Re: [PATCH V10 13/15] phy: tegra: Add PCIe PIPE2UPHY support

[Vidya Sagar <vidyas@nvidia.com>]

On 6/21/2019 4:53 AM, Dmitry Osipenko wrote:
> 20.06.2019 10:24, Kishon Vijay Abraham I пишет:
>>
>>
>> On 12/06/19 3:23 PM, 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.
>>
>> One minor comment below. With that fixed
>>
>> Acked-by: Kishon Vijay Abraham I <kishon@ti.com>
>>>
>>> Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
>>> ---
>>> Changes since [v9]:
>>> * Used _relaxed() versions of readl() & writel()
>>>
>>> Changes since [v8]:
>>> * Made it dependent on ARCH_TEGRA_194_SOC directly instead of ARCH_TEGRA
>>>
>>> Changes since [v7]:
>>> * Changed P2U driver file name from pcie-p2u-tegra194.c to phy-tegra194-p2u.c
>>>
>>> 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/phy-tegra194-p2u.c | 120 +++++++++++++++++++++++++++
>>>   3 files changed, 128 insertions(+)
>>>   create mode 100644 drivers/phy/tegra/phy-tegra194-p2u.c
>>>
>>> diff --git a/drivers/phy/tegra/Kconfig b/drivers/phy/tegra/Kconfig
>>> index e516967d695b..f9817c3ae85f 100644
>>> --- a/drivers/phy/tegra/Kconfig
>>> +++ b/drivers/phy/tegra/Kconfig
>>> @@ -7,3 +7,10 @@ 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_P2U
>>> +	tristate "NVIDIA Tegra194 PIPE2UPHY PHY driver"
>>> +	depends on ARCH_TEGRA_194_SOC || 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 64ccaeacb631..320dd389f34d 100644
>>> --- a/drivers/phy/tegra/Makefile
>>> +++ b/drivers/phy/tegra/Makefile
>>> @@ -6,3 +6,4 @@ 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_P2U) += phy-tegra194-p2u.o
>>> diff --git a/drivers/phy/tegra/phy-tegra194-p2u.c b/drivers/phy/tegra/phy-tegra194-p2u.c
>>> new file mode 100644
>>> index 000000000000..df009abd2482
>>> --- /dev/null
>>> +++ b/drivers/phy/tegra/phy-tegra194-p2u.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/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 inline void p2u_writel(struct tegra_p2u *phy, const u32 value,
>>> +			      const u32 reg)
>>> +{
>>> +	writel_relaxed(value, phy->base + reg);
>>> +}
>>> +
>>> +static inline u32 p2u_readl(struct tegra_p2u *phy, const u32 reg)
>>> +{
>>> +	return readl_relaxed(phy->base + reg);
>>> +}
>>> +
>>> +static int tegra_p2u_power_on(struct phy *x)
>>> +{
>>> +	struct tegra_p2u *phy = phy_get_drvdata(x);
>>> +	u32 val;
>>> +
>>> +	val = p2u_readl(phy, 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;
>>> +	p2u_writel(phy, val, P2U_PERIODIC_EQ_CTRL_GEN3);
>>> +
>>> +	val = p2u_readl(phy, P2U_PERIODIC_EQ_CTRL_GEN4);
>>> +	val |= P2U_PERIODIC_EQ_CTRL_GEN4_INIT_PRESET_EQ_TRAIN_EN;
>>> +	p2u_writel(phy, val, P2U_PERIODIC_EQ_CTRL_GEN4);
>>> +
>>> +	val = p2u_readl(phy, P2U_RX_DEBOUNCE_TIME);
>>> +	val &= ~P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_MASK;
>>> +	val |= P2U_RX_DEBOUNCE_TIME_DEBOUNCE_TIMER_VAL;
>>> +	p2u_writel(phy, val, 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;
>>
>> Just make this..
>> phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
>> return PTR_ERR_OR_ZERO(phy_provider);
> 
> There is a need to s/PTR_ERR_OR_ZERO/PTR_ERR/ for all of the occurrences
> in this patch because it is impossible to get ZERO if we already know
> that pointer is a error.
Agree with this point.

> 
> Secondly, it is always cleaner to return 0 explicitly on success and
> PTR_ERR_OR_ZERO(phy_provider) is a much less readable form than a simple
> return 0. So I'm suggesting to keep that part as-is.
> 
yes, true that. I'll address these in the next series