linux-kernel - Re: [PATCH v3] mfd: atmel-hlcdc: implement config synchronization

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Message-ID: <20150723144601.GF3436@x1>
Date:	Thu, 23 Jul 2015 15:46:01 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH v3] mfd: atmel-hlcdc: implement config synchronization

On Tue, 07 Jul 2015, Boris Brezillon wrote:

> Some HLCDC registers cannot be written until the hardware has finished
> applying the previous configuration request. If they are written while
> an action is still in progress, the new configuration might be silently
> ignored, resulting in unpredictable behavior.
> 
> Hide the config synchronization stuff in a regmap implementation and use
> this implementation instead of the generic mmio one.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
> 
> ---
> Changes since v2:
>  - reword the commit message
> 
> Changes since v1:
>  - add a 100 usec timeout
> ---
>  drivers/mfd/atmel-hlcdc.c | 35 +++++++++++++++++++++++++++++++++--
>  1 file changed, 33 insertions(+), 2 deletions(-)

Applied, thanks.

> diff --git a/drivers/mfd/atmel-hlcdc.c b/drivers/mfd/atmel-hlcdc.c
> index cfd58f4..04e01cc 100644
> --- a/drivers/mfd/atmel-hlcdc.c
> +++ b/drivers/mfd/atmel-hlcdc.c
> @@ -18,6 +18,7 @@
>   */
>  
>  #include <linux/clk.h>
> +#include <linux/iopoll.h>
>  #include <linux/mfd/atmel-hlcdc.h>
>  #include <linux/mfd/core.h>
>  #include <linux/module.h>
> @@ -37,11 +38,41 @@ static const struct mfd_cell atmel_hlcdc_cells[] = {
>  	},
>  };
>  
> +static int regmap_atmel_hlcdc_reg_write(void *context, unsigned int reg,
> +					unsigned int val)
> +{
> +	void __iomem *regs = context;
> +
> +	if (reg <= ATMEL_HLCDC_DIS) {
> +		u32 status;
> +
> +		readl_poll_timeout(regs + ATMEL_HLCDC_SR, status,
> +				   !(status & ATMEL_HLCDC_SIP), 1, 100);
> +	}
> +
> +	writel(val, regs + reg);
> +
> +	return 0;
> +}
> +
> +static int regmap_atmel_hlcdc_reg_read(void *context, unsigned int reg,
> +				       unsigned int *val)
> +{
> +	void __iomem *regs = context;
> +
> +	*val = readl(regs + reg);
> +
> +	return 0;
> +}
> +
>  static const struct regmap_config atmel_hlcdc_regmap_config = {
>  	.reg_bits = 32,
>  	.val_bits = 32,
>  	.reg_stride = 4,
>  	.max_register = ATMEL_HLCDC_REG_MAX,
> +	.reg_write = regmap_atmel_hlcdc_reg_write,
> +	.reg_read = regmap_atmel_hlcdc_reg_read,
> +	.fast_io = true,
>  };
>  
>  static int atmel_hlcdc_probe(struct platform_device *pdev)
> @@ -82,8 +113,8 @@ static int atmel_hlcdc_probe(struct platform_device *pdev)
>  		return PTR_ERR(hlcdc->slow_clk);
>  	}
>  
> -	hlcdc->regmap = devm_regmap_init_mmio(dev, regs,
> -					      &atmel_hlcdc_regmap_config);
> +	hlcdc->regmap = devm_regmap_init(dev, NULL, regs,
> +					 &atmel_hlcdc_regmap_config);
>  	if (IS_ERR(hlcdc->regmap))
>  		return PTR_ERR(hlcdc->regmap);
>  

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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