[PATCH u-boot 1/3] usb: host: Add simple of glue driver for DWC3 USB Controllers integration

[narmstrong@baylibre.com (Neil Armstrong)]

On 29/03/2018 15:52, Marek Vasut wrote:
> On 03/29/2018 03:42 PM, Neil Armstrong wrote:
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> ---
>>  drivers/usb/host/Kconfig          |   7 ++
>>  drivers/usb/host/Makefile         |   1 +
>>  drivers/usb/host/dwc3-of-simple.c | 187 ++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 195 insertions(+)
>>  create mode 100644 drivers/usb/host/dwc3-of-simple.c
>>
>> diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
>> index a7249b7..6caa615 100644
>> --- a/drivers/usb/host/Kconfig
>> +++ b/drivers/usb/host/Kconfig
>> @@ -21,6 +21,13 @@ config USB_XHCI_DWC3
>>  	  Say Y or if your system has a Dual Role SuperSpeed
>>  	  USB controller based on the DesignWare USB3 IP Core.
>>  
>> +config USB_XHCI_DWC3_OF_SIMPLE
>> +	bool "DesignWare USB3 DRD Generic OF Simple Glue Layer"
>> +	select MISC
>> +	help
>> +	  Support USB2/3 functionality in simple SoC integrations with
>> +	  USB controller based on the DesignWare USB3 IP Core.
>> +
>>  config USB_XHCI_MVEBU
>>  	bool "MVEBU USB 3.0 support"
>>  	default y
>> diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
>> index 9819489..abe4f90 100644
>> --- a/drivers/usb/host/Makefile
>> +++ b/drivers/usb/host/Makefile
>> @@ -49,6 +49,7 @@ obj-$(CONFIG_USB_EHCI_ZYNQ) += ehci-zynq.o
>>  # xhci
>>  obj-$(CONFIG_USB_XHCI_HCD) += xhci.o xhci-mem.o xhci-ring.o
>>  obj-$(CONFIG_USB_XHCI_DWC3) += xhci-dwc3.o
>> +obj-$(CONFIG_USB_XHCI_DWC3_OF_SIMPLE) += dwc3-of-simple.o
>>  obj-$(CONFIG_USB_XHCI_ROCKCHIP) += xhci-rockchip.o
>>  obj-$(CONFIG_USB_XHCI_ZYNQMP) += xhci-zynqmp.o
>>  obj-$(CONFIG_USB_XHCI_KEYSTONE) += xhci-keystone.o
>> diff --git a/drivers/usb/host/dwc3-of-simple.c b/drivers/usb/host/dwc3-of-simple.c
>> new file mode 100644
>> index 0000000..826a996
>> --- /dev/null
>> +++ b/drivers/usb/host/dwc3-of-simple.c
>> @@ -0,0 +1,187 @@
>> +/*
>> + * dwc3-of-simple.c - OF glue layer for simple integrations
>> + *
>> + * Copyright (c) 2015 Texas Instruments Incorporated - http://www.ti.com
>> + *
>> + * Author: Felipe Balbi <balbi@ti.com>
>> + *
>> + * Copyright (C) 2018 BayLibre, SAS
>> + * Author: Neil Armstrong <narmstron@baylibre.com>
>> + *
>> + * SPDX-License-Identifier:     GPL-2.0+
>> + */
>> +
>> +#include <common.h>
>> +#include <dm.h>
>> +#include <fdtdec.h>
>> +#include <reset.h>
>> +#include <clk.h>
>> +
>> +DECLARE_GLOBAL_DATA_PTR;
>> +
>> +struct dwc3_of_simple {
>> +#if CONFIG_IS_ENABLED(CLK)
>> +	struct clk		*clks;
>> +	int			num_clocks;
>> +#endif
>> +#if CONFIG_IS_ENABLED(DM_RESET)
>> +	struct reset_ctl	*resets;
>> +	int			num_resets;
>> +#endif
>> +};
>> +
>> +#if CONFIG_IS_ENABLED(DM_RESET)
>> +static int dwc3_of_simple_reset_init(struct udevice *dev,
>> +				     struct dwc3_of_simple *simple,
>> +				     int count)
>> +{
>> +	int i, ret, err;
>> +
>> +	if (!count)
>> +		return 0;
>> +
>> +	simple->resets = devm_kcalloc(dev, count, sizeof(struct reset_ctl),
>> +				      GFP_KERNEL);
>> +	if (!simple->resets)
>> +		return -ENOMEM;
>> +
>> +	for (i = 0; i < count; i++) {
>> +		ret = reset_get_by_index(dev, i, &simple->resets[i]);
>> +		if (ret < 0)
>> +			break;
>> +
>> +		ret = reset_request(&simple->resets[i]);
>> +		if (ret) {
>> +			pr_err("failed to request reset line %d\n", i);
>> +			reset_free(&simple->resets[i]);
>> +			goto reset_err;
>> +		}
>> +
>> +		
>> +		++simple->num_resets;
>> +	}
>> +
>> +	for (i = 0; i < simple->num_resets; i++) {
>> +		ret = reset_deassert(&simple->resets[i]);
>> +		if (ret && ret != -ENOSYS && ret != -ENOTSUPP) {
>> +			pr_err("failed to deassert reset line %d\n", i);
>> +			goto reset_err;
>> +		}
>> +	}
>> +
>> +	return 0;
> 
> This looks like some driver I've seen before. Isn't there similar code
> for simple EHCI or OHCI driver already ?
> 

Hi,

This is not an EHCI/OHCI driver, only the glue to init the clocks and reset,
it's the exact same as the drivers/usb/dwc3/dwc3-of-simple.c adapted to U-Boot.

yes, similar code exists in drivers/usb/host/ehci-generic.c and
drivers/usb/host/ohci-generic.c but the goal here is not to initialize the controller
but only the glue.

The device tree representation is :
glue@ {
	compatible = "amlogic,meson-gxl-dwc3";
	clocks = <>;
	resets = <>;

	dwc3@ {
		compatible = "snps,dwc3";
		clocks = <>;
		phys = <>;
	};
};

Neil