[RFC/RFT 4/6] PCI: rockchip-dwc: add pcie bifurcation

[Bjorn Helgaas]

On Sat, Apr 16, 2022 at 03:54:56PM +0200, Frank Wunderlich wrote:
> From: Frank Wunderlich <frank-w at public-files.de>
> 
> PCIe Lanes can be split to 2 slots with bifurcation.
> Add support for this in existing pcie driver.

Please s/pcie/PCIe/ in subject and above to be consistent.  You also
have kind of a random usage in other patches.

Mention the DT property used for this in the commit log.

Is the "rockchip,bifurcation" DT property something that should be
generalized so it's not rockchip-specific?  Other controllers are
likely to support similar functionality.

> Co-developed-by: Peter Geis <pgwipeout at gmail.com>
> Signed-off-by: Frank Wunderlich <frank-w at public-files.de>
> ---
>  drivers/pci/controller/dwc/pcie-dw-rockchip.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> index 863374604fb1..1b0c2115b32e 100644
> --- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> +++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
> @@ -20,6 +20,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/regmap.h>
>  #include <linux/reset.h>
> +#include <linux/phy/pcie.h>
>  
>  #include "pcie-designware.h"
>  
> @@ -59,6 +60,7 @@ struct rockchip_pcie {
>  	struct regulator                *vpcie3v3;
>  	struct irq_domain		*irq_domain;
>  	raw_spinlock_t			irq_lock;
> +	bool				bifurcation;
>  };
>  
>  static int rockchip_pcie_readl_apb(struct rockchip_pcie *rockchip,
> @@ -273,6 +275,12 @@ static int rockchip_pcie_phy_init(struct rockchip_pcie *rockchip)
>  		return dev_err_probe(dev, PTR_ERR(rockchip->phy),
>  				     "missing PHY\n");
>  
> +	if (rockchip->bifurcation) {
> +		ret = phy_set_mode_ext(rockchip->phy, PHY_MODE_PCIE, PHY_MODE_PCIE_BIFURCATION);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	ret = phy_init(rockchip->phy);
>  	if (ret < 0)
>  		return ret;
> @@ -345,6 +353,9 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> +	if (device_property_read_bool(dev, "rockchip,bifurcation"))
> +		rockchip->bifurcation = true;
> +
>  	ret = rockchip_pcie_phy_init(rockchip);
>  	if (ret)
>  		goto disable_regulator;
> -- 
> 2.25.1
> 
> 
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