[PATCH v2] dmaengine: dw-axi-dmac: convert clock handling to clk_bulk API

The driver managed its two mandatory clocks (core-clk and cfgr-clk)
individually. This was error prone: axi_dma_resume() enabled cfgr_clk
and then core_clk, and if enabling core_clk failed it returned the
error without disabling cfgr_clk, leaving the clock refcount
unbalanced.

Convert the driver to the clk_bulk API. The two clocks are always
acquired, enabled and disabled together, so a clk_bulk_data array
expresses this naturally and shrinks the get/enable/disable paths.
clk_bulk_prepare_enable() also unwinds any clock it already enabled
when a later one fails, which fixes the resume imbalance.

Fixes: 1fe20f1b8454 ("dmaengine: Introduce DW AXI DMAC driver")
Signed-off-by: Chaithanya Lagisetty <[email protected]>
---
Changes since v1:
- Convert the driver to the clk_bulk API instead of manually disabling
  cfgr_clk on the error path, as suggested by Frank Li.
- v1: https://lore.kernel.org/all/[email protected]/

 .../dma/dw-axi-dmac/dw-axi-dmac-platform.c    | 28 ++++++++-----------
 drivers/dma/dw-axi-dmac/dw-axi-dmac.h         |  3 +-
 2 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
index bcefaff03b5c..254167a558ff 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -1320,8 +1320,7 @@ static int axi_dma_suspend(struct axi_dma_chip *chip)
 	axi_dma_irq_disable(chip);
 	axi_dma_disable(chip);
 
-	clk_disable_unprepare(chip->core_clk);
-	clk_disable_unprepare(chip->cfgr_clk);
+	clk_bulk_disable_unprepare(ARRAY_SIZE(chip->clks), chip->clks);
 
 	return 0;
 }
@@ -1330,11 +1329,7 @@ static int axi_dma_resume(struct axi_dma_chip *chip)
 {
 	int ret;
 
-	ret = clk_prepare_enable(chip->cfgr_clk);
-	if (ret < 0)
-		return ret;
-
-	ret = clk_prepare_enable(chip->core_clk);
+	ret = clk_bulk_prepare_enable(ARRAY_SIZE(chip->clks), chip->clks);
 	if (ret < 0)
 		return ret;
 
@@ -1524,13 +1519,11 @@ static int dw_probe(struct platform_device *pdev)
 
 	chip->dw->hdata->use_cfg2 = !!(flags & AXI_DMA_FLAG_USE_CFG2);
 
-	chip->core_clk = devm_clk_get(chip->dev, "core-clk");
-	if (IS_ERR(chip->core_clk))
-		return PTR_ERR(chip->core_clk);
-
-	chip->cfgr_clk = devm_clk_get(chip->dev, "cfgr-clk");
-	if (IS_ERR(chip->cfgr_clk))
-		return PTR_ERR(chip->cfgr_clk);
+	chip->clks[0].id = "core-clk";
+	chip->clks[1].id = "cfgr-clk";
+	ret = devm_clk_bulk_get(chip->dev, ARRAY_SIZE(chip->clks), chip->clks);
+	if (ret)
+		return dev_err_probe(chip->dev, ret, "failed to get clocks\n");
 
 	ret = parse_device_properties(chip);
 	if (ret)
@@ -1640,10 +1633,13 @@ static void dw_remove(struct platform_device *pdev)
 	struct dw_axi_dma *dw = chip->dw;
 	struct axi_dma_chan *chan, *_chan;
 	u32 i;
+	int ret;
 
 	/* Enable clk before accessing to registers */
-	clk_prepare_enable(chip->cfgr_clk);
-	clk_prepare_enable(chip->core_clk);
+	ret = clk_bulk_prepare_enable(ARRAY_SIZE(chip->clks), chip->clks);
+	if (ret)
+		dev_warn(chip->dev, "failed to enable clocks before remove: %d\n",
+			 ret);
 	axi_dma_irq_disable(chip);
 	for (i = 0; i < dw->hdata->nr_channels; i++) {
 		axi_chan_disable(&chip->dw->chan[i]);
diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
index 67cc199e24d1..039316c42f05 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
@@ -69,8 +69,7 @@ struct axi_dma_chip {
 	int			irq[DMAC_MAX_CHANNELS];
 	void __iomem		*regs;
 	void __iomem		*apb_regs;
-	struct clk		*core_clk;
-	struct clk		*cfgr_clk;
+	struct clk_bulk_data	clks[2];
 	struct dw_axi_dma	*dw;
 };
 
-- 
2.43.0