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

Alim Akhtar
2017-02-03T09:19:09Z

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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>>>
>>>> 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>>> Signed-off-by: Alim Akhtar <alim.akhtar-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>>>> Cc: Kishon Vijay Abraham I <kishon-l0cyMroinI0@public.gmane.org>
>>>> ---
>>>> 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>>>> + *
>>>> + * 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:
* 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.
This approach solves exynos-ufs-phy calibration as well.
please have a look on the snapshot below, if you are ok, will post a
proper patch for this:

[1]: https://patchwork.kernel.org/patch/4545941/
----
diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
index a268f4d..78cec14 100644
--- a/drivers/phy/phy-core.c
+++ b/drivers/phy/phy-core.c
@@ -357,6 +357,26 @@ int phy_set_mode(struct phy *phy, enum phy_mode mode)
}
EXPORT_SYMBOL_GPL(phy_set_mode);

+int phy_calibrate(struct phy *phy)
+{
+ int ret = -ENOTSUPP;
+
+ if(!phy || !phy->ops->calibrate)
+ return 0;
+
+ mutex_lock(&phy->mutex);
+ ret = phy->ops->calibrate(phy);
+ if (ret < 0) {
+ dev_err(&phy->dev, "phy calibration failed %d\n", ret);
+ goto out;
+ }
+
+out:
+ mutex_unlock(&phy->mutex);
+
+ return ret;
+}
+
int phy_reset(struct phy *phy)
{
int ret;
diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
index 78bb0d7..ca3a6d4 100644
--- a/include/linux/phy/phy.h
+++ b/include/linux/phy/phy.h
@@ -45,6 +45,7 @@ struct phy_ops {
int (*power_on)(struct phy *phy);
int (*power_off)(struct phy *phy);
int (*set_mode)(struct phy *phy, enum phy_mode mode);
+ int (*calibrate)(struct phy *phy);
int (*reset)(struct phy *phy);
struct module *owner;
};
@@ -67,6 +68,7 @@ struct phy_attrs {
* @init_count: used to protect when the PHY is used by multiple consumers
* @power_count: used to protect when the PHY is used by multiple
consumers
* @phy_attrs: used to specify PHY specific attributes
+ * @priv: used to specify PHY specific private data
*/
struct phy {
struct device dev;
@@ -77,6 +79,7 @@ struct phy {
int power_count;
struct phy_attrs attrs;
struct regulator *pwr;
+ void *priv;
};

/**
@@ -138,6 +141,7 @@ int phy_exit(struct phy *phy);
int phy_power_on(struct phy *phy);
int phy_power_off(struct phy *phy);
int phy_set_mode(struct phy *phy, enum phy_mode mode);
+int phy_calibrate(struct phy *phy);
int phy_reset(struct phy *phy);
static inline int phy_get_bus_width(struct phy *phy)
{
@@ -253,6 +257,13 @@ static inline int phy_set_mode(struct phy *phy,
enum phy_mode mode)
return -ENOSYS;
}

+static inline int phy_calibrate(struct phy *phy)
+{
+ if (!phy)
+ return 0;
+ return -ENOSYS;
+}
+
static inline int phy_reset(struct phy *phy)
{
if (!phy)

> Thanks
> Kishon
>
>
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