[PATCH 15/19] driver: add devm_request_mem_resource()

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

From: Ahmad Fatoum <a.fatoum@barebox.org>

Drivers using dev_request_mem_resource() have to release the region in
every later error path and on remove. Add a managed variant that does
this for them.

Assisted-by: Claude:opus-5-1m
Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 drivers/base/devres.c | 36 ++++++++++++++++++++++++++++++++++++
 include/driver.h      |  3 +++
 test/self/devres.c    | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 77 insertions(+)

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index bf118ae0820d..efc810a8898f 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -5,6 +5,7 @@
  * Managed resources are children of a per-device talloc context.
  */
 
+#include <barebox.h>
 #include <driver.h>
 #include <dma.h>
 #include <talloc.h>
@@ -168,3 +169,38 @@ int devm_add_action(struct device *dev, void (*action)(void *), void *data)
 	return talloc_add_destructor(ctx, action, data);
 }
 EXPORT_SYMBOL(devm_add_action);
+
+static void devm_region_release(void *res)
+{
+	/* No need to release regions when shutting down */
+	if (barebox_system_state == BAREBOX_EXITING)
+		return;
+
+	release_region(res);
+}
+
+/**
+ * devm_request_mem_resource() - exclusively request resource 'num' for a device
+ * @dev: device to request the memory resource for
+ * @num: index of the memory resource
+ *
+ * Like dev_request_mem_resource(), but device-managed.
+ *
+ * Return: the requested resource or an ERR_PTR() on failure.
+ */
+struct resource *devm_request_mem_resource(struct device *dev, int num)
+{
+	struct resource *res;
+	int ret;
+
+	res = dev_request_mem_resource(dev, num);
+	if (IS_ERR(res))
+		return res;
+
+	ret = devm_add_action_or_reset(dev, devm_region_release, res);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return res;
+}
+EXPORT_SYMBOL(devm_request_mem_resource);
diff --git a/include/driver.h b/include/driver.h
index c394c455b971..4005804bb1a9 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -193,6 +193,9 @@ struct resource *dev_request_mem_resource(struct device *dev, int num);
 struct resource *dev_request_mem_resource_by_name(struct device *dev,
 						  const char *name);
 
+/* Like dev_request_mem_resource(), but released when the device goes away */
+struct resource *devm_request_mem_resource(struct device *dev, int num);
+
 void __iomem *dev_platform_get_and_ioremap_resource(struct device *dev,
 						    int num,
 						    struct resource **out_res);
diff --git a/test/self/devres.c b/test/self/devres.c
index 4fdc71064b4a..6992eb20ace3 100644
--- a/test/self/devres.c
+++ b/test/self/devres.c
@@ -8,6 +8,7 @@
 #include <linux/bitmap.h>
 #include <driver.h>
 #include <linux/device.h>
+#include <linux/sizes.h>
 
 BSELFTEST_GLOBALS();
 
@@ -136,6 +137,42 @@ static void test_devres_shutdown(void)
 	free_device(dev);
 }
 
+static void test_devres_region(void)
+{
+	/* The last page of the address space, skipped if it's in use */
+	resource_size_t start = iomem_resource.end - SZ_4K + 1;
+	enum system_states state = barebox_system_state;
+	struct device *dev = device_alloc("devres-test", DEVICE_ID_DYNAMIC);
+	struct resource *res;
+
+	device_add_resource(dev, NULL, start, SZ_4K, IORESOURCE_MEM);
+	if (selftest_check(register_device(dev) == 0) == false)
+		return;
+
+	res = devm_request_mem_resource(dev, 0);
+	if (IS_ERR(res)) {
+		skipped_tests++;
+		goto out;
+	}
+
+	/* Shutdown keeps the region, but drops the action all the same */
+	barebox_system_state = BAREBOX_EXITING;
+	devres_run_actions(dev);
+	barebox_system_state = state;
+	if (selftest_check(IS_ERR(devm_request_mem_resource(dev, 0))))
+		release_region(res);
+
+	/* Releasing frees it */
+	selftest_check(!IS_ERR(devm_request_mem_resource(dev, 0)));
+	devres_release_all(dev);
+	res = request_iomem_region("devres-test", start, iomem_resource.end);
+	if (selftest_check(!IS_ERR(res)))
+		release_region(res);
+out:
+	unregister_device(dev);
+	free_device(dev);
+}
+
 static int probe_result;
 static char *probe_buf;
 
@@ -282,6 +319,7 @@ static void test_devres(void)
 	test_devres_alloc();
 	test_devres_action();
 	test_devres_shutdown();
+	test_devres_region();
 	test_devres_probe();
 	test_devres_unbind();
 	test_devres_child();
-- 
2.47.3