Re: [PATCH 2/2] usb: dwc3: Add driver for Xilinx platforms

[Philipp Zabel <p.zabel@pengutronix.de>]

Hi Manish,

On Thu, 2020-08-27 at 00:14 +0530, Manish Narani wrote:
> Add a new driver for supporting Xilinx platforms. This driver handles
> the USB 3.0 PHY initialization and PIPE control & reset operations for
> ZynqMP platforms. This also handles the USB 2.0 PHY initialization and
> reset operations for Versal platforms.
> 
> Signed-off-by: Manish Narani <manish.narani@xilinx.com>
> ---
[...]
> +static int dwc3_xlnx_rst_assert(struct reset_control *rstc)
> +{
> +	unsigned long loop_time = msecs_to_jiffies(RST_TIMEOUT);
> +	unsigned long timeout;
> +
> +	reset_control_assert(rstc);
> +
> +	/* wait until reset is asserted or timeout */
> +	timeout = jiffies + loop_time;
> +
> +	while (!time_after_eq(jiffies, timeout)) {
> +		if (reset_control_status(rstc) > 0)
> +			return 0;
> +
> +		cpu_relax();
> +	}
> +
> +	return -ETIMEDOUT;
> +}

I think this should be done in the reset controller driver instead.

When reset_control_assert() is called with an exclusive reset control,
the reset line should be already asserted when the function returns.

> +
> +static int dwc3_xlnx_rst_deassert(struct reset_control *rstc)
> +{
> +	unsigned long loop_time = msecs_to_jiffies(RST_TIMEOUT);
> +	unsigned long timeout;
> +
> +	reset_control_deassert(rstc);
> +
> +	/* wait until reset is de-asserted or timeout */
> +	timeout = jiffies + loop_time;
> +	while (!time_after_eq(jiffies, timeout)) {
> +		if (!reset_control_status(rstc))
> +			return 0;
> +
> +		cpu_relax();
> +	}
> +
> +	return -ETIMEDOUT;
> +}

Same as above, this belongs in the reset controller driver.

> +static int dwc3_xlnx_init_versal(struct dwc3_xlnx *priv_data)
> +{
> +	struct device *dev = priv_data->dev;
> +	int ret;
> +
> +	dwc3_xlnx_mask_phy_rst(priv_data, false);
> +
> +	/* Assert and De-assert reset */
> +	ret = zynqmp_pm_reset_assert(VERSAL_USB_RESET_ID,
> +				     PM_RESET_ACTION_ASSERT);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to assert Reset\n");
> +		return ret;
> +	}
> +
> +	ret = zynqmp_pm_reset_assert(VERSAL_USB_RESET_ID,
> +				     PM_RESET_ACTION_RELEASE);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to De-assert Reset\n");
> +		return ret;
> +	}
> +
> +	dwc3_xlnx_mask_phy_rst(priv_data, true);
> +
> +	return 0;
> +}
> +
> +static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
> +{
> +	struct device *dev = priv_data->dev;
> +	int ret;
> +	u32 reg;
> +
> +	priv_data->crst = devm_reset_control_get(dev, "usb_crst");

Please use devm_reset_control_get_exclusive() instead.

> +	if (IS_ERR(priv_data->crst)) {
> +		dev_err(dev, "failed to get %s reset signal\n", "usb_crst");

Consider using dev_err_probe() to hide -EPROBE_DEFER error values.

> +		ret = PTR_ERR(priv_data->crst);
> +		goto err;
> +	}
> +
> +	priv_data->hibrst = devm_reset_control_get(dev, "usb_hibrst");
> +	if (IS_ERR(priv_data->hibrst)) {
> +		dev_err(dev, "failed to get %s reset signal\n", "usb_hibrst");
> +		ret = PTR_ERR(priv_data->hibrst);
> +		goto err;
> +	}
> +
> +	priv_data->apbrst = devm_reset_control_get(dev, "usb_apbrst");
> +	if (IS_ERR(priv_data->apbrst)) {
> +		dev_err(dev, "failed to get %s reset signal\n", "usb_apbrst");
> +		ret = PTR_ERR(priv_data->apbrst);
> +		goto err;
> +	}

Same as above for the other two reset controls.

> +	priv_data->usb3_phy = devm_phy_get(dev, "usb3-phy");
> +
> +	ret = dwc3_xlnx_rst_assert(priv_data->crst);
> +	if (ret < 0) {
> +		dev_err(dev, "%s: %d: Failed to assert reset\n",
> +			__func__, __LINE__);
> +		goto err;
> +	}
> +
> +	ret = dwc3_xlnx_rst_assert(priv_data->hibrst);
> +	if (ret < 0) {
> +		dev_err(dev, "%s: %d: Failed to assert reset\n",
> +			__func__, __LINE__);
> +		goto err;
> +	}
> +
> +	ret = dwc3_xlnx_rst_assert(priv_data->apbrst);
> +	if (ret < 0) {
> +		dev_err(dev, "%s: %d: Failed to assert reset\n",
> +			__func__, __LINE__);
> +		goto err;
> +	}
> +
> +	ret = phy_init(priv_data->usb3_phy);
> +	if (ret < 0) {
> +		phy_exit(priv_data->usb3_phy);
> +		goto err;
> +	}
> +
> +	ret = dwc3_xlnx_rst_deassert(priv_data->apbrst);
> +	if (ret < 0) {
> +		dev_err(dev, "%s: %d: Failed to release reset\n",
> +			__func__, __LINE__);
> +		goto err;
> +	}
> +
> +	/* Set PIPE power present signal */
> +	writel(PIPE_POWER_ON, priv_data->regs + PIPE_POWER_OFFSET);
> +
> +	/* Clear PIPE CLK signal */
> +	writel(PIPE_CLK_OFF, priv_data->regs + PIPE_CLK_OFFSET);
> +
> +	ret = dwc3_xlnx_rst_deassert(priv_data->crst);
> +	if (ret < 0) {
> +		dev_err(dev, "%s: %d: Failed to release reset\n",
> +			__func__, __LINE__);
> +		goto err;
> +	}
> +
> +	ret = dwc3_xlnx_rst_deassert(priv_data->hibrst);
> +	if (ret < 0) {
> +		dev_err(dev, "%s: %d: Failed to release reset\n",
> +			__func__, __LINE__);
> +		goto err;
> +	}
> +
> +	ret = phy_power_on(priv_data->usb3_phy);
> +	if (ret < 0) {
> +		phy_exit(priv_data->usb3_phy);
> +		goto err;
> +	}
> +
> +	/*
> +	 * This routes the usb dma traffic to go through CCI path instead
> +	 * of reaching DDR directly. This traffic routing is needed to
> +	 * make SMMU and CCI work with USB dma.
> +	 */
> +	if (of_dma_is_coherent(dev->of_node) || dev->iommu_group) {
> +		reg = readl(priv_data->regs + XLNX_USB_COHERENCY);
> +		reg |= XLNX_USB_COHERENCY_ENABLE;
> +		writel(reg, priv_data->regs + XLNX_USB_COHERENCY);
> +	}
> +
> +err:
> +	return ret;
> +}
> +
> +static int dwc3_xlnx_probe(struct platform_device *pdev)
> +{
> +	struct dwc3_xlnx	*priv_data;
> +	struct device		*dev = &pdev->dev;
> +	struct device_node	*np = dev->of_node;
> +	struct resource		*res;
> +	void __iomem		*regs;
> +	int			ret;
> +
> +	priv_data = devm_kzalloc(dev, sizeof(*priv_data), GFP_KERNEL);
> +	if (!priv_data)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res) {
> +		dev_err(dev, "missing memory resource\n");
> +		return -ENODEV;
> +	}
> +
> +	regs = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(regs))
> +		return PTR_ERR(regs);
> +
> +	/* Store the usb control regs into priv_data for further usage */
> +	priv_data->regs = regs;
> +
> +	priv_data->dev = dev;
> +
> +	platform_set_drvdata(pdev, priv_data);
> +
> +	ret = clk_bulk_get_all(priv_data->dev, &priv_data->clks);

Why not use devm_clk_bulk_get_all()?

regards
Philipp