[U-Boot] [PATCH v2 05/13] usb: dwc3: change DWC3 core support code into a driver

[Roger Quadros]

On 17/05/16 11:57, Masahiro Yamada wrote:
> Hi Roger,
> 
> 
> 2016-05-17 17:20 GMT+09:00 Roger Quadros <rogerq at ti.com>:
>> Hi Masahiro,
>>
>> On 16/05/16 15:51, Masahiro Yamada wrote:
>>> Synopsys DWC3 IP generally works with an SoC-specific glue layer.
>>> DT binding for that is like this:
>>>
>>>   usb3_glue {
>>>           compatible = "foo,dwc3";
>>>           ...
>>>
>>>           usb3 {
>>>                   compatible = "snps,dwc3";
>>>                   ...
>>>           };
>>>   };
>>>
>>> The glue layer initializes some SoC-specific parts, then populates
>>> the child DWC3 core.  To see how it works, refer to
>>>
>>>   drivers/usb/dwc3/dwc3-exynos.c
>>>   drivers/usb/dwc3/dwc3-keystone.c
>>>   drivers/usb/dwc3/dwc3-omap.c
>>>   drivers/usb/dwc3/dwc3-st.c
>>>
>>> of Linux Kernel.
>>>
>>> This commit implements a driver compatible with "snps,dwc3", allowing
>>> to use the same binding in U-Boot.  The glue layer can be simply
>>> implemented based on Simple Bus Uclass.
>>>
>>> Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
>>> Reviewed-by: Marek Vasut <marex at denx.de>
>>> ---
>>>
>>> Changes in v2: None
>>>
>>>  drivers/usb/host/xhci-dwc3.c | 71 +++++++++++++++++++++++++++++++++++++++++++-
>>
>> "snps,dwc3" compatible is for the dual-role controller that implements both
>> device and host controllers.
> 
> I know this fact.
> The "snps,dwc3" on my SoC only works in host mode, though.
> 
> 
>> So calling the driver xhci-dwc3.c is a bit misleading.
> 
> 
> 
> I think we have separate work for
>  - drivers/usb/host/xhci-dwc3.c   (only for host mode)
>  - drivers/usb/dwc3/*             (currently, for gadget ??)
> 
> This is unfortunate, though.

If we use the same compatible for both host and gadget, how do we specify
in the device tree which driver to probe?
> 
> 
>>>  1 file changed, 70 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/usb/host/xhci-dwc3.c b/drivers/usb/host/xhci-dwc3.c
>>> index 33961cd..c7c8324 100644
>>> --- a/drivers/usb/host/xhci-dwc3.c
>>> +++ b/drivers/usb/host/xhci-dwc3.c
>>> @@ -9,8 +9,13 @@
>>>   */
>>>
>>>  #include <common.h>
>>> -#include <asm/io.h>
>>> +#include <dm/device.h>
>>> +#include <mapmem.h>
>>> +#include <linux/io.h>
>>>  #include <linux/usb/dwc3.h>
>>> +#include <linux/sizes.h>
>>> +
>>> +#include "xhci.h"
>>>
>>>  void dwc3_set_mode(struct dwc3 *dwc3_reg, u32 mode)
>>>  {
>>> @@ -97,3 +102,67 @@ void dwc3_set_fladj(struct dwc3 *dwc3_reg, u32 val)
>>>       setbits_le32(&dwc3_reg->g_fladj, GFLADJ_30MHZ_REG_SEL |
>>>                       GFLADJ_30MHZ(val));
>>>  }
>>> +
>>> +struct dwc3_priv {
>>> +     struct xhci_ctrl ctrl;  /* should be the first member */
>>> +     void __iomem *regs;
>>> +};
>>> +
>>> +static int dwc3_probe(struct udevice *dev)
>>> +{
>>> +     struct dwc3_priv *priv = dev_get_priv(dev);
>>> +     struct xhci_hccr *hccr;
>>> +     struct xhci_hcor *hcor;
>>> +     fdt_addr_t base;
>>> +     int ret;
>>> +
>>> +     base = dev_get_addr(dev);
>>> +     if (base == FDT_ADDR_T_NONE)
>>> +             return -EINVAL;
>>> +
>>> +     priv->regs = map_sysmem(base, SZ_32K);
>>> +     if (!priv->regs)
>>> +             return -ENOMEM;
>>> +
>>> +     hccr = priv->regs;
>>> +
>>> +     hcor = priv->regs + HC_LENGTH(xhci_readl(&hccr->cr_capbase));
>>> +
>>> +     ret = dwc3_core_init(priv->regs + DWC3_REG_OFFSET);
>>> +     if (ret) {
>>> +             puts("XHCI: failed to initialize controller\n");
>>> +             return ret;
>>> +     }
>>> +
>>> +     /* We are hard-coding DWC3 core to Host Mode */
>>> +     dwc3_set_mode(priv->regs + DWC3_REG_OFFSET, DWC3_GCTL_PRTCAP_HOST);
>>
>> Why are we hard-coding it to host mode?
> 
> Because this file is used for host mode.
> It is enabled by CONFIG_USB_XHCI_DWC3, like follows.
> 
> obj-$(CONFIG_USB_XHCI_DWC3) += xhci-dwc3.o
> 
> Boards defining CONFIG_USB_XHCI_DWC3 expect
> this driver works in the host mode, I guess.

OK as part of code will only be called for host mode.
> 
> 
>> We need to take into account
>> the dr_mode DT property and the Kconfig options to decide which mode
>> we can operate in.
> 
> 
> I thought drivers/usb/dwc3/* was working only for GADGET,
> because currently USB_DWC3 depends on (USB && USB_GADGET).
> 
> As far as I understand, it will work for host mode with your series applied.
> Correct?

I'm still unsure as to how all this fits in.

> 
> If so, cool!
> I am happy to move to drivers/usb/dwc3/*.
> 

Maybe Marek can share his view.

cheers,
-roger