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

[Vidya Sagar <vidyas@nvidia.com>]

On 4/15/2019 9:01 PM, Thierry Reding wrote:
> 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 <vidyas@nvidia.com>
>> ---
>> 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.
Done.

> 
>> 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 <vidyas@nvidia.com>
>> + */
>> +
>> +#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.
Done.

> 
>> +
>> +#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.
Done.

> 
>> +};
>> +
>> +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.
Done. Took care of this in pcie-tegra194.c as well.

> 
>> +
>> +	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.
I want to make this as a loadable module hence i kep t .remove()
implementation.
  
> 
>> +
>> +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 <vidyas@nvidia.com>");
>> +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"
> 
> ?
Done.

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