PCI devices on s390 have a DMA offset that is reported via CLP.  In
preparation for allowing identity domains, enable ARCH_HAS_PHYS_TO_DMA
for s390 and get the dma offset for all PCI devices from the reported
CLP value.

Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
 arch/s390/Kconfig                  |  1 +
 arch/s390/include/asm/device.h     | 12 ++++++++++++
 arch/s390/include/asm/dma-direct.h | 14 ++++++++++++++
 arch/s390/pci/pci_bus.c            |  2 ++
 4 files changed, 29 insertions(+)
 create mode 100644 arch/s390/include/asm/device.h
 create mode 100644 arch/s390/include/asm/dma-direct.h

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 0077969170e8..5746d8abc8a7 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -83,6 +83,7 @@ config S390
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_GIGANTIC_PAGE
+	select ARCH_HAS_PHYS_TO_DMA
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_MEMBARRIER_SYNC_CORE
 	select ARCH_HAS_MEM_ENCRYPT
diff --git a/arch/s390/include/asm/device.h b/arch/s390/include/asm/device.h
new file mode 100644
index 000000000000..a6bf5e137a17
--- /dev/null
+++ b/arch/s390/include/asm/device.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_S390_DEVICE_H
+#define _ASM_S390_DEVICE_H
+
+struct dev_archdata {
+	dma_addr_t		dma_offset;
+};
+
+struct pdev_archdata {
+};
+
+#endif /* _ASM_S390_DEVICE_H */
diff --git a/arch/s390/include/asm/dma-direct.h b/arch/s390/include/asm/dma-direct.h
new file mode 100644
index 000000000000..9391820fca2c
--- /dev/null
+++ b/arch/s390/include/asm/dma-direct.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ASM_S390_DMA_DIRECT_H
+#define ASM_S390_DMA_DIRECT_H 1
+
+static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
+{
+	return paddr + dev->archdata.dma_offset;
+}
+
+static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
+{
+	return daddr - dev->archdata.dma_offset;
+}
+#endif /* ASM_S390_DMA_DIRECT_H */
diff --git a/arch/s390/pci/pci_bus.c b/arch/s390/pci/pci_bus.c
index d5ace00d10f0..ec874ba858c6 100644
--- a/arch/s390/pci/pci_bus.c
+++ b/arch/s390/pci/pci_bus.c
@@ -288,6 +288,8 @@ void pcibios_bus_add_device(struct pci_dev *pdev)
 {
 	struct zpci_dev *zdev = to_zpci(pdev);
 
+	pdev->dev.archdata.dma_offset = zdev->start_dma;
+
 	/*
 	 * With pdev->no_vf_scan the common PCI probing code does not
 	 * perform PF/VF linking.
-- 
2.47.0

On Mon, Dec 09, 2024 at 02:23:59PM -0500, Matthew Rosato wrote:
> PCI devices on s390 have a DMA offset that is reported via CLP.  In
> preparation for allowing identity domains, enable ARCH_HAS_PHYS_TO_DMA
> for s390 and get the dma offset for all PCI devices from the reported
> CLP value.

Nothing new should select ARCH_HAS_PHYS_TO_DMA, please fill out the
bus_dma_region attached to the device instead.

On 12/9/24 11:33 PM, Christoph Hellwig wrote:
> On Mon, Dec 09, 2024 at 02:23:59PM -0500, Matthew Rosato wrote:
>> PCI devices on s390 have a DMA offset that is reported via CLP.  In
>> preparation for allowing identity domains, enable ARCH_HAS_PHYS_TO_DMA
>> for s390 and get the dma offset for all PCI devices from the reported
>> CLP value.
> 
> Nothing new should select ARCH_HAS_PHYS_TO_DMA, please fill out the
> bus_dma_region attached to the device instead.
> 

OK, thanks for the pointer.  I think I've got it converted, will test some more and include this change in next version.