linux-kernel - Re: [PATCH RESEND v21] clk: npcm8xx: add clock controller

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Message-ID: <5b31aa5cfb1e819b03678d080b630667.sboyd@kernel.org>
Date: Tue, 02 Jan 2024 15:52:49 -0800
From: Stephen Boyd <sboyd@...nel.org>
To: Tomer Maimon <tmaimon77@...il.com>
Cc: avifishman70@...il.com, benjaminfair@...gle.com, joel@....id.au, mturquette@...libre.com, tali.perry1@...il.com, venture@...gle.com, yuenn@...gle.com, openbmc@...ts.ozlabs.org, linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v21] clk: npcm8xx: add clock controller

Quoting Tomer Maimon (2023-12-21 05:43:20)
> Hi Stephen,
> 
> Thanks for your comments
> 
> On Thu, 21 Dec 2023 at 00:09, Stephen Boyd <sboyd@...nel.org> wrote:
> >
> > Quoting Tomer Maimon (2023-12-18 09:04:04)
> > > diff --git a/drivers/clk/clk-npcm8xx.c b/drivers/clk/clk-npcm8xx.c
> > > new file mode 100644
> > > index 000000000000..e6c5111cc255
> > > --- /dev/null
> > > +++ b/drivers/clk/clk-npcm8xx.c
> > > @@ -0,0 +1,552 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Nuvoton NPCM8xx Clock Generator
> > > + * All the clocks are initialized by the bootloader, so this driver allows only
> > > + * reading of current settings directly from the hardware.
> > > + *
> > > + * Copyright (C) 2020 Nuvoton Technologies
> > > + * Author: Tomer Maimon <tomer.maimon@...oton.com>
> > > + */
> > > +
> > > +#define pr_fmt(fmt) "npcm8xx_clk: " fmt
> > > +
> > > +#include <linux/bitfield.h>
> > > +#include <linux/clk-provider.h>
> > > +#include <linux/err.h>
> > > +#include <linux/io.h>
> > > +#include <linux/kernel.h>
> > > +#include <linux/module.h>
> > > +#include <linux/platform_device.h>
> > > +#include <linux/slab.h>
> > > +#include <linux/regmap.h>
> > [...]
> > > +#define NPCM8XX_CLK_S_CLKOUT      "clkout"
> > > +#define NPCM8XX_CLK_S_PRE_ADC     "pre adc"
> > > +#define NPCM8XX_CLK_S_UART        "uart"
> > > +#define NPCM8XX_CLK_S_UART2       "uart2"
> > > +#define NPCM8XX_CLK_S_TIMER       "timer"
> > > +#define NPCM8XX_CLK_S_MMC         "mmc"
> > > +#define NPCM8XX_CLK_S_SDHC        "sdhc"
> > > +#define NPCM8XX_CLK_S_ADC         "adc"
> > > +#define NPCM8XX_CLK_S_GFX         "gfx0_gfx1_mem"
> > > +#define NPCM8XX_CLK_S_USBIF       "serial_usbif"
> > > +#define NPCM8XX_CLK_S_USB_HOST    "usb_host"
> > > +#define NPCM8XX_CLK_S_USB_BRIDGE  "usb_bridge"
> > > +#define NPCM8XX_CLK_S_PCI         "pci"
> > > +#define NPCM8XX_CLK_S_TH          "th"
> > > +#define NPCM8XX_CLK_S_ATB         "atb"
> > > +#define NPCM8XX_CLK_S_PRE_CLK     "pre_clk"
> > > +#define NPCM8XX_CLK_S_RG         "rg"
> > > +#define NPCM8XX_CLK_S_RCP        "rcp"
> > > +
> > > +static struct clk_hw hw_pll1_div2, hw_pll2_div2, hw_gfx_div2, hw_pre_clk;
> > > +static struct npcm8xx_clk_pll_data npcm8xx_pll_clks[] = {
> > > +       { NPCM8XX_CLK_S_PLL0, { .name = NPCM8XX_CLK_S_REFCLK }, NPCM8XX_PLLCON0, 0 },
> >
> > This is a new driver, so please stop using .name in clk_parent_data
> > structures.
> A few versions ago you suggested defining the reference clock in the
> device tree,Can I use .fw_name since the reference clock in the device
> tree
> 
>         refclk: refclk-25mhz {
>                 compatible = "fixed-clock";
>                 clock-output-names = "refclk";

Please don't use clock-output-names property.

>                 clock-frequency = <25000000>;
>                 #clock-cells = <0>;
>         };

Use of this binding is fine assuming the reference clk is a real thing
that exists outside the SoC. Is it?

> 
>         clk: clock-controller@...01000 {
>                  compatible = "nuvoton,npcm845-clk";
>                  nuvoton,sysclk = <&rst>;
>                  #clock-cells = <1>;
>                  clocks = <&refclk>;

This is index = 0

>                  clock-names = "refclk";
>          };
> 
> I will make sure to add refclk-25mhz to NPCM8xx device tree.
> >
> > > +       { NPCM8XX_CLK_S_PLL1, { .name = NPCM8XX_CLK_S_REFCLK }, NPCM8XX_PLLCON1, 0 },
> > > +       { NPCM8XX_CLK_S_PLL2, { .name = NPCM8XX_CLK_S_REFCLK }, NPCM8XX_PLLCON2, 0 },
> > > +       { NPCM8XX_CLK_S_PLL_GFX, { .name = NPCM8XX_CLK_S_REFCLK }, NPCM8XX_PLLCONG, 0 },
> > > +};
> > > +
> > > +static const u32 cpuck_mux_table[] = { 0, 1, 2, 7 };
> > > +static const struct clk_parent_data cpuck_mux_parents[] = {
> > > +       { .hw = &npcm8xx_pll_clks[0].hw },
> > > +       { .hw = &npcm8xx_pll_clks[1].hw },
> > > +       { .index = 0 },
> >
> > This requires a binding update. As of today, there isn't a 'clocks'
> > property for the nuvoton,npcm845-clk binding.
> Can I use fw_name = NPCM8XX_CLK_S_REFCLK instead of  .index = 0 in
> that way, I will not need to modify nuvoton,npcm845-clk binding.

Why don't you want to modify the binding? If you add a clocks property
like in the example above you will have to modify the binding.