Re: [PATCH] perf/arm-cmn: Fix and refactor device mapping resource

From: Robin Murphy
Date: Mon Mar 27 2023 - 10:28:46 EST


On 2023-03-27 15:05, Will Deacon wrote:
[+Robin and Ilkka, as they contribute most to this driver]

On Thu, Feb 16, 2023 at 04:17:50PM +0800, Jing Zhang wrote:
The devm_platform_ioremap_resource() won't let the platform device
claim resource when the ACPI companion device has already claimed it.
If CMN-ANY except CMN600 is ACPI companion device, it will return
-EBUSY in devm_platform_ioremap_resource(), and the driver cannot be
successfully installed.

So let ACPI companion device call arm_cmn_acpi_probe and not claim
resource again. In addition, the arm_cmn_acpi_probe() and
arm_cmn_of_probe() functions are refactored to make them compatible
with both CMN600 and CMN-ANY.

No, the whole point of CMN-600 probing being a special case is that the ACPI and DT bindings for CMN-600 are special cases. In ACPI, only ARMHC600 has the two nested memory resources; all the other models should only have one memory resource because one is all that is meaningful. See table 16 the document[1] in where the description of ROOTNODEBASE says "This field is specific to the CMN-600 device object."

Similarly in DT, "arm,root-node" is only required for "arm,cmn-600" - it didn't seem worth overcomplicating the schema to actively disallow it for other models, but that is supposed to be implied by its description as "not relevant for newer CMN/CI products".

If you're hitting this because you've written your ACPI DSDT incorrectly, it's a sign that you should fix your DSDT.

Thanks,
Robin.

[1] https://developer.arm.com/documentation/den0093/latest/

Fixes: 61ec1d875812 ("perf/arm-cmn: Demarcate CMN-600 specifics")
Signed-off-by: Jing Zhang <renyu.zj@xxxxxxxxxxxxxxxxx>
---
drivers/perf/arm-cmn.c | 57 ++++++++++++++++++++++++++++++++------------------
1 file changed, 37 insertions(+), 20 deletions(-)

diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index 1deb61b..beb3b37 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -2206,7 +2206,7 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
return 0;
}
-static int arm_cmn600_acpi_probe(struct platform_device *pdev, struct arm_cmn *cmn)
+static int arm_cmn_acpi_probe(struct platform_device *pdev, struct arm_cmn *cmn)
{
struct resource *cfg, *root;
@@ -2214,12 +2214,21 @@ static int arm_cmn600_acpi_probe(struct platform_device *pdev, struct arm_cmn *c
if (!cfg)
return -EINVAL;
- root = platform_get_resource(pdev, IORESOURCE_MEM, 1);
- if (!root)
- return -EINVAL;
+ /* If ACPI defines more than one resource, such as cmn-600, then there may be
+ * a deviation between ROOTNODEBASE and PERIPHBASE, and ROOTNODEBASE can
+ * be obtained from the second resource. Otherwise, it can be considered that
+ * ROOT NODE BASE is PERIPHBASE. This is compatible with cmn-600 and cmn-any.
+ */
+ if (pdev->num_resources > 1) {
+ root = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+ if (!root)
+ return -EINVAL;
- if (!resource_contains(cfg, root))
- swap(cfg, root);
+ if (!resource_contains(cfg, root))
+ swap(cfg, root);
+ } else {
+ root = cfg;
+ }
/*
* Note that devm_ioremap_resource() is dumb and won't let the platform
* device claim cfg when the ACPI companion device has already claimed
@@ -2227,17 +2236,30 @@ static int arm_cmn600_acpi_probe(struct platform_device *pdev, struct arm_cmn *c
* appropriate name, we don't really need to do it again here anyway.
*/
cmn->base = devm_ioremap(cmn->dev, cfg->start, resource_size(cfg));
- if (!cmn->base)
- return -ENOMEM;
+ if (IS_ERR(cmn->base))
+ return PTR_ERR(cmn->base);
return root->start - cfg->start;
}
-static int arm_cmn600_of_probe(struct device_node *np)
+static int arm_cmn_of_probe(struct platform_device *pdev, struct arm_cmn *cmn)
{
u32 rootnode;
+ int ret;
+
+ cmn->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(cmn->base))
+ return PTR_ERR(cmn->base);
- return of_property_read_u32(np, "arm,root-node", &rootnode) ?: rootnode;
+ /* If of_property_read_u32() return EINVAL, it means that device tree has
+ * not define root-node, and root-node will return 0, which is compatible
+ * with cmn-600 and cmn-any.
+ */
+ ret = of_property_read_u32(pdev->dev.of_node, "arm,root-node", &rootnode);
+ if (ret == -EINVAL)
+ return 0;
+
+ return rootnode;
}
static int arm_cmn_probe(struct platform_device *pdev)
@@ -2255,16 +2277,11 @@ static int arm_cmn_probe(struct platform_device *pdev)
cmn->model = (unsigned long)device_get_match_data(cmn->dev);
platform_set_drvdata(pdev, cmn);
- if (cmn->model == CMN600 && has_acpi_companion(cmn->dev)) {
- rootnode = arm_cmn600_acpi_probe(pdev, cmn);
- } else {
- rootnode = 0;
- cmn->base = devm_platform_ioremap_resource(pdev, 0);
- if (IS_ERR(cmn->base))
- return PTR_ERR(cmn->base);
- if (cmn->model == CMN600)
- rootnode = arm_cmn600_of_probe(pdev->dev.of_node);
- }
+ if (has_acpi_companion(cmn->dev))
+ rootnode = arm_cmn_acpi_probe(pdev, cmn);
+ else
+ rootnode = arm_cmn_of_probe(pdev, cmn);
+
if (rootnode < 0)
return rootnode;
--
1.8.3.1