Re: [PATCH v3 5/7] PCI: dwc: support AC5 Legacy PCIe interrupts

[Bjorn Helgaas <helgaas@kernel.org>]

On Thu, Feb 23, 2023 at 08:05:29PM +0200, Elad Nachman wrote:
> From: Elad Nachman <enachman@marvell.com>
> 
> Support message emulation of Legacy PCIe interrupts for Marvell AC5/X.
> These message emulations require writing an additional status register
> with acknowledge bits.
> 
> Signed-off-by: Elad Nachman <enachman@marvell.com>
> ---
>  drivers/pci/controller/dwc/pcie-armada8k.c | 41 +++++++++++++++-------
>  1 file changed, 28 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-armada8k.c b/drivers/pci/controller/dwc/pcie-armada8k.c
> index 02481ecadd25..145434c7a9fb 100644
> --- a/drivers/pci/controller/dwc/pcie-armada8k.c
> +++ b/drivers/pci/controller/dwc/pcie-armada8k.c
> @@ -46,7 +46,7 @@ struct armada8k_pcie_of_data {
>  	const struct dw_pcie_ops *pcie_ops;
>  };
>  
> -#define PCIE_VENDOR_REGS_OFFSET		0x8000	/* in ac5 is 0x10000 */
> +#define PCIE_VENDOR_REGS_OFFSET		0x8000	/* in ac5 is in another region */
>  
>  #define PCIE_GLOBAL_CONTROL_REG		(PCIE_VENDOR_REGS_OFFSET + 0x0)
>  #define PCIE_APP_LTSSM_EN		BIT(2)
> @@ -61,6 +61,7 @@ struct armada8k_pcie_of_data {
>  
>  #define PCIE_GLOBAL_INT_CAUSE1_REG	(PCIE_VENDOR_REGS_OFFSET + 0x1C)
>  #define PCIE_GLOBAL_INT_MASK1_REG	(PCIE_VENDOR_REGS_OFFSET + 0x20)
> +#define PCIE_GLOBAL_INT_CAUSE2_REG	(PCIE_VENDOR_REGS_OFFSET + 0x24)
>  #define PCIE_GLOBAL_INT_MASK2_REG	(PCIE_VENDOR_REGS_OFFSET + 0x28)
>  #define PCIE_INT_A_ASSERT_MASK		BIT(9)
>  #define PCIE_INT_B_ASSERT_MASK		BIT(10)
> @@ -267,8 +268,14 @@ static irqreturn_t armada8k_pcie_irq_handler(int irq, void *arg)
>  	 */
>  	val = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_INT_CAUSE1_REG);
>  	dw_pcie_writel_dbi(pci, PCIE_GLOBAL_INT_CAUSE1_REG, val);
> -	if ((PCIE_MSI_MASK_AC5 & val) && (pcie->pcie_type == ARMADA8K_PCIE_TYPE_AC5))
> -		dw_handle_msi_irq(&pci->pp);
> +	if (pcie->pcie_type == ARMADA8K_PCIE_TYPE_AC5) {
> +		if (PCIE_MSI_MASK_AC5 & val)
> +			dw_handle_msi_irq(&pci->pp);
> +
> +		val = dw_pcie_readl_dbi(pci, PCIE_GLOBAL_INT_CAUSE2_REG);
> +		/* Now clear the second interrupt cause. */
> +		dw_pcie_writel_dbi(pci, PCIE_GLOBAL_INT_CAUSE2_REG, val);
> +	}
>  
>  	return IRQ_HANDLED;
>  }
> @@ -307,24 +314,29 @@ static int armada8k_add_pcie_port(struct armada8k_pcie *pcie,
>  	return 0;
>  }
>  
> -static u32 ac5_xlate_dbi_reg(u32 reg)
> +static void __iomem *ac5_xlate_dbi_reg(struct dw_pcie *pci,
> +				       void __iomem *base,
> +				       u32 reg)
>  {
>  	/* Handle AC5 ATU access */
>  	if ((reg & ~0xfffff) == PCIE_ATU_ACCESS_MASK_AC5) {
>  		reg &= 0xfffff;
> -		/* ATU registers offset is 0xC00 + 0x200 * n,
> +		/* ATU registers offset is 0xC000 + 0x200 * n,
>  		 * from RFU registers.
>  		 */
> -		reg = 0xc000 | (0x200 * (reg >> 9)) | (reg & 0xff);
> +		reg = (0x200 * (reg >> 9)) | (reg & 0xff);

Is this change from 0xC00 to 0xC000 a bug fix?  This purports to only
add functionality.  A bug fix should be split to its own patch.

The armada8k_pcie_irq_handler() change above looks like it goes with
the commit log, but all this other stuff looks like separate logical
changes that should be in separate patches.

> +		return pci->atu_base + reg;
>  	} else if ((reg & 0xfffff000) == PCIE_VENDOR_REGS_OFFSET) {
>  		/* PCIe RFU registers in A8K are at offset 0x8000 from base
>  		 * (0xf2600000) while in AC5 offset is 0x10000 from base
> -		 * (0x800a0000) therefore need the addition of 0x8000.
> +		 * (0x800a0000) therefore need to be reduced by 0x8000
> +		 * and rebased from dbi2 base, which is set to the PCIe rfu
> +		 * base in the AC5 dts:
>  		 */
> -		reg += PCIE_VENDOR_REGS_OFFSET;
> +		reg -= PCIE_VENDOR_REGS_OFFSET;
> +		return pci->dbi_base2 + reg;
>  	}
> -
> -	return reg;
> +	return base + reg;
>  }
>  
>  static u32 ac5_pcie_read_dbi(struct dw_pcie *pci, void __iomem *base,
> @@ -332,14 +344,14 @@ static u32 ac5_pcie_read_dbi(struct dw_pcie *pci, void __iomem *base,
>  {
>  	u32 val;
>  
> -	dw_pcie_read(base + ac5_xlate_dbi_reg(reg), size, &val);
> +	dw_pcie_read(ac5_xlate_dbi_reg(pci, base, reg), size, &val);
>  	return val;
>  }
>  
>  static void ac5_pcie_write_dbi(struct dw_pcie *pci, void __iomem *base,
>  			       u32 reg, size_t size, u32 val)
>  {
> -	dw_pcie_write(base + ac5_xlate_dbi_reg(reg), size, val);
> +	dw_pcie_write(ac5_xlate_dbi_reg(pci, base, reg), size, val);
>  }
>  
>  static const struct dw_pcie_ops armada8k_dw_pcie_ops = {
> @@ -418,7 +430,6 @@ static int armada8k_pcie_probe(struct platform_device *pdev)
>  		ret = PTR_ERR(pci->dbi_base);
>  		goto fail_clkreg;
>  	}
> -
>  	ret = armada8k_pcie_setup_phys(pcie);
>  	if (ret)
>  		goto fail_clkreg;
> @@ -429,6 +440,10 @@ static int armada8k_pcie_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto disable_phy;
>  
> +	/* backwards compatibility with older dts files: */
> +	if (!pci->dbi_base2)
> +		pci->dbi_base2 = pci->dbi_base;
> +
>  	return 0;
>  
>  disable_phy:
> -- 
> 2.17.1
>