[PATCH 03/10] clk: sunxi: Add driver for A80 MMC config clocks/resets - Chen-Yu Tsai

From: wens@csie.org (Chen-Yu Tsai)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 03/10] clk: sunxi: Add driver for A80 MMC config clocks/resets
Date: Sun, 7 Dec 2014 09:30:34 +0800	[thread overview]
Message-ID: <CAGb2v66kWnGh1t6wCjH1_uiWr0Px_O7x_camWSGhkGw2DzHc2A@mail.gmail.com> (raw)
In-Reply-To: <20141206180144.GD12434@lukather>

Hi,

On Sun, Dec 7, 2014 at 2:01 AM, Maxime Ripard
<maxime.ripard@free-electrons.com> wrote:
> Hi,
>
> On Wed, Dec 03, 2014 at 02:35:58PM +0800, Chen-Yu Tsai wrote:
>> On the A80 SoC, the 4 mmc controllers each have a separate register
>> controlling their register access clocks and reset controls. These
>> registers in turn share a ahb clock gate and reset control.
>>
>> This patch adds a platform device driver for these controls. It
>> requires both clocks and reset controls to be available, so using
>> CLK_OF_DECLARE might not be the best way.
>>
>> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
>> ---
>>  Documentation/devicetree/bindings/clock/sunxi.txt |   1 +
>>  drivers/clk/sunxi/Makefile                        |   1 +
>>  drivers/clk/sunxi/clk-sun9i-mmc.c                 | 228 ++++++++++++++++++++++
>>  3 files changed, 230 insertions(+)
>>  create mode 100644 drivers/clk/sunxi/clk-sun9i-mmc.c
>>
>> diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
>> index d0fb9c5..2de90ea 100644
>> --- a/Documentation/devicetree/bindings/clock/sunxi.txt
>> +++ b/Documentation/devicetree/bindings/clock/sunxi.txt
>> @@ -65,6 +65,7 @@ Required properties:
>>       "allwinner,sun4i-a10-usb-clk" - for usb gates + resets on A10 / A20
>>       "allwinner,sun5i-a13-usb-clk" - for usb gates + resets on A13
>>       "allwinner,sun6i-a31-usb-clk" - for usb gates + resets on A31
>> +     "allwinner,sun9i-a80-mmc-clk" - for mmc gates + resets on A80
>
> Please document the arguments required for this clock as well.

Ok.

>>
>>  Required properties for all clocks:
>>  - reg : shall be the control register address for the clock.
>> diff --git a/drivers/clk/sunxi/Makefile b/drivers/clk/sunxi/Makefile
>> index a66953c..3a5292e 100644
>> --- a/drivers/clk/sunxi/Makefile
>> +++ b/drivers/clk/sunxi/Makefile
>> @@ -8,6 +8,7 @@ obj-y += clk-a20-gmac.o
>>  obj-y += clk-mod0.o
>>  obj-y += clk-sun8i-mbus.o
>>  obj-y += clk-sun9i-core.o
>> +obj-y += clk-sun9i-mmc.o
>>
>>  obj-$(CONFIG_MFD_SUN6I_PRCM) += \
>>       clk-sun6i-ar100.o clk-sun6i-apb0.o clk-sun6i-apb0-gates.o \
>> diff --git a/drivers/clk/sunxi/clk-sun9i-mmc.c b/drivers/clk/sunxi/clk-sun9i-mmc.c
>> new file mode 100644
>> index 0000000..7569625
>> --- /dev/null
>> +++ b/drivers/clk/sunxi/clk-sun9i-mmc.c
>> @@ -0,0 +1,228 @@
>> +/*
>> + * Copyright 2013 Chen-Yu Tsai
>> + *
>> + * Chen-Yu Tsai      <wens@csie.org>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/clk-provider.h>
>> +#include <linux/clkdev.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/reset.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset-controller.h>
>> +#include <linux/spinlock.h>
>> +
>> +#define SUN9I_MMC_WIDTH              4
>> +
>> +#define SUN9I_MMC_GATE_BIT   16
>> +#define SUN9I_MMC_RESET_BIT  18
>> +
>> +struct sun9i_mmc_clk_data {
>> +     spinlock_t                      lock;
>> +     void __iomem                    *membase;
>> +     struct clk                      *clk;
>> +     struct reset_control            *reset;
>> +     struct clk_onecell_data         clk_data;
>> +     struct reset_controller_dev     rcdev;
>> +};
>> +
>> +static int sun9i_mmc_reset_assert(struct reset_controller_dev *rcdev,
>> +                           unsigned long id)
>> +{
>> +     struct sun9i_mmc_clk_data *data = container_of(rcdev,
>> +                                                    struct sun9i_mmc_clk_data,
>> +                                                    rcdev);
>> +     unsigned long flags;
>> +     void __iomem *reg = data->membase + SUN9I_MMC_WIDTH * id;
>> +     u32 val;
>> +
>> +     spin_lock_irqsave(&data->lock, flags);
>> +
>> +     val = readl(reg);
>> +     writel(val & ~BIT(SUN9I_MMC_RESET_BIT), reg);
>> +
>> +     spin_unlock_irqrestore(&data->lock, flags);
>> +
>> +     return 0;
>> +}
>> +
>> +static int sun9i_mmc_reset_deassert(struct reset_controller_dev *rcdev,
>> +                             unsigned long id)
>> +{
>> +     struct sun9i_mmc_clk_data *data = container_of(rcdev,
>> +                                                    struct sun9i_mmc_clk_data,
>> +                                                    rcdev);
>> +     unsigned long flags;
>> +     void __iomem *reg = data->membase + SUN9I_MMC_WIDTH * id;
>> +     u32 val;
>> +
>> +     spin_lock_irqsave(&data->lock, flags);
>> +
>> +     val = readl(reg);
>> +     writel(val | BIT(SUN9I_MMC_RESET_BIT), reg);
>> +
>> +     spin_unlock_irqrestore(&data->lock, flags);
>> +
>> +     return 0;
>> +}
>> +
>> +static struct reset_control_ops sun9i_mmc_reset_ops = {
>> +     .assert         = sun9i_mmc_reset_assert,
>> +     .deassert       = sun9i_mmc_reset_deassert,
>> +};
>> +
>> +static int sun9i_a80_mmc_clk_probe(struct platform_device *pdev)
>> +{
>> +     struct device_node *np = pdev->dev.of_node;
>> +     struct sun9i_mmc_clk_data *data;
>> +     struct clk_onecell_data *clk_data;
>> +     const char *clk_name = np->name;
>> +     const char *clk_parent;
>> +     struct resource *r;
>> +     int count, i, ret;
>> +
>> +     data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>> +     if (!data)
>> +             return -ENOMEM;
>> +
>> +     spin_lock_init(&data->lock);
>> +
>> +     r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +     /* one clock/reset pair per word */
>> +     count = (r->end - r->start + 1) / SUN9I_MMC_WIDTH;
>
> div_round_up(resource_size(r), sizeof(u32)) ?

Will fix.

>> +     data->membase = devm_ioremap_resource(&pdev->dev, r);
>> +     if (IS_ERR(data->membase))
>> +             return PTR_ERR(data->membase);
>> +
>> +     clk_data = &data->clk_data;
>> +     clk_data->clk_num = count;
>> +     clk_data->clks = devm_kcalloc(&pdev->dev, count, sizeof(struct clk *),
>> +                                   GFP_KERNEL);
>> +     if (!clk_data->clks)
>> +             return -ENOMEM;
>> +
>> +     clk_parent = of_clk_get_parent_name(np, 0);
>> +     if (!clk_parent)
>> +             return -EINVAL;
>> +
>> +     data->clk = devm_clk_get(&pdev->dev, NULL);
>> +     if (IS_ERR(data->clk)) {
>> +             dev_err(&pdev->dev, "Could not get clock\n");
>> +             return PTR_ERR(data->clk);
>> +     }
>> +
>> +     data->reset = devm_reset_control_get(&pdev->dev, NULL);
>> +     if (IS_ERR(data->reset)) {
>> +             dev_err(&pdev->dev, "Could not get reset control\n");
>> +             return PTR_ERR(data->reset);
>> +     }
>> +
>> +     ret = clk_prepare_enable(data->clk);
>> +     if (ret) {
>> +             dev_err(&pdev->dev, "Clock enable err %d\n", ret);
>> +             return ret;
>> +     }
>
> So that means that the clock will always be enabled, even if there's
> no downstream users?

Yes.

> Having the either clk_prepare_enable (or clk_enable if you're in
> atomic context) in the assert/deassert seems more logical.

I'll try it out and see if it works. Didn't work so well with the
USB clocks...

>> +     ret = reset_control_deassert(data->reset);
>> +     if (ret) {
>> +             dev_err(&pdev->dev, "Reset deassert err %d\n", ret);
>> +             goto err_reset;
>> +     }
>> +
>> +     for (i = 0; i < count; i++) {
>> +             of_property_read_string_index(np, "clock-output-names",
>> +                                           i, &clk_name);
>> +
>> +             clk_data->clks[i] = clk_register_gate(&pdev->dev, clk_name,
>> +                                                   clk_parent, 0,
>> +                                                   data->membase + SUN9I_MMC_WIDTH * i,
>> +                                                   SUN9I_MMC_GATE_BIT, 0,
>> +                                                   &data->lock);
>> +
>> +             if (IS_ERR(clk_data->clks[i])) {
>> +                     ret = PTR_ERR(clk_data->clks[i]);
>> +                     goto err_clk_register;
>> +             }
>> +     }
>> +
>> +     ret = of_clk_add_provider(np, of_clk_src_onecell_get, clk_data);
>> +     if (ret)
>> +             goto err_clk_provider;
>> +
>> +     data->rcdev.owner = THIS_MODULE;
>> +     data->rcdev.nr_resets = count;
>> +     data->rcdev.ops = &sun9i_mmc_reset_ops;
>> +     data->rcdev.of_node = pdev->dev.of_node;
>> +
>> +     ret = reset_controller_register(&data->rcdev);
>> +     if (ret)
>> +             goto err_rc_reg;
>> +
>> +     platform_set_drvdata(pdev, data);
>> +
>> +     return 0;
>> +
>> +err_rc_reg:
>> +     of_clk_del_provider(np);
>> +
>> +err_clk_provider:
>> +     for (i = 0; i < count; i++)
>> +             clk_unregister(clk_data->clks[i]);
>> +
>> +err_clk_register:
>> +     reset_control_assert(data->reset);
>> +
>> +err_reset:
>> +     clk_disable_unprepare(data->clk);
>> +
>> +     return ret;
>> +}
>> +
>> +static int sun9i_a80_mmc_clk_remove(struct platform_device *pdev)
>> +{
>> +     struct device_node *np = pdev->dev.of_node;
>> +     struct sun9i_mmc_clk_data *data = platform_get_drvdata(pdev);
>> +     struct clk_onecell_data *clk_data = &data->clk_data;
>> +     int i;
>> +
>> +     reset_controller_unregister(&data->rcdev);
>> +     of_clk_del_provider(np);
>> +     for (i = 0; i < clk_data->clk_num; i++)
>> +             clk_unregister(clk_data->clks[i]);
>> +
>> +     reset_control_assert(data->reset);
>> +     clk_disable_unprepare(data->clk);
>> +
>> +     return 0;
>> +}
>> +
>> +static const struct of_device_id sun9i_a80_mmc_clk_dt_ids[] = {
>> +     { .compatible = "allwinner,sun9i-a80-mmc-clk" },
>> +     { /* sentinel */ }
>> +};
>> +
>> +static struct platform_driver sun9i_a80_mmc_clk_driver = {
>> +     .driver = {
>> +             .name = "sun9i-a80-mmc-clk",
>> +             .of_match_table = sun9i_a80_mmc_clk_dt_ids,
>> +     },
>> +     .probe = sun9i_a80_mmc_clk_probe,
>> +     .remove = sun9i_a80_mmc_clk_remove,
>> +};
>> +module_platform_driver(sun9i_a80_mmc_clk_driver);
>> +
>> +MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
>> +MODULE_DESCRIPTION("Allwinner A80 MMC clock/reset Driver");
>> +MODULE_LICENSE("GPL v2");
>
> What's the real benefit of enabling it as a platform driver? the reset
> framework is set up early enough that you can use OF_CLK_DECLARE.

This clock/reset block also requires a reset control de-asserted. The
reset controllers are currently setup using platform devices. Are you
suggesting I use "allwinner,sun6i-a31-ahb1-reset" instead? That would
also imply having a .init_time callback for sun9i, and having
sun6i_reset_init() before of_clk_init(). Kind of confusing (not sure
this is the right word) for something not so critical.

Also we get to use devres, but that's just a bonus.

Thanks
ChenYu