[PATCH 1/3] PCI: rcar-gen4: Configure AXIINTC if iMSI-RX not used

[Manivannan Sadhasivam]

On Wed, Jun 17, 2026 at 04:59:44AM +0200, Marek Vasut wrote:
> In case MSI are enabled, but DWC built-in iMSI-RX is not in use, the
> MSI are handled via GIC ITS. Configure all controller MSI registers
> fully.
> 
> Set or clear MSI capability register MSICAP0 MSI enable MSIE bit and
> PCIe Interrupt Status 0 Enable register PCIEINTSTS0EN MSI interrupt
> enable MSI_CTRL_INT bit according to MSI enable state, set both bits
> if MSI are enabled, clear both bits if MSI are disabled.
> 
> If MSI are disabled, or MSI are enabled and iMSI-RX is used, then
> deconfigure AXIINTCADDR and AXIINTCCONT to 0, which disables any
> pass through of MSI TLPs onto the AXI bus and then further into
> GIC ITS translation registers.
> 
> If MSI are enabled and iMSI-RX is not used, the configure AXIINTCADDR
> with target address of GIC ITS translation registers, and configure
> AXIINTCCONT to enable MSI TLP pass through onto AXI bus and into the
> GIC ITS. This specific configuration allows handling of MSI via the
> GIC ITS instead of integrated iMSI-RX.
> 
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh at renesas.com>
> Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
> ---
> NOTE: This would not be possible without prior work from Shimoda-san
> ---
> Cc: "Krzysztof Wilczyński" <kwilczynski at kernel.org>
> Cc: Bjorn Helgaas <bhelgaas at google.com>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Conor Dooley <conor+dt at kernel.org>
> Cc: Geert Uytterhoeven <geert+renesas at glider.be>
> Cc: Krzysztof Kozlowski <krzk+dt at kernel.org>
> Cc: Lorenzo Pieralisi <lpieralisi at kernel.org>
> Cc: Manivannan Sadhasivam <mani at kernel.org>
> Cc: Marc Zyngier <maz at kernel.org>
> Cc: Rob Herring <robh at kernel.org>
> Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh at renesas.com>
> Cc: devicetree at vger.kernel.org
> Cc: linux-arm-kernel at lists.infradead.org
> Cc: linux-doc at vger.kernel.org
> Cc: linux-kernel at vger.kernel.org
> Cc: linux-pci at vger.kernel.org
> Cc: linux-renesas-soc at vger.kernel.org
> ---
>  drivers/pci/controller/dwc/pcie-rcar-gen4.c | 53 +++++++++++++++++++--
>  1 file changed, 48 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> index 485cfa8bd9692..ba6e3bedd6d0a 100644
> --- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> @@ -31,6 +31,10 @@
>  #define DEVICE_TYPE_RC		BIT(4)
>  #define BIFUR_MOD_SET_ON	BIT(0)
>  
> +/* MSI Capability */
> +#define MSICAP0			0x0050
> +#define MSICAP0_MSIE		BIT(16)
> +
>  /* PCIe Interrupt Status 0 */
>  #define PCIEINTSTS0		0x0084
>  
> @@ -55,6 +59,16 @@
>  #define APP_HOLD_PHY_RST	BIT(16)
>  #define APP_LTSSM_ENABLE	BIT(0)
>  
> +/* INTC address */
> +#define AXIINTCADDR		0x0a00
> +/* GITS GIC ITS translation register */
> +#define AXIINTCADDR_VAL		0xf1050000

As Marc pointed out, this address should be fetched from DT, not hardcoded in
the driver.

> +
> +/* INTC control & mask */
> +#define AXIINTCCONT		0x0a04
> +#define INTC_EN			BIT(31)
> +#define INTC_MASK		GENMASK(11, 2)
> +
>  /* PCIe Power Management Control */
>  #define PCIEPWRMNGCTRL		0x0070
>  #define APP_CLK_REQ_N		BIT(11)
> @@ -305,6 +319,39 @@ static struct rcar_gen4_pcie *rcar_gen4_pcie_alloc(struct platform_device *pdev)
>  	return rcar;
>  }
>  
> +static void rcar_gen4_pcie_host_msi_init(struct dw_pcie_rp *pp)
> +{
> +	struct dw_pcie *dw = to_dw_pcie_from_pp(pp);
> +	struct rcar_gen4_pcie *rcar = to_rcar_gen4_pcie(dw);
> +	u32 val;
> +
> +	/* Make sure MSICAP0 MSIE is configured. */
> +	val = dw_pcie_readl_dbi(dw, MSICAP0);
> +	if (pci_msi_enabled())
> +		val |= MSICAP0_MSIE;
> +	else
> +		val &= ~MSICAP0_MSIE;
> +	dw_pcie_writel_dbi(dw, MSICAP0, val);
> +
> +	if (!pci_msi_enabled() || pp->use_imsi_rx) {

If MSI is not enabled, then what's the point in clearing these registers (also
above)? I see it as a redundant code. Is there a necessity to clear them?

- Mani

-- 
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