[PATCH] dmaengine: bestcomm: ioremap early

[Rosen Penev]

Doing so allows handling potential -EPROBE_DEFER before any work gets
done.

Replace the open-coded resource lookup, request_mem_region, ioremap and
the manual iounmap/release_mem_region cleanup in probe/remove with the
managed devm_platform_get_and_ioremap_resource() helper. This removes the
now-unused error-unmap/release paths and simplifies probing.

This also fixes a resource size mismatch between allocating and freeing.
>From sashiko:

>  	release_mem_region(res_bcom.start, sizeof(struct mpc52xx_sdma));

This is a pre-existing issue, but does this mismatch in size during release
cause a permanent resource leak?
The memory region is requested earlier in mpc52xx_bcom_probe() using the
device tree node size:
    if (!request_mem_region(res_bcom.start, resource_size(&res_bcom),
                            DRIVER_NAME)) {
However, the error path above attempts to release the region using a fixed
compile-time size: sizeof(struct mpc52xx_sdma). Since __release_region()
strictly verifies the boundaries of the requested resource, if these sizes
differ, the check fails and the I/O memory region is never freed. Driver
unbinding in mpc52xx_bcom_remove() also uses this same fixed size.

Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
---
 drivers/dma/bestcomm/bestcomm.c | 45 ++++++++-------------------------
 1 file changed, 10 insertions(+), 35 deletions(-)

diff --git a/drivers/dma/bestcomm/bestcomm.c b/drivers/dma/bestcomm/bestcomm.c
index 432b43520ddc..44ff4a42376b 100644
--- a/drivers/dma/bestcomm/bestcomm.c
+++ b/drivers/dma/bestcomm/bestcomm.c
@@ -13,7 +13,6 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/of.h>
-#include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <asm/io.h>
@@ -365,13 +364,19 @@ bcom_engine_cleanup(void)
 static int mpc52xx_bcom_probe(struct platform_device *op)
 {
 	struct device_node *ofn_sram;
-	struct resource res_bcom;
+	struct resource *res_bcom;
+	void __iomem *regs;
 
 	int rv;
 
 	/* Inform user we're ok so far */
 	printk(KERN_INFO "DMA: MPC52xx BestComm driver\n");
 
+	/* Get, reserve & map io */
+	regs = devm_platform_get_and_ioremap_resource(op, 0, &res_bcom);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
 	/* Get the bestcomm node */
 	of_node_get(op->dev.of_node);
 
@@ -402,35 +407,13 @@ static int mpc52xx_bcom_probe(struct platform_device *op)
 	/* Save the node */
 	bcom_eng->ofnode = op->dev.of_node;
 
-	/* Get, reserve & map io */
-	if (of_address_to_resource(op->dev.of_node, 0, &res_bcom)) {
-		printk(KERN_ERR DRIVER_NAME ": "
-			"Can't get resource\n");
-		rv = -EINVAL;
-		goto error_sramclean;
-	}
-
-	if (!request_mem_region(res_bcom.start, resource_size(&res_bcom),
-				DRIVER_NAME)) {
-		printk(KERN_ERR DRIVER_NAME ": "
-			"Can't request registers region\n");
-		rv = -EBUSY;
-		goto error_sramclean;
-	}
-
-	bcom_eng->regs_base = res_bcom.start;
-	bcom_eng->regs = ioremap(res_bcom.start, sizeof(struct mpc52xx_sdma));
-	if (!bcom_eng->regs) {
-		printk(KERN_ERR DRIVER_NAME ": "
-			"Can't map registers\n");
-		rv = -ENOMEM;
-		goto error_release;
-	}
+	bcom_eng->regs = regs;
+	bcom_eng->regs_base = res_bcom->start;
 
 	/* Now, do the real init */
 	rv = bcom_engine_init();
 	if (rv)
-		goto error_unmap;
+		goto error_sramclean;
 
 	/* Done ! */
 	printk(KERN_INFO "DMA: MPC52xx BestComm engine @%08lx ok !\n",
@@ -439,10 +422,6 @@ static int mpc52xx_bcom_probe(struct platform_device *op)
 	return 0;
 
 	/* Error path */
-error_unmap:
-	iounmap(bcom_eng->regs);
-error_release:
-	release_mem_region(res_bcom.start, sizeof(struct mpc52xx_sdma));
 error_sramclean:
 	kfree(bcom_eng);
 	bcom_sram_cleanup();
@@ -463,10 +442,6 @@ static void mpc52xx_bcom_remove(struct platform_device *op)
 	/* Cleanup SRAM */
 	bcom_sram_cleanup();
 
-	/* Release regs */
-	iounmap(bcom_eng->regs);
-	release_mem_region(bcom_eng->regs_base, sizeof(struct mpc52xx_sdma));
-
 	/* Release the node */
 	of_node_put(bcom_eng->ofnode);
 
-- 
2.55.0