linux-kernel - Re: [PATCH v5 RESEND] drivers: bus: simple-pm-bus: Use clocks

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Date:   Tue, 10 Jan 2023 11:50:47 +0800
From:   Liu Ying <victor.liu@....com>
To:     linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, geert+renesas@...der.be,
        saravanak@...gle.com, linux-imx@....com, greg@...ah.com,
        arnd@...db.de
Subject: Re: [PATCH v5 RESEND] drivers: bus: simple-pm-bus: Use clocks

On Mon, 2022-12-26 at 11:14 +0800, Liu Ying wrote:
> Simple Power-Managed bus controller may need functional clock(s)
> to be enabled before child devices connected to the bus can be
> accessed.  Get the clock(s) as a bulk and enable/disable the
> clock(s) when the bus is being power managed.
> 
> One example is that Freescale i.MX8qxp pixel link MSI bus controller
> needs MSI clock and AHB clock to be enabled before accessing child
> devices.
> 
> Signed-off-by: Liu Ying <victor.liu@....com>
> ---
> v4->v5:
> * Fix build warnings when CONFIG_PM=n by using RUNTIME_PM_OPS,
>   NOIRQ_SYSTEM_SLEEP_PM_OPS and pm_ptr macros.
> * Drop Geert's R-b tag due to the fix.
> * Resend based on v6.2-rc1.
> 
> v3->v4:
> * Drop unnecessary 'bus == NULL' check from
> simple_pm_bus_runtime_{suspend,resume}.
>   (Geert)
> * Add Geert's R-b tag.
> 
> v1->v3:
> * No change.
> 
>  drivers/bus/simple-pm-bus.c | 46
> +++++++++++++++++++++++++++++++++++++
>  1 file changed, 46 insertions(+)

Gentle ping.

Regards,
Liu Ying

> 
> diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-
> bus.c
> index 6b8d6257ed8a..7afe1947e1c0 100644
> --- a/drivers/bus/simple-pm-bus.c
> +++ b/drivers/bus/simple-pm-bus.c
> @@ -8,17 +8,24 @@
>   * for more details.
>   */
>  
> +#include <linux/clk.h>
>  #include <linux/module.h>
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
>  
> +struct simple_pm_bus {
> +	struct clk_bulk_data *clks;
> +	int num_clks;
> +};
> +
>  static int simple_pm_bus_probe(struct platform_device *pdev)
>  {
>  	const struct device *dev = &pdev->dev;
>  	const struct of_dev_auxdata *lookup = dev_get_platdata(dev);
>  	struct device_node *np = dev->of_node;
>  	const struct of_device_id *match;
> +	struct simple_pm_bus *bus;
>  
>  	/*
>  	 * Allow user to use driver_override to bind this driver to a
> @@ -44,6 +51,16 @@ static int simple_pm_bus_probe(struct
> platform_device *pdev)
>  			return -ENODEV;
>  	}
>  
> +	bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
> +	if (!bus)
> +		return -ENOMEM;
> +
> +	bus->num_clks = devm_clk_bulk_get_all(&pdev->dev, &bus->clks);
> +	if (bus->num_clks < 0)
> +		return dev_err_probe(&pdev->dev, bus->num_clks, "failed
> to get clocks\n");
> +
> +	dev_set_drvdata(&pdev->dev, bus);
> +
>  	dev_dbg(&pdev->dev, "%s\n", __func__);
>  
>  	pm_runtime_enable(&pdev->dev);
> @@ -67,6 +84,34 @@ static int simple_pm_bus_remove(struct
> platform_device *pdev)
>  	return 0;
>  }
>  
> +static int simple_pm_bus_runtime_suspend(struct device *dev)
> +{
> +	struct simple_pm_bus *bus = dev_get_drvdata(dev);
> +
> +	clk_bulk_disable_unprepare(bus->num_clks, bus->clks);
> +
> +	return 0;
> +}
> +
> +static int simple_pm_bus_runtime_resume(struct device *dev)
> +{
> +	struct simple_pm_bus *bus = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = clk_bulk_prepare_enable(bus->num_clks, bus->clks);
> +	if (ret) {
> +		dev_err(dev, "failed to enable clocks: %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops simple_pm_bus_pm_ops = {
> +	RUNTIME_PM_OPS(simple_pm_bus_runtime_suspend,
> simple_pm_bus_runtime_resume, NULL)
> +	NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> pm_runtime_force_resume)
> +};
> +
>  #define ONLY_BUS	((void *) 1) /* Match if the device is only a
> bus. */
>  
>  static const struct of_device_id simple_pm_bus_of_match[] = {
> @@ -85,6 +130,7 @@ static struct platform_driver simple_pm_bus_driver
> = {
>  	.driver = {
>  		.name = "simple-pm-bus",
>  		.of_match_table = simple_pm_bus_of_match,
> +		.pm = pm_ptr(&simple_pm_bus_pm_ops),
>  	},
>  };
>