Re: [PATCH v9 2/7] coresight: tmc-etr: Add support to use reserved trace memory
From: Suzuki K Poulose
Date: Fri Jun 07 2024 - 11:58:23 EST
Hi Linu
On 05/06/2024 09:17, Linu Cherian wrote:
Add support to use reserved memory for coresight ETR trace buffer.
Introduce a new ETR buffer mode called ETR_MODE_RESRV, which
becomes available when ETR device tree node is supplied with a valid
reserved memory region.
ETR_MODE_RESRV can be selected only by explicit user request.
$ echo resrv >/sys/bus/coresight/devices/tmc_etr<N>/buf_mode_preferred
Signed-off-by: Anil Kumar Reddy <areddy3@xxxxxxxxxxx>
Signed-off-by: Linu Cherian <lcherian@xxxxxxxxxxx>
Reviewed-by: James Clark <james.clark@xxxxxxx>
Some minor comments below.
---
Changelog from v8:
Added Reviewed-by tag.
.../hwtracing/coresight/coresight-tmc-core.c | 47 +++++++++++
.../hwtracing/coresight/coresight-tmc-etr.c | 79 +++++++++++++++++++
drivers/hwtracing/coresight/coresight-tmc.h | 27 +++++++
3 files changed, 153 insertions(+)
diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index 741ce1748e75..6beb69d74d0a 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
@@ -23,6 +23,7 @@
#include <linux/spinlock.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
+#include <linux/of_address.h>
#include <linux/coresight.h>
#include <linux/amba/bus.h>
#include <linux/platform_device.h>
@@ -400,6 +401,50 @@ static inline bool tmc_etr_has_non_secure_access(struct tmc_drvdata *drvdata)
static const struct amba_id tmc_ids[];
+static struct device_node *tmc_get_region_byname(struct device_node *node,
+ char *name)
+{
+ int index;
+
+ index = of_property_match_string(node, "memory-region-names", name);
+ if (index < 0)
+ return ERR_PTR(-ENODEV);
+
+ return of_parse_phandle(node, "memory-region", index);
+}
+
+static void tmc_get_reserved_region(struct device *parent)
+{
+ struct tmc_drvdata *drvdata = dev_get_drvdata(parent);
+ struct device_node *node;
+ struct resource res;
+ int rc;
+
+ node = tmc_get_region_byname(parent->of_node, "tracedata");
+ if (IS_ERR_OR_NULL(node)) {
+ dev_dbg(parent, "No reserved trace buffer specified\n");
+ return;
+ }
+
+ rc = of_address_to_resource(node, 0, &res);
This sequence is repeated again in the metadat area, where :
1. We get region by name.
2. Read the resource details.
Could we not make "the helper" do both and move the "of_node_put()"
inside the helper ?
static int of_tmc_get_reserved_resource_by_name(struct device *dev,
const char *name,
struct resource *res)
{
> + int index, rc = -ENODEV;
> + struct device_node *node;
if (!is_of_node(dev_fwnode(dev->fwnode)))
return -ENODEV;
> +
> + index = of_property_match_string(dev->of_node,
"memory-region-names", name);
> + if (index < 0)
> + return rc;
> +
> + node = of_parse_phandle(node, "memory-region", index);
if (!node)
return rc;
if (!of_address_to_resource(node, 0, res) &&
res->start != 0 && resource_size(res) != 0)
rc = 0;
of_node_put(node);
return rc;
}
+ of_node_put(node);
+ if (rc || res.start == 0 || resource_size(&res) == 0) {
+ dev_err(parent, "Reserved trace buffer memory is invalid\n");
+ return;
+ }
and the caller does :
if (of_tmc_get_reserved_area_by_name(parent, "tracedata", &res))
return;
+
+ drvdata->crash_tbuf.vaddr = memremap(res.start,
+ resource_size(&res),
+ MEMREMAP_WC);
+ if (IS_ERR_OR_NULL(drvdata->crash_tbuf.vaddr)) {
+ dev_err(parent, "Reserved trace buffer mapping failed\n");
+ return;
+ }
+
+ drvdata->crash_tbuf.paddr = res.start;
+ drvdata->crash_tbuf.size = resource_size(&res);
+}
+
/* Detect and initialise the capabilities of a TMC ETR */
static int tmc_etr_setup_caps(struct device *parent, u32 devid,
struct csdev_access *access)
@@ -510,6 +555,8 @@ static int __tmc_probe(struct device *dev, struct resource *res)
drvdata->size = readl_relaxed(drvdata->base + TMC_RSZ) * 4;
}
+ tmc_get_reserved_region(dev);
+
desc.dev = dev;
switch (drvdata->config_type) {
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index e75428fa1592..041c428dd7cd 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -30,6 +30,7 @@ struct etr_buf_hw {
bool has_iommu;
bool has_etr_sg;
bool has_catu;
+ bool has_resrv;
};
/*
@@ -694,6 +695,75 @@ static const struct etr_buf_operations etr_flat_buf_ops = {
.get_data = tmc_etr_get_data_flat_buf,
};
+/*
+ * tmc_etr_alloc_resrv_buf: Allocate a contiguous DMA buffer from reserved region.
+ */
+static int tmc_etr_alloc_resrv_buf(struct tmc_drvdata *drvdata,
+ struct etr_buf *etr_buf, int node,
+ void **pages)
+{
+ struct etr_flat_buf *resrv_buf;
+ struct device *real_dev = drvdata->csdev->dev.parent;
+
+ /* We cannot reuse existing pages for resrv buf */
+ if (pages)
+ return -EINVAL;
+
+ resrv_buf = kzalloc(sizeof(*resrv_buf), GFP_KERNEL);
+ if (!resrv_buf)
+ return -ENOMEM;
+
+ resrv_buf->daddr = dma_map_resource(real_dev, drvdata->crash_tbuf.paddr,
+ drvdata->crash_tbuf.size,
+ DMA_FROM_DEVICE, 0);
+ if (dma_mapping_error(real_dev, resrv_buf->daddr)) {
+ dev_err(real_dev, "failed to map source buffer address\n");
+ kfree(resrv_buf);
+ return -ENOMEM;
+ }
+
+ resrv_buf->vaddr = drvdata->crash_tbuf.vaddr;
+ resrv_buf->size = etr_buf->size = drvdata->crash_tbuf.size;
+ resrv_buf->dev = &drvdata->csdev->dev;
+ etr_buf->hwaddr = resrv_buf->daddr;
+ etr_buf->mode = ETR_MODE_RESRV;
+ etr_buf->private = resrv_buf;
+ return 0;
+}
+
+static void tmc_etr_free_resrv_buf(struct etr_buf *etr_buf)
+{
+ struct etr_flat_buf *resrv_buf = etr_buf->private;
+
+ if (resrv_buf && resrv_buf->daddr) {
+ struct device *real_dev = resrv_buf->dev->parent;
+
+ dma_unmap_resource(real_dev, resrv_buf->daddr,
+ resrv_buf->size, DMA_FROM_DEVICE, 0);
+ }
+ kfree(resrv_buf);
+}
+
+static void tmc_etr_sync_resrv_buf(struct etr_buf *etr_buf, u64 rrp, u64 rwp)
+{
+ /*
+ * Adjust the buffer to point to the beginning of the trace data
+ * and update the available trace data.
+ */
+ etr_buf->offset = rrp - etr_buf->hwaddr;
+ if (etr_buf->full)
+ etr_buf->len = etr_buf->size;
+ else
+ etr_buf->len = rwp - rrp;
+}
+
+static const struct etr_buf_operations etr_resrv_buf_ops = {
+ .alloc = tmc_etr_alloc_resrv_buf,
+ .free = tmc_etr_free_resrv_buf,
+ .sync = tmc_etr_sync_resrv_buf,
+ .get_data = tmc_etr_get_data_flat_buf,
+};
+
/*
* tmc_etr_alloc_sg_buf: Allocate an SG buf @etr_buf. Setup the parameters
* appropriately.
@@ -800,6 +870,7 @@ static const struct etr_buf_operations *etr_buf_ops[] = {
[ETR_MODE_FLAT] = &etr_flat_buf_ops,
[ETR_MODE_ETR_SG] = &etr_sg_buf_ops,
[ETR_MODE_CATU] = NULL,
+ [ETR_MODE_RESRV] = &etr_resrv_buf_ops
};
void tmc_etr_set_catu_ops(const struct etr_buf_operations *catu)
@@ -825,6 +896,7 @@ static inline int tmc_etr_mode_alloc_buf(int mode,
case ETR_MODE_FLAT:
case ETR_MODE_ETR_SG:
case ETR_MODE_CATU:
+ case ETR_MODE_RESRV:
if (etr_buf_ops[mode] && etr_buf_ops[mode]->alloc)
rc = etr_buf_ops[mode]->alloc(drvdata, etr_buf,
node, pages);
@@ -843,6 +915,7 @@ static void get_etr_buf_hw(struct device *dev, struct etr_buf_hw *buf_hw)
buf_hw->has_iommu = iommu_get_domain_for_dev(dev->parent);
buf_hw->has_etr_sg = tmc_etr_has_cap(drvdata, TMC_ETR_SG);
buf_hw->has_catu = !!tmc_etr_get_catu_device(drvdata);
+ buf_hw->has_resrv = is_tmc_reserved_region_valid(dev->parent);
Minor nit: In line with the other helpers, please could we rename this to :
tmc_has_reserved_buffer(drvdata) ?
We already have access to drvdata and we can pass that directly instead
of passing the dev->parent and then fetch drvdata again.
}
static bool etr_can_use_flat_mode(struct etr_buf_hw *buf_hw, ssize_t etr_buf_size)
@@ -1830,6 +1903,7 @@ static const char *const buf_modes_str[] = {
[ETR_MODE_FLAT] = "flat",
[ETR_MODE_ETR_SG] = "tmc-sg",
[ETR_MODE_CATU] = "catu",
+ [ETR_MODE_RESRV] = "resrv",
[ETR_MODE_AUTO] = "auto",
};
@@ -1848,6 +1922,9 @@ static ssize_t buf_modes_available_show(struct device *dev,
if (buf_hw.has_catu)
size += sysfs_emit_at(buf, size, "%s ", buf_modes_str[ETR_MODE_CATU]);
+ if (buf_hw.has_resrv)
+ size += sysfs_emit_at(buf, size, "%s ", buf_modes_str[ETR_MODE_RESRV]);
+
size += sysfs_emit_at(buf, size, "\n");
return size;
}
@@ -1875,6 +1952,8 @@ static ssize_t buf_mode_preferred_store(struct device *dev,
drvdata->etr_mode = ETR_MODE_ETR_SG;
else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_CATU]) && buf_hw.has_catu)
drvdata->etr_mode = ETR_MODE_CATU;
+ else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_RESRV]) && buf_hw.has_resrv)
+ drvdata->etr_mode = ETR_MODE_RESRV;
else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_AUTO]))
drvdata->etr_mode = ETR_MODE_AUTO;
else
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index c77763b49de0..c23dc9917ab9 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -135,6 +135,7 @@ enum etr_mode {
ETR_MODE_FLAT, /* Uses contiguous flat buffer */
ETR_MODE_ETR_SG, /* Uses in-built TMC ETR SG mechanism */
ETR_MODE_CATU, /* Use SG mechanism in CATU */
+ ETR_MODE_RESRV, /* Use reserved region contiguous buffer */
ETR_MODE_AUTO, /* Use the default mechanism */
};
@@ -164,6 +165,17 @@ struct etr_buf {
void *private;
};
+/**
+ * @paddr : Start address of reserved memory region.
+ * @vaddr : Corresponding CPU virtual address.
+ * @size : Size of reserved memory region.
+ */
+struct tmc_resrv_buf {
+ phys_addr_t paddr;
+ void *vaddr;
+ size_t size;
+};
+
/**
* struct tmc_drvdata - specifics associated to an TMC component
* @pclk: APB clock if present, otherwise NULL
@@ -188,6 +200,10 @@ struct etr_buf {
* @idr_mutex: Access serialisation for idr.
* @sysfs_buf: SYSFS buffer for ETR.
* @perf_buf: PERF buffer for ETR.
+ * @crash_tbuf: Used by ETR as hardware trace buffer and for trace data
+ * retention (after crash) only when ETR_MODE_RESRV buffer
+ * mode is enabled. Used by ETF for trace data retention
+ * (after crash) by default.
Minor nit: This need not be called crash_tbuf, could instead be
resrv_buf as we use it everywhere.
Suzuki
*/
struct tmc_drvdata {
struct clk *pclk;
@@ -213,6 +229,7 @@ struct tmc_drvdata {
struct mutex idr_mutex;
struct etr_buf *sysfs_buf;
struct etr_buf *perf_buf;
+ struct tmc_resrv_buf crash_tbuf;
};
struct etr_buf_operations {
@@ -330,6 +347,16 @@ tmc_sg_table_buf_size(struct tmc_sg_table *sg_table)
return (unsigned long)sg_table->data_pages.nr_pages << PAGE_SHIFT;
}
+static inline bool is_tmc_reserved_region_valid(struct device *dev)
+{
+ struct tmc_drvdata *drvdata = dev_get_drvdata(dev);
+
+ if (drvdata->crash_tbuf.paddr &&
+ drvdata->crash_tbuf.size)
+ return true;
+ return false;
+}
+
struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);
void tmc_etr_set_catu_ops(const struct etr_buf_operations *catu);