[PATCH 1/2] phy: zynqmp: Add phy driver for xilinx zynqmp phy core

Anurag Kumar Vulisha anuragku at xilinx.com
Tue Sep 25 03:55:26 PDT 2018


HI Vivek,

>-----Original Message-----
>From: Vivek Gautam [mailto:vivek.gautam at codeaurora.org]
>Sent: Tuesday, September 25, 2018 3:44 PM
>To: Anurag Kumar Vulisha <anuragku at xilinx.com>; Kishon Vijay Abraham I
><kishon at ti.com>; Michal Simek <michals at xilinx.com>; robh+dt at kernel.org;
>mark.rutland at arm.com
>Cc: v.anuragkumar at gmail.com; linux-kernel at vger.kernel.org; linux-arm-
>kernel at lists.infradead.org; devicetree at vger.kernel.org; Ajay Yugalkishore Pandey
><APANDEY at xilinx.com>
>Subject: Re: [PATCH 1/2] phy: zynqmp: Add phy driver for xilinx zynqmp phy core
>
>
>
>On 9/25/2018 12:57 PM, Anurag Kumar Vulisha wrote:
>> HI Kishon,
>>
>> Thanks a lot for spending your time in reviewing this patch. Please
>> find my comments inline
>>
>>> -----Original Message-----
>>> From: Kishon Vijay Abraham I [mailto:kishon at ti.com]
>>> Sent: Tuesday, September 25, 2018 10:59 AM
>>> To: Anurag Kumar Vulisha <anuragku at xilinx.com>; Michal Simek
>>> <michals at xilinx.com>; robh+dt at kernel.org; mark.rutland at arm.com;
>>> vivek.gautam at codeaurora.org
>>> Cc: v.anuragkumar at gmail.com; linux-kernel at vger.kernel.org; linux-arm-
>>> kernel at lists.infradead.org; devicetree at vger.kernel.org
>>> Subject: Re: [PATCH 1/2] phy: zynqmp: Add phy driver for xilinx zynqmp phy core
>>>
>>> Hi,
>>>
>>> On Wednesday 29 August 2018 07:37 PM, Anurag Kumar Vulisha wrote:
>>>> ZynqMP SoC has a Gigabit Transceiver with four lanes. All the high
>>>> speed peripherals such as USB, SATA, PCIE, Display Port and Ethernet
>>>> SGMII can rely on any of the four GT lanes for PHY layer. This patch
>>>> adds driver for that ZynqMP GT core.
>>>>
>>>> Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha at xilinx.com>
>>>> ---
>>>>   drivers/phy/Kconfig            |    8 +
>>>>   drivers/phy/Makefile           |    1 +
>>>>   drivers/phy/phy-zynqmp.c       | 1579
>>> ++++++++++++++++++++++++++++++++++++++++
>>>>   include/dt-bindings/phy/phy.h  |    2 +
>>>>   include/linux/phy/phy-zynqmp.h |   52 ++
>>>>   5 files changed, 1642 insertions(+)
>>>>   create mode 100644 drivers/phy/phy-zynqmp.c  create mode 100644
>>>> include/linux/phy/phy-zynqmp.h
>>>>
>>>> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig index
>>>> 5c8d452..14cf3330 100644
>>>> --- a/drivers/phy/Kconfig
>>>> +++ b/drivers/phy/Kconfig
>>>> @@ -40,6 +40,14 @@ config PHY_XGENE
>>>>   	help
>>>>   	  This option enables support for APM X-Gene SoC multi-purpose PHY.
>>>>
>>>> +config PHY_XILINX_ZYNQMP
>>>> +	tristate "Xilinx ZynqMP PHY driver"
>>>> +	depends on ARCH_ZYNQMP
>>>> +	select GENERIC_PHY
>>>> +	help
>>>> +	  Enable this to support ZynqMP High Speed Gigabit Transceiver
>>>> +	  that is part of ZynqMP SoC.
>>>> +
>>>>   source "drivers/phy/allwinner/Kconfig"
>>>>   source "drivers/phy/amlogic/Kconfig"
>>>>   source "drivers/phy/broadcom/Kconfig"
>>>> diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile index
>>>> 84e3bd9..f2a8d27 100644
>>>> --- a/drivers/phy/Makefile
>>>> +++ b/drivers/phy/Makefile
>>>> @@ -7,6 +7,7 @@ obj-$(CONFIG_GENERIC_PHY)		+= phy-core.o
>>>>   obj-$(CONFIG_PHY_LPC18XX_USB_OTG)	+= phy-lpc18xx-usb-otg.o
>>>>   obj-$(CONFIG_PHY_XGENE)			+= phy-xgene.o
>>>>   obj-$(CONFIG_PHY_PISTACHIO_USB)		+= phy-pistachio-usb.o
>>>> +obj-$(CONFIG_PHY_XILINX_ZYNQMP)		+= phy-zynqmp.o
>>>>   obj-$(CONFIG_ARCH_SUNXI)		+= allwinner/
>>>>   obj-$(CONFIG_ARCH_MESON)		+= amlogic/
>>>>   obj-$(CONFIG_LANTIQ)			+= lantiq/
>>>> diff --git a/drivers/phy/phy-zynqmp.c b/drivers/phy/phy-zynqmp.c new
>>>> file mode 100644 index 0000000..306cedd
>>>> --- /dev/null
>>>> +++ b/drivers/phy/phy-zynqmp.c
>>>> @@ -0,0 +1,1579 @@
>>>> +// SPDX-License-Identifier: GPL-2.0
>>>> +/*
>>>> + * phy-zynqmp.c - PHY driver for Xilinx ZynqMP GT.
>>>> + *
>>>> + * Copyright (C) 2018 Xilinx Inc.
>>>> + *
>>>> + * Author: Anurag Kumar Vulisha <anuragku at xilinx.com>
>>>> + *
>>>> + * This driver is tested for USB, SATA and Display Port currently.
>>>> + * Other controllers PCIe and SGMII should also work but that is
>>>> + * experimental as of now.
>>>> + */
>>>> +
>>>> +#include <linux/clk.h>
>>>> +#include <linux/delay.h>
>>>> +#include <linux/io.h>
>>>> +#include <linux/kernel.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/of.h>
>>>> +#include <linux/of_platform.h>
>>>> +#include <linux/of_address.h>
>>>> +#include <linux/phy/phy.h>
>>>> +#include <linux/phy/phy-zynqmp.h>
>>>> +#include <linux/platform_device.h>
>>>> +#include <linux/delay.h>
>>>> +#include <dt-bindings/phy/phy.h>
>>>> +#include <linux/reset.h>
>>>> +#include <linux/list.h>
>>>> +#include <linux/slab.h>
>>>> +/* Total number of controllers */
>>>> +#define CONTROLLERS_PER_LANE		5
>>>> +
>>>> +/* USB pipe control parameters */
>>>> +#define PIPE_CLK_OFFSET			0x7c
>>>> +#define PIPE_POWER_OFFSET		0x80
>>>> +#define PIPE_CLK_ON			1
>>>> +#define PIPE_CLK_OFF			0
>>>> +#define PIPE_POWER_ON			1
>>>> +#define PIPE_POWER_OFF			0
>>>> +
>>>> +
>>>> +/**
>>>> + * struct xpsgtr_ssc - structure to hold SSC settings for a lane
>>>> + * @refclk_rate: PLL reference clock frequency
>>>> + * @pll_ref_clk: value to be written to register for corresponding
>>>> +ref clk rate
>>>> + * @steps: number of steps of SSC (Spread Spectrum Clock)
>>>> + * @step_size: step size of each step  */ struct xpsgtr_ssc {
>>>> +	u32 refclk_rate;
>>>> +	u8  pll_ref_clk;
>>>> +	u32 steps;
>>>> +	u32 step_size;
>>>> +};
>>>> +
>>>> +/* lookup table to hold all settings needed for a ref clock frequency
>>>> +*/ static struct xpsgtr_ssc ssc_lookup[MAX_REFCLK] = {
>>>> +	{19200000, 0x05, 608, 264020},
>>>> +	{20000000, 0x06, 634, 243454},
>>>> +	{24000000, 0x07, 760, 168973},
>>>> +	{26000000, 0x08, 824, 143860},
>>>> +	{27000000, 0x09, 856, 86551},
>>>> +	{38400000, 0x0A, 1218, 65896},
>>>> +	{40000000, 0x0B, 634, 243454},
>>>> +	{52000000, 0x0C, 824, 143860},
>>>> +	{100000000, 0x0D, 1058, 87533},
>>>> +	{108000000, 0x0E, 856, 86551},
>>>> +	{125000000, 0x0F, 992, 119497},
>>>> +	{135000000, 0x10, 1070, 55393},
>>>> +	{150000000, 0x11, 792, 187091}
>>>> +};
>>>> +
>>>> +/**
>>>> + * struct xpsgtr_dev - representation of a ZynMP GT device
>>>> + * @dev: pointer to device
>>>> + * @serdes: serdes base address
>>>> + * @siou: siou base address
>>>> + * @gtr_mutex: mutex for locking
>>>> + * @phys: pointer to all the lanes
>>>> + * @tx_term_fix: fix for GT issue
>>>> + * @saved_icm_cfg0: stored value of ICM CFG0 register
>>>> + * @saved_icm_cfg1: stored value of ICM CFG1 register
>>>> + * @sata_rst: a reset control for SATA
>>>> + * @dp_rst: a reset control for DP
>>>> + * @usb0_crst: a reset control for usb0 core
>>>> + * @usb1_crst: a reset control for usb1 core
>>>> + * @usb0_hibrst: a reset control for usb0 hibernation module
>>>> + * @usb1_hibrst: a reset control for usb1 hibernation module
>>>> + * @usb0_apbrst: a reset control for usb0 apb bus
>>>> + * @usb1_apbrst: a reset control for usb1 apb bus
>>>> + * @gem0_rst: a reset control for gem0
>>>> + * @gem1_rst: a reset control for gem1
>>>> + * @gem2_rst: a reset control for gem2
>>>> + * @gem3_rst: a reset control for gem3  */ struct xpsgtr_dev {
>>>> +	struct device *dev;
>>>> +	void __iomem *serdes;
>>>> +	void __iomem *siou;
>>>> +	struct mutex gtr_mutex; /* mutex for locking */
>>>> +	struct xpsgtr_phy **phys;
>>>> +	bool tx_term_fix;
>>>> +	unsigned int saved_icm_cfg0;
>>>> +	unsigned int saved_icm_cfg1;
>>>> +	struct reset_control *sata_rst;
>>>> +	struct reset_control *dp_rst;
>>>> +	struct reset_control *usb0_crst;
>>>> +	struct reset_control *usb1_crst;
>>>> +	struct reset_control *usb0_hibrst;
>>>> +	struct reset_control *usb1_hibrst;
>>>> +	struct reset_control *usb0_apbrst;
>>>> +	struct reset_control *usb1_apbrst;
>>>> +	struct reset_control *gem0_rst;
>>>> +	struct reset_control *gem1_rst;
>>>> +	struct reset_control *gem2_rst;
>>>> +	struct reset_control *gem3_rst;
>>>> +};
>>>> +
>>>> +/**
>>>> + * xpsgtr_override_deemph - override PIPE TX de-emphasis
>>>> + * @phy: pointer to phy
>>>> + * @plvl: pre-emphasis level
>>>> + * @vlvl: voltage swing level
>>>> + *
>>>> + * Return: None
>>>> + */
>>>> +void xpsgtr_override_deemph(struct phy *phy, u8 plvl, u8 vlvl) {
>>>> +	struct xpsgtr_phy *gtr_phy = phy_get_drvdata(phy);
>>>> +	struct xpsgtr_dev *gtr_dev = gtr_phy->data;
>>>> +	static u8 pe[4][4] = { { 0x2, 0x2, 0x2, 0x2 },
>>>> +			       { 0x1, 0x1, 0x1, 0xFF },
>>>> +			       { 0x0, 0x0, 0xFF, 0xFF },
>>>> +			       { 0xFF, 0xFF, 0xFF, 0xFF } };
>>>> +
>>>> +	writel(pe[plvl][vlvl],
>>>> +	       gtr_dev->serdes + gtr_phy->lane * L0_TX_ANA_TM_18_OFFSET +
>>>> +	       L0_TX_ANA_TM_18);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(xpsgtr_override_deemph);
>>> Why can't these be included in one of the phy_ops? Why do you need export
>symbols
>>> here and below?
>>>
>> Display Port has a HPD (Hot Plug Detect) feature where any DP Sink Device can be
>connected
>> at runtime and DPCD (Display Port Control Data) would be read by the DP driver to
>determine
>> whether the link training happened properly or not. If link training fails, the DP driver
>needs
>> to update the Voltage Swing & De-emphasis values at runtime in the phy  based on
>the values
>> read in DPCD and restart the link training sequence. Because of this reason we are
>exporting these
>> functions so that the DP driver can use them when required.
>
>Can't this be added to phy_calibrate() so that you can call calibrate
>everytime you want to
>change the phy configuration based on DPCD config?
>

Thanks for your reply.  DP driver reads the DPCD and passes the VS/DE values
as the argument to phy-zynqmp driver. The phy-zynqmp driver will do the
required register updates based on the passed VS/DE values. There are two
functions xpsgtr_override_deemph() and xpsgtr_margining_factor () which will
be used by DP driver when required. Since there is dependency on the values
that needs to be passed by DP driver, I think phy_calibrate() alone may not
solve the purpose. Using phy platform data for sending the VS/DE values
from DP driver may do the hack, but increases the complexity and reduces
readability. So, I think the current exporting implementation is simple and fits
my requirement. Please correct me , if my understanding is wrong.
	
Thanks,
Anurag Kumar Vulisha



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