Subject: Re: [PATCH V7 13/15] phy: tegra: Add PCIe PIPE2UPHY support

From: Thierry Reding <[email-masked]>
Date: Tue, 21 May 2019 13:00:11 +0200

On Fri, May 17, 2019 at 06:08:44PM +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 [v6]:
> * None
> 
> Changes since [v5]:
> * Addressed review comments from Thierry
> 
> Changes since [v4]:
> * None
> 
> Changes since [v3]:
> * Rebased on top of linux-next top of the tree
> 
> Changes since [v2]:
> * Replaced spaces with tabs in Kconfig file
> * Sorted header file inclusion alphabetically
> 
> 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 | 109 ++++++++++++++++++++++++++
>  3 files changed, 117 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..06d423fa85b4 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"

The Kconfig symbol and driver are named inconsistently. That's not
inherently wrong, but I think it unnecessarily complicates things. Why
not just do something like:

	config PHY_TEGRA194_P2U

and name the 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.
> diff --git a/drivers/phy/tegra/Makefile b/drivers/phy/tegra/Makefile
> index a93cd9a499b2..1aaca794f40c 100644
> --- a/drivers/phy/tegra/Makefile
> +++ b/drivers/phy/tegra/Makefile
> @@ -5,3 +5,4 @@ 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-$(CONFIG_ARCH_TEGRA_210_SOC) += xusb-tegra210.o
>  phy-tegra-xusb-$(CONFIG_ARCH_TEGRA_186_SOC) += xusb-tegra186.o
> +obj-$(CONFIG_PHY_TEGRA194_PCIE_P2U) += pcie-p2u-tegra194.o

... phy-tegra194-p2u here? Or perhaps even leave away the 194 and make
it just phy-tegra-p2u. That would make it consistent with the
phy-tegra-xusb driver.

Looks good otherwise.

Thierry

> diff --git a/drivers/phy/tegra/pcie-p2u-tegra194.c b/drivers/phy/tegra/pcie-p2u-tegra194.c
> new file mode 100644
> index 000000000000..fae2afe1a1aa
> --- /dev/null
> +++ b/drivers/phy/tegra/pcie-p2u-tegra194.c
> @@ -0,0 +1,109 @@
> +// 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/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/phy/phy.h>
> +
> +#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
> +#define P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL		160
> +
> +struct tegra_p2u {
> +	void __iomem *base;
> +};
> +
> +static int tegra_p2u_power_on(struct phy *x)
> +{
> +	struct tegra_p2u *phy = phy_get_drvdata(x);
> +	u32 val;
> +
> +	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 phy_provider *phy_provider;
> +	struct device *dev = &pdev->dev;
> +	struct phy *generic_phy;
> +	struct tegra_p2u *phy;
> +	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 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,
> +	.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 PIPE2UPHY PHY driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.17.1
> 
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