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Subject[PATCH] devres: keep both device name and resource name in pretty name
Date
From: Vladimir Oltean <vladimir.oltean@nxp.com>

Some device drivers have many memory regions, and sometimes debugging is
easiest using devmem on its register map. Take for example a networking
switch. Its memory map used to look like this in /proc/iomem:

1fc000000-1fc3fffff : pcie@1f0000000
1fc000000-1fc3fffff : 0000:00:00.5
1fc010000-1fc01ffff : sys
1fc030000-1fc03ffff : rew
1fc060000-1fc0603ff : s2
1fc070000-1fc0701ff : devcpu_gcb
1fc080000-1fc0800ff : qs
1fc090000-1fc0900cb : ptp
1fc100000-1fc10ffff : port0
1fc110000-1fc11ffff : port1
1fc120000-1fc12ffff : port2
1fc130000-1fc13ffff : port3
1fc140000-1fc14ffff : port4
1fc150000-1fc15ffff : port5
1fc200000-1fc21ffff : qsys
1fc280000-1fc28ffff : ana

But after said patch, the information is now presented in a much more
opaque way:

1fc000000-1fc3fffff : pcie@1f0000000
1fc000000-1fc3fffff : 0000:00:00.5
1fc010000-1fc01ffff : 0000:00:00.5
1fc030000-1fc03ffff : 0000:00:00.5
1fc060000-1fc0603ff : 0000:00:00.5
1fc070000-1fc0701ff : 0000:00:00.5
1fc080000-1fc0800ff : 0000:00:00.5
1fc090000-1fc0900cb : 0000:00:00.5
1fc100000-1fc10ffff : 0000:00:00.5
1fc110000-1fc11ffff : 0000:00:00.5
1fc120000-1fc12ffff : 0000:00:00.5
1fc130000-1fc13ffff : 0000:00:00.5
1fc140000-1fc14ffff : 0000:00:00.5
1fc150000-1fc15ffff : 0000:00:00.5
1fc200000-1fc21ffff : 0000:00:00.5
1fc280000-1fc28ffff : 0000:00:00.5

It is a fair comment that /proc/iomem might be confusing when it shows
resources without an associated device, but we can do better than just
hide the resource name altogether. Namely, we can print the device
name _and_ the resource name. Like this:

1fc000000-1fc3fffff : pcie@1f0000000
1fc000000-1fc3fffff : 0000:00:00.5
1fc010000-1fc01ffff : 0000:00:00.5 sys
1fc030000-1fc03ffff : 0000:00:00.5 rew
1fc060000-1fc0603ff : 0000:00:00.5 s2
1fc070000-1fc0701ff : 0000:00:00.5 devcpu_gcb
1fc080000-1fc0800ff : 0000:00:00.5 qs
1fc090000-1fc0900cb : 0000:00:00.5 ptp
1fc100000-1fc10ffff : 0000:00:00.5 port0
1fc110000-1fc11ffff : 0000:00:00.5 port1
1fc120000-1fc12ffff : 0000:00:00.5 port2
1fc130000-1fc13ffff : 0000:00:00.5 port3
1fc140000-1fc14ffff : 0000:00:00.5 port4
1fc150000-1fc15ffff : 0000:00:00.5 port5
1fc200000-1fc21ffff : 0000:00:00.5 qsys
1fc280000-1fc28ffff : 0000:00:00.5 ana

Fixes: 8d84b18f5678 ("devres: always use dev_name() in devm_ioremap_resource()")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
lib/devres.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/devres.c b/lib/devres.c
index 6ef51f159c54..25b78b0cb5cc 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -119,6 +119,7 @@ __devm_ioremap_resource(struct device *dev, const struct resource *res,
{
resource_size_t size;
void __iomem *dest_ptr;
+ char *pretty_name;

BUG_ON(!dev);

@@ -129,7 +130,16 @@ __devm_ioremap_resource(struct device *dev, const struct resource *res,

size = resource_size(res);

- if (!devm_request_mem_region(dev, res->start, size, dev_name(dev))) {
+ if (res->name) {
+ int len = strlen(dev_name(dev)) + strlen(res->name) + 2;
+
+ pretty_name = devm_kzalloc(dev, len, GFP_KERNEL);
+ sprintf(pretty_name, "%s %s", dev_name(dev), res->name);
+ } else {
+ pretty_name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL);
+ }
+
+ if (!devm_request_mem_region(dev, res->start, size, pretty_name)) {
dev_err(dev, "can't request region for resource %pR\n", res);
return IOMEM_ERR_PTR(-EBUSY);
}
--
2.25.1
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