[PATCHv2 3/4] dma: fsl_raid: keep MMIO bases as void __iomem and cast at access

[Rosen Penev]

The fsl_re_ctrl and fsl_re_chan_cfg structures describe memory-mapped
RAID Engine registers accessed only via ioread32be()/iowrite32be(), yet
the pointers to them (re_regs in struct fsl_re_drv_private, and jrregs
in struct fsl_re_chan) were not __iomem-qualified, so sparse emitted
"different address spaces" warnings for every register access.

Store both MMIO bases as a plain void __iomem * and derive jrregs with
void __iomem * arithmetic from re_regs, rather than carrying typed
register struct pointers through the driver. Each function that touches
the registers introduces a local typed pointer (struct fsl_re_ctrl
__iomem *ctrl) and uses ->field, which is the idiomatic kernel pattern
 and keeps the registers' __iomem qualification intact.

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Fixes: https://lore.kernel.org/oe-kbuild-all/202008111749.yy85rFMD%25lkp@xxxxxxxxx/
Assisted-by: opencode:hy3-free
Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
---
 drivers/dma/fsl_raid.c | 19 ++++++++++---------
 drivers/dma/fsl_raid.h |  4 ++--
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/dma/fsl_raid.c b/drivers/dma/fsl_raid.c
index 888f55b672a5..524f83faf3da 100644
--- a/drivers/dma/fsl_raid.c
+++ b/drivers/dma/fsl_raid.c
@@ -657,8 +657,7 @@ static int fsl_re_chan_probe(struct platform_device *ofdev,
 		goto err_free;
 	}
 
-	chan->jrregs = (struct fsl_re_chan_cfg *)((u8 *)re_priv->re_regs +
-			off + ptr);
+	chan->jrregs = re_priv->base + off + ptr;
 
 	/* read irq property from dts */
 	chan->irq = irq_of_parse_and_map(np, 0);
@@ -746,6 +745,7 @@ static int fsl_re_chan_probe(struct platform_device *ofdev,
 /* Probe function for RAID Engine */
 static int fsl_re_probe(struct platform_device *ofdev)
 {
+	struct fsl_re_ctrl __iomem *re_regs;
 	struct fsl_re_drv_private *re_priv;
 	struct device_node *child;
 	u32 off;
@@ -764,20 +764,21 @@ static int fsl_re_probe(struct platform_device *ofdev)
 		return -ENODEV;
 
 	/* IOMAP the entire RAID Engine region */
-	re_priv->re_regs = devm_ioremap(dev, res->start, resource_size(res));
-	if (!re_priv->re_regs)
+	re_regs = devm_ioremap(dev, res->start, resource_size(res));
+	if (!re_regs)
 		return -EBUSY;
+	re_priv->base = re_regs;
 
 	/* Program the RE mode */
-	out_be32(&re_priv->re_regs->global_config, FSL_RE_NON_DPAA_MODE);
+	out_be32(&re_regs->global_config, FSL_RE_NON_DPAA_MODE);
 
 	/* Program Galois Field polynomial */
-	out_be32(&re_priv->re_regs->galois_field_config, FSL_RE_GFM_POLY);
+	out_be32(&re_regs->galois_field_config, FSL_RE_GFM_POLY);
 
 	dev_info(dev, "version %x, mode %x, gfp %x\n",
-		 in_be32(&re_priv->re_regs->re_version_id),
-		 in_be32(&re_priv->re_regs->global_config),
-		 in_be32(&re_priv->re_regs->galois_field_config));
+		 in_be32(&re_regs->re_version_id),
+		 in_be32(&re_regs->global_config),
+		 in_be32(&re_regs->galois_field_config));
 
 	dma_dev = &re_priv->dma_dev;
 	dma_dev->dev = dev;
diff --git a/drivers/dma/fsl_raid.h b/drivers/dma/fsl_raid.h
index 69d743c04973..adbfede330a7 100644
--- a/drivers/dma/fsl_raid.h
+++ b/drivers/dma/fsl_raid.h
@@ -256,7 +256,7 @@ struct fsl_re_hw_desc {
 struct fsl_re_drv_private {
 	u8 total_chans;
 	struct dma_device dma_dev;
-	struct fsl_re_ctrl *re_regs;
+	void __iomem *base;
 	struct fsl_re_chan *re_jrs[FSL_RE_MAX_CHANS];
 	struct dma_pool *cf_desc_pool;
 	struct dma_pool *hw_desc_pool;
@@ -273,7 +273,7 @@ struct fsl_re_chan {
 	struct device *dev;
 	struct fsl_re_drv_private *re_dev;
 	struct dma_chan chan;
-	struct fsl_re_chan_cfg *jrregs;
+	struct fsl_re_chan_cfg __iomem *jrregs;
 	int irq;
 	struct tasklet_struct irqtask;
 	u32 alloc_count;
-- 
2.55.0