linux-kernel - Re: [PATCH v10 5/6] usb:cdns3 Add Cadence USB3 DRD Driver

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Date:   Wed, 14 Aug 2019 16:38:17 +0300
From:   Roger Quadros <rogerq@...com>
To:     Pawel Laszczak <pawell@...ence.com>, <felipe.balbi@...ux.intel.com>
CC:     <gregkh@...uxfoundation.org>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <jbergsagel@...com>,
        <nsekhar@...com>, <nm@...com>, <sureshp@...ence.com>,
        <jpawar@...ence.com>, <kurahul@...ence.com>, <aniljoy@...ence.com>
Subject: Re: [PATCH v10 5/6] usb:cdns3 Add Cadence USB3 DRD Driver



On 21/07/2019 21:32, Pawel Laszczak wrote:
> This patch introduce new Cadence USBSS DRD driver to Linux kernel.
> 
> The Cadence USBSS DRD Controller is a highly configurable IP Core which
> can be instantiated as Dual-Role Device (DRD), Peripheral Only and
> Host Only (XHCI)configurations.
> 
> The current driver has been validated with FPGA platform. We have
> support for PCIe bus, which is used on FPGA prototyping.
> 
> The host side of USBSS-DRD controller is compliant with XHCI
> specification, so it works with standard XHCI Linux driver.
> 
> Signed-off-by: Pawel Laszczak <pawell@...ence.com>
> ---
>  drivers/usb/Kconfig                |    2 +
>  drivers/usb/Makefile               |    2 +
>  drivers/usb/cdns3/Kconfig          |   46 +
>  drivers/usb/cdns3/Makefile         |   17 +
>  drivers/usb/cdns3/cdns3-pci-wrap.c |  203 +++
>  drivers/usb/cdns3/core.c           |  554 +++++++
>  drivers/usb/cdns3/core.h           |  109 ++
>  drivers/usb/cdns3/debug.h          |  171 ++
>  drivers/usb/cdns3/debugfs.c        |   87 ++
>  drivers/usb/cdns3/drd.c            |  390 +++++
>  drivers/usb/cdns3/drd.h            |  166 ++
>  drivers/usb/cdns3/ep0.c            |  914 +++++++++++
>  drivers/usb/cdns3/gadget-export.h  |   28 +
>  drivers/usb/cdns3/gadget.c         | 2338 ++++++++++++++++++++++++++++
>  drivers/usb/cdns3/gadget.h         | 1321 ++++++++++++++++
>  drivers/usb/cdns3/host-export.h    |   28 +
>  drivers/usb/cdns3/host.c           |   71 +
>  drivers/usb/cdns3/trace.c          |   11 +
>  drivers/usb/cdns3/trace.h          |  493 ++++++
>  19 files changed, 6951 insertions(+)
>  create mode 100644 drivers/usb/cdns3/Kconfig
>  create mode 100644 drivers/usb/cdns3/Makefile
>  create mode 100644 drivers/usb/cdns3/cdns3-pci-wrap.c
>  create mode 100644 drivers/usb/cdns3/core.c
>  create mode 100644 drivers/usb/cdns3/core.h
>  create mode 100644 drivers/usb/cdns3/debug.h
>  create mode 100644 drivers/usb/cdns3/debugfs.c
>  create mode 100644 drivers/usb/cdns3/drd.c
>  create mode 100644 drivers/usb/cdns3/drd.h
>  create mode 100644 drivers/usb/cdns3/ep0.c
>  create mode 100644 drivers/usb/cdns3/gadget-export.h
>  create mode 100644 drivers/usb/cdns3/gadget.c
>  create mode 100644 drivers/usb/cdns3/gadget.h
>  create mode 100644 drivers/usb/cdns3/host-export.h
>  create mode 100644 drivers/usb/cdns3/host.c
>  create mode 100644 drivers/usb/cdns3/trace.c
>  create mode 100644 drivers/usb/cdns3/trace.h
> 

<snip>

> diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c
> new file mode 100644
> index 000000000000..291f08be56fe
> --- /dev/null
> +++ b/drivers/usb/cdns3/gadget.c
> @@ -0,0 +1,2338 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Cadence USBSS DRD Driver - gadget side.
> + *
> + * Copyright (C) 2018-2019 Cadence Design Systems.
> + * Copyright (C) 2017-2018 NXP
> + *
> + * Authors: Pawel Jez <pjez@...ence.com>,
> + *          Pawel Laszczak <pawell@...ence.com>
> + *          Peter Chen <peter.chen@....com>
> + */
> +

<snip>

> +
> +static void cdns3_gadget_config(struct cdns3_device *priv_dev)
> +{
> +	struct cdns3_usb_regs __iomem *regs = priv_dev->regs;
> +	u32 reg;
> +
> +	cdns3_ep0_config(priv_dev);
> +
> +	/* enable interrupts for endpoint 0 (in and out) */
> +	writel(EP_IEN_EP_OUT0 | EP_IEN_EP_IN0, &regs->ep_ien);
> +
> +	/*
> +	 * Driver needs to modify LFPS minimal U1 Exit time for DEV_VER_TI_V1
> +	 * revision of controller.
> +	 */
> +	if (priv_dev->dev_ver == DEV_VER_TI_V1) {
> +		reg = readl(&regs->dbg_link1);
> +
> +		reg &= ~DBG_LINK1_LFPS_MIN_GEN_U1_EXIT_MASK;
> +		reg |= DBG_LINK1_LFPS_MIN_GEN_U1_EXIT(0x55) |
> +		       DBG_LINK1_LFPS_MIN_GEN_U1_EXIT_SET;
> +		writel(reg, &regs->dbg_link1);
> +	}
> +
> +	/*
> +	 * By default some platforms has set protected access to memory.
> +	 * This cause problem with cache, so driver restore non-secure
> +	 * access to memory.
> +	 */
> +	reg = readl(&regs->dma_axi_ctrl);

Why read the reg at all if you are just overwriting it below?

> +	reg = DMA_AXI_CTRL_MARPROT(DMA_AXI_CTRL_NON_SECURE) |
> +	      DMA_AXI_CTRL_MAWPROT(DMA_AXI_CTRL_NON_SECURE);


Otherwise you need to read modify only necessary bits and then write.
i.e.
	#define DMA_AXI_CTRL_MAPROT_MASK 0x3
	reg &= ~(DMA_AXI_CTRL_MARPROT(DMA_AXI_CTRL_MAPROT_MASK) |
		 DMA_AXI_CTRL_MARPROT(DMA_AXI_CTRL_MAPROT_MASK))
	reg |= DMA_AXI_CTRL_MARPROT(DMA_AXI_CTRL_NON_SECURE) |
	       DMA_AXI_CTRL_MAWPROT(DMA_AXI_CTRL_NON_SECURE);

> +	writel(reg, &regs->dma_axi_ctrl);
> +
> +	/* enable generic interrupt*/
> +	writel(USB_IEN_INIT, &regs->usb_ien);
> +	writel(USB_CONF_CLK2OFFDS | USB_CONF_L1DS, &regs->usb_conf);
> +
> +	cdns3_configure_dmult(priv_dev, NULL);
> +
> +	cdns3_gadget_pullup(&priv_dev->gadget, 1);
> +}
> +

<snip>

cheers,
-roger
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