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SubjectRe: [PATCH 2/4] phy: socionext: add USB3 PHY driver for UniPhier SoC
On Mon, 9 Jul 2018 20:23:19 +0900 <hayashi.kunihiko@socionext.com> wrote:

> Hi Kishon,
> Thank you for your comments.
>
> On Mon, 9 Jul 2018 10:49:50 +0530 <kishon@ti.com> wrote:
>
> > Hi,
> >
> > On Friday 29 June 2018 02:08 PM, Kunihiko Hayashi wrote:
> > > Add a driver for PHY interface built into USB3 controller
> > > implemented in UniPhier SoCs.
> > > This driver supports High-Speed PHY and Super-Speed PHY.
> > >
> > > Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
> > > Signed-off-by: Motoya Tanigawa <tanigawa.motoya@socionext.com>
> > > Signed-off-by: Masami Hiramatsu <masami.hiramatsu@linaro.org>
> > > ---
> > > drivers/phy/Kconfig | 1 +
> > > drivers/phy/Makefile | 1 +
> > > drivers/phy/socionext/Kconfig | 12 +
> > > drivers/phy/socionext/Makefile | 6 +
> > > drivers/phy/socionext/phy-uniphier-usb3hs.c | 422 ++++++++++++++++++++++++++++
> > > drivers/phy/socionext/phy-uniphier-usb3ss.c | 369 ++++++++++++++++++++++++
> > > 6 files changed, 811 insertions(+)
> > > create mode 100644 drivers/phy/socionext/Kconfig
> > > create mode 100644 drivers/phy/socionext/Makefile
> > > create mode 100644 drivers/phy/socionext/phy-uniphier-usb3hs.c
> > > create mode 100644 drivers/phy/socionext/phy-uniphier-usb3ss.c
>
> (snip...)
>
> > > --- /dev/null
> > > +++ b/drivers/phy/socionext/phy-uniphier-usb3hs.c
> > > @@ -0,0 +1,422 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * phy-uniphier-usb3hs.c - HS-PHY driver for Socionext UniPhier USB3 controller
> > > + * Copyright 2015-2018 Socionext Inc.
> > > + * Author:
> > > + * Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
> > > + * Contributors:
> > > + * Motoya Tanigawa <tanigawa.motoya@socionext.com>
> > > + * Masami Hiramatsu <masami.hiramatsu@linaro.org>
> > > + */
> > > +
> > > +#include <linux/bitfield.h>
> > > +#include <linux/bitops.h>
> > > +#include <linux/clk.h>
> > > +#include <linux/io.h>
> > > +#include <linux/mfd/syscon.h>
> > > +#include <linux/module.h>
> > > +#include <linux/nvmem-consumer.h>
> > > +#include <linux/of.h>
> > > +#include <linux/of_platform.h>
> > > +#include <linux/phy/phy.h>
> > > +#include <linux/platform_device.h>
> > > +#include <linux/reset.h>
> > > +#include <linux/slab.h>
> > > +
> > > +#define HSPHY_CFG0 0x0
> > > +#define HSPHY_CFG0_HS_I_MASK GENMASK(31, 28)
> > > +#define HSPHY_CFG0_HSDISC_MASK GENMASK(27, 26)
> > > +#define HSPHY_CFG0_SWING_MASK GENMASK(17, 16)
> > > +#define HSPHY_CFG0_SEL_T_MASK GENMASK(15, 12)
> > > +#define HSPHY_CFG0_RTERM_MASK GENMASK(7, 6)
> > > +#define HSPHY_CFG0_TRIMMASK (HSPHY_CFG0_HS_I_MASK \
> > > + | HSPHY_CFG0_SEL_T_MASK \
> > > + | HSPHY_CFG0_RTERM_MASK)
> > > +
> > > +#define HSPHY_CFG1 0x4
> > > +#define HSPHY_CFG1_DAT_EN BIT(29)
> > > +#define HSPHY_CFG1_ADR_EN BIT(28)
> > > +#define HSPHY_CFG1_ADR_MASK GENMASK(27, 16)
> > > +#define HSPHY_CFG1_DAT_MASK GENMASK(23, 16)
> > > +
> > > +#define MAX_CLKS 3
> > > +#define MAX_RSTS 2
> > > +#define MAX_PHY_PARAMS 1
> > > +
> > > +struct uniphier_u3hsphy_param {
> > > + u32 addr;
> > > + u32 mask;
> > > + u32 val;
> > > +};
> >
> > I'd like to avoid configure the PHY this way, since it's impossible to know
> > which register is being configured.
>

This way might be misunderstood.
These HS-PHY and SS-PHY have "internal" registers, which are not memory-mapped.

And to access these internal registers, we need to specify the number
corresponding to the register.

The "addr" in "uniphier_u3hsphy_param" is just the number of the register.
The "mask" shows a bitfield of the register, that means one of PHY parameters.
The "value" shows a parameter value to set to the bitfield.


> I see.
> In order to know which register is set, I'll add definitions for address
> and mask.
> And I think the driver might have functions for each SoC to configure
> the registers instead of uniphier_u3hsphy_param.

Then, I think it's sufficient to define a macro with a meaningful label for
each bitfield, and PHY parameters are expressed like that.

{ 10, FOO_BAR_MODE, 0x2 }, /* set 2 to FOO_BAR_MODE in register 10 */

In this case, we need to shift "value" according to "mask".

Thank you,

---
Best Regards,
Kunihiko Hayashi


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