linux-kernel - Re: [PATCH 2/5] soundwire: qcom: add support for mmio soundwire devices

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Date:   Mon, 8 Jun 2020 16:31:51 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Jonathan Marek <jonathan@...ek.ca>, alsa-devel@...a-project.org
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Vinod Koul <vkoul@...nel.org>,
        Sanyog Kale <sanyog.r.kale@...el.com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] soundwire: qcom: add support for mmio soundwire
 devices



On 6/8/20 3:43 PM, Jonathan Marek wrote:
> Adds support for qcom soundwire devices with memory mapped IO registers.

'device' is an ambiguous term for SoundWire.

Seems to me this is a SoundWire Master device directly accessed with 
mmio registers instead of over a SLIMbus link?

> 
> Signed-off-by: Jonathan Marek <jonathan@...ek.ca>
> ---
>   drivers/soundwire/qcom.c | 25 +++++++++++++++++++++++--
>   1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
> index f38d1fd3679f..628747df1c75 100644
> --- a/drivers/soundwire/qcom.c
> +++ b/drivers/soundwire/qcom.c
> @@ -90,6 +90,7 @@ struct qcom_swrm_ctrl {
>   	struct sdw_bus bus;
>   	struct device *dev;
>   	struct regmap *regmap;
> +	void __iomem *mmio;
>   	struct completion *comp;
>   	struct work_struct slave_work;
>   	/* read/write lock */
> @@ -154,6 +155,20 @@ static int qcom_swrm_ahb_reg_write(struct qcom_swrm_ctrl *ctrl,
>   	return SDW_CMD_OK;
>   }
>   
> +static int qcom_swrm_cpu_reg_read(struct qcom_swrm_ctrl *ctrl, int reg,
> +				  u32 *val)
> +{
> +	*val = readl(ctrl->mmio + reg);
> +	return SDW_CMD_OK;
> +}
> +
> +static int qcom_swrm_cpu_reg_write(struct qcom_swrm_ctrl *ctrl, int reg,
> +				   int val)
> +{
> +	writel(val, ctrl->mmio + reg);
> +	return SDW_CMD_OK;
> +}
> +
>   static int qcom_swrm_cmd_fifo_wr_cmd(struct qcom_swrm_ctrl *ctrl, u8 cmd_data,
>   				     u8 dev_addr, u16 reg_addr)
>   {
> @@ -746,6 +761,7 @@ static int qcom_swrm_probe(struct platform_device *pdev)
>   	struct sdw_master_prop *prop;
>   	struct sdw_bus_params *params;
>   	struct qcom_swrm_ctrl *ctrl;
> +	struct resource *res;
>   	int ret;
>   	u32 val;
>   
> @@ -760,8 +776,13 @@ static int qcom_swrm_probe(struct platform_device *pdev)
>   		if (!ctrl->regmap)
>   			return -EINVAL;
>   	} else {
> -		/* Only WCD based SoundWire controller is supported */
> -		return -ENOTSUPP;

I would move patch4 before this one, and add the functionality *after* 
removing the SLIMbus dependency.

> +		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +
> +		ctrl->reg_read = qcom_swrm_cpu_reg_read;
> +		ctrl->reg_write = qcom_swrm_cpu_reg_write;
> +		ctrl->mmio = devm_ioremap_resource(dev, res);
> +		if (IS_ERR(ctrl->mmio))
> +			return PTR_ERR(ctrl->mmio);

maybe deal with the resource checks before setting callbacks?

There are quite a few drivers who do things this way:

clk/qcom/common.c-      res = platform_get_resource(pdev, 
IORESOURCE_MEM, 0);
clk/qcom/common.c:      base = devm_ioremap_resource(dev, res);
--


>   	}
>   
>   	ctrl->irq = of_irq_get(dev->of_node, 0);
>