[PATCH v2] dmaengine: axi-dmac: move to device managed probe

[Nuno Sa <nuno.sa@analog.com>]

In axi_dmac_probe(), there's a mix in using device managed APIs and
explicitly cleaning things in the driver .remove() hook. Move to use
device managed APIs and thus drop the .remove() hook.

While doing this move request_irq() before of_dma_controller_register()
so the previous cleanup order in the .remove() hook is preserved.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
Changes in v2:
- Keep devm_request_irq() after of_dma_controller_register() so we free
  the irq first and avoid any possible race agains
  of_dma_controller_register().
- Link to v1: https://lore.kernel.org/r/20240214-axi-dmac-devm-probe-v1-1-22d633da19cb@analog.com

Vinod,

This actually made me think if I shouldn't have a preliminary patch
just moving free_irq() before of_dma_controller_register() and treating
it as bug (adding a proper fixes tag). Then moving to devm_ in a follow up
patch.

What do you think? Is it worth it to backport this?
---
 drivers/dma/dma-axi-dmac.c | 78 ++++++++++++++++++++--------------------------
 1 file changed, 34 insertions(+), 44 deletions(-)

diff --git a/drivers/dma/dma-axi-dmac.c b/drivers/dma/dma-axi-dmac.c
index 4e339c04fc1e..bdb752f11869 100644
--- a/drivers/dma/dma-axi-dmac.c
+++ b/drivers/dma/dma-axi-dmac.c
@@ -1002,6 +1002,16 @@ static int axi_dmac_detect_caps(struct axi_dmac *dmac, unsigned int version)
 	return 0;
 }
 
+static void axi_dmac_tasklet_kill(void *task)
+{
+	tasklet_kill(task);
+}
+
+static void axi_dmac_free_dma_controller(void *of_node)
+{
+	of_dma_controller_free(of_node);
+}
+
 static int axi_dmac_probe(struct platform_device *pdev)
 {
 	struct dma_device *dma_dev;
@@ -1025,14 +1035,10 @@ static int axi_dmac_probe(struct platform_device *pdev)
 	if (IS_ERR(dmac->base))
 		return PTR_ERR(dmac->base);
 
-	dmac->clk = devm_clk_get(&pdev->dev, NULL);
+	dmac->clk = devm_clk_get_enabled(&pdev->dev, NULL);
 	if (IS_ERR(dmac->clk))
 		return PTR_ERR(dmac->clk);
 
-	ret = clk_prepare_enable(dmac->clk);
-	if (ret < 0)
-		return ret;
-
 	version = axi_dmac_read(dmac, ADI_AXI_REG_VERSION);
 
 	if (version >= ADI_AXI_PCORE_VER(4, 3, 'a'))
@@ -1041,7 +1047,7 @@ static int axi_dmac_probe(struct platform_device *pdev)
 		ret = axi_dmac_parse_dt(&pdev->dev, dmac);
 
 	if (ret < 0)
-		goto err_clk_disable;
+		return ret;
 
 	INIT_LIST_HEAD(&dmac->chan.active_descs);
 
@@ -1072,7 +1078,7 @@ static int axi_dmac_probe(struct platform_device *pdev)
 
 	ret = axi_dmac_detect_caps(dmac, version);
 	if (ret)
-		goto err_clk_disable;
+		return ret;
 
 	dma_dev->copy_align = (dmac->chan.address_align_mask + 1);
 
@@ -1088,57 +1094,42 @@ static int axi_dmac_probe(struct platform_device *pdev)
 		    !AXI_DMAC_DST_COHERENT_GET(ret)) {
 			dev_err(dmac->dma_dev.dev,
 				"Coherent DMA not supported in hardware");
-			ret = -EINVAL;
-			goto err_clk_disable;
+			return -EINVAL;
 		}
 	}
 
-	ret = dma_async_device_register(dma_dev);
+	ret = dmaenginem_async_device_register(dma_dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * Put the action in here so it get's done before unregistering the DMA
+	 * device.
+	 */
+	ret = devm_add_action_or_reset(&pdev->dev, axi_dmac_tasklet_kill,
+				       &dmac->chan.vchan.task);
 	if (ret)
-		goto err_clk_disable;
+		return ret;
 
 	ret = of_dma_controller_register(pdev->dev.of_node,
 		of_dma_xlate_by_chan_id, dma_dev);
 	if (ret)
-		goto err_unregister_device;
+		return ret;
 
-	ret = request_irq(dmac->irq, axi_dmac_interrupt_handler, IRQF_SHARED,
-		dev_name(&pdev->dev), dmac);
+	ret = devm_add_action_or_reset(&pdev->dev, axi_dmac_free_dma_controller,
+				       pdev->dev.of_node);
 	if (ret)
-		goto err_unregister_of;
+		return ret;
 
-	platform_set_drvdata(pdev, dmac);
+	ret = devm_request_irq(&pdev->dev, dmac->irq, axi_dmac_interrupt_handler,
+			       IRQF_SHARED, dev_name(&pdev->dev), dmac);
+	if (ret)
+		return ret;
 
 	regmap = devm_regmap_init_mmio(&pdev->dev, dmac->base,
 		 &axi_dmac_regmap_config);
-	if (IS_ERR(regmap)) {
-		ret = PTR_ERR(regmap);
-		goto err_free_irq;
-	}
-
-	return 0;
-
-err_free_irq:
-	free_irq(dmac->irq, dmac);
-err_unregister_of:
-	of_dma_controller_free(pdev->dev.of_node);
-err_unregister_device:
-	dma_async_device_unregister(&dmac->dma_dev);
-err_clk_disable:
-	clk_disable_unprepare(dmac->clk);
-
-	return ret;
-}
-
-static void axi_dmac_remove(struct platform_device *pdev)
-{
-	struct axi_dmac *dmac = platform_get_drvdata(pdev);
 
-	of_dma_controller_free(pdev->dev.of_node);
-	free_irq(dmac->irq, dmac);
-	tasklet_kill(&dmac->chan.vchan.task);
-	dma_async_device_unregister(&dmac->dma_dev);
-	clk_disable_unprepare(dmac->clk);
+	return PTR_ERR_OR_ZERO(regmap);
 }
 
 static const struct of_device_id axi_dmac_of_match_table[] = {
@@ -1153,7 +1144,6 @@ static struct platform_driver axi_dmac_driver = {
 		.of_match_table = axi_dmac_of_match_table,
 	},
 	.probe = axi_dmac_probe,
-	.remove_new = axi_dmac_remove,
 };
 module_platform_driver(axi_dmac_driver);
 

---
base-commit: de7d9cb3b064fdfb2e0e7706d14ffee20b762ad2
change-id: 20240214-axi-dmac-devm-probe-d718ef36fb58
--

Thanks!
- Nuno Sá