Re: [PATCH v5 02/11] phy: exynos-ufs: add UFS PHY driver for EXYNOS SoC

Alim Akhtar
2017-02-27T14:15:10Z

Hi Kishon,

On 02/27/2017 10:56 AM, Kishon Vijay Abraham I wrote:
> Hi,
>
> On Thursday 23 February 2017 12:20 AM, Alim Akhtar wrote:
>> On Fri, Feb 3, 2017 at 2:49 PM, Alim Akhtar <alim.akhtar@samsung.com> wrote:
>>> Hi Kishon,
>>>
>>>
>>> On 11/19/2015 07:09 PM, Kishon Vijay Abraham I wrote:
>>>>
>>>> Hi,
>>>>
>>>> On Tuesday 17 November 2015 01:41 PM, Alim Akhtar wrote:
>>>>>
>>>>> Hi
>>>>> Thanks again for looking into this.
>>>>>
>>>>> On 11/17/2015 11:46 AM, Kishon Vijay Abraham I wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> On Monday 09 November 2015 10:56 AM, Alim Akhtar wrote:
>>>>>>>
>>>>>>> From: Seungwon Jeon <essuuj@gmail.com>
>>>>>>>
>>>>>>> This patch introduces Exynos UFS PHY driver. This driver
>>>>>>> supports to deal with phy calibration and power control
>>>>>>> according to UFS host driver's behavior.
>>>>>>>
>>>>>>> Signed-off-by: Seungwon Jeon <essuuj@gmail.com>
>>>>>>> Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
>>>>>>> Cc: Kishon Vijay Abraham I <kishon@ti.com>
>>>>>>> ---
>>>>>>> drivers/phy/Kconfig | 7 ++
>>>>>>> drivers/phy/Makefile | 1 +
>>>>>>> drivers/phy/phy-exynos-ufs.c | 241
>>>>>>> ++++++++++++++++++++++++++++++++++++
>>>>>>> drivers/phy/phy-exynos-ufs.h | 85 +++++++++++++
>>>>>>> drivers/phy/phy-exynos7-ufs.h | 89 +++++++++++++
>>>>>>> include/linux/phy/phy-exynos-ufs.h | 85 +++++++++++++
>>>>>>> 6 files changed, 508 insertions(+)
>>>>>>> create mode 100644 drivers/phy/phy-exynos-ufs.c
>>>>>>> create mode 100644 drivers/phy/phy-exynos-ufs.h
>>>>>>> create mode 100644 drivers/phy/phy-exynos7-ufs.h
>>>>>>> create mode 100644 include/linux/phy/phy-exynos-ufs.h
>>>>>>>
>>>>>>> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
>>>>>>> index 7eb5859dd035..7d38a92e0297 100644
>>>>>>> --- a/drivers/phy/Kconfig
>>>>>>> +++ b/drivers/phy/Kconfig
>>>>>>> @@ -389,4 +389,11 @@ config PHY_CYGNUS_PCIE
>>>>>>> Enable this to support the Broadcom Cygnus PCIe PHY.
>>>>>>> If unsure, say N.
>>>>>>>
>>>>>>> +config PHY_EXYNOS_UFS
>>>>>>> + tristate "EXYNOS SoC series UFS PHY driver"
>>>>>>> + depends on OF && ARCH_EXYNOS || COMPILE_TEST
>>>>>>> + select GENERIC_PHY
>>>>>>> + help
>>>>>>> + Support for UFS PHY on Samsung EXYNOS chipsets.
>>>>>>> +
>>>>>>> endmenu
>>>>>>> diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
>>>>>>> index 075db1a81aa5..9bec4d1a89e1 100644
>>>>>>> --- a/drivers/phy/Makefile
>>>>>>> +++ b/drivers/phy/Makefile
>>>>>>> @@ -10,6 +10,7 @@ obj-$(CONFIG_ARMADA375_USBCLUSTER_PHY) +=
>>>>>>> phy-armada375-usb2.o
>>>>>>> obj-$(CONFIG_BCM_KONA_USB2_PHY) += phy-bcm-kona-usb2.o
>>>>>>> obj-$(CONFIG_PHY_EXYNOS_DP_VIDEO) += phy-exynos-dp-video.o
>>>>>>> obj-$(CONFIG_PHY_EXYNOS_MIPI_VIDEO) += phy-exynos-mipi-video.o
>>>>>>> +obj-$(CONFIG_PHY_EXYNOS_UFS) += phy-exynos-ufs.o
>>>>>>> obj-$(CONFIG_PHY_LPC18XX_USB_OTG) += phy-lpc18xx-usb-otg.o
>>>>>>> obj-$(CONFIG_PHY_PXA_28NM_USB2) += phy-pxa-28nm-usb2.o
>>>>>>> obj-$(CONFIG_PHY_PXA_28NM_HSIC) += phy-pxa-28nm-hsic.o
>>>>>>> diff --git a/drivers/phy/phy-exynos-ufs.c
>>>>>>> b/drivers/phy/phy-exynos-ufs.c
>>>>>>> new file mode 100644
>>>>>>> index 000000000000..cb1aeaa3d4eb
>>>>>>> --- /dev/null
>>>>>>> +++ b/drivers/phy/phy-exynos-ufs.c
>>>>>>> @@ -0,0 +1,241 @@
>>>>>>> +/*
>>>>>>> + * UFS PHY driver for Samsung EXYNOS SoC
>>>>>>> + *
>>>>>>> + * Copyright (C) 2015 Samsung Electronics Co., Ltd.
>>>>>>> + * Author: Seungwon Jeon <essuuj@gmail.com>
>>>>>>> + *
>>>>>>> + * This program is free software; you can redistribute it and/or
>>>>>>> modify
>>>>>>> + * it under the terms of the GNU General Public License as published
>>>>>>> by
>>>>>>> + * the Free Software Foundation; either version 2 of the License, or
>>>>>>> + * (at your option) any later version.
>>>>>>> + */
>>>>>>> +#include <linux/clk.h>
>>>>>>> +#include <linux/delay.h>
>>>>>>> +#include <linux/err.h>
>>>>>>> +#include <linux/io.h>
>>>>>>> +#include <linux/iopoll.h>
>>>>>>> +#include <linux/mfd/syscon.h>
>>>>>>> +#include <linux/module.h>
>>>>>>> +#include <linux/of.h>
>>>>>>> +#include <linux/phy/phy.h>
>>>>>>> +#include <linux/phy/phy-exynos-ufs.h>
>>>>>>> +#include <linux/platform_device.h>
>>>>>>> +#include <linux/regmap.h>
>>>>>>> +
>>>>>>> +#include "phy-exynos-ufs.h"
>>>>>>> +
>>>>>>> +#define for_each_phy_lane(phy, i) \
>>>>>>> + for (i = 0; i < (phy)->lane_cnt; i++)
>>>>>>> +#define for_each_phy_cfg(cfg) \
>>>>>>> + for (; (cfg)->id; (cfg)++)
>>>>>>> +
>>>>>>> +#define PHY_DEF_LANE_CNT 1
>>>>>>> +
>>>>>>> +static void exynos_ufs_phy_config(struct exynos_ufs_phy *phy,
>>>>>>> + const struct exynos_ufs_phy_cfg *cfg, u8 lane)
>>>>>>> +{
>>>>>>> + enum {LANE_0, LANE_1}; /* lane index */
>>>>>>> +
>>>>>>> + switch (lane) {
>>>>>>> + case LANE_0:
>>>>>>> + writel(cfg->val, (phy)->reg_pma + cfg->off_0);
>>>>>>> + break;
>>>>>>> + case LANE_1:
>>>>>>> + if (cfg->id == PHY_TRSV_BLK)
>>>>>>> + writel(cfg->val, (phy)->reg_pma + cfg->off_1);
>>>>>>> + break;
>>>>>>> + }
>>>>>>> +}
>>>>>>> +
>>>>>>> +static bool match_cfg_to_pwr_mode(u8 desc, u8 required_pwr)
>>>>>>> +{
>>>>>>> + if (IS_PWR_MODE_ANY(desc))
>>>>>>> + return true;
>>>>>>> +
>>>>>>> + if (IS_PWR_MODE_HS(required_pwr) && IS_PWR_MODE_HS_ANY(desc))
>>>>>>> + return true;
>>>>>>> +
>>>>>>> + if (COMP_PWR_MODE(required_pwr, desc))
>>>>>>> + return true;
>>>>>>> +
>>>>>>> + if (COMP_PWR_MODE_MD(required_pwr, desc) &&
>>>>>>> + COMP_PWR_MODE_GEAR(required_pwr, desc) &&
>>>>>>> + COMP_PWR_MODE_SER(required_pwr, desc))
>>>>>>> + return true;
>>>>>>> +
>>>>>>> + return false;
>>>>>>> +}
>>>>>>> +
>>>>>>> +int exynos_ufs_phy_calibrate(struct phy *phy,
>>>>>>> + enum phy_cfg_tag tag, u8 pwr)
>>>>>>
>>>>>>
>>>>>> This is similar to the first version of your patch without
>>>>>> EXPORT_SYMBOL.
>>>>>>
>>>>>> I think you have to create a new generic PHY_OPS for calibrate PHY while
>>>>>> making
>>>>>> sure that it is as generic as possible (which means calibrate_phy
>>>>>> shouldn't
>>>>>> have tag and pwr arguments or a strong justification as to why those
>>>>>> arguments
>>>>>> are required in a generic API).
>>>>>
>>>>> I don't see the advantage to making this a generic phy_ops, this is
>>>>> exynos
>>>>> specific ufs-phy, please have a look at other implementations
>>>>
>>>>
>>>> only the implementation is specific to exynos. I've seen lot of other
>>>> vendors
>>>> want to do something like calibrate phy.
>>>>
>>>> So if we add something like (*calibrate)(struct phy *phy), then it can be
>>>> used
>>>> by others as well. Russell King also want to minimize the code to program
>>>> calibration settings. So it would be good to come up with a set of
>>>> standard
>>>> bindings like 'phy,tx-swing', 'phy,emphasis', 'phy,amplitude' etc.. to
>>>> program
>>>> these settings.
>>>>>
>>>>> drivers/phy/phy-qcom-ufs.c (which I belive mereged recently)
>>>>
>>>>
>>>> Thats why I hate when someone else merge PHY drivers :-( That driver can
>>>> as
>>>> well be in drivers/misc as it doesn't use PHY framework as it is supposed
>>>> to be
>>>> used. It just exports a dozen of API's to be used by controller drivers.
>>>> ick..
>>>>
>>>>> may be other vendors might come with there own implementation of phy.
>>>>
>>>>
>>>> right, it's all about providing the correct callback functions.
>>>>>
>>>>> I am using what is currently provided by the generic phy framework.
>>>>
>>>>
>>>> I think for your use case, what is currently provided in the PHY framework
>>>> is
>>>> not sufficient.
>>>>
>>> Its little over a year since last time we discuss about adding a generic
>>> calibration API. I can see in the past people tried adding *calibration* API
>>> [1] but not sure why [1] was not landed in mainline.
>>> Anyway now we have many users of phy_calibration API, like UFS, USB and may
>>> be PCIe, there is a real need to add this functionality. So, here is my
>>> approach:
>
> Agree, there are quite a few users that require calibration of phy parameters.
> I think previously it was accommodated in phy_init, hence it was not merged.
Ok, thanks for this information.

>>> * Along with [1], we can add a void *priv for handling device specific phy
>>> private data, and before calling phy_calibration() from phy consumer,
>>> phy->priv is populated with private data.
>
> Not sure how you plan to use priv here?
>
From ufs driver I am populating PHY _priv_ data and calling phy_calibrate()

e.g
----------------------- from ufs-exynos.c
Instead of using below code earlier
- exynos_ufs_phy_calibrate(generic_phy,CFG_PRE_INIT,PWR_MODE_ANY);

Now I am using below from ufs-exynos driver

+ generic_phy->priv =(void*)CFG_PRE_INIT;
+ phy_calibrate(generic_phy);

and in drivers/phy/phy-exynos-ufs.c
using phy->priv in calibration function.

Let me know if you need more details here.

I think this will work well for other drivers like PCIe or USB etc.

> Thanks
> Kishon
>
>
>