Re: [PATCH v4 1/5] clk: sunxi: Add CLK_OF_DECLARE support for sun8i-a23-apb0-clk driver

[Chen-Yu Tsai]

On Tue, Dec 1, 2015 at 10:19 PM, Chen-Yu Tsai <wens@xxxxxxxx> wrote:
> On Tue, Dec 1, 2015 at 8:50 PM, Maxime Ripard
> <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
>> On Tue, Dec 01, 2015 at 07:54:06PM +0800, Chen-Yu Tsai wrote:
>>> On Tue, Dec 1, 2015 at 6:04 PM, Maxime Ripard
>>> <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:
>>> > Hi,
>>> >
>>> > On Sun, Nov 29, 2015 at 11:03:06AM +0800, Chen-Yu Tsai wrote:
>>> >> The APBS clock on sun9i is the same as the APB0 clock on sun8i. With
>>> >> sun9i we are supporting the PRCM clocks by using CLK_OF_DECLARE,
>>> >> instead of through a PRCM mfd device and subdevices for each clock
>>> >> and reset control. As such we need a CLK_OF_DECLARE version of
>>> >> the sun8i-a23-apb0-clk driver.
>>> >>
>>> >> Also, build it for sun9i/A80, and not just for configurations with
>>> >> MFD_SUN6I_PRCM enabled.
>>> >>
>>> >> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
>>> >> ---
>>> >>  drivers/clk/sunxi/Makefile         |  5 +--
>>> >>  drivers/clk/sunxi/clk-sun8i-apb0.c | 71 +++++++++++++++++++++++++++++++-------
>>> >>  2 files changed, 62 insertions(+), 14 deletions(-)
>>> >>
>>> >> diff --git a/drivers/clk/sunxi/Makefile b/drivers/clk/sunxi/Makefile
>>> >> index cb4c299214ce..c55d5cd1c0e5 100644
>>> >> --- a/drivers/clk/sunxi/Makefile
>>> >> +++ b/drivers/clk/sunxi/Makefile
>>> >> @@ -15,6 +15,7 @@ obj-y += clk-sun9i-core.o
>>> >>  obj-y += clk-sun9i-mmc.o
>>> >>  obj-y += clk-usb.o
>>> >>
>>> >> +obj-$(CONFIG_MACH_SUN9I) += clk-sun8i-apb0.o
>>> >> +
>>> >
>>> > So sun8i doesn't use it?
>>>
>>> Shit... I messed up. clk-sun8i-apb0.o should also be under
>>> CONFIG_MFD_SUN6I_PRCM.
>>>
>>> I'll send a new version of this patch. No need to keep spamming
>>> people with the whole series.
>>
>> Ok.
>>
>>> >>  obj-$(CONFIG_MFD_SUN6I_PRCM) += \
>>> >> -     clk-sun6i-ar100.o clk-sun6i-apb0.o clk-sun6i-apb0-gates.o \
>>> >> -     clk-sun8i-apb0.o
>>> >> +     clk-sun6i-ar100.o clk-sun6i-apb0.o clk-sun6i-apb0-gates.o
>>> >> diff --git a/drivers/clk/sunxi/clk-sun8i-apb0.c b/drivers/clk/sunxi/clk-sun8i-apb0.c
>>> >> index 7ae5d2c2cde1..c1e2ac8f4b0d 100644
>>> >> --- a/drivers/clk/sunxi/clk-sun8i-apb0.c
>>> >> +++ b/drivers/clk/sunxi/clk-sun8i-apb0.c
>>> >> @@ -17,13 +17,68 @@
>>> >>  #include <linux/clk-provider.h>
>>> >>  #include <linux/module.h>
>>> >>  #include <linux/of.h>
>>> >> +#include <linux/of_address.h>
>>> >>  #include <linux/platform_device.h>
>>> >>
>>> >> +static struct clk *sun8i_a23_apb0_register(struct device_node *node,
>>> >> +                                        void __iomem *reg)
>>> >> +{
>>> >> +     const char *clk_name = node->name;
>>> >> +     const char *clk_parent;
>>> >> +     struct clk *clk;
>>> >> +     int ret;
>>> >> +
>>> >> +     clk_parent = of_clk_get_parent_name(node, 0);
>>> >> +     if (!clk_parent)
>>> >> +             return ERR_PTR(-EINVAL);
>>> >> +
>>> >> +     of_property_read_string(node, "clock-output-names", &clk_name);
>>> >> +
>>> >> +     /* The A23 APB0 clock is a standard 2 bit wide divider clock */
>>> >> +     clk = clk_register_divider(NULL, clk_name, clk_parent, 0, reg,
>>> >> +                                0, 2, CLK_DIVIDER_POWER_OF_TWO, NULL);
>>> >> +     if (IS_ERR(clk))
>>> >> +             return clk;
>>> >> +
>>> >> +     ret = of_clk_add_provider(node, of_clk_src_simple_get, clk);
>>> >> +     if (ret)
>>> >> +             goto err_unregister;
>>> >> +
>>> >> +     return clk;
>>> >> +
>>> >> +err_unregister:
>>> >> +     clk_unregister_divider(clk);
>>> >> +
>>> >> +     return ERR_PTR(ret);
>>> >> +}
>>> >> +
>>> >> +static void sun8i_a23_apb0_setup(struct device_node *node)
>>> >> +{
>>> >> +     void __iomem *reg;
>>> >> +     struct resource res;
>>> >> +     struct clk *clk;
>>> >> +
>>> >> +     reg = of_io_request_and_map(node, 0, of_node_full_name(node));
>>> >> +     if (IS_ERR(reg))
>>> >> +             return;
>>> >> +
>>> >> +     clk = sun8i_a23_apb0_register(node, reg);
>>> >> +     if (IS_ERR(clk))
>>> >> +             goto err_unmap;
>>> >> +
>>> >> +     return;
>>> >> +
>>> >> +err_unmap:
>>> >> +     iounmap(reg);
>>> >> +     of_address_to_resource(node, 0, &res);
>>> >> +     release_mem_region(res.start, resource_size(&res));
>>> >> +}
>>> >> +CLK_OF_DECLARE(sun8i_a23_apb0, "allwinner,sun8i-a23-apb0-clk",
>>> >> +            sun8i_a23_apb0_setup);
>>> >> +
>>> >>  static int sun8i_a23_apb0_clk_probe(struct platform_device *pdev)
>>> >>  {
>>> >>       struct device_node *np = pdev->dev.of_node;
>>> >> -     const char *clk_name = np->name;
>>> >> -     const char *clk_parent;
>>> >>       struct resource *r;
>>> >>       void __iomem *reg;
>>> >>       struct clk *clk;
>>> >> @@ -33,19 +88,11 @@ static int sun8i_a23_apb0_clk_probe(struct platform_device *pdev)
>>> >>       if (IS_ERR(reg))
>>> >>               return PTR_ERR(reg);
>>> >>
>>> >> -     clk_parent = of_clk_get_parent_name(np, 0);
>>> >> -     if (!clk_parent)
>>> >> -             return -EINVAL;
>>> >> -
>>> >> -     of_property_read_string(np, "clock-output-names", &clk_name);
>>> >> -
>>> >> -     /* The A23 APB0 clock is a standard 2 bit wide divider clock */
>>> >> -     clk = clk_register_divider(&pdev->dev, clk_name, clk_parent, 0, reg,
>>> >> -                                0, 2, CLK_DIVIDER_POWER_OF_TWO, NULL);
>>> >> +     clk = sun8i_a23_apb0_register(np, reg);
>>> >>       if (IS_ERR(clk))
>>> >>               return PTR_ERR(clk);
>>> >>
>>> >> -     return of_clk_add_provider(np, of_clk_src_simple_get, clk);
>>> >> +     return 0;
>>> >>  }
>>> >
>>> > Won't this probe twice now? First the CLK_OF_DECLARE will register a
>>> > clock, and then the device model will call probe a second time.
>>>
>>> AFAIK it will.
>>>
>>> > I guess then request_mem_region will catch it, but then you return an
>>> > error code, which is probably an error success, since the clock is
>>> > registered :)
>>>
>>> Indeed. clk-mod0.c actually has a comment block explaining this.
>>> I didn't want to repeat the whole thing though.
>>
>> I guess, we can simply return 0 if of_io_request_and_map returns
>> EBUSY, since it would simply mean that we already probed.
>
> I think CLK_OF_DECLARE gets probed first, then platform devices.
> of_io_request_and_map fails for mfd cells, which have no DT reg
> properties. So we should be ignoring -EINVAL instead of -EBUSY.

Right... I misread your comment. You're talking about the platform device
part. About ignoring the error here: normally we use CLK_OF_DECLARE with
clocks under the "clocks" node, which don't get registered as platform
device. (Or is this not so common?) So if one does get probed twice, I
think we shouldn't ignore the error. It's likely the DT has a problem
and the probe error will let the user know.

What do you think?

ChenYu

> But yeah, I'll have it return 0 in this case, and add a brief
> comment.
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