Subject: Re: [PATCH V2 14/16] phy: tegra: Add PCIe PIPE2UPHY support

From: Thierry Reding <[email-masked]>
Date: Mon, 15 Apr 2019 17:31:48 +0200

On Fri, Apr 05, 2019 at 01:24:41AM +0530, Vidya Sagar wrote:
> Synopsys DesignWare core based PCIe controllers in Tegra 194 SoC interface
> with Universal PHY (UPHY) module through a PIPE2UPHY (P2U) module.
> For each PCIe lane of a controller, there is a P2U unit instantiated at
> hardware level. This driver provides support for the programming required
> for each P2U that is going to be used for a PCIe controller.
> 
> Signed-off-by: Vidya Sagar <[email-masked]>
> ---
> Changes since [v1]:
> * Added COMPILE_TEST in Kconfig
> * Removed empty phy_ops implementations
> * Modified code according to DT documentation file modifications
> 
>  drivers/phy/tegra/Kconfig             |   7 ++
>  drivers/phy/tegra/Makefile            |   1 +
>  drivers/phy/tegra/pcie-p2u-tegra194.c | 120 ++++++++++++++++++++++++++++++++++
>  3 files changed, 128 insertions(+)
>  create mode 100644 drivers/phy/tegra/pcie-p2u-tegra194.c
> 
> diff --git a/drivers/phy/tegra/Kconfig b/drivers/phy/tegra/Kconfig
> index a3b1de953fb7..eb93ee72ecf0 100644
> --- a/drivers/phy/tegra/Kconfig
> +++ b/drivers/phy/tegra/Kconfig
> @@ -6,3 +6,10 @@ config PHY_TEGRA_XUSB
>  
>  	  To compile this driver as a module, choose M here: the module will
>  	  be called phy-tegra-xusb.
> +
> +config PHY_TEGRA194_PCIE_P2U
> +        tristate "NVIDIA Tegra P2U PHY Driver"
> +        depends on ARCH_TEGRA || COMPILE_TEST
> +        select GENERIC_PHY
> +        help
> +          Enable this to support the P2U (PIPE to UPHY) that is part of Tegra 19x SOCs.

This should be using tabs for indentation.

> diff --git a/drivers/phy/tegra/Makefile b/drivers/phy/tegra/Makefile
> index 898589238fd9..f85b2c86643d 100644
> --- a/drivers/phy/tegra/Makefile
> +++ b/drivers/phy/tegra/Makefile
> @@ -4,3 +4,4 @@ phy-tegra-xusb-y += xusb.o
>  phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_124_SOC) += xusb-tegra124.o
>  phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_132_SOC) += xusb-tegra124.o
>  phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_210_SOC) += xusb-tegra210.o
> +obj-$(CONFIG_PHY_TEGRA194_PCIE_P2U) += pcie-p2u-tegra194.o
> diff --git a/drivers/phy/tegra/pcie-p2u-tegra194.c b/drivers/phy/tegra/pcie-p2u-tegra194.c
> new file mode 100644
> index 000000000000..d4df8bfa9979
> --- /dev/null
> +++ b/drivers/phy/tegra/pcie-p2u-tegra194.c
> @@ -0,0 +1,120 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * P2U (PIPE to UPHY) driver for Tegra T194 SoC
> + *
> + * Copyright (C) 2019 NVIDIA Corporation.
> + *
> + * Author: Vidya Sagar <[email-masked]>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/phy/phy.h>
> +#include <linux/of.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/of_platform.h>
> +#include <soc/tegra/bpmp-abi.h>

It's a good idea to keep these sorted alphabetically. That makes it a
lot easier to insert new ones in the right place subsequently.

> +
> +#define P2U_PERIODIC_EQ_CTRL_GEN3	0xc0
> +#define P2U_PERIODIC_EQ_CTRL_GEN3_PERIODIC_EQ_EN		BIT(0)
> +#define P2U_PERIODIC_EQ_CTRL_GEN3_INIT_PRESET_EQ_TRAIN_EN	BIT(1)
> +#define P2U_PERIODIC_EQ_CTRL_GEN4	0xc4
> +#define P2U_PERIODIC_EQ_CTRL_GEN4_INIT_PRESET_EQ_TRAIN_EN	BIT(1)
> +
> +#define P2U_RX_DEBOUNCE_TIME				0xa4
> +#define P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_MASK	0xFFFF

Use consistent case for hexadecimal. All other register definitions use
lower-case, so this one should, too.

> +#define P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL		160
> +
> +struct tegra_p2u {
> +	void __iomem		*base;

I personally wouldn't bother with the extra padding. A single space is
enough and avoid extra churn if you ever add something here that doesn't
fit into the existing padding space.

> +};
> +
> +static int tegra_p2u_power_on(struct phy *x)
> +{
> +	u32 val;
> +	struct tegra_p2u *phy = phy_get_drvdata(x);

It's often common to structure these as "reverse christmas tree" so that
the longest lines go first, followed by shorter lines. Not sure if
Kishon cares, though.

> +
> +	val = readl(phy->base + P2U_PERIODIC_EQ_CTRL_GEN3);
> +	val &= ~P2U_PERIODIC_EQ_CTRL_GEN3_PERIODIC_EQ_EN;
> +	val |= P2U_PERIODIC_EQ_CTRL_GEN3_INIT_PRESET_EQ_TRAIN_EN;
> +	writel(val, phy->base + P2U_PERIODIC_EQ_CTRL_GEN3);
> +
> +	val = readl(phy->base + P2U_PERIODIC_EQ_CTRL_GEN4);
> +	val |= P2U_PERIODIC_EQ_CTRL_GEN4_INIT_PRESET_EQ_TRAIN_EN;
> +	writel(val, phy->base + P2U_PERIODIC_EQ_CTRL_GEN4);
> +
> +	val = readl(phy->base + P2U_RX_DEBOUNCE_TIME);
> +	val &= ~P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_MASK;
> +	val |= P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL;
> +	writel(val, phy->base + P2U_RX_DEBOUNCE_TIME);
> +
> +	return 0;
> +}
> +
> +static const struct phy_ops ops = {
> +	.power_on	= tegra_p2u_power_on,
> +	.owner		= THIS_MODULE,
> +};
> +
> +static int tegra_p2u_probe(struct platform_device *pdev)
> +{
> +	struct tegra_p2u *phy;
> +	struct phy *generic_phy;
> +	struct phy_provider *phy_provider;
> +	struct device *dev = &pdev->dev;
> +	struct resource *res;
> +
> +	phy = devm_kzalloc(dev, sizeof(*phy), GFP_KERNEL);
> +	if (!phy)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ctl");
> +	phy->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(phy->base))
> +		return PTR_ERR_OR_ZERO(phy->base);
> +
> +	platform_set_drvdata(pdev, phy);
> +
> +	generic_phy = devm_phy_create(dev, NULL, &ops);
> +	if (IS_ERR(generic_phy))
> +		return PTR_ERR_OR_ZERO(generic_phy);
> +
> +	phy_set_drvdata(generic_phy, phy);
> +
> +	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
> +	if (IS_ERR(phy_provider))
> +		return PTR_ERR_OR_ZERO(phy_provider);
> +
> +	return 0;
> +}
> +
> +static int tegra_p2u_remove(struct platform_device *pdev)
> +{
> +	return 0;
> +}

I think you can drop this.

> +
> +static const struct of_device_id tegra_p2u_id_table[] = {
> +	{
> +		.compatible = "nvidia,tegra194-p2u",
> +	},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, tegra_p2u_id_table);
> +
> +static struct platform_driver tegra_p2u_driver = {
> +	.probe		= tegra_p2u_probe,
> +	.remove		= tegra_p2u_remove,
> +	.driver		= {
> +		.name	= "tegra194-p2u",
> +		.of_match_table = tegra_p2u_id_table,
> +	},
> +};
> +
> +module_platform_driver(tegra_p2u_driver);
> +
> +MODULE_AUTHOR("Vidya Sagar <[email-masked]>");
> +MODULE_DESCRIPTION("NVIDIA Tegra PIPE_To_UPHY phy driver");

The driver description is somewhat odd here. Perhaps something like:

	"NVIDIA Tegra PIPE to UPHY PHY driver"

?

Thierry

> +MODULE_LICENSE("GPL v2");
> -- 
> 2.7.4
> 
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