Subject: [PATCH 5/7] clk: sunxi: add PRCM (Power/Reset/Clock Management) clks support

From: [email-masked] (Boris BREZILLON)
Date: Mon, 28 Apr 2014 19:14:50 +0200

Hi Chen-Yu,

On 28/04/2014 17:59, Chen-Yu Tsai wrote:
> Hi,
>
> On Mon, Apr 28, 2014 at 10:58 PM, Boris BREZILLON
> <[email-masked]> wrote:
>> The PRCM (Power/Reset/Clock Management) unit provides several clock
>> devices:
>> - AR100 clk: used to clock the Power Management co-processor
>> - AHB0 clk: used to clock the AHB0 bus
>> - APB0 clk and gates: used to clk
>>
>> Add support for these clks in a separate driver so that they can be probed
>> as platform devices instead of registered during early init.
>> We need this to be able to probe PRCM MFD subdevices.
>>
>> Signed-off-by: Boris BREZILLON <[email-masked]>
>> ---
>>  drivers/clk/sunxi/Makefile         |   2 +
>>  drivers/clk/sunxi/clk-sun6i-prcm.c | 253 +++++++++++++++++++++++++++++++++++++
>>  2 files changed, 255 insertions(+)
>>  create mode 100644 drivers/clk/sunxi/clk-sun6i-prcm.c
>>
>> diff --git a/drivers/clk/sunxi/Makefile b/drivers/clk/sunxi/Makefile
>> index b5bac91..ef8cdc9 100644
>> --- a/drivers/clk/sunxi/Makefile
>> +++ b/drivers/clk/sunxi/Makefile
>> @@ -3,3 +3,5 @@
>>  #
>>
>>  obj-y += clk-sunxi.o clk-factors.o
>> +
>> +obj-$(CONFIG_MFD_SUN6I_PRCM) += clk-sun6i-prcm.o
>> diff --git a/drivers/clk/sunxi/clk-sun6i-prcm.c b/drivers/clk/sunxi/clk-sun6i-prcm.c
>> new file mode 100644
>> index 0000000..bb7b25a
>> --- /dev/null
>> +++ b/drivers/clk/sunxi/clk-sun6i-prcm.c
>> @@ -0,0 +1,253 @@
>> +/*
>> + * Copyright (C) 2014 Free Electrons
>> + *
>> + * License Terms: GNU General Public License v2
>> + * Author: Boris BREZILLON <[email-masked]>
>> + *
>> + * Allwinner PRCM (Power/Reset/Clock Management) driver
>> + *
>> + */
>> +
>> +#include <linux/clk-provider.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +
>> +#define SUN6I_APB0_GATES_MAX_SIZE      32
>> +#define SUN6I_AR100_MAX_PARENTS                4
>> +
>> +static int sun6i_a31_ar100_mux_clk_register(struct platform_device *pdev)
>> +{
>> +       const char *parents[SUN6I_AR100_MAX_PARENTS];
>> +       struct device_node *np = pdev->dev.of_node;
>> +       const char *clk_name = np->name;
>> +       struct resource *r;
>> +       void __iomem *reg;
>> +       struct clk *clk;
>> +       int nparents;
>> +       int i;
>> +
>> +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       reg = devm_ioremap(&pdev->dev, r->start, resource_size(r));
>> +       if (IS_ERR(reg))
>> +               return PTR_ERR(reg);
>> +
>> +       nparents = of_clk_get_parent_count(np);
>> +       if (nparents > SUN6I_AR100_MAX_PARENTS)
>> +               nparents = SUN6I_AR100_MAX_PARENTS;
>> +
>> +       for (i = 0; i < nparents; i++)
>> +               parents[i] = of_clk_get_parent_name(np, i);
>> +
>> +       of_property_read_string(np, "clock-output-names", &clk_name);
>> +
>> +       clk = clk_register_mux(&pdev->dev, clk_name, parents, nparents,
>> +                              CLK_SET_RATE_NO_REPARENT, reg,
>> +                              16, 2, 0, NULL);
>> +       if (IS_ERR(clk))
>> +               return PTR_ERR(clk);
>> +
>> +       return of_clk_add_provider(np, of_clk_src_simple_get, clk);
>> +}
>> +
>> +static int sun6i_a31_ar100_clk_register(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;
>> +
>> +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       reg = devm_ioremap(&pdev->dev, r->start, resource_size(r));
>> +       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);
>> +
>> +       clk = clk_register_divider(&pdev->dev, clk_name, clk_parent,
>> +                                  0, reg, 4, 2, CLK_DIVIDER_POWER_OF_TWO,
>> +                                  NULL);
>> +       if (IS_ERR(clk))
>> +               return PTR_ERR(clk);
>> +
>> +       return of_clk_add_provider(np, of_clk_src_simple_get, clk);
>> +}
>> +
>> +static int sun6i_a31_ar100_div_clk_register(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;
>> +
>> +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       reg = devm_ioremap(&pdev->dev, r->start, resource_size(r));
>> +       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);
>> +
>> +       clk = clk_register_divider(&pdev->dev, clk_name, clk_parent,
>> +                                  0, reg, 8, 5, 0, NULL);
>> +       if (IS_ERR(clk))
>> +               return PTR_ERR(clk);
>> +
>> +       return of_clk_add_provider(np, of_clk_src_simple_get, clk);
>> +}
> Would it be possible to merge the 3 ar100 clocks into 1 composite clock?
> They do share the same register, and are related to each other.

Okay, I'll take a look at composite clocks.

> It might be possible to re-use some code from the sunxi clock driver
> for this, though I'm not sure if that's a good idea, sharing code
> between modules. Emilio?

Actually, this is what I tried in the first place, but then I realized
it would require exporting some functions declared as static in clk-sunxi.c.
Moreover, these functions do not make use of devm functions (because all
the clks declared in clk-sunxi.c are initiliazed during early), and I'd
like to uses devm function when clks are declared as platform devices.

Anyway, I'll wait for Emilio's review ;-).

>
>> +
>> +static int sun6i_a31_apb0_clk_register(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;
>> +
>> +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       reg = devm_ioremap_resource(&pdev->dev, r);
>> +       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);
>> +
>> +       clk = clk_register_divider(&pdev->dev, clk_name, clk_parent,
>> +                                  0, reg, 0, 2, CLK_DIVIDER_POWER_OF_TWO,
>> +                                  NULL);
> I just looked at the sun6i kernel code again.
>
>   http://git.rhombus-tech.net/?p=linux.git;a=blob;f=arch/arm/mach-sun6i/clock/ccm_i.h;hb=refs/heads/allwinner-sunxi-a31#l376
>
> and
>
>   http://git.rhombus-tech.net/?p=linux.git;a=blob;f=arch/arm/mach-sun6i/clock/sys_clk.c;hb=refs/heads/allwinner-sunxi-a31#l882
>
> The divider on the A31 is /2, /2, /4, /8. You might need a table for that.

I saw that in the datasheet, but I just thought it was a mistake (that's
weird to have 2 times the same divisor).

> This is different from the A23 manual I used to document most of the PRCM.
> I apologize for not catching this earlier. I have updated the wiki.

No problem.

>
>> +       if (IS_ERR(clk))
>> +               return PTR_ERR(clk);
>> +
>> +       return of_clk_add_provider(np, of_clk_src_simple_get, clk);
>> +}
>> +
>> +static int sun6i_a31_apb0_gates_clk_register(struct platform_device *pdev)
>> +{
>> +       struct device_node *np = pdev->dev.of_node;
>> +       struct clk_onecell_data *clk_data;
>> +       const char *clk_parent;
>> +       const char *clk_name;
>> +       struct resource *r;
>> +       void __iomem *reg;
>> +       int gate_id;
>> +       int ngates;
>> +       int i;
>> +
>> +       r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       reg = devm_ioremap_resource(&pdev->dev, r);
>> +       if (!reg)
>> +               return PTR_ERR(reg);
>> +
>> +       clk_parent = of_clk_get_parent_name(np, 0);
>> +       if (!clk_parent)
>> +               return -EINVAL;
>> +
>> +       ngates = of_property_count_strings(np, "clock-output-names");
>> +       if (ngates < 0)
>> +               return ngates;
>> +
>> +       if (!ngates || ngates > SUN6I_APB0_GATES_MAX_SIZE)
>> +               return -EINVAL;
>> +
>> +       clk_data = devm_kzalloc(&pdev->dev, sizeof(struct clk_onecell_data),
>> +                               GFP_KERNEL);
>> +       if (!clk_data)
>> +               return -ENOMEM;
>> +
>> +       clk_data->clks = devm_kzalloc(&pdev->dev,
>> +                                     SUN6I_APB0_GATES_MAX_SIZE *
>> +                                     sizeof(struct clk *),
>> +                                     GFP_KERNEL);
>> +       if (!clk_data->clks)
>> +               return -ENOMEM;
>> +
>> +       for (i = 0; i < ngates; i++) {
>> +               of_property_read_string_index(np, "clock-output-names",
>> +                                             i, &clk_name);
>> +
>> +               gate_id = i;
>> +               of_property_read_u32_index(np, "clock-indices", i, &gate_id);
>> +
>> +               WARN_ON(gate_id >= SUN6I_APB0_GATES_MAX_SIZE);
>> +               if (gate_id >= SUN6I_APB0_GATES_MAX_SIZE)
>> +                       continue;
>> +
>> +               clk_data->clks[gate_id] = clk_register_gate(&pdev->dev,
>> +                                                           clk_name,
>> +                                                           clk_parent, 0,
>> +                                                           reg, gate_id,
>> +                                                           0, NULL);
>> +               WARN_ON(IS_ERR(clk_data->clks[gate_id]));
>> +       }
>> +
>> +       clk_data->clk_num = ngates;
>> +
>> +       return of_clk_add_provider(np, of_clk_src_onecell_get, clk_data);
>> +}
>> +
>> +const struct of_device_id sun6i_a31_prcm_clk_dt_ids[] = {
>> +       {
>> +               .compatible = "allwinner,sun6i-a31-ar100-mux-clk",
>> +               .data = sun6i_a31_ar100_mux_clk_register,
>> +       },
>> +       {
>> +               .compatible = "allwinner,sun6i-a31-ar100-clk",
>> +               .data = sun6i_a31_ar100_clk_register,
>> +       },
>> +       {
>> +               .compatible = "allwinner,sun6i-a31-ar100-div-clk",
>> +               .data = sun6i_a31_ar100_div_clk_register,
>> +       },
>> +       {
>> +               .compatible = "allwinner,sun6i-a31-apb0-clk",
>> +               .data = sun6i_a31_apb0_clk_register,
>> +       },
>> +       {
>> +               .compatible = "allwinner,sun6i-a31-apb0-gates-clk",
>> +               .data = sun6i_a31_apb0_gates_clk_register,
>> +       },
>> +       { /* sentinel */ }
>> +};
>> +
>> +static int sun6i_a31_prcm_clk_probe(struct platform_device *pdev)
>> +{
>> +       struct device_node *np = pdev->dev.of_node;
>> +       int (*register_func)(struct platform_device *pdev);
>> +       const struct of_device_id *match;
>> +
>> +       match = of_match_node(sun6i_a31_prcm_clk_dt_ids, np);
>> +       if (!match)
>> +               return -EINVAL;
>> +
>> +       register_func = match->data;
>> +       return register_func(pdev);
>> +}
>> +
>> +static struct platform_driver sun6i_a31_prcm_clk_driver = {
>> +       .driver = {
>> +               .name = "sun6i-a31-prcm-clk",
>> +               .owner = THIS_MODULE,
>> +               .of_match_table = sun6i_a31_prcm_clk_dt_ids,
>> +       },
>> +       .probe = sun6i_a31_prcm_clk_probe,
>> +};
>> +module_platform_driver(sun6i_a31_prcm_clk_driver);
>> +
>> +MODULE_AUTHOR("Boris BREZILLON <[email-masked]");
>> +MODULE_DESCRIPTION("Allwinner Reset Controller Driver");
>> +MODULE_LICENSE("GPL v2");
> The rest looks good to me, but Emilio should be able to give you more feedback.
>
> Thanks for all the sun6i support you've done!

Thanks for your review.

Best Regards,

Boris
> Cheers
> ChenYu

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com