Re: [PATCH 09/13] mfd: omap-usb-host: Add device tree support and binding information

[Roger Quadros <rogerq@ti.com>]

On 02/05/2013 02:11 PM, kishon wrote:
> Hi,
> 
> On Tuesday 05 February 2013 04:28 PM, Roger Quadros wrote:
>> On 02/05/2013 08:16 AM, kishon wrote:
>>> On Monday 04 February 2013 09:28 PM, Roger Quadros wrote:
>>>> Allows the OMAP HS USB host controller to be specified
>>>> via device tree.
>>>>
>>>> CC: Samuel Ortiz <sameo@linux.intel.com>
>>>> Signed-off-by: Roger Quadros <rogerq@ti.com>
>>>> ---
>>>>    .../devicetree/bindings/mfd/omap-usb-host.txt      |   68 ++++++++++++++++
>>>>    drivers/mfd/omap-usb-host.c                        |   83 ++++++++++++++++++--
>>>>    2 files changed, 145 insertions(+), 6 deletions(-)
>>>>    create mode 100644 Documentation/devicetree/bindings/mfd/omap-usb-host.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/mfd/omap-usb-host.txt b/Documentation/devicetree/bindings/mfd/omap-usb-host.txt
>>>> new file mode 100644
>>>> index 0000000..2196893
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/mfd/omap-usb-host.txt
>>>> @@ -0,0 +1,68 @@
>>>> +OMAP HS USB Host
>>>> +
>>>> +Required properties:
>>>> +
>>>> +- compatible: should be "ti,usbhs-host"
>>>> +- reg: should contain one register range i.e. start and length
>>>> +- ti,hwmods: must contain "usb_host_hs"
>>>> +
>>>> +Optional properties:
>>>> +
>>>> +- nports: number of USB ports. Usually this is automatically detected
>>>> +  from the IP's revision register but can be overridden by specifying
>>>> +  this property.
>>>> +
>>>> +- portN_mode: Integer specifying the port mode for port N, where N can be
>>>> +  from 1 to nports. The port mode must be as per enum usbhs_omap_port_mode
>>>> +  in include/linux/platform_data/usb-omap.h
>>>> +  If the port mode is not specified, that port is treated as unused.
>>>> +
>>>> +- single_ulpi_bypass: Must be present if the controller contains a single
>>>> +  ULPI bypass control bit. e.g. OMAP3 silicon <= ES2.1
>>>> +
>>>> +Required properties if child node exists:
>>>> +
>>>> +- #address-cells: Must be 1
>>>> +- #size-cells: Must be 1
>>>> +- ranges: must be present
>>>> +
>>>> +Properties for children:
>>>> +
>>>> +The OMAP HS USB Host subsystem contains EHCI and OHCI controllers.
>>>> +See Documentation/devicetree/bindings/usb/omap-ehci.txt and
>>>> +omap3-ohci.txt
>>>> +
>>>> +Example for OMAP4:
>>>> +
>>>> +usbhshost: usbhshost@0x4a064000 {
>>>> +    compatible = "ti,usbhs-host";
>>>> +    reg = <0x4a064000 0x800>;
>>>> +    ti,hwmods = "usb_host_hs";
>>>> +    #address-cells = <1>;
>>>> +    #size-cells = <1>;
>>>> +    ranges;
>>>> +
>>>> +    usbhsohci: ohci@0x4a064800 {
>>>> +        compatible = "ti,omap3-ohci", "usb-ohci";
>>>> +        reg = <0x4a064800 0x400>;
>>>> +        interrupt-parent = <&gic>;
>>>> +        interrupts = <0 76 0x4>;
>>>> +    };
>>>> +
>>>> +    usbhsehci: ehci@0x4a064c00 {
>>>> +        compatible = "ti,omap-ehci", "usb-ehci";
>>>> +        reg = <0x4a064c00 0x400>;
>>>> +        interrupt-parent = <&gic>;
>>>> +        interrupts = <0 77 0x4>;
>>>> +    };
>>>> +};
>>>> +
>>>> +&usbhshost {
>>>> +    port1_mode = <1>; /* OMAP_EHCI_PORT_MODE_PHY */
>>>> +    port2_mode = <2>; /* OMAP_EHCI_PORT_MODE_TLL */
>>>> +    port3_mode = <1>; /* OMAP_EHCI_PORT_MODE_PHY */
>>>> +};
>>>> +
>>>> +&usbhsehci {
>>>> +    phy = <&hsusb1_phy 0 &hsusb3_phy>;
>>>> +};
>>>> diff --git a/drivers/mfd/omap-usb-host.c b/drivers/mfd/omap-usb-host.c
>>>> index f8ed08e..0f67856 100644
>>>> --- a/drivers/mfd/omap-usb-host.c
>>>> +++ b/drivers/mfd/omap-usb-host.c
>>>> @@ -1,8 +1,9 @@
>>>>    /**
>>>>     * omap-usb-host.c - The USBHS core driver for OMAP EHCI & OHCI
>>>>     *
>>>> - * Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com
>>>> + * Copyright (C) 2011-2013 Texas Instruments Incorporated - http://www.ti.com
>>>>     * Author: Keshava Munegowda <keshava_mgowda@ti.com>
>>>> + * Author: Roger Quadros <rogerq@ti.com>
>>>>     *
>>>>     * This program is free software: you can redistribute it and/or modify
>>>>     * it under the terms of the GNU General Public License version 2  of
>>>> @@ -27,6 +28,8 @@
>>>>    #include <linux/platform_device.h>
>>>>    #include <linux/platform_data/usb-omap.h>
>>>>    #include <linux/pm_runtime.h>
>>>> +#include <linux/of.h>
>>>> +#include <linux/of_platform.h>
>>>>
>>>>    #include "omap-usb.h"
>>>>
>>>> @@ -464,6 +467,37 @@ static void omap_usbhs_init(struct device *dev)
>>>>        pm_runtime_put_sync(dev);
>>>>    }
>>>>
>>>> +static int usbhs_omap_get_dt_pdata(struct device_node *node,
>>>> +                    struct usbhs_omap_platform_data *pdata)
>>>> +{
>>>> +    int ret, i;
>>>> +
>>>> +    ret = of_property_read_u32(node, "nports", &pdata->nports);
>>>> +    if (ret)
>>>> +        pdata->nports = 0;
>>>> +
>>>> +    /* get port modes */
>>>> +    for (i = 0; i < OMAP3_HS_USB_PORTS; i++) {
>>>> +        char prop[11];
>>>> +
>>>> +        snprintf(prop, sizeof(prop), "port%d_mode", i + 1);
>>>> +        ret = of_property_read_u32(node, prop, &pdata->port_mode[i]);
>>>> +        if (ret)
>>>> +            pdata->port_mode[i] = OMAP_USBHS_PORT_MODE_UNUSED;
>>>> +    }
>>>> +
>>>> +    /* get flags */
>>>> +    pdata->single_ulpi_bypass = of_property_read_bool(node,
>>>> +                        "single_ulpi_bypass");
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static struct of_device_id usbhs_child_match_table[] __initdata = {
>>>> +    { .compatible = "ti,omap-ehci", },
>>>> +    { .compatible = "ti,omap-ohci", },
>>>> +    { }
>>>> +};
>>>> +
>>>>    /**
>>>>     * usbhs_omap_probe - initialize TI-based HCDs
>>>>     *
>>>> @@ -479,6 +513,21 @@ static int usbhs_omap_probe(struct platform_device *pdev)
>>>>        int                i;
>>>>        bool                need_logic_fck;
>>>>
>>>> +    if (dev->of_node) {
>>>> +        /* For DT boot we populate platform data from OF node */
>>>> +        pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
>>>> +        if (!pdata)
>>>> +            return -ENOMEM;
>>>> +
>>>> +        if (usbhs_omap_get_dt_pdata(dev->of_node, pdata)) {
>>>> +            dev_err(dev,
>>>> +                "Error getting platform data from DT node\n");
>>>> +            return -ENODEV;
>>>> +        }
>>>> +
>>>> +        dev->platform_data = pdata;
>>>> +    }
>>>> +
>>>>        if (!pdata) {
>>>>            dev_err(dev, "Missing platform data\n");
>>>>            return -ENODEV;
>>>> @@ -490,7 +539,7 @@ static int usbhs_omap_probe(struct platform_device *pdev)
>>>>            return -ENOMEM;
>>>>        }
>>>>
>>>> -    res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "uhh");
>>>> +    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>>        omap->uhh_base = devm_request_and_ioremap(dev, res);
>>>>        if (!omap->uhh_base) {
>>>>            dev_err(dev, "Resource request/ioremap failed\n");
>>>> @@ -661,10 +710,23 @@ static int usbhs_omap_probe(struct platform_device *pdev)
>>>>        }
>>>>
>>>>        omap_usbhs_init(dev);
>>>> -    ret = omap_usbhs_alloc_children(pdev);
>>>> -    if (ret) {
>>>> -        dev_err(dev, "omap_usbhs_alloc_children failed\n");
>>>> -        goto err_alloc;
>>>> +
>>>> +    if (dev->of_node) {
>>>> +        ret = of_platform_populate(dev->of_node,
>>>> +                usbhs_child_match_table, NULL, dev);
>>>> +
>>>> +        if (ret) {
>>>> +            dev_err(dev, "Failed to create DT children: %d\n", ret);
>>>> +            goto err_alloc;
>>>> +        }
>>>> +
>>>> +    } else {
>>>> +        ret = omap_usbhs_alloc_children(pdev);
>>>> +        if (ret) {
>>>> +            dev_err(dev, "omap_usbhs_alloc_children failed: %d\n",
>>>> +                        ret);
>>>> +            goto err_alloc;
>>>> +        }
>>> These child devices should be destroyed on driver remove..no?
>>>
>> I could not find a function that does the opposite of of_platform_populate() or
>> of_platform_device_create_pdata(). It seems that platform devices created via
>> device tree are never meant to be destroyed.
> 
> No. I've done it for dwc3 in usb/dwc3/dwc3-omap.c. (you can check usb-next)

OK, so platform_device_unregister() is sufficient it seems. Thanks for the hint.

>>
>> It kind of makes sense for EHCI/OHCI, cause the devices are always present
>> on the SoC.
> Not true for devices created in drivers/ IMHO. It makes sense only if you create the device in some platform specific initialization file.
> 
>> Also, this driver can't be built as a module so it can never be removed.
> Why is this restriction btw?

I think it is because of the interdependency to load the omap-usb-tll driver before the omap-usb-host driver.
Now that we have deferred probing mechanism, I don't think it should be a problem any more.

cheers,
-roger