linux-kernel - [PATCH v1 1/7] auxdisplay: arm-charlcd: convert to use device managed APIs

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Message-ID: <20251229142349.1251843-2-andriy.shevchenko@linux.intel.com>
Date: Mon, 29 Dec 2025 14:52:34 +0100
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Cc: Andy Shevchenko <andy@...nel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH v1 1/7] auxdisplay: arm-charlcd: convert to use device managed APIs

The current probe function of the driver is implemented by using
plain old APIs. As Geert noted, one of the error paths has a mistake
that may lead to a wrong call. Instead of targeting that particular
issue, convert the driver to use device managed APIs altogether.
It's not needed per se (driver can never be removed once loaded),
but it simplifies coding and error handling.

Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Closes: https://lore.kernel.org/r/CAMuHMdVquNEoxRQkcBEH0nC+CDuib6o0H6m3CBk3ZN2267LpQw@mail.gmail.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/auxdisplay/arm-charlcd.c | 49 ++++++--------------------------
 1 file changed, 9 insertions(+), 40 deletions(-)

diff --git a/drivers/auxdisplay/arm-charlcd.c b/drivers/auxdisplay/arm-charlcd.c
index 4e22882f57c9..0dab69938352 100644
--- a/drivers/auxdisplay/arm-charlcd.c
+++ b/drivers/auxdisplay/arm-charlcd.c
@@ -14,7 +14,6 @@
 #include <linux/completion.h>
 #include <linux/delay.h>
 #include <linux/io.h>
-#include <linux/slab.h>
 #include <linux/workqueue.h>
 #include <generated/utsrelease.h>
 
@@ -56,8 +55,6 @@
 /**
  * struct charlcd - Private data structure
  * @dev: a pointer back to containing device
- * @phybase: the offset to the controller in physical memory
- * @physize: the size of the physical page
  * @virtbase: the offset to the controller in virtual memory
  * @irq: reserved interrupt number
  * @complete: completion structure for the last LCD command
@@ -65,8 +62,6 @@
  */
 struct charlcd {
 	struct device *dev;
-	u32 phybase;
-	u32 physize;
 	void __iomem *virtbase;
 	int irq;
 	struct completion complete;
@@ -266,44 +261,27 @@ static void charlcd_init_work(struct work_struct *work)
 
 static int __init charlcd_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
 	int ret;
 	struct charlcd *lcd;
 	struct resource *res;
 
-	lcd = kzalloc(sizeof(*lcd), GFP_KERNEL);
+	lcd = devm_kzalloc(dev, sizeof(*lcd), GFP_KERNEL);
 	if (!lcd)
 		return -ENOMEM;
 
 	lcd->dev = &pdev->dev;
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	if (!res) {
-		ret = -ENOENT;
-		goto out_no_resource;
-	}
-	lcd->phybase = res->start;
-	lcd->physize = resource_size(res);
-
-	if (request_mem_region(lcd->phybase, lcd->physize,
-			       DRIVERNAME) == NULL) {
-		ret = -EBUSY;
-		goto out_no_memregion;
-	}
-
-	lcd->virtbase = ioremap(lcd->phybase, lcd->physize);
-	if (!lcd->virtbase) {
-		ret = -ENOMEM;
-		goto out_no_memregion;
-	}
+	lcd->virtbase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+	if (IS_ERR(lcd->virtbase))
+		return PTR_ERR(lcd->virtbase);
 
 	lcd->irq = platform_get_irq(pdev, 0);
 	/* If no IRQ is supplied, we'll survive without it */
 	if (lcd->irq >= 0) {
-		if (request_irq(lcd->irq, charlcd_interrupt, 0,
-				DRIVERNAME, lcd)) {
-			ret = -EIO;
-			goto out_no_irq;
-		}
+		ret = devm_request_irq(dev, lcd->irq, charlcd_interrupt, 0, DRIVERNAME, lcd);
+		if (ret)
+			return ret;
 	}
 
 	platform_set_drvdata(pdev, lcd);
@@ -315,18 +293,9 @@ static int __init charlcd_probe(struct platform_device *pdev)
 	INIT_DELAYED_WORK(&lcd->init_work, charlcd_init_work);
 	schedule_delayed_work(&lcd->init_work, 0);
 
-	dev_info(&pdev->dev, "initialized ARM character LCD at %08x\n",
-		lcd->phybase);
+	dev_info(dev, "initialized ARM character LCD at %pa\n", &res->start);
 
 	return 0;
-
-out_no_irq:
-	iounmap(lcd->virtbase);
-out_no_memregion:
-	release_mem_region(lcd->phybase, lcd->physize);
-out_no_resource:
-	kfree(lcd);
-	return ret;
 }
 
 static int charlcd_suspend(struct device *dev)
-- 
2.50.1