Re: [PATCH 3/4] hwspinlock: qcom: Allow mmio usage in addition to syscon

From: Vinod Koul <vkoul@kernel.org>
To: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Andy Gross <agross@kernel.org>, Ohad Ben-Cohen <ohad@wizery.com>,
	Baolin Wang <baolin.wang7@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	linux-arm-msm@vger.kernel.org, linux-remoteproc@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] hwspinlock: qcom: Allow mmio usage in addition to syscon
Date: Thu, 14 May 2020 19:45:23 +0530	[thread overview]
Message-ID: <20200514141523.GW14092@vkoul-mobl> (raw)
In-Reply-To: <20200513005441.1102586-4-bjorn.andersson@linaro.org>

On 12-05-20, 17:54, Bjorn Andersson wrote:
> In all modern Qualcomm platforms the mutex region of the TCSR is forked
> off into its own block, all with a offset of 0 and stride of 4096. So
> add support for directly memory mapping this register space, to avoid
> the need to represent this block using a syscon.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
>  drivers/hwspinlock/qcom_hwspinlock.c | 72 +++++++++++++++++++++-------
>  1 file changed, 56 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/hwspinlock/qcom_hwspinlock.c b/drivers/hwspinlock/qcom_hwspinlock.c
> index f0da544b14d2..d8d4d729816c 100644
> --- a/drivers/hwspinlock/qcom_hwspinlock.c
> +++ b/drivers/hwspinlock/qcom_hwspinlock.c
> @@ -70,41 +70,81 @@ static const struct of_device_id qcom_hwspinlock_of_match[] = {
>  };
>  MODULE_DEVICE_TABLE(of, qcom_hwspinlock_of_match);
>  
> -static int qcom_hwspinlock_probe(struct platform_device *pdev)
> +static struct regmap *qcom_hwspinlock_probe_syscon(struct platform_device *pdev,
> +						   u32 *base, u32 *stride)
>  {
> -	struct hwspinlock_device *bank;
>  	struct device_node *syscon;
> -	struct reg_field field;
>  	struct regmap *regmap;
> -	size_t array_size;
> -	u32 stride;
> -	u32 base;
>  	int ret;
> -	int i;
>  
>  	syscon = of_parse_phandle(pdev->dev.of_node, "syscon", 0);
> -	if (!syscon) {
> -		dev_err(&pdev->dev, "no syscon property\n");

any reason to drop the log?

> -		return -ENODEV;
> -	}
> +	if (!syscon)
> +		return ERR_PTR(-ENODEV);
>  
>  	regmap = syscon_node_to_regmap(syscon);
>  	of_node_put(syscon);
>  	if (IS_ERR(regmap))
> -		return PTR_ERR(regmap);
> +		return regmap;
>  
> -	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 1, &base);
> +	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 1, base);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "no offset in syscon\n");
> -		return -EINVAL;
> +		return ERR_PTR(-EINVAL);
>  	}
>  
> -	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 2, &stride);
> +	ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 2, stride);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "no stride syscon\n");
> -		return -EINVAL;
> +		return ERR_PTR(-EINVAL);
>  	}
>  
> +	return regmap;
> +}
> +
> +static const struct regmap_config tcsr_mutex_config = {
> +	.reg_bits		= 32,
> +	.reg_stride		= 4,
> +	.val_bits		= 32,
> +	.max_register		= 0x40000,
> +	.fast_io		= true,
> +};
> +
> +static struct regmap *qcom_hwspinlock_probe_mmio(struct platform_device *pdev,
> +						 u32 *offset, u32 *stride)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct resource *res;
> +	void __iomem *base;
> +
> +	/* All modern platform has offset 0 and stride of 4k */
> +	*offset = 0;
> +	*stride = 0x1000;

Wouldn't it make sense to read this from DT rather than code in kernel?

-- 
~Vinod