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Date:   Wed, 9 Jan 2019 08:01:44 -0600
From:   Bin Liu <b-liu@ti.com>
To:     Min Guo <min.guo@mediatek.com>
CC:     Rob Herring <robh+dt@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Alan Stern <stern@rowland.harvard.edu>,
        <chunfeng.yun@mediatek.com>, <linux-usb@vger.kernel.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-mediatek@lists.infradead.org>,
        Yonglong Wu <yonglong.wu@mediatek.com>
Subject: Re: [PATCH 4/4] usb: musb: Add support for MediaTek musb controller
Message-ID: <20190109140144.GI25910@uda0271908>
Mail-Followup-To: Bin Liu <b-liu@ti.com>, Min Guo <min.guo@mediatek.com>,
        Rob Herring <robh+dt@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Alan Stern <stern@rowland.harvard.edu>, chunfeng.yun@mediatek.com,
        linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        Yonglong Wu <yonglong.wu@mediatek.com>
References: <1545896066-897-1-git-send-email-min.guo@mediatek.com>
 <1545896066-897-5-git-send-email-min.guo@mediatek.com>
 <20190108154441.GG25910@uda0271908>
 <1547037068.4433.122.camel@mhfsdcap03>
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Hi Min,

On Wed, Jan 09, 2019 at 08:31:08PM +0800, Min Guo wrote:
> Hi Bin,
> On Tue, 2019-01-08 at 09:44 -0600, Bin Liu wrote:
> > Hi,
> > 
> > On Thu, Dec 27, 2018 at 03:34:26PM +0800, min.guo@mediatek.com wrote:
> > > From: Min Guo <min.guo@mediatek.com>
> > > 
> > > This adds support for MediaTek musb controller in
> > > host, peripheral and otg mode
> > > 
> > > Signed-off-by: Min Guo <min.guo@mediatek.com>
> > > Signed-off-by: Yonglong Wu <yonglong.wu@mediatek.com>
> > > ---
> > >  drivers/usb/musb/Kconfig     |   8 +-
> > >  drivers/usb/musb/Makefile    |   1 +
> > >  drivers/usb/musb/mediatek.c  | 562 +++++++++++++++++++++++++++++++++++++++++++
> > >  drivers/usb/musb/musb_core.c |  10 +
> > >  drivers/usb/musb/musb_core.h |   1 +
> > >  drivers/usb/musb/musb_dma.h  |   1 +
> > >  drivers/usb/musb/musb_host.c |  79 ++++--
> > >  drivers/usb/musb/musb_regs.h |   6 +
> > >  drivers/usb/musb/musbhsdma.c |  34 ++-
> > >  9 files changed, 671 insertions(+), 31 deletions(-)
> > >  create mode 100644 drivers/usb/musb/mediatek.c
> > > 
> > > diff --git a/drivers/usb/musb/Kconfig b/drivers/usb/musb/Kconfig
> > > index ad08895..540fc9f 100644
> > > --- a/drivers/usb/musb/Kconfig
> > > +++ b/drivers/usb/musb/Kconfig
> > > @@ -115,6 +115,12 @@ config USB_MUSB_JZ4740
> > >  	depends on USB_MUSB_GADGET
> > >  	depends on USB_OTG_BLACKLIST_HUB
> > >  
> > > +config USB_MUSB_MEDIATEK
> > > +	tristate "MediaTek platforms"
> > > +	depends on ARCH_MEDIATEK
> > 
> > Please also add '|| COMPILE_TEST' to make testing easier.
> 
> Ok
> 
> > > +	depends on NOP_USB_XCEIV
> > > +	depends on GENERIC_PHY
> > > +
> > >  config USB_MUSB_AM335X_CHILD
> > >  	tristate
> > >  
> > > @@ -141,7 +147,7 @@ config USB_UX500_DMA
> > >  
> > >  config USB_INVENTRA_DMA
> > >  	bool 'Inventra'
> > > -	depends on USB_MUSB_OMAP2PLUS
> > > +	depends on USB_MUSB_OMAP2PLUS || USB_MUSB_MEDIATEK
> > >  	help
> > >  	  Enable DMA transfers using Mentor's engine.
> > >  
> > > diff --git a/drivers/usb/musb/Makefile b/drivers/usb/musb/Makefile
> > > index 3a88c79..63d82d0 100644
> > > --- a/drivers/usb/musb/Makefile
> > > +++ b/drivers/usb/musb/Makefile
> > > @@ -24,6 +24,7 @@ obj-$(CONFIG_USB_MUSB_DA8XX)			+= da8xx.o
> > >  obj-$(CONFIG_USB_MUSB_UX500)			+= ux500.o
> > >  obj-$(CONFIG_USB_MUSB_JZ4740)			+= jz4740.o
> > >  obj-$(CONFIG_USB_MUSB_SUNXI)			+= sunxi.o
> > > +obj-$(CONFIG_USB_MUSB_MEDIATEK)      		+= mediatek.o
> > >  
> > >  
> > >  obj-$(CONFIG_USB_MUSB_AM335X_CHILD)		+= musb_am335x.o
> > > diff --git a/drivers/usb/musb/mediatek.c b/drivers/usb/musb/mediatek.c
> > > new file mode 100644
> > > index 0000000..15a6460
> > > --- /dev/null
> > > +++ b/drivers/usb/musb/mediatek.c
> > 
> > [snip]
> > I will review this section later after we sorted out other things.
> > 
> > > diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
> > > index b7d5627..d60f76f 100644
> > > --- a/drivers/usb/musb/musb_core.c
> > > +++ b/drivers/usb/musb/musb_core.c
> > > @@ -1028,6 +1028,16 @@ static void musb_disable_interrupts(struct musb *musb)
> > >  	temp = musb_readb(mbase, MUSB_INTRUSB);
> > >  	temp = musb_readw(mbase, MUSB_INTRTX);
> > >  	temp = musb_readw(mbase, MUSB_INTRRX);
> > > +
> > > +	/*  MediaTek controller interrupt status is W1C */
> > 
> > This W1C doesn't match to the MUSB Programming Guide that I have. Those
> > registers are read-only.
> > Is the difference due to the IP intergration in the mtk platforms? or is
> > it a new version of the MUSB controller? If latter, what is the version?
> 
> This is difference due to the IP intergration in mtk platforms. W1C is
> easy for CpdeViser debug.
> 
> > > +	if (musb->ops->quirks & MUSB_MTK_QUIRKS) {
> > 
> > Basically we don't want to use this type of platform specific quirks if
> > possible, so let's try to not use it.
> 
> I will try my best to avoid using it.

Thanks.

> 
> > > +		musb_writeb(mbase, MUSB_INTRUSB,
> > > +			musb_readb(mbase, MUSB_INTRUSB));
> > 
> > For this clearing register bit operation, please create platform hooks
> > musb_clearb() and musb_clearw() in struct musb_platform_ops instead,
> > then follow how musb_readb() pointer is assigned in
> > musb_init_controller() to use the W1C version for mtk platform.
> 
> I have tried implementing musb_readb(), musb_readw() interface with
> interrupt status W1C function in struct musb_platform_ops. But this
> interface will require a global variable to hold MAC basic address for
> judgment, and then special handling of the interrupt state. A global
> variable will make the driver work with only a single instance, so it
> can't work on some MTK platforms which have two instances.

I didn't mean to modify musb_read*(), but

> How about creating musb_clearb/w() as following:
> void (*clearb)(void __iomem *addr, unsigned offset, u8 data);
> void (*clearw)(void __iomem *addr, unsigned offset, u16 data);

this is what I was asking for, similar to what musb_readb/w() is
implemented.

> 
> 
> > > +		musb_writew(mbase, MUSB_INTRRX,
> > > +			musb_readw(mbase, MUSB_INTRRX));
> > > +		musb_writew(mbase, MUSB_INTRTX,
> > > +			musb_readw(mbase, MUSB_INTRTX));
> > > +	}
> > >  }
> > >  
> > >  static void musb_enable_interrupts(struct musb *musb)
> > > diff --git a/drivers/usb/musb/musb_core.h b/drivers/usb/musb/musb_core.h
> > > index 04203b7..1bf4e9a 100644
> > > --- a/drivers/usb/musb/musb_core.h
> > > +++ b/drivers/usb/musb/musb_core.h
> > > @@ -138,6 +138,7 @@ enum musb_g_ep0_state {
> > >   */
> > >  struct musb_platform_ops {
> > >  
> > > +#define MUSB_MTK_QUIRKS	BIT(10)
> > >  #define MUSB_G_NO_SKB_RESERVE	BIT(9)
> > >  #define MUSB_DA8XX		BIT(8)
> > >  #define MUSB_PRESERVE_SESSION	BIT(7)
> > > diff --git a/drivers/usb/musb/musb_dma.h b/drivers/usb/musb/musb_dma.h
> > > index 281e75d3..b218210 100644
> > > --- a/drivers/usb/musb/musb_dma.h
> > > +++ b/drivers/usb/musb/musb_dma.h
> > > @@ -197,6 +197,7 @@ static inline void musb_dma_controller_destroy(struct dma_controller *d) { }
> > >  extern struct dma_controller *
> > >  musbhs_dma_controller_create(struct musb *musb, void __iomem *base);
> > >  extern void musbhs_dma_controller_destroy(struct dma_controller *c);
> > > +extern irqreturn_t dma_controller_irq(int irq, void *private_data);
> > >  
> > >  extern struct dma_controller *
> > >  tusb_dma_controller_create(struct musb *musb, void __iomem *base);
> > > diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> > > index b59ce9a..b1b0216 100644
> > > --- a/drivers/usb/musb/musb_host.c
> > > +++ b/drivers/usb/musb/musb_host.c
> > > @@ -292,20 +292,73 @@ static inline void musb_save_toggle(struct musb_qh *qh, int is_in,
> > >  {
> > >  	void __iomem		*epio = qh->hw_ep->regs;
> > >  	u16			csr;
> > > +	struct musb *musb = qh->hw_ep->musb;
> > >  
> > >  	/*
> > >  	 * FIXME: the current Mentor DMA code seems to have
> > >  	 * problems getting toggle correct.
> > >  	 */
> > >  
> > > -	if (is_in)
> > > -		csr = musb_readw(epio, MUSB_RXCSR) & MUSB_RXCSR_H_DATATOGGLE;
> > > -	else
> > > -		csr = musb_readw(epio, MUSB_TXCSR) & MUSB_TXCSR_H_DATATOGGLE;
> > > +	/* MediaTek controller has private toggle register */
> > 
> > only one toggle register for all endpoints? how does it handle
> > difference toggle values for different endpoints?
> 
> MediaTek controller has separate registers to describe TX/RX toggle.

Is it one register per endpoint?

> 
> > > +	if (musb->ops->quirks & MUSB_MTK_QUIRKS) {
> > > +		u16 toggle;
> > > +		u8 epnum = qh->hw_ep->epnum;
> > > +
> > > +		if (is_in)
> > > +			toggle = musb_readl(musb->mregs, MUSB_RXTOG);

this line seems telling there is just *one* register for all endpoints.

> > 
> > should use musb_readw() instead? MUSB_RXTOG seems to be 16bit.
> 
> Ok
> 
> > > +		else
> > > +			toggle = musb_readl(musb->mregs, MUSB_TXTOG);
> > > +
> > > +		csr = toggle & (1 << epnum);
> > > +	} else {
> > > +		if (is_in)
> > > +			csr = musb_readw(epio, MUSB_RXCSR)
> > > +				& MUSB_RXCSR_H_DATATOGGLE;
> > > +		else
> > > +			csr = musb_readw(epio, MUSB_TXCSR)
> > > +				& MUSB_TXCSR_H_DATATOGGLE;
> > 
> > Does this logic still work for the mtk platform even if it has its own
> > private toggle register? If so, we don't need to change here.
> 
> Sorry, this logic can not work on mtk platform, bit
> MUSB_RXCSR_H_DATATOGGLE and MUSB_TXCSR_H_DATATOGGLE are used for other
> function.

Is there a different controller RTL version we can use to
differentiate?

> 
> > If not, let's try to not use this quirk flag. Please create a hook
> > musb_platform_get_toggle() in struct musb_platform_ops.
> 
> Does the method of implement musb_platform_get_toggle() is prepare
> musb_default_get_toggle with common function, then follow how
> musb_readb() pointer is assigned in musb_init_controller()?

Yes, similar to musb_readb() implementation.

> How about creating musb_platform_get_toggle() as following:
> u16 (*get_toggle)(struct musb* musb, struct musb_qh *qh, int is_in);

yes, it is part of the implementation, then add it in struct musb_io.

> 
> > > +	}
> > >  
> > >  	usb_settoggle(urb->dev, qh->epnum, !is_in, csr ? 1 : 0);
> > >  }
> > >  
> > > +static inline u16 musb_set_toggle(struct musb_qh *qh, int is_in,
> > > +					struct urb *urb)
> > > +{
> > > +	u16 csr = 0;
> > > +	u16 toggle = 0;
> > > +	struct musb *musb = qh->hw_ep->musb;
> > > +	u8 epnum = qh->hw_ep->epnum;
> > > +
> > > +	toggle = usb_gettoggle(urb->dev, qh->epnum, !is_in);
> > > +
> > > +	/* MediaTek controller has private toggle register */
> > > +	if (musb->ops->quirks & MUSB_MTK_QUIRKS) {
> > > +		if (is_in) {
> > > +			musb_writel(musb->mregs, MUSB_RXTOGEN, (1 << epnum));
> > > +			musb_writel(musb->mregs, MUSB_RXTOG, (toggle << epnum));
> > > +		} else {
> > > +			musb_writel(musb->mregs, MUSB_TXTOGEN, (1 << epnum));
> > > +			musb_writel(musb->mregs, MUSB_TXTOG, (toggle << epnum));
> > > +		}
> > > +	} else {
> > > +		if (is_in) {
> > > +			if (toggle)
> > > +				csr = MUSB_RXCSR_H_WR_DATATOGGLE
> > > +						| MUSB_RXCSR_H_DATATOGGLE;
> > > +			else
> > > +				csr = 0;
> > > +		} else {
> > > +			if (toggle)
> > > +				csr |= MUSB_TXCSR_H_WR_DATATOGGLE
> > > +						| MUSB_TXCSR_H_DATATOGGLE;
> > > +			else
> > > +				csr |= MUSB_TXCSR_CLRDATATOG;

'? :' operation probably is better than 'if else' here.

> > > +		}
> > > +	}
> > > +	return csr;
> > 
> > Please create a seperate patch for this musb_set_toggle() without adding
> > the mtk logic. It is a nice cleanup.
> 
> Does this like get toggle implementation, create a hook
> musb_platform_set_toggle() in struct musb_platform_ops?

You did the code cleanup by creating musb_set_toggle(), please make it
in a separate patch, like

static u16 musb_set_toggle(struct musb_qh *qh, int is_in, struct urb *urb)
{
	toggle = usb_gettoggle(urb->dev, qh->epnum, !is_in);
	if (is_in)
		csr = toggle ? 
			(MUSB_RXCSR_H_WR_DATATOGGLE | MUSB_RXCSR_H_DATATOGGLE) :
			0;
	else
		csr = toggle ?
			MUSB_TXCSR_H_WR_DATATOGGLE | MUSB_TXCSR_H_DATATOGGLE :
			MUSB_TXCSR_CLRDATATOG;
	return csr;
}

/* use musb_set_toggle() in the two instances */

then in this patch you add the mtk implementation similar as
*get_toggle() discussed above.

> 
> > > +}
> > > +
> > >  /*
> > >   * Advance this hardware endpoint's queue, completing the specified URB and
> > >   * advancing to either the next URB queued to that qh, or else invalidating
> > > @@ -772,13 +825,8 @@ static void musb_ep_program(struct musb *musb, u8 epnum,
> > >  					);
> > >  			csr |= MUSB_TXCSR_MODE;
> > >  
> > > -			if (!hw_ep->tx_double_buffered) {
> > > -				if (usb_gettoggle(urb->dev, qh->epnum, 1))
> > > -					csr |= MUSB_TXCSR_H_WR_DATATOGGLE
> > > -						| MUSB_TXCSR_H_DATATOGGLE;
> > > -				else
> > > -					csr |= MUSB_TXCSR_CLRDATATOG;
> > > -			}
> > > +			if (!hw_ep->tx_double_buffered)
> > > +				csr |= musb_set_toggle(qh, !is_out, urb);
> > >  
> > >  			musb_writew(epio, MUSB_TXCSR, csr);
> > >  			/* REVISIT may need to clear FLUSHFIFO ... */
> > > @@ -860,17 +908,12 @@ static void musb_ep_program(struct musb *musb, u8 epnum,
> > >  
> > >  	/* IN/receive */
> > >  	} else {
> > > -		u16	csr;
> > > +		u16	csr = 0;
> > >  
> > >  		if (hw_ep->rx_reinit) {
> > >  			musb_rx_reinit(musb, qh, epnum);
> > > +			csr |= musb_set_toggle(qh, !is_out, urb);
> > >  
> > > -			/* init new state: toggle and NYET, maybe DMA later */
> > > -			if (usb_gettoggle(urb->dev, qh->epnum, 0))
> > > -				csr = MUSB_RXCSR_H_WR_DATATOGGLE
> > > -					| MUSB_RXCSR_H_DATATOGGLE;
> > > -			else
> > > -				csr = 0;
> > >  			if (qh->type == USB_ENDPOINT_XFER_INT)
> > >  				csr |= MUSB_RXCSR_DISNYET;
> > >  
> > > diff --git a/drivers/usb/musb/musb_regs.h b/drivers/usb/musb/musb_regs.h
> > > index 5cd7264..ffbe267 100644
> > > --- a/drivers/usb/musb/musb_regs.h
> > > +++ b/drivers/usb/musb/musb_regs.h
> > > @@ -273,6 +273,12 @@
> > >  #define MUSB_RXHUBADDR		0x06
> > >  #define MUSB_RXHUBPORT		0x07
> > >  
> > > +/* MediaTek controller toggle enable and status reg */
> > > +#define MUSB_RXTOG		0x80
> > > +#define MUSB_RXTOGEN		0x82
> > > +#define MUSB_TXTOG		0x84
> > > +#define MUSB_TXTOGEN		0x86
> > 
> > Again, these offsets are for different registers in the MUSB version I
> > have, please let me know if you have different version of the MUSB IP.
> 
> Sorry, these are MediaTek controller private registers used for control
> toggle.

Okay. Once the platform get/set_toggle() are implemented, those
registers can be defined in the mtk glue driver instead of here.

Regards,
-Bin.