[RFC PATCH 5/9] rpi4: add a mapping for the PCIe XHCI controller MMIO registers (ARM 32bit)

[Sylwester Nawrocki]

From: Marek Szyprowski <m.szyprowski at samsung.com>

Create a non-cacheable mapping for the 0x600000000 physical memory region,
where MMIO registers for the PCIe XHCI controller are instantiated by the
PCIe bridge. Due to 32bit limit in the CPU virtual address space in ARM
32bit mode, this region is mapped at 0xff800000 CPU virtual address.

Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
---
 arch/arm/mach-bcm283x/Kconfig             |  1 +
 arch/arm/mach-bcm283x/include/mach/base.h |  7 +++++
 arch/arm/mach-bcm283x/init.c              | 52 +++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+)

diff --git a/arch/arm/mach-bcm283x/Kconfig b/arch/arm/mach-bcm283x/Kconfig
index 00419bf..bcb7f1d 100644
--- a/arch/arm/mach-bcm283x/Kconfig
+++ b/arch/arm/mach-bcm283x/Kconfig
@@ -36,6 +36,7 @@ config BCM2711_32B
 	select BCM2711
 	select ARMV7_LPAE
 	select CPU_V7A
+	select PHYS_64BIT
 
 config BCM2711_64B
 	bool "Broadcom BCM2711 SoC 64-bit support"
diff --git a/arch/arm/mach-bcm283x/include/mach/base.h b/arch/arm/mach-bcm283x/include/mach/base.h
index c4ae398..1d10dc9 100644
--- a/arch/arm/mach-bcm283x/include/mach/base.h
+++ b/arch/arm/mach-bcm283x/include/mach/base.h
@@ -6,6 +6,13 @@
 #ifndef _BCM283x_BASE_H_
 #define _BCM283x_BASE_H_
 
+#include <linux/types.h>
+
 extern unsigned long rpi_bcm283x_base;
 
+#ifdef CONFIG_ARMV7_LPAE
+extern void *rpi4_phys_to_virt(phys_addr_t paddr);
+#define phys_to_virt(x) rpi4_phys_to_virt(x)
+#endif
+
 #endif
diff --git a/arch/arm/mach-bcm283x/init.c b/arch/arm/mach-bcm283x/init.c
index 6a748da..5d0d160 100644
--- a/arch/arm/mach-bcm283x/init.c
+++ b/arch/arm/mach-bcm283x/init.c
@@ -145,6 +145,58 @@ int mach_cpu_init(void)
 }
 
 #ifdef CONFIG_ARMV7_LPAE
+
+#define BCM2711_RPI4_PCIE_XHCI_MMIO_VIRT	0xff800000UL
+
+void *rpi4_phys_to_virt(phys_addr_t paddr)
+{
+	if (paddr >= BCM2711_RPI4_PCIE_XHCI_MMIO_PHYS)
+		paddr = paddr - BCM2711_RPI4_PCIE_XHCI_MMIO_PHYS +
+			BCM2711_RPI4_PCIE_XHCI_MMIO_VIRT;
+	return (void *)(unsigned long)paddr;
+}
+
+static void set_section_phys(unsigned int section, phys_addr_t phys,
+			     enum dcache_option option)
+{
+	u64 *page_table = (u64 *)gd->arch.tlb_addr;
+	/* Need to set the access flag to not fault */
+	u64 value = TTB_SECT_AP | TTB_SECT_AF;
+
+	/* Add the page offset */
+	value |= (phys);
+
+	/* Add caching bits */
+	value |= option;
+
+	/* Set PTE */
+	page_table[section] = value;
+}
+
+static void rpi4_create_pcie_xhci_mapping(void)
+{
+	unsigned sect = BCM2711_RPI4_PCIE_XHCI_MMIO_VIRT >> MMU_SECTION_SHIFT;
+	phys_addr_t phys_addr = BCM2711_RPI4_PCIE_XHCI_MMIO_PHYS;
+	unsigned int size = BCM2711_RPI4_PCIE_XHCI_MMIO_SIZE;
+
+	while (size) {
+		set_section_phys(sect, phys_addr, DCACHE_OFF);
+		sect++;
+		phys_addr += MMU_SECTION_SIZE;
+		size -= MMU_SECTION_SIZE;
+	}
+}
+
+void arm_init_domains(void)
+{
+	/*
+	 * Hijack this function to prepare a mappings for the PCIe MMIO
+	 * region for the XHCI controller on RPi4 board.
+	 * This code is called before enabling the MMU in ARM 32bit mode.
+	 */
+	rpi4_create_pcie_xhci_mapping();
+}
+
 void enable_caches(void)
 {
 	dcache_enable();
-- 
2.7.4