Re: [PATCH 2/2] PCI: meson: add the Amlogic Meson PCIe phy driver

From: Hanjie Lin <hanjie.lin@amlogic.com>
To: Jerome Brunet <jbrunet@baylibre.com>,
	Kishon Vijay Abraham I <kishon@ti.com>
Cc: Yue Wang <yue.wang@amlogic.com>, <linux-kernel@vger.kernel.org>,
	<linux-amlogic@lists.infradead.org>, <linux-pci@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Carlo Caione <carlo@caione.org>, Rob Herring <robh@kernel.org>,
	<shawn.lin@rock-chips.com>
Subject: Re: [PATCH 2/2] PCI: meson: add the Amlogic Meson PCIe phy driver
Date: Thu, 16 Aug 2018 11:05:16 +0800	[thread overview]
Message-ID: <2b87e834-41e3-e418-95f0-c6d695cd8b3f@amlogic.com> (raw)
In-Reply-To: <486e8ab477cc22ff231d2e18d7de22efba2c5abd.camel@baylibre.com>

On 2018/8/14 18:41, Jerome Brunet wrote:
> On Tue, 2018-08-14 at 02:12 -0400, Hanjie Lin wrote:
>> From: Yue Wang <yue.wang@amlogic.com>
>>
>> The Meson-PCIE-PHY controller supports the 5-Gbps data rate
>> of the PCI Express Gen 2 specification and is backwardcompatible
>> with the 2.5-Gbps Gen 1.1 specification with only
>> inferred idle detection supported on AMLOGIC SoCs.
> 
> It looks like the sole purpose of this driver is to provide the reset lines to
> pcie driver.
> 
> I wonder why we need this ? Can't the pcie driver claim the reset lines itself.
> 
> Also, an init of this phy will always reset both port. What will happen if the
> first port is in use and the 2nd port comes up ?? 
> 
> Looks the the pcie driver should claim 'apb' and 'phy' reset lines as "shared"
> reset and the required 'port' as 'exclusive'
> 

Thank you for your response.

Yes, 'apb' and 'phy' reset lines are shared, and ‘port' reset line is exclusive.
If we handle all reset lines during the first port initial sequence, 
and when the second port comes up, we will do nothing about the rest lines, 
and don't need a extra API to do ‘port' reset;

>>
>> Signed-off-by: Yue Wang <yue.wang@amlogic.com>
>> Signed-off-by: Hanjie Lin <hanjie.lin@amlogic.com>
>> ---
>>  drivers/phy/amlogic/Kconfig              |   8 ++
>>  drivers/phy/amlogic/Makefile             |   1 +
>>  drivers/phy/amlogic/phy-meson-axg-pcie.c | 160 +++++++++++++++++++++++++++++++
>>  3 files changed, 169 insertions(+)
>>  create mode 100644 drivers/phy/amlogic/phy-meson-axg-pcie.c
>>
>> diff --git a/drivers/phy/amlogic/Kconfig b/drivers/phy/amlogic/Kconfig
>> index 23fe1cd..3ab07f9 100644
>> --- a/drivers/phy/amlogic/Kconfig
>> +++ b/drivers/phy/amlogic/Kconfig
>> @@ -36,3 +36,11 @@ config PHY_MESON_GXL_USB3
>>  	  Enable this to support the Meson USB3 PHY and OTG detection
>>  	  IP block found in Meson GXL and GXM SoCs.
>>  	  If unsure, say N.
>> +
>> +config PHY_MESON_AXG_PCIE
>> +	bool "Meson AXG PCIe PHY driver"
>> +	depends on OF && (ARCH_MESON || COMPILE_TEST)
>> +	select GENERIC_PHY
>> +	help
>> +	  Enable PCIe PHY support for Meson AXG SoC series.
>> +	  This driver provides PHY interface for Meson PCIe controller.
>> \ No newline at end of file
>> diff --git a/drivers/phy/amlogic/Makefile b/drivers/phy/amlogic/Makefile
>> index 4fd8848..5ab8578 100644
>> --- a/drivers/phy/amlogic/Makefile
>> +++ b/drivers/phy/amlogic/Makefile
>> @@ -1,3 +1,4 @@
>>  obj-$(CONFIG_PHY_MESON8B_USB2)		+= phy-meson8b-usb2.o
>>  obj-$(CONFIG_PHY_MESON_GXL_USB2)	+= phy-meson-gxl-usb2.o
>>  obj-$(CONFIG_PHY_MESON_GXL_USB3)	+= phy-meson-gxl-usb3.o
>> +obj-$(CONFIG_PHY_MESON_AXG_PCIE)	+= phy-meson-axg-pcie.o
>> diff --git a/drivers/phy/amlogic/phy-meson-axg-pcie.c b/drivers/phy/amlogic/phy-meson-axg-pcie.c
>> new file mode 100644
>> index 0000000..8bc5c49
>> --- /dev/null
>> +++ b/drivers/phy/amlogic/phy-meson-axg-pcie.c
>> @@ -0,0 +1,160 @@
>> +// SPDX-License-Identifier: (GPL-2.0+ or MIT)
>> +/*
>> + * Amlogic MESON SoC series PCIe PHY driver
>> + *
>> + * Phy provider for PCIe controller on MESON SoC series
>> + *
>> + * Copyright (c) 2018 Amlogic, inc.
>> + * Yue Wang <yue.wang@amlogic.com>
>> + */
>> +
>> +#include <linux/delay.h>
>> +#include <linux/io.h>
>> +#include <linux/of.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/phy/phy.h>
>> +#include <linux/reset.h>
>> +
>> +struct meson_pcie_phy_data {
>> +	const struct phy_ops	*ops;
>> +};
>> +
>> +struct meson_pcie_reset {
>> +	struct reset_control	*port_a;
>> +	struct reset_control	*port_b;
>> +	struct reset_control	*phy;
>> +	struct reset_control	*apb;
>> +};
>> +
>> +struct meson_pcie_phy {
>> +	const struct meson_pcie_phy_data	*data;
>> +	struct meson_pcie_reset	reset;
>> +	void __iomem	*phy_base;
>> +};
>> +
>> +static int meson_pcie_phy_init(struct phy *phy)
>> +{
>> +	struct meson_pcie_phy *mphy = phy_get_drvdata(phy);
>> +	struct meson_pcie_reset *mrst = &mphy->reset;
>> +
>> +	writel(0x1c, mphy->phy_base);
>> +	reset_control_assert(mrst->port_a);
>> +	reset_control_assert(mrst->port_b);
>> +	reset_control_assert(mrst->phy);
>> +	reset_control_assert(mrst->apb);
>> +	udelay(400);
>> +	reset_control_deassert(mrst->port_a);
>> +	reset_control_deassert(mrst->port_b);
>> +	reset_control_deassert(mrst->phy);
>> +	reset_control_deassert(mrst->apb);
>> +	udelay(500);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct phy_ops meson_phy_ops = {
>> +	.init		= meson_pcie_phy_init,
>> +	.owner		= THIS_MODULE,
>> +};
>> +
>> +static const struct meson_pcie_phy_data meson_pcie_phy_data = {
>> +	.ops		= &meson_phy_ops,
>> +};
>> +
>> +static const struct of_device_id meson_pcie_phy_match[] = {
>> +	{
>> +		.compatible = "amlogic,axg-pcie-phy",
>> +		.data = &meson_pcie_phy_data,
>> +	},
>> +	{},
>> +};
>> +
>> +static int meson_pcie_phy_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct meson_pcie_phy *mphy;
>> +	struct meson_pcie_reset *mrst;
>> +	struct phy *generic_phy;
>> +	struct phy_provider *phy_provider;
>> +	struct resource *res;
>> +	const struct meson_pcie_phy_data *data;
>> +
>> +	data = of_device_get_match_data(dev);
>> +	if (!data)
>> +		return -ENODEV;
>> +
>> +	mphy = devm_kzalloc(dev, sizeof(*mphy), GFP_KERNEL);
>> +	if (!mphy)
>> +		return -ENOMEM;
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	mphy->phy_base = devm_ioremap_resource(dev, res);
>> +	if (IS_ERR(mphy->phy_base))
>> +		return PTR_ERR(mphy->phy_base);
>> +
>> +	mrst = &mphy->reset;
>> +
>> +	mrst->port_a = devm_reset_control_get_shared(dev, "port_a");
>> +	if (IS_ERR(mrst->port_a)) {
>> +		if (PTR_ERR(mrst->port_a) != -EPROBE_DEFER)
>> +			dev_err(dev, "couldn't get port a reset %ld\n",
>> +				PTR_ERR(mrst->port_a));
>> +
>> +		return PTR_ERR(mrst->port_a);
>> +	}
>> +
>> +	mrst->port_b = devm_reset_control_get_shared(dev, "port_b");
>> +	if (IS_ERR(mrst->port_b)) {
>> +		if (PTR_ERR(mrst->port_b) != -EPROBE_DEFER)
>> +			dev_err(dev, "couldn't get port b reset %ld\n",
>> +				PTR_ERR(mrst->port_b));
>> +
>> +		return PTR_ERR(mrst->port_b);
>> +	}
>> +
>> +	mrst->phy = devm_reset_control_get_shared(dev, "phy");
>> +	if (IS_ERR(mrst->phy)) {
>> +		if (PTR_ERR(mrst->phy) != -EPROBE_DEFER)
>> +			dev_err(dev, "couldn't get phy reset\n");
>> +
>> +		return PTR_ERR(mrst->phy);
>> +	}
>> +
>> +	mrst->apb = devm_reset_control_get_shared(dev, "apb");
>> +	if (IS_ERR(mrst->apb)) {
>> +		if (PTR_ERR(mrst->apb) != -EPROBE_DEFER)
>> +			dev_err(dev, "couldn't get apb reset\n");
>> +
>> +		return PTR_ERR(mrst->apb);
>> +	}
>> +
>> +	reset_control_deassert(mrst->port_a);
>> +	reset_control_deassert(mrst->port_b);
>> +	reset_control_deassert(mrst->phy);
>> +	reset_control_deassert(mrst->apb);
>> +
>> +	mphy->data = data;
>> +
>> +	generic_phy = devm_phy_create(dev, dev->of_node, mphy->data->ops);
>> +	if (IS_ERR(generic_phy)) {
>> +		if (PTR_ERR(generic_phy) != -EPROBE_DEFER)
>> +			dev_err(dev, "failed to create PHY\n");
>> +
>> +		return PTR_ERR(generic_phy);
>> +	}
>> +
>> +	phy_set_drvdata(generic_phy, mphy);
>> +	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
>> +
>> +	return PTR_ERR_OR_ZERO(phy_provider);
>> +}
>> +
>> +static struct platform_driver meson_pcie_phy_driver = {
>> +	.probe	= meson_pcie_phy_probe,
>> +	.driver = {
>> +		.of_match_table	= meson_pcie_phy_match,
>> +		.name		= "meson-pcie-phy",
>> +	}
>> +};
>> +
>> +builtin_platform_driver(meson_pcie_phy_driver);
> 
> 
> .
> 