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

[Kishon Vijay Abraham I]

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@xxxxxxxxx>
>>>
>>> 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@xxxxxxxxx>
>>> Signed-off-by: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
>>> Cc: Kishon Vijay Abraham I <kishon@xxxxxx>
>>> ---
>>>   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@xxxxxxxxx>
>>> + *
>>> + * 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.

Thanks
Kishon
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