linux-kernel - [PATCH 6/6] driver core: initialize a default DMA mask for platform device

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Message-Id: <20190811080520.21712-7-hch@lst.de>
Date:   Sun, 11 Aug 2019 10:05:20 +0200
From:   Christoph Hellwig <hch@....de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc:     Gavin Li <git@...gavinli.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Minas Harutyunyan <hminas@...opsys.com>,
        Alan Stern <stern@...land.harvard.edu>,
        Geoff Levand <geoff@...radead.org>,
        Michal Simek <michal.simek@...inx.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Olav Kongas <ok@...ecdesign.ee>,
        Tony Prisk <linux@...sktech.co.nz>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Bin Liu <b-liu@...com>, linux-arm-kernel@...ts.infradead.org,
        linux-usb@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        iommu@...ts.linux-foundation.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 6/6] driver core: initialize a default DMA mask for platform device

We still treat devices without a DMA mask as defaulting to 32-bits for
both mask, but a few releases ago we've started warning about such
cases, as they require special cases to work around this sloppyness.
Add a dma_mask field to struct platform_object so that we can initialize
the dma_mask pointer in struct device and initialize both masks to
32-bits by default.  Architectures can still override this in
arch_setup_pdev_archdata if needed.

Note that the code looks a little odd with the various conditionals
because we have to support platform_device structures that are
statically allocated.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 drivers/base/platform.c         | 15 +++++++++++++--
 include/linux/platform_device.h |  1 +
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index ec974ba9c0c4..b216fcb0a8af 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -264,6 +264,17 @@ struct platform_object {
 	char name[];
 };
 
+static void setup_pdev_archdata(struct platform_device *pdev)
+{
+	if (!pdev->dev.coherent_dma_mask)
+		pdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
+	if (!pdev->dma_mask)
+		pdev->dma_mask = DMA_BIT_MASK(32);
+	if (!pdev->dev.dma_mask)
+		pdev->dev.dma_mask = &pdev->dma_mask;
+	arch_setup_pdev_archdata(pdev);
+};
+
 /**
  * platform_device_put - destroy a platform device
  * @pdev: platform device to free
@@ -310,7 +321,7 @@ struct platform_device *platform_device_alloc(const char *name, int id)
 		pa->pdev.id = id;
 		device_initialize(&pa->pdev.dev);
 		pa->pdev.dev.release = platform_device_release;
-		arch_setup_pdev_archdata(&pa->pdev);
+		setup_pdev_archdata(&pa->pdev);
 	}
 
 	return pa ? &pa->pdev : NULL;
@@ -512,7 +523,7 @@ EXPORT_SYMBOL_GPL(platform_device_del);
 int platform_device_register(struct platform_device *pdev)
 {
 	device_initialize(&pdev->dev);
-	arch_setup_pdev_archdata(pdev);
+	setup_pdev_archdata(pdev);
 	return platform_device_add(pdev);
 }
 EXPORT_SYMBOL_GPL(platform_device_register);
diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h
index 9bc36b589827..a2abde2aef25 100644
--- a/include/linux/platform_device.h
+++ b/include/linux/platform_device.h
@@ -24,6 +24,7 @@ struct platform_device {
 	int		id;
 	bool		id_auto;
 	struct device	dev;
+	u64		dma_mask;
 	u32		num_resources;
 	struct resource	*resource;
 
-- 
2.20.1