spi: fix controller deregistration (part 2/2)

Johan Hovold <johan@kernel.org> says:

Device managed registration generally only works if all involved
resources are managed as otherwise resources may be disabled or freed
while they are still in use.

This series fixes the SPI controller drivers that get this wrong by
disabling resources such as clocks, DMA and interrupts while the
controller (and its devices) are still registered, which can lead to
issues like system errors due to unclocked accesses, NULL-pointer
dereferences, hangs or just prevent SPI device drivers from doing I/O
during during deregistration (e.g. to power down devices).

I decided to split these fixes in two parts consisting of 20 and 26
patches respectively in order not to spam the lists too much.

I've also prepared a follow-on series to convert the drivers here that
do not yet use device managed controller allocation (which avoids taking
extra references during deregistration).

After that it should be possible to change the SPI API so that it no
longer drops a reference during deregistration without too much effort
(cf. [1]).

Note that this series is based on spi/for-next which specifically has
commit 1f8fd94 ("spi: zynq-qspi: Simplify clock handling with
devm_clk_get_enabled()") (which is not in the for-7.1 branch).

Johan

[1] https://lore.kernel.org/lkml/20260325145319.1132072-1-johan@kernel.org/

Author: broonie

drivers/spi/spi-mt65xx.c

@@ -1325,7 +1325,7 @@ static int mtk_spi_probe(struct platform_device *pdev)
 
 	pm_runtime_enable(dev);
 
-	ret = devm_spi_register_controller(dev, host);
+	ret = spi_register_controller(host);
 	if (ret) {
 		pm_runtime_disable(dev);
 		return dev_err_probe(dev, ret, "failed to register host\n");
@@ -1340,6 +1340,8 @@ static void mtk_spi_remove(struct platform_device *pdev)
 	struct mtk_spi *mdata = spi_controller_get_devdata(host);
 	int ret;
 
+	spi_unregister_controller(host);
+
 	cpu_latency_qos_remove_request(&mdata->qos_request);
 	if (mdata->use_spimem && !completion_done(&mdata->spimem_done))
 		complete(&mdata->spimem_done);

drivers/spi/spi-mtk-nor.c

@@ -913,7 +913,7 @@ static int mtk_nor_probe(struct platform_device *pdev)
 	pm_runtime_enable(&pdev->dev);
 	pm_runtime_get_noresume(&pdev->dev);
 
-	ret = devm_spi_register_controller(&pdev->dev, ctlr);
+	ret = spi_register_controller(ctlr);
 	if (ret < 0)
 		goto err_probe;
 
@@ -938,6 +938,8 @@ static void mtk_nor_remove(struct platform_device *pdev)
 	struct spi_controller *ctlr = dev_get_drvdata(&pdev->dev);
 	struct mtk_nor *sp = spi_controller_get_devdata(ctlr);
 
+	spi_unregister_controller(ctlr);
+
 	pm_runtime_disable(&pdev->dev);
 	pm_runtime_set_suspended(&pdev->dev);
 	pm_runtime_dont_use_autosuspend(&pdev->dev);

drivers/spi/spi-mxs.c

@@ -619,7 +619,7 @@ static int mxs_spi_probe(struct platform_device *pdev)
 	if (ret)
 		goto out_pm_runtime_put;
 
-	ret = devm_spi_register_controller(&pdev->dev, host);
+	ret = spi_register_controller(host);
 	if (ret) {
 		dev_err(&pdev->dev, "Cannot register SPI host, %d\n", ret);
 		goto out_pm_runtime_put;
@@ -650,11 +650,17 @@ static void mxs_spi_remove(struct platform_device *pdev)
 	spi = spi_controller_get_devdata(host);
 	ssp = &spi->ssp;
 
+	spi_controller_get(host);
+
+	spi_unregister_controller(host);
+
 	pm_runtime_disable(&pdev->dev);
 	if (!pm_runtime_status_suspended(&pdev->dev))
 		mxs_spi_runtime_suspend(&pdev->dev);
 
 	dma_release_channel(ssp->dmach);
+
+	spi_controller_put(host);
 }
 
 static struct platform_driver mxs_spi_driver = {

drivers/spi/spi-npcm-pspi.c

@@ -413,7 +413,7 @@ static int npcm_pspi_probe(struct platform_device *pdev)
 	/* set to default clock rate */
 	npcm_pspi_set_baudrate(priv, NPCM_PSPI_DEFAULT_CLK);
 
-	ret = devm_spi_register_controller(&pdev->dev, host);
+	ret = spi_register_controller(host);
 	if (ret)
 		goto out_disable_clk;
 
@@ -434,8 +434,14 @@ static void npcm_pspi_remove(struct platform_device *pdev)
 	struct spi_controller *host = platform_get_drvdata(pdev);
 	struct npcm_pspi *priv = spi_controller_get_devdata(host);
 
+	spi_controller_get(host);
+
+	spi_unregister_controller(host);
+
 	npcm_pspi_reset_hw(priv);
 	clk_disable_unprepare(priv->clk);
+
+	spi_controller_put(host);
 }
 
 static const struct of_device_id npcm_pspi_match[] = {

drivers/spi/spi-omap2-mcspi.c

@@ -1592,7 +1592,7 @@ static int omap2_mcspi_probe(struct platform_device *pdev)
 	if (status < 0)
 		goto disable_pm;
 
-	status = devm_spi_register_controller(&pdev->dev, ctlr);
+	status = spi_register_controller(ctlr);
 	if (status < 0)
 		goto disable_pm;
 
@@ -1613,11 +1613,17 @@ static void omap2_mcspi_remove(struct platform_device *pdev)
 	struct spi_controller *ctlr = platform_get_drvdata(pdev);
 	struct omap2_mcspi *mcspi = spi_controller_get_devdata(ctlr);
 
+	spi_controller_get(ctlr);
+
+	spi_unregister_controller(ctlr);
+
 	omap2_mcspi_release_dma(ctlr);
 
 	pm_runtime_dont_use_autosuspend(mcspi->dev);
 	pm_runtime_put_sync(mcspi->dev);
 	pm_runtime_disable(&pdev->dev);
+
+	spi_controller_put(ctlr);
 }
 
 /* work with hotplug and coldplug */

drivers/spi/spi-pic32-sqi.c

@@ -642,7 +642,7 @@ static int pic32_sqi_probe(struct platform_device *pdev)
 	host->prepare_transfer_hardware	= pic32_sqi_prepare_hardware;
 	host->unprepare_transfer_hardware	= pic32_sqi_unprepare_hardware;
 
-	ret = devm_spi_register_controller(&pdev->dev, host);
+	ret = spi_register_controller(host);
 	if (ret) {
 		dev_err(&host->dev, "failed registering spi host\n");
 		free_irq(sqi->irq, sqi);
@@ -665,9 +665,15 @@ static void pic32_sqi_remove(struct platform_device *pdev)
 {
 	struct pic32_sqi *sqi = platform_get_drvdata(pdev);
 
+	spi_controller_get(sqi->host);
+
+	spi_unregister_controller(sqi->host);
+
 	/* release resources */
 	free_irq(sqi->irq, sqi);
 	ring_desc_ring_free(sqi);
+
+	spi_controller_put(sqi->host);
 }
 
 static const struct of_device_id pic32_sqi_of_ids[] = {

drivers/spi/spi-pic32.c

@@ -821,7 +821,7 @@ static int pic32_spi_probe(struct platform_device *pdev)
 	}
 
 	/* register host */
-	ret = devm_spi_register_controller(&pdev->dev, host);
+	ret = spi_register_controller(host);
 	if (ret) {
 		dev_err(&host->dev, "failed registering spi host\n");
 		goto err_bailout;
@@ -840,11 +840,16 @@ static int pic32_spi_probe(struct platform_device *pdev)
 
 static void pic32_spi_remove(struct platform_device *pdev)
 {
-	struct pic32_spi *pic32s;
+	struct pic32_spi *pic32s = platform_get_drvdata(pdev);
+
+	spi_controller_get(pic32s->host);
+
+	spi_unregister_controller(pic32s->host);
 
-	pic32s = platform_get_drvdata(pdev);
 	pic32_spi_disable(pic32s);
 	pic32_spi_dma_unprep(pic32s);
+
+	spi_controller_put(pic32s->host);
 }
 
 static const struct of_device_id pic32_spi_of_match[] = {

drivers/spi/spi-pl022.c

@@ -1956,7 +1956,7 @@ static int pl022_probe(struct amba_device *adev, const struct amba_id *id)
 
 	/* Register with the SPI framework */
 	amba_set_drvdata(adev, pl022);
-	status = devm_spi_register_controller(&adev->dev, host);
+	status = spi_register_controller(host);
 	if (status != 0) {
 		dev_err_probe(&adev->dev, status,
 			      "problem registering spi host\n");
@@ -1997,6 +1997,10 @@ pl022_remove(struct amba_device *adev)
 	if (!pl022)
 		return;
 
+	spi_controller_get(pl022->host);
+
+	spi_unregister_controller(pl022->host);
+
 	/*
 	 * undo pm_runtime_put() in probe.  I assume that we're not
 	 * accessing the primecell here.
@@ -2008,6 +2012,8 @@ pl022_remove(struct amba_device *adev)
 		pl022_dma_remove(pl022);
 
 	amba_release_regions(adev);
+
+	spi_controller_put(pl022->host);
 }
 
 #ifdef CONFIG_PM_SLEEP

drivers/spi/spi-qup.c

@@ -1193,7 +1193,7 @@ static int spi_qup_probe(struct platform_device *pdev)
 	pm_runtime_set_active(dev);
 	pm_runtime_enable(dev);
 
-	ret = devm_spi_register_controller(dev, host);
+	ret = spi_register_controller(host);
 	if (ret)
 		goto disable_pm;
 
@@ -1320,6 +1320,10 @@ static void spi_qup_remove(struct platform_device *pdev)
 	struct spi_qup *controller = spi_controller_get_devdata(host);
 	int ret;
 
+	spi_controller_get(host);
+
+	spi_unregister_controller(host);
+
 	ret = pm_runtime_get_sync(&pdev->dev);
 
 	if (ret >= 0) {
@@ -1339,6 +1343,8 @@ static void spi_qup_remove(struct platform_device *pdev)
 
 	pm_runtime_put_noidle(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
+
+	spi_controller_put(host);
 }
 
 static const struct of_device_id spi_qup_dt_match[] = {

drivers/spi/spi-rspi.c

@@ -1171,8 +1171,14 @@ static void rspi_remove(struct platform_device *pdev)
 {
 	struct rspi_data *rspi = platform_get_drvdata(pdev);
 
+	spi_controller_get(rspi->ctlr);
+
+	spi_unregister_controller(rspi->ctlr);
+
 	rspi_release_dma(rspi->ctlr);
 	pm_runtime_disable(&pdev->dev);
+
+	spi_controller_put(rspi->ctlr);
 }
 
 static const struct spi_ops rspi_ops = {
@@ -1376,9 +1382,9 @@ static int rspi_probe(struct platform_device *pdev)
 	if (ret < 0)
 		dev_warn(&pdev->dev, "DMA not available, using PIO\n");
 
-	ret = devm_spi_register_controller(&pdev->dev, ctlr);
+	ret = spi_register_controller(ctlr);
 	if (ret < 0) {
-		dev_err(&pdev->dev, "devm_spi_register_controller error.\n");
+		dev_err(&pdev->dev, "failed to register controller\n");
 		goto error3;
 	}