linux-kernel - Re: [PATCH v4 6/6] usb: musb: Add support for MediaTek musb controller

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Date:   Mon, 21 Jan 2019 10:07:49 -0600
From:   Bin Liu <b-liu@...com>
To:     <min.guo@...iatek.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Alan Stern <stern@...land.harvard.edu>,
        <chunfeng.yun@...iatek.com>, <linux-usb@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <tony@...mide.com>,
        <hdegoede@...hat.com>, Yonglong Wu <yonglong.wu@...iatek.com>
Subject: Re: [PATCH v4 6/6] usb: musb: Add support for MediaTek musb
 controller

Hi Min,

On Mon, Jan 21, 2019 at 08:22:31PM +0800, min.guo@...iatek.com wrote:
> From: Min Guo <min.guo@...iatek.com>
> 
> This adds support for MediaTek musb controller in
> host, peripheral and otg mode.
> There are some quirk of MediaTek musb controller, such as:
>  -W1C interrupt status registers
>  -Private data toggle registers
>  -No dedicated DMA interrupt line
> 
> Signed-off-by: Min Guo <min.guo@...iatek.com>
> Signed-off-by: Yonglong Wu <yonglong.wu@...iatek.com>
> ---
> changes in v4:
> 1. no changes
> 
> changes in v3:
> suggested by Bin:
> 1. Remove 'u8/u16 data' parameter in clearb/w() hooks
> 2. Replace musb_readb/w() with musb_clearb/w() to clear interrupts status
> 
> changes in v2:
> suggested by Bin:
> 1. Add summarize of MediaTek musb controller differences in the commit log
> 2. Add "|| COMPILE_TEST" in Kconfig
> 3. Move MediaTek's private toggle registers from musb_regs.h to mediatek.c
> 4. Replace musb_readl() with musb_readw() to read 16bit toggle register
> ---
>  drivers/usb/musb/Kconfig    |   8 +-
>  drivers/usb/musb/Makefile   |   1 +
>  drivers/usb/musb/mediatek.c | 624 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 632 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/usb/musb/mediatek.c
> 

[snip]

> +static irqreturn_t generic_interrupt(int irq, void *__hci)
> +{
> +	unsigned long flags;
> +	irqreturn_t retval = IRQ_NONE;
> +	struct musb *musb = __hci;
> +
> +	spin_lock_irqsave(&musb->lock, flags);
> +	musb->int_usb = musb_readb(musb->mregs, MUSB_INTRUSB) &
> +	    musb_readb(musb->mregs, MUSB_INTRUSBE);
> +	musb->int_tx = musb_readw(musb->mregs, MUSB_INTRTX)
> +	    & musb_readw(musb->mregs, MUSB_INTRTXE);
> +	musb->int_rx = musb_readw(musb->mregs, MUSB_INTRRX)
> +	    & musb_readw(musb->mregs, MUSB_INTRRXE);

Based on my comment in 5/6, the above 3 musb_readb/w() can be changed to

> +	/* MediaTek controller interrupt status is W1C */
> +	musb_clearw(musb->mregs, MUSB_INTRRX);
> +	musb_clearw(musb->mregs, MUSB_INTRTX);
> +	musb_clearb(musb->mregs, MUSB_INTRUSB);

	musb->int_usb = musb_clearb(musb->mregs, MUSB_INTRUSB)
	musb->int_tx = musb_clearw(musb->mregs, MUSB_INTRTX);
	musb->int_rx = musb_clearw(musb->mregs, MUSB_INTRRX);

> +
> +	if (musb->int_usb || musb->int_tx || musb->int_rx)
> +		retval = musb_interrupt(musb);
> +
> +	spin_unlock_irqrestore(&musb->lock, flags);
> +
> +	return retval;
> +}
> +

[snip]

> +
> +static u8 mtk_musb_clearb(void __iomem *addr, unsigned int offset)
> +{
> +	u8 data;
> +
> +	/* W1C */
> +	data = musb_readb(addr, offset);
> +	musb_writeb(addr, offset, data);
> +	return musb_readb(addr, offset);

	return data;

> +}
> +
> +static u16 mtk_musb_clearw(void __iomem *addr, unsigned int offset)
> +{
> +	u16 data;
> +
> +	/* W1C */
> +	data = musb_readw(addr, offset);
> +	musb_writew(addr, offset, data);
> +	return musb_readw(addr, offset);

	return data;


Regards,
-Bin.