Date:   Tue, 2 Nov 2021 11:06:12 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Rob Herring <robh@...nel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>, linuxarm@...wei.com,
        mauro.chehab@...wei.com,
        Krzysztof Wilczyński <kw@...ux.com>,
        Binghui Wang <wangbinghui@...ilicon.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Xiaowei Song <songxiaowei@...ilicon.com>,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        Kishon Vijay Abraham I <kishon@...com>
Subject: Re: [PATCH v15 04/13] PCI: kirin: Add support for bridge slot DT
 schema

On Thu, Oct 21, 2021 at 11:45:11AM +0100, Mauro Carvalho Chehab wrote:
> On HiKey970, there's a PEX 8606 PCI bridge on its PHY with
> 6 lanes. Only 4 lanes are connected:
> 
> 	lane 0 - connected to Kirin 970;
> 	lane 4 - M.2 slot;
> 	lane 5 - mini PCIe slot;
> 	lane 6 - in-board Ethernet controller.
> 
> Each lane has its own PERST# gpio pin, and needs a clock
> request.
> 
> Add support to parse a DT schema containing the above data.
> 
> Cc: Kishon Vijay Abraham I <kishon@...com>
> Acked-by: Xiaowei Song <songxiaowei@...ilicon.com>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> ---
> 
> To mailbombing on a large number of people, only mailing lists were C/C on the cover.
> See [PATCH v15 00/13] at: https://lore.kernel.org/all/cover.1634812676.git.mchehab+huawei@kernel.org/
> 
>  drivers/pci/controller/dwc/pcie-kirin.c | 262 +++++++++++++++++++++---
>  1 file changed, 231 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-kirin.c b/drivers/pci/controller/dwc/pcie-kirin.c
> index 86c13661e02d..de375795a3b8 100644
> --- a/drivers/pci/controller/dwc/pcie-kirin.c
> +++ b/drivers/pci/controller/dwc/pcie-kirin.c
> @@ -52,6 +52,19 @@
>  #define PCIE_DEBOUNCE_PARAM	0xF0F400
>  #define PCIE_OE_BYPASS		(0x3 << 28)
>  
> +/*
> + * Max number of connected PCI slots at an external PCI bridge
> + *
> + * This is used on HiKey 970, which has a PEX 8606 bridge with has
> + * 4 connected lanes (lane 0 upstream, and the other tree lanes,
> + * one connected to an in-board Ethernet adapter and the other two
> + * connected to M.2 and mini PCI slots.
> + *
> + * Each slot has a different clock source and uses a separate PERST#
> + * pin.
> + */
> +#define MAX_PCI_SLOTS		3
> +
>  enum pcie_kirin_phy_type {
>  	PCIE_KIRIN_INTERNAL_PHY,
>  	PCIE_KIRIN_EXTERNAL_PHY
> @@ -64,6 +77,19 @@ struct kirin_pcie {
>  	struct regmap   *apb;
>  	struct phy	*phy;
>  	void		*phy_priv;	/* only for PCIE_KIRIN_INTERNAL_PHY */
> +
> +	/* DWC PERST# */
> +	int		gpio_id_dwc_perst;
> +
> +	/* Per-slot PERST# */
> +	int		num_slots;
> +	int		gpio_id_reset[MAX_PCI_SLOTS];
> +	const char	*reset_names[MAX_PCI_SLOTS];
> +
> +	/* Per-slot clkreq */
> +	int		n_gpio_clkreq;
> +	int		gpio_id_clkreq[MAX_PCI_SLOTS];
> +	const char	*clkreq_names[MAX_PCI_SLOTS];

I think there's been previous discussion about this, but I didn't
follow it, so I'm just double-checking that this is what we want here.

IIUC, this (MAX_PCI_SLOTS, "hisilicon,clken-gpios") applies to an
external PEX 8606 bridge, which seems a little strange to be
hard-coded into the kirin driver this way.

I see that "hisilicon,clken-gpios" is optional, but what if some
platform connects all 6 lanes?  What if there's a different bridge
altogether?

I'll assume this is actually the way we want thing unless I hear
otherwise.

>  };
>  
>  /*
> @@ -108,7 +134,6 @@ struct hi3660_pcie_phy {
>  	struct clk	*phy_ref_clk;
>  	struct clk	*aclk;
>  	struct clk	*aux_clk;
> -	int		gpio_id_reset;
>  };
>  
>  /* Registers in PCIePHY */
> @@ -171,16 +196,6 @@ static int hi3660_pcie_phy_get_resource(struct hi3660_pcie_phy *phy)
>  	if (IS_ERR(phy->sysctrl))
>  		return PTR_ERR(phy->sysctrl);
>  
> -	/* gpios */
> -	phy->gpio_id_reset = of_get_named_gpio(dev->of_node,
> -					       "reset-gpios", 0);
> -	if (phy->gpio_id_reset == -EPROBE_DEFER) {
> -		return -EPROBE_DEFER;
> -	} else if (!gpio_is_valid(phy->gpio_id_reset)) {
> -		dev_err(phy->dev, "unable to get a valid gpio pin\n");
> -		return -ENODEV;
> -	}
> -
>  	return 0;
>  }
>  
> @@ -297,15 +312,7 @@ static int hi3660_pcie_phy_power_on(struct kirin_pcie *pcie)
>  	if (ret)
>  		goto disable_clks;
>  
> -	/* perst assert Endpoint */
> -	if (!gpio_request(phy->gpio_id_reset, "pcie_perst")) {
> -		usleep_range(REF_2_PERST_MIN, REF_2_PERST_MAX);
> -		ret = gpio_direction_output(phy->gpio_id_reset, 1);
> -		if (ret)
> -			goto disable_clks;
> -		usleep_range(PERST_2_ACCESS_MIN, PERST_2_ACCESS_MAX);
> -		return 0;
> -	}
> +	return 0;
>  
>  disable_clks:
>  	hi3660_pcie_phy_clk_ctrl(phy, false);
> @@ -347,11 +354,98 @@ static const struct regmap_config pcie_kirin_regmap_conf = {
>  	.reg_stride = 4,
>  };
>  
> +static int kirin_pcie_get_gpio_enable(struct kirin_pcie *pcie,
> +				      struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	char name[32];
> +	int ret, i;
> +
> +	/* This is an optional property */
> +	ret = of_gpio_named_count(np, "hisilicon,clken-gpios");
> +	if (ret < 0)
> +		return 0;
> +
> +	if (ret > MAX_PCI_SLOTS) {
> +		dev_err(dev, "Too many GPIO clock requests!\n");
> +		return -EINVAL;
> +	}
> +
> +	pcie->n_gpio_clkreq = ret;
> +
> +	for (i = 0; i < pcie->n_gpio_clkreq; i++) {
> +		pcie->gpio_id_clkreq[i] = of_get_named_gpio(dev->of_node,
> +							    "hisilicon,clken-gpios", i);
> +		if (pcie->gpio_id_clkreq[i] < 0)
> +			return pcie->gpio_id_clkreq[i];
> +
> +		sprintf(name, "pcie_clkreq_%d", i);
> +		pcie->clkreq_names[i] = devm_kstrdup_const(dev, name,
> +							    GFP_KERNEL);
> +		if (!pcie->clkreq_names[i])
> +			return -ENOMEM;
> +	}
> +
> +	return 0;
> +}
> +
> +static int kirin_pcie_parse_port(struct kirin_pcie *pcie,
> +				 struct platform_device *pdev,
> +				 struct device_node *node)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *parent, *child;
> +	int ret, slot, i;
> +	char name[32];
> +
> +	for_each_available_child_of_node(node, parent) {
> +		for_each_available_child_of_node(parent, child) {
> +			i = pcie->num_slots;
> +
> +			pcie->gpio_id_reset[i] = of_get_named_gpio(child,
> +								"reset-gpios", 0);
> +			if (pcie->gpio_id_reset[i] < 0)
> +				continue;
> +
> +			pcie->num_slots++;
> +			if (pcie->num_slots > MAX_PCI_SLOTS) {
> +				dev_err(dev, "Too many PCI slots!\n");
> +				return -EINVAL;
> +			}
> +
> +			ret = of_pci_get_devfn(child);
> +			if (ret < 0) {
> +				dev_err(dev, "failed to parse devfn: %d\n", ret);
> +				goto put_node;
> +			}
> +
> +			slot = PCI_SLOT(ret);
> +
> +			sprintf(name, "pcie_perst_%d", slot);
> +			pcie->reset_names[i] = devm_kstrdup_const(dev, name,
> +								GFP_KERNEL);
> +			if (!pcie->reset_names[i]) {
> +				ret = -ENOMEM;
> +				goto put_node;
> +			}
> +		}
> +	}
> +
> +	return 0;
> +
> +put_node:
> +	of_node_put(child);
> +	return ret;
> +}
> +
>  static long kirin_pcie_get_resource(struct kirin_pcie *kirin_pcie,
>  				    struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> +	struct device_node *child, *node = dev->of_node;
>  	void __iomem *apb_base;
> +	int ret;
>  
>  	apb_base = devm_platform_ioremap_resource_byname(pdev, "apb");
>  	if (IS_ERR(apb_base))
> @@ -362,7 +456,32 @@ static long kirin_pcie_get_resource(struct kirin_pcie *kirin_pcie,
>  	if (IS_ERR(kirin_pcie->apb))
>  		return PTR_ERR(kirin_pcie->apb);
>  
> +	/* pcie internal PERST# gpio */
> +	kirin_pcie->gpio_id_dwc_perst = of_get_named_gpio(dev->of_node,
> +							  "reset-gpios", 0);
> +	if (kirin_pcie->gpio_id_dwc_perst == -EPROBE_DEFER) {
> +		return -EPROBE_DEFER;
> +	} else if (!gpio_is_valid(kirin_pcie->gpio_id_dwc_perst)) {
> +		dev_err(dev, "unable to get a valid gpio pin\n");
> +		return -ENODEV;
> +	}
> +
> +	ret = kirin_pcie_get_gpio_enable(kirin_pcie, pdev);
> +	if (ret)
> +		return ret;
> +
> +	/* Parse OF children */
> +	for_each_available_child_of_node(node, child) {
> +		ret = kirin_pcie_parse_port(kirin_pcie, pdev, child);
> +		if (ret)
> +			goto put_node;
> +	}
> +
>  	return 0;
> +
> +put_node:
> +	of_node_put(child);
> +	return ret;
>  }
>  
>  static void kirin_pcie_sideband_dbi_w_mode(struct kirin_pcie *kirin_pcie,
> @@ -419,9 +538,33 @@ static int kirin_pcie_wr_own_conf(struct pci_bus *bus, unsigned int devfn,
>  	return PCIBIOS_SUCCESSFUL;
>  }
>  
> +static int kirin_pcie_add_bus(struct pci_bus *bus)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(bus->sysdata);
> +	struct kirin_pcie *kirin_pcie = to_kirin_pcie(pci);
> +	int i, ret;
> +
> +	if (!kirin_pcie->num_slots)
> +		return 0;
> +
> +	/* Send PERST# to each slot */
> +	for (i = 0; i < kirin_pcie->num_slots; i++) {
> +		ret = gpio_direction_output(kirin_pcie->gpio_id_reset[i], 1);
> +		if (ret) {
> +			dev_err(pci->dev, "PERST# %s error: %d\n",
> +				kirin_pcie->reset_names[i], ret);
> +		}
> +	}
> +	usleep_range(PERST_2_ACCESS_MIN, PERST_2_ACCESS_MAX);
> +
> +	return 0;
> +}
> +
> +
>  static struct pci_ops kirin_pci_ops = {
>  	.read = kirin_pcie_rd_own_conf,
>  	.write = kirin_pcie_wr_own_conf,
> +	.add_bus = kirin_pcie_add_bus,
>  };
>  
>  static u32 kirin_pcie_read_dbi(struct dw_pcie *pci, void __iomem *base,
> @@ -477,6 +620,44 @@ static int kirin_pcie_host_init(struct pcie_port *pp)
>  	return 0;
>  }
>  
> +static int kirin_pcie_gpio_request(struct kirin_pcie *kirin_pcie,
> +				   struct device *dev)
> +{
> +	int ret, i;
> +
> +	for (i = 0; i < kirin_pcie->num_slots; i++) {
> +		if (!gpio_is_valid(kirin_pcie->gpio_id_reset[i])) {
> +			dev_err(dev, "unable to get a valid %s gpio\n",
> +				kirin_pcie->reset_names[i]);
> +			return -ENODEV;
> +		}
> +
> +		ret = devm_gpio_request(dev, kirin_pcie->gpio_id_reset[i],
> +					kirin_pcie->reset_names[i]);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; i < kirin_pcie->n_gpio_clkreq; i++) {
> +		if (!gpio_is_valid(kirin_pcie->gpio_id_clkreq[i])) {
> +			dev_err(dev, "unable to get a valid %s gpio\n",
> +				kirin_pcie->clkreq_names[i]);
> +			return -ENODEV;
> +		}
> +
> +		ret = devm_gpio_request(dev, kirin_pcie->gpio_id_clkreq[i],
> +					kirin_pcie->clkreq_names[i]);
> +		if (ret)
> +			return ret;
> +
> +		ret = gpio_direction_output(kirin_pcie->gpio_id_clkreq[i], 0);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static const struct dw_pcie_ops kirin_dw_pcie_ops = {
>  	.read_dbi = kirin_pcie_read_dbi,
>  	.write_dbi = kirin_pcie_write_dbi,
> @@ -499,24 +680,43 @@ static int kirin_pcie_power_on(struct platform_device *pdev,
>  		if (ret)
>  			return ret;
>  
> -		return hi3660_pcie_phy_power_on(kirin_pcie);
> +		ret = hi3660_pcie_phy_power_on(kirin_pcie);
> +		if (ret)
> +			return ret;
> +	} else {
> +		kirin_pcie->phy = devm_of_phy_get(dev, dev->of_node, NULL);
> +		if (IS_ERR(kirin_pcie->phy))
> +			return PTR_ERR(kirin_pcie->phy);
> +
> +		ret = kirin_pcie_gpio_request(kirin_pcie, dev);
> +		if (ret)
> +			return ret;
> +
> +		ret = phy_init(kirin_pcie->phy);
> +		if (ret)
> +			goto err;
> +
> +		ret = phy_power_on(kirin_pcie->phy);
> +		if (ret)
> +			goto err;
>  	}
>  
> -	kirin_pcie->phy = devm_of_phy_get(dev, dev->of_node, NULL);
> -	if (IS_ERR(kirin_pcie->phy))
> -		return PTR_ERR(kirin_pcie->phy);
> +	/* perst assert Endpoint */
> +	usleep_range(REF_2_PERST_MIN, REF_2_PERST_MAX);
>  
> -	ret = phy_init(kirin_pcie->phy);
> -	if (ret)
> -		goto err;
> +	if (!gpio_request(kirin_pcie->gpio_id_dwc_perst, "pcie_perst_bridge")) {
> +		ret = gpio_direction_output(kirin_pcie->gpio_id_dwc_perst, 1);
> +		if (ret)
> +			goto err;
> +	}
>  
> -	ret = phy_power_on(kirin_pcie->phy);
> -	if (ret)
> -		goto err;
> +	usleep_range(PERST_2_ACCESS_MIN, PERST_2_ACCESS_MAX);
>  
>  	return 0;
>  err:
> -	phy_exit(kirin_pcie->phy);
> +	if (kirin_pcie->type != PCIE_KIRIN_INTERNAL_PHY)
> +		phy_exit(kirin_pcie->phy);
> +
>  	return ret;
>  }
>  
> -- 
> 2.31.1
> 

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