_table)
  * @size       - Total size of the data buffer
  * @pages      - Optional list of page virtual address
  */
-static struct etr_sg_table __maybe_unused *
+static struct etr_sg_table *
 tmc_init_etr_sg_table(struct device *dev, int node,
                      unsigned long size, void **pages)
 {
@@ -623,8 +623,86 @@ static const struct etr_buf_operations etr_flat_buf_ops = {
        .get_data = tmc_etr_get_data_flat_buf,
 };
 
+/*
+ * tmc_etr_alloc_sg_buf: Allocate an SG buf @etr_buf. Setup the parameters
+ * appropriately.
+ */
+static int tmc_etr_alloc_sg_buf(struct tmc_drvdata *drvdata,
+                               struct etr_buf *etr_buf, int node,
+                               void **pages)
+{
+       struct etr_sg_table *etr_table;
+
+       etr_table = tmc_init_etr_sg_table(drvdata->dev, node,
+                                         etr_buf->size, pages);
+       if (IS_ERR(etr_table))
+               return -ENOMEM;
+       etr_buf->hwaddr = etr_table->hwaddr;
+       etr_buf->mode = ETR_MODE_ETR_SG;
+       etr_buf->private = etr_table;
+       return 0;
+}
+
+static void tmc_etr_free_sg_buf(struct etr_buf *etr_buf)
+{
+       struct etr_sg_table *etr_table = etr_buf->private;
+
+       if (etr_table) {
+               tmc_free_sg_table(etr_table->sg_table);
+               kfree(etr_table);
+       }
+}
+
+static ssize_t tmc_etr_get_data_sg_buf(struct etr_buf *etr_buf, u64 offset,
+                                      size_t len, char **bufpp)
+{
+       struct etr_sg_table *etr_table = etr_buf->private;
+
+       return tmc_sg_table_get_data(etr_table->sg_table, offset, len, bufpp);
+}
+
+static void tmc_etr_sync_sg_buf(struct etr_buf *etr_buf, u64 rrp, u64 rwp)
+{
+       long r_offset, w_offset;
+       struct etr_sg_table *etr_table = etr_buf->private;
+       struct tmc_sg_table *table = etr_table->sg_table;
+
+       /* Convert hw address to offset in the buffer */
+       r_offset = tmc_sg_get_data_page_offset(table, rrp);
+       if (r_offset < 0) {
+               dev_warn(table->dev,
+                        "Unable to map RRP %llx to offset\n", rrp);
+               etr_buf->len = 0;
+               return;
+       }
+
+       w_offset = tmc_sg_get_data_page_offset(table, rwp);
+       if (w_offset < 0) {
+               dev_warn(table->dev,
+                        "Unable to map RWP %llx to offset\n", rwp);
+               etr_buf->len = 0;
+               return;
+       }
+
+       etr_buf->offset = r_offset;
+       if (etr_buf->full)
+               etr_buf->len = etr_buf->size;
+       else
+               etr_buf->len = ((w_offset < r_offset) ? etr_buf->size : 0) +
+                               w_offset - r_offset;
+       tmc_sg_table_sync_data_range(table, r_offset, etr_buf->len);
+}
+
+static const struct etr_buf_operations etr_sg_buf_ops = {
+       .alloc = tmc_etr_alloc_sg_buf,
+       .free = tmc_etr_free_sg_buf,
+       .sync = tmc_etr_sync_sg_buf,
+       .get_data = tmc_etr_get_data_sg_buf,
+};
+
 static const struct etr_buf_operations *etr_buf_ops[] = {
        [ETR_MODE_FLAT] = &etr_flat_buf_ops,
+       [ETR_MODE_ETR_SG] = &etr_sg_buf_ops,
 };
 
 static inline int tmc_etr_mode_alloc_buf(int mode,
@@ -636,6 +714,7 @@ static inline int tmc_etr_mode_alloc_buf(int mode,
 
        switch (mode) {
        case ETR_MODE_FLAT:
+       case ETR_MODE_ETR_SG:
                rc = etr_buf_ops[mode]->alloc(drvdata, etr_buf, node, pages);
                if (!rc)
                        etr_buf->ops = etr_buf_ops[mode];
@@ -657,17 +736,38 @@ static struct etr_buf *tmc_alloc_etr_buf(struct tmc_drvdata *drvdata,
                                         ssize_t size, int flags,
                                         int node, void **pages)
 {
-       int rc = 0;
+       int rc = -ENOMEM;
+       bool has_etr_sg, has_iommu;
        struct etr_buf *etr_buf;
 
+       has_etr_sg = tmc_etr_has_cap(drvdata, TMC_ETR_SG);
+       has_iommu = iommu_get_domain_for_dev(drvdata->dev);
+
        etr_buf = kzalloc(sizeof(*etr_buf), GFP_KERNEL);
        if (!etr_buf)
                return ERR_PTR(-ENOMEM);
 
        etr_buf->size = size;
 
-       rc = tmc_etr_mode_alloc_buf(ETR_MODE_FLAT, drvdata,
-                                   etr_buf, node, pages);
+       /*
+        * If we have to use an existing list of pages, we cannot reliably
+        * use a contiguous DMA memory (even if we have an IOMMU). Otherwise,
+        * we use the contiguous DMA memory if at least one of the following
+        * conditions is true:
+        *  a) The ETR cannot use Scatter-Gather.
+        *  b) we have a backing IOMMU
+        *  c) The requested memory size is smaller (< 1M).
+        *
+        * Fallback to available mechanisms.
+        *
+        */
+       if (!pages &&
+           (!has_etr_sg || has_iommu || size < SZ_1M))
+               rc = tmc_etr_mode_alloc_buf(ETR_MODE_FLAT, drvdata,
+                                           etr_buf, node, pages);
+       if (rc && has_etr_sg)
+               rc = tmc_etr_mode_alloc_buf(ETR_MODE_ETR_SG, drvdata,
+                                           etr_buf, node, pages);
        if (rc) {
                kfree(etr_buf);
                return ERR_PTR(rc);
@@ -761,6 +861,12 @@ static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
                axictl |= TMC_AXICTL_ARCACHE_OS;
        }
 
+       if (etr_buf->mode == ETR_MODE_ETR_SG) {
+               if (WARN_ON(!tmc_etr_has_cap(drvdata, TMC_ETR_SG)))
+                       return;
+               axictl |= TMC_AXICTL_SCT_GAT_MODE;
+       }
+
        writel_relaxed(axictl, drvdata->base + TMC_AXICTL);
        tmc_write_dba(drvdata, etr_buf->hwaddr);
        /*

diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index bbd65e2..e745657 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -125,6 +125,7 @@ enum tmc_mem_intf_width {
 
 enum etr_mode {
        ETR_MODE_FLAT,          /* Uses contiguous flat buffer */
+       ETR_MODE_ETR_SG,        /* Uses in-built TMC ETR SG mechanism */
 };
 
 struct etr_buf_operations;