spi: ar934x: Don't leak SPI master in probe error path

If the call to devm_spi_register_controller() fails on probe of the
Qualcomm Atheros AR934x/QCA95xx SPI driver, the spi_controller struct is
erroneously not freed.  Fix by switching over to the new
devm_spi_alloc_master() helper.

Moreover, the controller's clock is enabled on probe but not disabled if
any of the subsequent probe steps fail.

Finally, there's an ordering issue in ar934x_spi_remove() wherein the
clock is disabled even though the controller is not yet unregistered.
It is unregistered after ar934x_spi_remove() by the devres framework.
As long as it is not unregistered, SPI transfers may still be ongoing
and disabling the clock may break them.  It is not possible to use
devm_spi_register_controller() in this case, so move to the non-devm
variant.

All of these bugs have existed since the driver was first introduced,
so it seems fair to fix them together in a single commit.

Fixes: 047980c582 ("spi: add driver for ar934x spi controller")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v5.7+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v5.7+
Cc: Chuanhong Guo <gch981213@gmail.com>
Link: https://lore.kernel.org/r/1d58367d74d55741e0c2730a51a2b65012c8ab33.1607286887.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-ar934x.c

@@ -176,10 +176,11 @@ static int ar934x_spi_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	ctlr = spi_alloc_master(&pdev->dev, sizeof(*sp));
+	ctlr = devm_spi_alloc_master(&pdev->dev, sizeof(*sp));
 	if (!ctlr) {
 		dev_info(&pdev->dev, "failed to allocate spi controller\n");
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto err_clk_disable;
 	}
 
 	/* disable flash mapping and expose spi controller registers */
@@ -202,7 +203,13 @@ static int ar934x_spi_probe(struct platform_device *pdev)
 	sp->clk_freq = clk_get_rate(clk);
 	sp->ctlr = ctlr;
 
-	return devm_spi_register_controller(&pdev->dev, ctlr);
+	ret = spi_register_controller(ctlr);
+	if (!ret)
+		return 0;
+
+err_clk_disable:
+	clk_disable_unprepare(clk);
+	return ret;
 }
 
 static int ar934x_spi_remove(struct platform_device *pdev)
@@ -213,6 +220,7 @@ static int ar934x_spi_remove(struct platform_device *pdev)
 	ctlr = dev_get_drvdata(&pdev->dev);
 	sp = spi_controller_get_devdata(ctlr);
 
+	spi_unregister_controller(ctlr);
 	clk_disable_unprepare(sp->clk);
 
 	return 0;