can: grcan: use ofdev->dev when allocating DMA memory

Use the device of the device tree node should be rather than the
device of the struct net_device when allocating DMA buffers.

The driver got away with it on sparc32 until commit 53b7670e
("sparc: factor the dma coherent mapping into helper") after which the
driver oopses.

Fixes: 6cec9b07 ("can: grcan: Add device driver for GRCAN and GRHCAN cores")
Link: https://lore.kernel.org/all/20220429084656.29788-2-andreas@gaisler.com
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/grcan.c

@@ -248,6 +248,7 @@ struct grcan_device_config {
 struct grcan_priv {
 	struct can_priv can;	/* must be the first member */
 	struct net_device *dev;
+	struct device *ofdev_dev;
 	struct napi_struct napi;
 
 	struct grcan_registers __iomem *regs;	/* ioremap'ed registers */
@@ -921,7 +922,7 @@ static void grcan_free_dma_buffers(struct net_device *dev)
 	struct grcan_priv *priv = netdev_priv(dev);
 	struct grcan_dma *dma = &priv->dma;
 
-	dma_free_coherent(&dev->dev, dma->base_size, dma->base_buf,
+	dma_free_coherent(priv->ofdev_dev, dma->base_size, dma->base_buf,
 			  dma->base_handle);
 	memset(dma, 0, sizeof(*dma));
 }
@@ -946,7 +947,7 @@ static int grcan_allocate_dma_buffers(struct net_device *dev,
 
 	/* Extra GRCAN_BUFFER_ALIGNMENT to allow for alignment */
 	dma->base_size = lsize + ssize + GRCAN_BUFFER_ALIGNMENT;
-	dma->base_buf = dma_alloc_coherent(&dev->dev,
+	dma->base_buf = dma_alloc_coherent(priv->ofdev_dev,
 					   dma->base_size,
 					   &dma->base_handle,
 					   GFP_KERNEL);
@@ -1589,6 +1590,7 @@ static int grcan_setup_netdev(struct platform_device *ofdev,
 	memcpy(&priv->config, &grcan_module_config,
 	       sizeof(struct grcan_device_config));
 	priv->dev = dev;
+	priv->ofdev_dev = &ofdev->dev;
 	priv->regs = base;
 	priv->can.bittiming_const = &grcan_bittiming_const;
 	priv->can.do_set_bittiming = grcan_set_bittiming;