Message-ID: <20140619092847.GW19730@lukather>
Date:	Thu, 19 Jun 2014 11:28:47 +0200
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Chen-Yu Tsai <wens@...e.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Mike Turquette <mturquette@...aro.org>,
	Emilio Lopez <emilio@...pez.com.ar>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-serial@...r.kernel.org,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-sunxi <linux-sunxi@...glegroups.com>,
	devicetree <devicetree@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Boris BREZILLON <boris.brezillon@...e-electrons.com>,
	Luc Verhaegen <libv@...net.be>
Subject: Re: [PATCH v2 12/20] clk: sunxi: Add A23 APB0 support to
 sun6i-a31-apb0-clk

On Thu, Jun 19, 2014 at 12:33:41PM +0800, Chen-Yu Tsai wrote:
> On Wed, Jun 18, 2014 at 6:26 PM, Maxime Ripard
> <maxime.ripard@...e-electrons.com> wrote:
> > On Tue, Jun 17, 2014 at 10:52:49PM +0800, Chen-Yu Tsai wrote:
> >> The A23 has an almost identical PRCM clock tree. The difference in
> >> the APB0 clock is the smallest divisor is 1, instead of 2.
> >>
> >> This patch extends the sun6i-a31-apb0-clk driver to take divider
> >> tables associated to compatibles, and adds a compatible for the A23
> >> variant.
> >>
> >> Signed-off-by: Chen-Yu Tsai <wens@...e.org>
> >> ---
> >>  Documentation/devicetree/bindings/clock/sunxi.txt |  1 +
> >>  drivers/clk/sunxi/clk-sun6i-apb0.c                | 28 ++++++++++++++++++-----
> >>  2 files changed, 23 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
> >> index af9e47d..e3a47ec 100644
> >> --- a/Documentation/devicetree/bindings/clock/sunxi.txt
> >> +++ b/Documentation/devicetree/bindings/clock/sunxi.txt
> >> @@ -28,6 +28,7 @@ Required properties:
> >>       "allwinner,sun8i-a23-ahb1-gates-clk" - for the AHB1 gates on A23
> >>       "allwinner,sun4i-a10-apb0-clk" - for the APB0 clock
> >>       "allwinner,sun6i-a31-apb0-clk" - for the APB0 clock on A31
> >> +     "allwinner,sun8i-a23-apb0-clk" - for the APB0 clock on A23
> >>       "allwinner,sun4i-a10-apb0-gates-clk" - for the APB0 gates on A10
> >>       "allwinner,sun5i-a13-apb0-gates-clk" - for the APB0 gates on A13
> >>       "allwinner,sun5i-a10s-apb0-gates-clk" - for the APB0 gates on A10s
> >> diff --git a/drivers/clk/sunxi/clk-sun6i-apb0.c b/drivers/clk/sunxi/clk-sun6i-apb0.c
> >> index 11f17c3..2197ac7 100644
> >> --- a/drivers/clk/sunxi/clk-sun6i-apb0.c
> >> +++ b/drivers/clk/sunxi/clk-sun6i-apb0.c
> >> @@ -11,6 +11,7 @@
> >>  #include <linux/clk-provider.h>
> >>  #include <linux/module.h>
> >>  #include <linux/of.h>
> >> +#include <linux/of_device.h>
> >>  #include <linux/platform_device.h>
> >>
> >>  /*
> >> @@ -28,6 +29,21 @@ static const struct clk_div_table sun6i_a31_apb0_divs[] = {
> 
> For reference:
> 
> static const struct clk_div_table sun6i_a31_apb0_divs[] = {
>         { .val = 0, .div = 2, },
>         { .val = 1, .div = 2, },
>         { .val = 2, .div = 4, },
>         { .val = 3, .div = 8, },
>         { /* sentinel */ },
> };
> 
> 
> >>       { /* sentinel */ },
> >>  };
> >>
> >> +/* The A23 APB0 clock has a standard power of 2 divisor */
> >
> > Why not just pass CLK_DIVIDER_POWER_OF_TWO then, instead of a table?
> 
> The A31 APB0 clock uses a table for the odd /2 divisor for value 0.
> The standard table I'm using for the A23 is just to keep it simple
> and alike.
> 
> >> +static const struct clk_div_table sun8i_a23_apb0_divs[] = {
> >> +     { .val = 0, .div = 1, },
> >> +     { .val = 1, .div = 2, },
> >> +     { .val = 2, .div = 4, },
> >> +     { .val = 3, .div = 8, },
> >> +     { /* sentinel */ },
> >> +};
> >> +
> >> +const struct of_device_id sun6i_a31_apb0_clk_dt_ids[] = {
> >> +     { .compatible = "allwinner,sun6i-a31-apb0-clk", .data = &sun6i_a31_apb0_divs },
> >> +     { .compatible = "allwinner,sun8i-a23-apb0-clk", .data = &sun8i_a23_apb0_divs },
> >> +     { /* sentinel */ }
> >> +};
> >> +
> >>  static int sun6i_a31_apb0_clk_probe(struct platform_device *pdev)
> >>  {
> >>       struct device_node *np = pdev->dev.of_node;
> >> @@ -36,12 +52,17 @@ static int sun6i_a31_apb0_clk_probe(struct platform_device *pdev)
> >>       struct resource *r;
> >>       void __iomem *reg;
> >>       struct clk *clk;
> >> +     const struct of_device_id *device;
> >>
> >>       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >>       reg = devm_ioremap_resource(&pdev->dev, r);
> >>       if (IS_ERR(reg))
> >>               return PTR_ERR(reg);
> >>
> >> +     device = of_match_device(sun6i_a31_apb0_clk_dt_ids, &pdev->dev);
> >> +     if (!device)
> >> +             return -EINVAL;
> >> +
> >>       clk_parent = of_clk_get_parent_name(np, 0);
> >>       if (!clk_parent)
> >>               return -EINVAL;
> >> @@ -49,7 +70,7 @@ static int sun6i_a31_apb0_clk_probe(struct platform_device *pdev)
> >>       of_property_read_string(np, "clock-output-names", &clk_name);
> >>
> >>       clk = clk_register_divider_table(&pdev->dev, clk_name, clk_parent,
> >> -                                      0, reg, 0, 2, 0, sun6i_a31_apb0_divs,
> >> +                                      0, reg, 0, 2, 0, device->data,
> >
> > I'm not sure that it will actually work for the A31, since it does
> > define some dividers anyway, and the divider table is !NULL, even
> > though there's actually no dividers defined.
> 
> I'm not following. The A31 does have a table defined. It's just cut
> off in this patch. I asked Boris to add the table when he was working
> on the A31 PRCM clocks. See above.

Ah right. My bad.

If these two clocks are these different though, maybe it would just be
easier to add a new driver. These are trivial enough anyway.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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