Re: [PATCH 3/6] PCI: amlogic: meson: Add support for G12A

[Andrew Murray <andrew.murray@arm.com>]

On Sun, Sep 08, 2019 at 01:42:55PM +0000, Neil Armstrong wrote:
> Add support for the Amlogic G12A SoC using a separate shared PHY.
> 
> This adds support for fetching a PHY phandle and call the PHY init,
> reset and power on/off calls instead of writing in the PHY register or
> toggling the PHY reset line.
> 
> The MIPI clock is also made optional since it is used for setting up

Is it worth indicating here that the MIPI clock is *only required* for
the G12A (or controllers with a shared phy)? It's still required for
AXG. It's not optional for G12A - it's ignored.

> the PHY reference clock chared with the DSI controller on AXG.

s/chared/shared/

> 
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> ---
>  drivers/pci/controller/dwc/pci-meson.c | 101 ++++++++++++++++++++-----
>  1 file changed, 84 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-meson.c b/drivers/pci/controller/dwc/pci-meson.c
> index ab79990798f8..3fadad381762 100644
> --- a/drivers/pci/controller/dwc/pci-meson.c
> +++ b/drivers/pci/controller/dwc/pci-meson.c
> @@ -16,6 +16,7 @@
>  #include <linux/reset.h>
>  #include <linux/resource.h>
>  #include <linux/types.h>
> +#include <linux/phy/phy.h>
>  
>  #include "pcie-designware.h"
>  
> @@ -96,12 +97,18 @@ struct meson_pcie_rc_reset {
>  	struct reset_control *apb;
>  };
>  
> +struct meson_pcie_param {
> +	bool has_shared_phy;
> +};
> +
>  struct meson_pcie {
>  	struct dw_pcie pci;
>  	struct meson_pcie_mem_res mem_res;
>  	struct meson_pcie_clk_res clk_res;
>  	struct meson_pcie_rc_reset mrst;
>  	struct gpio_desc *reset_gpio;
> +	struct phy *phy;
> +	const struct meson_pcie_param *param;
>  };
>  
>  static struct reset_control *meson_pcie_get_reset(struct meson_pcie *mp,
> @@ -123,10 +130,12 @@ static int meson_pcie_get_resets(struct meson_pcie *mp)
>  {
>  	struct meson_pcie_rc_reset *mrst = &mp->mrst;
>  
> -	mrst->phy = meson_pcie_get_reset(mp, "phy", PCIE_SHARED_RESET);
> -	if (IS_ERR(mrst->phy))
> -		return PTR_ERR(mrst->phy);
> -	reset_control_deassert(mrst->phy);
> +	if (!mp->param->has_shared_phy) {
> +		mrst->phy = meson_pcie_get_reset(mp, "phy", PCIE_SHARED_RESET);
> +		if (IS_ERR(mrst->phy))
> +			return PTR_ERR(mrst->phy);
> +		reset_control_deassert(mrst->phy);
> +	}
>  
>  	mrst->port = meson_pcie_get_reset(mp, "port", PCIE_NORMAL_RESET);
>  	if (IS_ERR(mrst->port))
> @@ -180,6 +189,9 @@ static int meson_pcie_get_mems(struct platform_device *pdev,
>  	if (IS_ERR(mp->mem_res.cfg_base))
>  		return PTR_ERR(mp->mem_res.cfg_base);
>  
> +	if (mp->param->has_shared_phy)
> +		return 0;
> +

It may be more consistent if, rather than returning here, you wrapped
the following 3 lines by the if statement.

>  	/* Meson SoC has two PCI controllers use same phy register*/

I guess this comment should now be updated to refer to AXG?

>  	mp->mem_res.phy_base = meson_pcie_get_mem_shared(pdev, mp, "phy");
>  	if (IS_ERR(mp->mem_res.phy_base))
> @@ -188,19 +200,33 @@ static int meson_pcie_get_mems(struct platform_device *pdev,
>  	return 0;
>  }
>  
> -static void meson_pcie_power_on(struct meson_pcie *mp)
> +static int meson_pcie_power_on(struct meson_pcie *mp)
>  {
> -	writel(MESON_PCIE_PHY_POWERUP, mp->mem_res.phy_base);
> +	int ret = 0;
> +
> +	if (mp->param->has_shared_phy)
> +		ret = phy_power_on(mp->phy);

I haven't seen any phy_[init/exit] calls, should there be any?

> +	else
> +		writel(MESON_PCIE_PHY_POWERUP, mp->mem_res.phy_base);
> +
> +	return ret;
>  }
>  
> -static void meson_pcie_reset(struct meson_pcie *mp)
> +static int meson_pcie_reset(struct meson_pcie *mp)
>  {
>  	struct meson_pcie_rc_reset *mrst = &mp->mrst;
> -
> -	reset_control_assert(mrst->phy);
> -	udelay(PCIE_RESET_DELAY);
> -	reset_control_deassert(mrst->phy);
> -	udelay(PCIE_RESET_DELAY);
> +	int ret = 0;
> +
> +	if (mp->param->has_shared_phy) {
> +		ret = phy_reset(mp->phy);
> +		if (ret)
> +			return ret;
> +	} else {
> +		reset_control_assert(mrst->phy);
> +		udelay(PCIE_RESET_DELAY);
> +		reset_control_deassert(mrst->phy);
> +		udelay(PCIE_RESET_DELAY);
> +	}
>  
>  	reset_control_assert(mrst->port);
>  	reset_control_assert(mrst->apb);
> @@ -208,6 +234,8 @@ static void meson_pcie_reset(struct meson_pcie *mp)
>  	reset_control_deassert(mrst->port);
>  	reset_control_deassert(mrst->apb);
>  	udelay(PCIE_RESET_DELAY);
> +
> +	return 0;
>  }
>  
>  static inline struct clk *meson_pcie_probe_clock(struct device *dev,
> @@ -250,9 +278,11 @@ static int meson_pcie_probe_clocks(struct meson_pcie *mp)
>  	if (IS_ERR(res->port_clk))
>  		return PTR_ERR(res->port_clk);
>  
> -	res->mipi_gate = meson_pcie_probe_clock(dev, "mipi", 0);
> -	if (IS_ERR(res->mipi_gate))
> -		return PTR_ERR(res->mipi_gate);
> +	if (!mp->param->has_shared_phy) {
> +		res->mipi_gate = meson_pcie_probe_clock(dev, "mipi", 0);
> +		if (IS_ERR(res->mipi_gate))
> +			return PTR_ERR(res->mipi_gate);
> +	}
>  
>  	res->general_clk = meson_pcie_probe_clock(dev, "general", 0);
>  	if (IS_ERR(res->general_clk))
> @@ -524,6 +554,7 @@ static const struct dw_pcie_ops dw_pcie_ops = {
>  
>  static int meson_pcie_probe(struct platform_device *pdev)
>  {
> +	const struct meson_pcie_param *match_data;
>  	struct device *dev = &pdev->dev;
>  	struct dw_pcie *pci;
>  	struct meson_pcie *mp;
> @@ -537,6 +568,20 @@ static int meson_pcie_probe(struct platform_device *pdev)
>  	pci->dev = dev;
>  	pci->ops = &dw_pcie_ops;
>  
> +	match_data = of_device_get_match_data(dev);
> +	if (!match_data) {
> +		dev_err(dev, "failed to get match data\n");
> +		return -ENODEV;
> +	}
> +	mp->param = match_data;
> +
> +	if (mp->param->has_shared_phy) {
> +		mp->phy = devm_phy_get(dev, "pcie");
> +		if (IS_ERR(mp->phy)) {
> +			return PTR_ERR(mp->phy);
> +		}
> +	}
> +
>  	mp->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
>  	if (IS_ERR(mp->reset_gpio)) {
>  		dev_err(dev, "get reset gpio failed\n");
> @@ -555,8 +600,17 @@ static int meson_pcie_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> -	meson_pcie_power_on(mp);
> -	meson_pcie_reset(mp);
> +	ret = meson_pcie_power_on(mp);
> +	if (ret) {
> +		dev_err(dev, "phy power on failed, %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = meson_pcie_reset(mp);
> +	if (ret) {
> +		dev_err(dev, "reset failed, %d\n", ret);
> +		return ret;
> +	}
>  
>  	ret = meson_pcie_probe_clocks(mp);
>  	if (ret) {
> @@ -575,9 +629,22 @@ static int meson_pcie_probe(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +static struct meson_pcie_param meson_pcie_axg_param = {
> +	.has_shared_phy = false,
> +};
> +
> +static struct meson_pcie_param meson_pcie_g12a_param = {
> +	.has_shared_phy = true,
> +};
> +
>  static const struct of_device_id meson_pcie_of_match[] = {
>  	{
>  		.compatible = "amlogic,axg-pcie",
> +		.data = &meson_pcie_axg_param,
> +	},
> +	{
> +		.compatible = "amlogic,g12a-pcie",
> +		.data = &meson_pcie_g12a_param,

Here, we hard-code knowledge about the SOCs regarding if they have shared phys
or not. I guess the alternative would have been to assume there is a shared
phy if the DT has a phandle for it. I.e. instead of mp->param->has_shared_phy
everywhere you could test for mp->phy. Though I guess at least with the
current approach you guard against bad DTs, this seems OK.

Thanks,

Andrew Murray

>  	},
>  	{},
>  };
> -- 
> 2.17.1
> 

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