misc: sram: Improve and simplify clk handling

The current code tries to get an associated clk, ignores any errors in the
process and if there is a clock enables it unconditionally for the whole
lifetime of the sram device.

Instead use an "optional" variant of devm_clk_get() which handles the case
where no clk is needed for the sram device and do proper error handling
for the remaining error cases. Also use an "enabled" variant of
devm_clk_get() to simplify. With that .probe() is the only function using
struct sram_dev::clk, so it can be replaced by a local variable.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://lore.kernel.org/r/20230302091251.1852454-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/sram.c

@@ -381,6 +381,7 @@ static int sram_probe(struct platform_device *pdev)
 	struct sram_dev *sram;
 	int ret;
 	struct resource *res;
+	struct clk *clk;
 
 	config = of_device_get_match_data(&pdev->dev);
 
@@ -409,16 +410,14 @@ static int sram_probe(struct platform_device *pdev)
 			return PTR_ERR(sram->pool);
 	}
 
-	sram->clk = devm_clk_get(sram->dev, NULL);
-	if (IS_ERR(sram->clk))
-		sram->clk = NULL;
-	else
-		clk_prepare_enable(sram->clk);
+	clk = devm_clk_get_optional_enabled(sram->dev, NULL);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
 
 	ret = sram_reserve_regions(sram,
 			platform_get_resource(pdev, IORESOURCE_MEM, 0));
 	if (ret)
-		goto err_disable_clk;
+		return ret;
 
 	platform_set_drvdata(pdev, sram);
 
@@ -436,9 +435,6 @@ static int sram_probe(struct platform_device *pdev)
 
 err_free_partitions:
 	sram_free_partitions(sram);
-err_disable_clk:
-	if (sram->clk)
-		clk_disable_unprepare(sram->clk);
 
 	return ret;
 }
@@ -452,9 +448,6 @@ static int sram_remove(struct platform_device *pdev)
 	if (sram->pool && gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
 		dev_err(sram->dev, "removed while SRAM allocated\n");
 
-	if (sram->clk)
-		clk_disable_unprepare(sram->clk);
-
 	return 0;
 }
 

drivers/misc/sram.h

@@ -27,7 +27,6 @@ struct sram_dev {
 	bool no_memory_wc;
 
 	struct gen_pool *pool;
-	struct clk *clk;
 
 	struct sram_partition *partition;
 	u32 partitions;