[PATCH v4 1/2] dmaengine: tegra210-adma: Fix build error due to 64-by-32 division

Mohan Kumar D
2025-02-05T03:31:59Z

Kernel test robot reported the build errors on 32-bit platforms due to
plain 64-by-32 division. Following build erros were reported.

"ERROR: modpost: "__udivdi3" [drivers/dma/tegra210-adma.ko] undefined!
ld: drivers/dma/tegra210-adma.o: in function `tegra_adma_probe':
tegra210-adma.c:(.text+0x12cf): undefined reference to `__udivdi3'"

This can be fixed by using div_u64() for the adma address space

Fixes: 68811c928f88 ("dmaengine: tegra210-adma: Support channel page")
Cc: stable@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202412250204.GCQhdKe3-lkp@intel.com/
Signed-off-by: Mohan Kumar D <mkumard@nvidia.com>
---
drivers/dma/tegra210-adma.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/tegra210-adma.c b/drivers/dma/tegra210-adma.c
index 6896da8ac7ef..a0bd4822ed80 100644
--- a/drivers/dma/tegra210-adma.c
+++ b/drivers/dma/tegra210-adma.c
@@ -887,7 +887,8 @@ static int tegra_adma_probe(struct platform_device *pdev)
const struct tegra_adma_chip_data *cdata;
struct tegra_adma *tdma;
struct resource *res_page, *res_base;
- int ret, i, page_no;
+ u64 page_no, page_offset;
+ int ret, i;

cdata = of_device_get_match_data(&pdev->dev);
if (!cdata) {
@@ -914,10 +915,16 @@ static int tegra_adma_probe(struct platform_device *pdev)

res_base = platform_get_resource_byname(pdev, IORESOURCE_MEM, "global");
if (res_base) {
- page_no = (res_page->start - res_base->start) / cdata->ch_base_offset;
- if (page_no <= 0)
+ if (WARN_ON(res_page->start <= res_base->start))
return -EINVAL;
- tdma->ch_page_no = page_no - 1;
+
+ page_offset = res_page->start - res_base->start;
+ page_no = div_u64(page_offset, cdata->ch_base_offset);
+
+ if (WARN_ON(page_no == 0))
+ return -EINVAL;
+
+ tdma->ch_page_no = lower_32_bits(page_no) - 1;
tdma->base_addr = devm_ioremap_resource(&pdev->dev, res_base);
if (IS_ERR(tdma->base_addr))
return PTR_ERR(tdma->base_addr);
--
2.25.1