Re: [PATCH V12 1/6] PCI: loongson: Use generic 8/16/32-bit config ops on LS2K/LS7A

[Rob Herring <robh@kernel.org>]

On Sat, Feb 26, 2022 at 06:47:26PM +0800, Huacai Chen wrote:
> LS2K/LS7A support 8/16/32-bits PCI config access operations via CFG1, so
> we can disable CFG0 for them and safely use pci_generic_config_read()/
> pci_generic_config_write() instead of pci_generic_config_read32()/pci_
> generic_config_write32().
> 
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> ---
>  drivers/pci/controller/pci-loongson.c | 65 +++++++++++++++++++--------
>  1 file changed, 46 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-loongson.c b/drivers/pci/controller/pci-loongson.c
> index 48169b1e3817..433261c5f34c 100644
> --- a/drivers/pci/controller/pci-loongson.c
> +++ b/drivers/pci/controller/pci-loongson.c
> @@ -25,11 +25,16 @@
>  #define FLAG_CFG1	BIT(1)
>  #define FLAG_DEV_FIX	BIT(2)
>  
> +struct pci_controller_data {

struct loongson_pci_data

> +	u32 flags;
> +	struct pci_ops *ops;

const struct

> +};
> +
>  struct loongson_pci {
>  	void __iomem *cfg0_base;
>  	void __iomem *cfg1_base;
>  	struct platform_device *pdev;
> -	u32 flags;
> +	struct pci_controller_data *data;
>  };
>  
>  /* Fixup wrong class code in PCIe bridges */
> @@ -126,8 +131,8 @@ static void __iomem *pci_loongson_map_bus(struct pci_bus *bus, unsigned int devf
>  	 * Do not read more than one device on the bus other than
>  	 * the host bus. For our hardware the root bus is always bus 0.
>  	 */
> -	if (priv->flags & FLAG_DEV_FIX && busnum != 0 &&
> -		PCI_SLOT(devfn) > 0)
> +	if (priv->data->flags & FLAG_DEV_FIX &&
> +			busnum != 0 && PCI_SLOT(devfn) > 0)

Are you sure you need all this? The default for PCIe (not PCI) is to 
only scan device 0 on child buses.

In any case, use pci_is_root_bus() rather than checking bus number 
is/isn't 0.


>  		return NULL;
>  
>  	/* CFG0 can only access standard space */
> @@ -159,20 +164,42 @@ static int loongson_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
>  	return val;
>  }
>  
> -/* H/w only accept 32-bit PCI operations */
> +/* LS2K/LS7A accept 8/16/32-bit PCI config operations */
>  static struct pci_ops loongson_pci_ops = {
> +	.map_bus = pci_loongson_map_bus,
> +	.read	= pci_generic_config_read,
> +	.write	= pci_generic_config_write,
> +};
> +
> +/* RS780/SR5690 only accept 32-bit PCI config operations */
> +static struct pci_ops loongson_pci_ops32 = {
>  	.map_bus = pci_loongson_map_bus,
>  	.read	= pci_generic_config_read32,
>  	.write	= pci_generic_config_write32,
>  };
>  
> +static const struct pci_controller_data ls2k_pci_data = {
> +	.flags = FLAG_CFG1 | FLAG_DEV_FIX,
> +	.ops = &loongson_pci_ops,
> +};
> +
> +static const struct pci_controller_data ls7a_pci_data = {
> +	.flags = FLAG_CFG1 | FLAG_DEV_FIX,
> +	.ops = &loongson_pci_ops,
> +};
> +
> +static const struct pci_controller_data rs780e_pci_data = {
> +	.flags = FLAG_CFG0,
> +	.ops = &loongson_pci_ops32,
> +};
> +
>  static const struct of_device_id loongson_pci_of_match[] = {
>  	{ .compatible = "loongson,ls2k-pci",
> -		.data = (void *)(FLAG_CFG0 | FLAG_CFG1 | FLAG_DEV_FIX), },
> +		.data = (void *)&ls2k_pci_data, },

Don't need the cast IIRC.

>  	{ .compatible = "loongson,ls7a-pci",
> -		.data = (void *)(FLAG_CFG0 | FLAG_CFG1 | FLAG_DEV_FIX), },
> +		.data = (void *)&ls7a_pci_data, },
>  	{ .compatible = "loongson,rs780e-pci",
> -		.data = (void *)(FLAG_CFG0), },
> +		.data = (void *)&rs780e_pci_data, },
>  	{}
>  };
>  
> @@ -193,20 +220,20 @@ static int loongson_pci_probe(struct platform_device *pdev)
>  
>  	priv = pci_host_bridge_priv(bridge);
>  	priv->pdev = pdev;
> -	priv->flags = (unsigned long)of_device_get_match_data(dev);
> +	priv->data = (struct pci_controller_data *)of_device_get_match_data(dev);
>  
> -	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	if (!regs) {
> -		dev_err(dev, "missing mem resources for cfg0\n");
> -		return -EINVAL;
> +	if (priv->data->flags & FLAG_CFG0) {
> +		regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +		if (!regs)
> +			dev_err(dev, "missing mem resources for cfg0\n");
> +		else {
> +			priv->cfg0_base = devm_pci_remap_cfg_resource(dev, regs);
> +			if (IS_ERR(priv->cfg0_base))
> +				return PTR_ERR(priv->cfg0_base);
> +		}
>  	}
>  
> -	priv->cfg0_base = devm_pci_remap_cfg_resource(dev, regs);
> -	if (IS_ERR(priv->cfg0_base))
> -		return PTR_ERR(priv->cfg0_base);
> -
> -	/* CFG1 is optional */
> -	if (priv->flags & FLAG_CFG1) {
> +	if (priv->data->flags & FLAG_CFG1) {
>  		regs = platform_get_resource(pdev, IORESOURCE_MEM, 1);
>  		if (!regs)
>  			dev_info(dev, "missing mem resource for cfg1\n");
> @@ -218,7 +245,7 @@ static int loongson_pci_probe(struct platform_device *pdev)
>  	}
>  
>  	bridge->sysdata = priv;
> -	bridge->ops = &loongson_pci_ops;
> +	bridge->ops = priv->data->ops;
>  	bridge->map_irq = loongson_map_irq;
>  
>  	return pci_host_probe(bridge);
> -- 
> 2.27.0
>