linux-kernel - Re: [PATCH 2/2] clk: add artpec-6 pll1 clock driver

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Message-ID: <20160217000220.2278.30045@quark.deferred.io>
Date:	Tue, 16 Feb 2016 16:02:20 -0800
From:	Michael Turquette <mturquette@...libre.com>
To:	Lars Persson <lars.persson@...s.com>, devicetree@...r.kernel.org,
	linux-clk@...r.kernel.org
Cc:	sboyd@...eaurora.org, robh+dt@...nel.org, pawel.moll@....com,
	mark.rutland@....com, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, linux-kernel@...r.kernel.org,
	"Lars Persson" <larper@...s.com>
Subject: Re: [PATCH 2/2] clk: add artpec-6 pll1 clock driver

Hi Lars,

Quoting Lars Persson (2016-02-11 08:01:04)
> The PLL1 clock is a fixed-factor clock with factors derived from boot
> mode pins. This driver is a simple wrapper to register the fixed
> factor clock according to the pin settings.
> 
> Signed-off-by: Lars Persson <larper@...s.com>
> ---
>  drivers/clk/Makefile      |  1 +
>  drivers/clk/clk-artpec6.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 71 insertions(+)
>  create mode 100644 drivers/clk/clk-artpec6.c
> 
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index b038e36..388f0cf 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -17,6 +17,7 @@ endif
>  
>  # hardware specific clock types
>  # please keep this section sorted lexicographically by file/directory path name
> +obj-$(CONFIG_MACH_ARTPEC6)             += clk-artpec6.o
>  obj-$(CONFIG_MACH_ASM9260)             += clk-asm9260.o
>  obj-$(CONFIG_COMMON_CLK_AXI_CLKGEN)    += clk-axi-clkgen.o
>  obj-$(CONFIG_ARCH_AXXIA)               += clk-axm5516.o
> diff --git a/drivers/clk/clk-artpec6.c b/drivers/clk/clk-artpec6.c
> new file mode 100644
> index 0000000..3664c44
> --- /dev/null
> +++ b/drivers/clk/clk-artpec6.c

You mentioned having three drivers. Maybe consider putting this in
drivers/clk/axis?

Continuing my questions from patch #1, should this clock be coupled with
other artpec6 clocks sharing the same clock controller?

> @@ -0,0 +1,70 @@
> +/*
> + * ARTPEC-6 clock initialization
> + *
> + * Copyright 2015 Axis Comunications AB.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/clkdev.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +
> +static void __init of_artpec6_pll1_setup(struct device_node *np)
> +{
> +       void __iomem *devstat;
> +       struct clk *clk;
> +       const char *clk_name = np->name;
> +       const char *parent_name;
> +       u32 pll_mode, pll_m, pll_n;
> +
> +       parent_name = of_clk_get_parent_name(np, 0);
> +
> +       devstat = of_iomap(np, 0);
> +       if (devstat == NULL) {
> +               pr_err("error to ioremap DEVSTAT\n");
> +               return;
> +       }
> +
> +       /* DEVSTAT register contains PLL settings */
> +       pll_mode = (readl(devstat) >> 6) & 3;
> +       iounmap(devstat);
> +
> +       /*
> +        * pll1 settings are designed for different DDR speeds using a fixed
> +        * 50MHz external clock. However, a different external clock could be
> +        * used on different boards.
> +        * CPU clock is half the DDR clock.
> +        */
> +       switch (pll_mode) {
> +       case 0: /* DDR3-2133 mode */
> +               pll_m = 4;
> +               pll_n = 85;
> +               break;
> +       case 1: /* DDR3-1866 mode */
> +               pll_m = 6;
> +               pll_n = 112;
> +               break;
> +       case 2: /* DDR3-1600 mode */
> +               pll_m = 4;
> +               pll_n = 64;
> +               break;
> +       case 3: /* DDR3-1333 mode */
> +               pll_m = 8;
> +               pll_n = 106;
> +               break;
> +       }
> +       /* ext_clk is defined in device tree */
> +       clk = clk_register_fixed_factor(NULL, clk_name, parent_name, 0,
> +                       pll_n, pll_m);
> +       if (IS_ERR(clk)) {
> +               pr_err("%s not registered\n", clk_name);
> +               return;
> +       }
> +       of_clk_add_provider(np, of_clk_src_simple_get, clk);
> +}
> +CLK_OF_DECLARE(artpec6_pll1, "axis,artpec6-pll1-clock", of_artpec6_pll1_setup);

Instead of using CLK_OF_DECLARE can you make this a platform_driver?

Best regards,
Mike

> -- 
> 2.1.4
>