linux-kernel - Re: [PATCH v2 2/3] misc: aspeed-lpc: Request and enable LPC clock

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Date:   Tue, 20 Feb 2018 10:20:17 +1100
From:   Cyril Bur <cyrilbur@...il.com>
To:     Joel Stanley <joel@....id.au>, Lee Jones <lee.jones@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Cc:     Arnd Bergmann <arnd@...db.de>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Andrew Jeffery <andrew@...id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Ryan Chen <ryan_chen@...eedtech.com>,
        Lei YU <mine260309@...il.com>
Subject: Re: [PATCH v2 2/3] misc: aspeed-lpc: Request and enable LPC clock

On Mon, 2018-02-19 at 17:54 +1030, Joel Stanley wrote:
> The LPC device needs to ensure it's clock is enabled before it can do
> anything.
> 
> In the past the clock was enabled and left running by u-boot, however
> Linux now has an upstream clock driver that disables unused clocks.
> 
> Tested-by: Lei YU <mine260309@...il.com>
> Reviewed-by: Andrew Jeffery <andrew@...id.au>
> Signed-off-by: Joel Stanley <joel@....id.au>

Reviewed-by: Cyril Bur <cyrilbur@...il.com>

> ---
>  drivers/misc/aspeed-lpc-ctrl.c | 26 +++++++++++++++++++++++---
>  1 file changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/misc/aspeed-lpc-ctrl.c b/drivers/misc/aspeed-lpc-ctrl.c
> index b5439643f54b..1827b7aa6674 100644
> --- a/drivers/misc/aspeed-lpc-ctrl.c
> +++ b/drivers/misc/aspeed-lpc-ctrl.c
> @@ -7,6 +7,7 @@
>   * 2 of the License, or (at your option) any later version.
>   */
>  
> +#include <linux/clk.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/miscdevice.h>
>  #include <linux/mm.h>
> @@ -26,6 +27,7 @@
>  struct aspeed_lpc_ctrl {
>  	struct miscdevice	miscdev;
>  	struct regmap		*regmap;
> +	struct clk		*clk;
>  	phys_addr_t		mem_base;
>  	resource_size_t		mem_size;
>  	u32		pnor_size;
> @@ -221,16 +223,33 @@ static int aspeed_lpc_ctrl_probe(struct platform_device *pdev)
>  		return -ENODEV;
>  	}
>  
> +	lpc_ctrl->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(lpc_ctrl->clk)) {
> +		dev_err(dev, "couldn't get clock\n");
> +		return PTR_ERR(lpc_ctrl->clk);
> +	}
> +	rc = clk_prepare_enable(lpc_ctrl->clk);
> +	if (rc) {
> +		dev_err(dev, "couldn't enable clock\n");
> +		return rc;
> +	}
> +
>  	lpc_ctrl->miscdev.minor = MISC_DYNAMIC_MINOR;
>  	lpc_ctrl->miscdev.name = DEVICE_NAME;
>  	lpc_ctrl->miscdev.fops = &aspeed_lpc_ctrl_fops;
>  	lpc_ctrl->miscdev.parent = dev;
>  	rc = misc_register(&lpc_ctrl->miscdev);
> -	if (rc)
> +	if (rc) {
>  		dev_err(dev, "Unable to register device\n");
> -	else
> -		dev_info(dev, "Loaded at %pr\n", &resm);
> +		goto err;
> +	}
> +
> +	dev_info(dev, "Loaded at %pr\n", &resm);
> +
> +	return 0;
>  
> +err:
> +	clk_disable_unprepare(lpc_ctrl->clk);
>  	return rc;
>  }
>  
> @@ -239,6 +258,7 @@ static int aspeed_lpc_ctrl_remove(struct platform_device *pdev)
>  	struct aspeed_lpc_ctrl *lpc_ctrl = dev_get_drvdata(&pdev->dev);
>  
>  	misc_deregister(&lpc_ctrl->miscdev);
> +	clk_disable_unprepare(lpc_ctrl->clk);
>  
>  	return 0;
>  }