[PATCH v4 4/5] irqchip/gic-v3: Add Renesas R-Car Gen4 erratum workaround

[Marek Vasut <marek.vasut+renesas@mailbox.org>]

Renesas R-Car S4/V4H/V4M GIC600 integration has address width for AXI
or APB interface configured to 32 bit, it can therefore access only
the first 4 GiB of physical address space. This information comes from
R-Car V4H Interface Specification sheet, there is currently no technical
update number assigned to this limitation. Further input from hardware
engineer indicates that this limitation also applies to R-Car S4 and V4M.
Name the limitation GEN4GICITS1, and add a driver quirk to mitigate this
limitation.

The quirk is keyed on the combination of the GIC implementation
and the platform identification in the device tree.

Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Thomas Gleixner <tglx@kernel.org>
Co-developed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
NOTE: This would not be possible without prior work from Shimoda-san
      https://lore.kernel.org/all/20240214052050.1966439-1-yoshihiro.shimoda.uh@renesas.com/
---
Cc: "Krzysztof Wilczyński" <kwilczynski@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Conor Dooley <conor+dt@kernel.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
---
V2: Minimize the patch based on newly added patch in the series and
    only add entries into dma_32bit_impaired_platforms array. Update
    second paragraph of commit message slightly.
V3: - Add Co-developed-by to credit Shimoda-san
    - Add AB from Marc
V4: - Add AB from Thomas
---
 Documentation/arch/arm64/silicon-errata.rst | 1 +
 arch/arm64/Kconfig                          | 9 +++++++++
 drivers/irqchip/irq-gic-v3-its.c            | 5 +++++
 3 files changed, 15 insertions(+)

diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst
index 014aa1c215a16..b0c68b64f5ac2 100644
--- a/Documentation/arch/arm64/silicon-errata.rst
+++ b/Documentation/arch/arm64/silicon-errata.rst
@@ -352,6 +352,7 @@ stable kernels.
 +----------------+-----------------+-----------------+-----------------------------+
 | Qualcomm Tech. | Kryo4xx Gold    | N/A             | ARM64_ERRATUM_1286807       |
 +----------------+-----------------+-----------------+-----------------------------+
+| Renesas        | S4/V4H/V4M      | N/A             | RENESAS_ERRATUM_GEN4GICITS1 |
 +----------------+-----------------+-----------------+-----------------------------+
 | Rockchip       | RK3588          | #3588001        | ROCKCHIP_ERRATUM_3588001    |
 +----------------+-----------------+-----------------+-----------------------------+
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e136e5abdb33f..b1e0d4f1cd712 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1382,6 +1382,15 @@ config NVIDIA_CARMEL_CNP_ERRATUM
 
 	  If unsure, say Y.
 
+config RENESAS_ERRATUM_GEN4GICITS1
+	bool "Renesas R-Car Gen4: GIC600 can not access physical addresses above 4 GiB"
+	default y
+	help
+	  The Renesas R-Car Gen4 S4/V4H/V4M GIC600 SoC integrations have AXI
+	  addressing limited to the first 32-bit of physical address space.
+
+	  If unsure, say Y.
+
 config ROCKCHIP_ERRATUM_3568002
 	bool "Rockchip 3568002: GIC600 can not access physical addresses higher than 4GB"
 	default y
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index d7b46c10ef940..bf507f42ffb87 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -4889,6 +4889,11 @@ static bool __maybe_unused its_enable_quirk_hip09_162100801(void *data)
 }
 
 static const char * const dma_32bit_impaired_platforms[] = {
+#ifdef CONFIG_RENESAS_ERRATUM_GEN4GICITS1
+	"renesas,r8a779f0",
+	"renesas,r8a779g0",
+	"renesas,r8a779h0",
+#endif
 #ifdef CONFIG_ROCKCHIP_ERRATUM_3568002
 	"rockchip,rk3566",
 	"rockchip,rk3568",
-- 
2.53.0