lkml.org 
[lkml]   [2018]   [Dec]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC PATCH v2 04/15] usb:cdns3: Driver initialization code.
From
Date


On 04/12/18 10:50, Peter Chen wrote:
>>> + * Cadence USBSS DRD Driver.
>>> + *
>>> + * Copyright (C) 2018 Cadence.
>>> + *
>>> + * Author: Peter Chen <peter.chen@nxp.com>
>>> + * Pawel Laszczak <pawell@cadence.com>
>>> + */
>>> +
>>> +#include <linux/module.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/interrupt.h>
>>> +#include <linux/io.h>
>>> +#include <linux/pm_runtime.h>
>>> +
>>> +#include "gadget.h"
>>> +#include "core.h"
>>> +
>>> +static inline struct cdns3_role_driver *cdns3_get_current_role_driver(struct cdns3 *cdns)
>>> +{
>>> + WARN_ON(cdns->role >= CDNS3_ROLE_END || !cdns->roles[cdns->role]);
>>> + return cdns->roles[cdns->role];
>>> +}
>>> +
>>> +static inline int cdns3_role_start(struct cdns3 *cdns, enum cdns3_roles role)
>>> +{
>>> + int ret;
>>> +
>>> + if (role >= CDNS3_ROLE_END)
>>
>> WARN_ON()?
>>
>>> + return 0;
>>> +
>>> + if (!cdns->roles[role])
>>> + return -ENXIO;
>>> +
>>> + mutex_lock(&cdns->mutex);
>>> + cdns->role = role;
>>> + ret = cdns->roles[role]->start(cdns);
>>> + mutex_unlock(&cdns->mutex);
>>> + return ret;
>>> +}
>>> +
>>> +static inline void cdns3_role_stop(struct cdns3 *cdns)
>>> +{
>>> + enum cdns3_roles role = cdns->role;
>>> +
>>> + if (role == CDNS3_ROLE_END)
>>
>> WARN_ON(role >= CNDS3_ROLE_END) ?
>>
>>> + return;
>>> +
>>> + mutex_lock(&cdns->mutex);
>>> + cdns->roles[role]->stop(cdns);
>>> + cdns->role = CDNS3_ROLE_END;
>>
>> Why change the role here? You are just stopping the role not changing it.
>> I think cdns->role should remain unchanged, so we can call cdns3_role_start()
>> if required without error.
>>
>
> The current version of this IP has some issues to detect vbus status correctly,
> we have to force vbus status accordingly, so we need a status to indicate
> vbus disconnection, and add some code to let controller know vbus
> removal, in that case, the controller's state machine can be correct.
> So, we increase one role 'CDNS3_ROLE_END' to for this purpose.
>
> CDNS3_ROLE_GADGET: gadget mode and VBUS on
> CDNS3_ROLE_HOST: host mode and VBUS on
> CDNS3_ROLE_END: VBUS off, eg either host or device cable on the port.
>
> So, we may start role from CDNS3_ROLE_END at probe when nothing is connected,
> and need to set role as CDNS3_ROLE_END at ->stop for further handling at
> role switch routine.

OK. but still this (changing to ROLE_END) must be moved to the role switch routine
and the explanation you just mentioned must be added there.

>
>>> + mutex_unlock(&cdns->mutex);
>>> +}
>>> +
>>> +static enum cdns3_roles cdns3_get_role(struct cdns3 *cdns)
>>> +{
>>> + if (cdns->roles[CDNS3_ROLE_HOST] && cdns->roles[CDNS3_ROLE_GADGET]) {
>>> + //TODO: implements selecting device/host mode
>>> + return CDNS3_ROLE_HOST;
>>> + }
>>> + return cdns->roles[CDNS3_ROLE_HOST]
>>> + ? CDNS3_ROLE_HOST
>>> + : CDNS3_ROLE_GADGET;
>>
>> Why not just
>> return cdns->role;
>>
>> I'm wondering if we really need this function.
>
> cdns->role gets from cdns3_get_role, and this API tells role at the runtime.
> If both roles are supported, the role is decided by external
> conditions, eg, vbus/id
> or external connector. If only single role is supported, only one role structure
> is allocated, cdns->roles[CDNS3_ROLE_HOST] or cdns->roles[CDNS3_ROLE_GADGET]
>

How about adding this description in function documentation.

>>> +}
>>
>>> +
>>> +/**
>>> + * cdns3_core_init_role - initialize role of operation
>>> + * @cdns: Pointer to cdns3 structure
>>> + *
>>> + * Returns 0 on success otherwise negative errno
>>> + */
>>> +static int cdns3_core_init_role(struct cdns3 *cdns)
>>> +{
>>> + struct device *dev = cdns->dev;
>>> + enum usb_dr_mode dr_mode;
>>> +
>>> + dr_mode = usb_get_dr_mode(dev);
>>> + cdns->role = CDNS3_ROLE_END;
>>> +
>>> + /*
>>> + * If driver can't read mode by means of usb_get_dr_mdoe function then
>>> + * chooses mode according with Kernel configuration. This setting
>>> + * can be restricted later depending on strap pin configuration.
>>> + */
>>> + if (dr_mode == USB_DR_MODE_UNKNOWN) {
>>> + if (IS_ENABLED(CONFIG_USB_CDNS3_HOST) &&
>>> + IS_ENABLED(CONFIG_USB_CDNS3_GADGET))
>>> + dr_mode = USB_DR_MODE_OTG;
>>> + else if (IS_ENABLED(CONFIG_USB_CDNS3_HOST))
>>> + dr_mode = USB_DR_MODE_HOST;
>>> + else if (IS_ENABLED(CONFIG_USB_CDNS3_GADGET))
>>> + dr_mode = USB_DR_MODE_PERIPHERAL;
>>> + }
>>> +
>>> + if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_HOST) {
>>> + //TODO: implements host initialization
>>
>> /* TODO: Add host role */ ?
>>
>>> + }
>>> +
>>> + if (dr_mode == USB_DR_MODE_OTG || dr_mode == USB_DR_MODE_PERIPHERAL) {
>>> + //TODO: implements device initialization
>>
>> /* TODO: Add device role */ ?
>>
>
> Yes, it needs to allocate cdns->roles[CDNS3_ROLE_HOST] and
> cdns->roles[CDNS3_ROLE_GADGET].
>
>>> + }
>>> +
>>> + if (!cdns->roles[CDNS3_ROLE_HOST] && !cdns->roles[CDNS3_ROLE_GADGET]) {
>>> + dev_err(dev, "no supported roles\n");
>>> + return -ENODEV;
>>> + }
>>> +
>>> + cdns->dr_mode = dr_mode;
>
> Pawel, why dr_mode needs to be introduced?
>
>>> + return 0;
>>> +}
>>> +
>>> +/**
>>> + * cdns3_irq - interrupt handler for cdns3 core device
>>> + *
>>> + * @irq: irq number for cdns3 core device
>>> + * @data: structure of cdns3
>>> + *
>>> + * Returns IRQ_HANDLED or IRQ_NONE
>>> + */
>>> +static irqreturn_t cdns3_irq(int irq, void *data)
>>> +{
>>> + struct cdns3 *cdns = data;
>>> + irqreturn_t ret = IRQ_NONE;
>>> +
>>> + /* Handle device/host interrupt */
>>> + if (cdns->role != CDNS3_ROLE_END)
>>
>> Is it because of this that you need to set role to END at role_stop?
>> I think it is better to add a state variable to struct cdns3_role_driver, so we can
>> check if it is active or stopped.
>>
>> e.g.
>> if (cdns3_get_current_role_driver(cdns)->state == CDNS3_ROLE_STATE_ACTIVE)
>>
>>> + ret = cdns3_get_current_role_driver(cdns)->irq(cdns);
>>> +
>>> + return ret;
>>> +}
>>> +
>
> CDNS3_ROLE_END is introduced from above comments, we don't
> need another flag for it.
> If cdns->role == CDNS3_ROLE_END, it handles VBUS and ID interrupt.
>
>>> +static void cdns3_remove_roles(struct cdns3 *cdns)
>>
>> Should this be called cdns3_exit_roles() to be opposite of cdns3_init_roles()?
>>
>
> It is planed to called when at ->remove.
>>> +{
>>> + //TODO: implements this function
>>> +}
>>
>>> +
>>> +static int cdns3_do_role_switch(struct cdns3 *cdns, enum cdns3_roles role)
>>> +{
>>> + enum cdns3_roles current_role;
>>> + int ret = 0;
>>> +
>>> + current_role = cdns->role;
>>> +
>>> + if (role == CDNS3_ROLE_END)
>>> + return 0;
>>
>> role == END looks like error state. and it should never happen.
>> WARN here?
>>
>
> See my comments above.
>
>>> +
>>> + dev_dbg(cdns->dev, "Switching role");
>>> +
>>
>> Don't you have to stop the previous role before starting the new role?
>>
>
> Yes, it is needed. Pawel may simply some flows to suit his platform.
>
>>> + ret = cdns3_role_start(cdns, role);
>>> + if (ret) {
>>> + /* Back to current role */
>>> + dev_err(cdns->dev, "set %d has failed, back to %d\n",
>>> + role, current_role);
>>> + ret = cdns3_role_start(cdns, current_role);
>>> + }
>>> +
>>> + return ret;
>>> +}
>>> +
>>> +/**
>>> + * cdns3_role_switch - work queue handler for role switch
>>> + *
>>> + * @work: work queue item structure
>>> + *
>>> + * Handles below events:
>>> + * - Role switch for dual-role devices
>>> + * - CDNS3_ROLE_GADGET <--> CDNS3_ROLE_END for peripheral-only devices
>>> + */
>>> +static void cdns3_role_switch(struct work_struct *work)
>>> +{
>>> + enum cdns3_roles role = CDNS3_ROLE_END;
>>> + struct cdns3 *cdns;
>>> + bool device, host;
>>> +
>>> + cdns = container_of(work, struct cdns3, role_switch_wq);
>>> +
>>> + //TODO: implements this functions.
>>> + //host = cdns3_is_host(cdns);
>>> + //device = cdns3_is_device(cdns);
>>> + host = 1;
>>> + device = 0;
>>> +
>>> + if (host)
>>> + role = CDNS3_ROLE_HOST;
>>> + else if (device)
>>> + role = CDNS3_ROLE_GADGET;
>>> +
>>> + if (cdns->desired_dr_mode == cdns->current_dr_mode &&
>>> + cdns->role == role)
>>> + return;
>>> +
>>
>> I think all the below code can be moved to cdns3_do_role_switch().
>>
>>> + pm_runtime_get_sync(cdns->dev);
>>> + cdns3_role_stop(cdns);
>>> +
>>> + if (host) {
>>> + if (cdns->roles[CDNS3_ROLE_HOST])
>>> + cdns3_do_role_switch(cdns, CDNS3_ROLE_HOST);
>>> + pm_runtime_put_sync(cdns->dev);
>>> + return;
>>> + }
>>> +
>>> + if (device)
>>> + cdns3_do_role_switch(cdns, CDNS3_ROLE_GADGET);
>>> + else
>>> + cdns3_do_role_switch(cdns, CDNS3_ROLE_END);
>>> +
>>> + pm_runtime_put_sync(cdns->dev);
>>> +}
>>> +
>>> +/**
>>> + * cdns3_probe - probe for cdns3 core device
>>> + * @pdev: Pointer to cdns3 core platform device
>>> + *
>>> + * Returns 0 on success otherwise negative errno
>>> + */
>>> +static int cdns3_probe(struct platform_device *pdev)
>>> +{
>>> + struct device *dev = &pdev->dev;
>>> + struct resource *res;
>>> + struct cdns3 *cdns;
>>> + void __iomem *regs;
>>> + int ret;
>>> +
>>> + cdns = devm_kzalloc(dev, sizeof(*cdns), GFP_KERNEL);
>>> + if (!cdns)
>>> + return -ENOMEM;
>>> +
>>> + cdns->dev = dev;
>>> +
>>> + platform_set_drvdata(pdev, cdns);
>>> +
>>> + res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
>>> + if (!res) {
>>> + dev_err(dev, "missing IRQ\n");
>>> + return -ENODEV;
>>> + }
>>> + cdns->irq = res->start;
>>> +
>>> + /*
>>> + * Request memory region
>>> + * region-0: xHCI
>>> + * region-1: Peripheral
>>> + * region-2: OTG registers
>>> + */
>>
>> The memory region order is different from the dt-binding.
>> There it is OTG, host(xhci), device (peripheral).
>>
>>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> + regs = devm_ioremap_resource(dev, res);
>>> +
>>> + if (IS_ERR(regs))
>>> + return PTR_ERR(regs);
>>> + cdns->xhci_regs = regs;
>>> + cdns->xhci_res = res;
>>> +
>>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
>>> + regs = devm_ioremap_resource(dev, res);
>>> + if (IS_ERR(regs))
>>> + return PTR_ERR(regs);
>>> + cdns->dev_regs = regs;
>>> +
>>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 2);
>>> + regs = devm_ioremap_resource(dev, res);
>>> + if (IS_ERR(regs))
>>> + return PTR_ERR(regs);
>>> + cdns->otg_regs = regs;
>>> +
>>> + mutex_init(&cdns->mutex);
>>> +
>>> + cdns->phy = devm_phy_get(dev, "cdns3,usbphy");
>>
>> "cdns3,usbphy" is not documented in dt-binding.
>>
>>> + if (IS_ERR(cdns->phy)) {
>>> + dev_info(dev, "no generic phy found\n");
>>> + cdns->phy = NULL;
>>> + /*
>>> + * fall through here!
>>> + * if no generic phy found, phy init
>>> + * should be done under boot!
>>> + */
>>
>> No you shouldn't fall through always if it is an error condition.
>> Something like this should work better.
>>
>> if (IS_ERR(cnds->phy)) {
>> ret = PTR_ERR(cdns->phy);
>> if (ret == -ENOSYS || ret == -ENODEV) {
>> cdns->phy = NULL;
>> } else if (ret == -EPROBE_DEFER) {
>> return ret;
>> } else {
>> dev_err(dev, "no phy found\n");
>> goto err0;
>> }
>> }
>>
>> So if PHY was provided in DT, and PHY support/drivers is present
>> and error condition means something is wrong and we have to error out.
>>
>>> + } else {
>>> + phy_init(cdns->phy);
>>> + }
>>
>> You can do phy_init() outside the else.
>>
>>> +
>>> + ret = cdns3_core_init_role(cdns);
>>> + if (ret)
>>> + goto err1;
>>> +
>>> + INIT_WORK(&cdns->role_switch_wq, cdns3_role_switch);
>>> + if (ret)
>>> + goto err2;
>>> +
>>> + if (ret)
>>> + goto err2;
>>> +
>>> + cdns->role = cdns3_get_role(cdns);
>>
>> I think this should move to cdns3_core_init_role().
>>
>
> I agree.
>
>>> +
>>> + ret = devm_request_irq(dev, cdns->irq, cdns3_irq, IRQF_SHARED,
>>> + dev_name(dev), cdns);
>>> +
>>> + if (ret)
>>> + goto err2;
>>
>> How about moving request_irq to before cdsn3_core_init_role()?
>>
>> Then you can move cdns3_role_start() as well to core_init_role().
>>
>
> Usually, we request irq after hardware initialization has finished, if not,
> there may unexpected interrupt.

Doesn't kernel warn if interrupt happens and there is no handler?
To avoid that I was suggesting to request_irq first.

cheers,
-roger

--
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

\
 
 \ /
  Last update: 2018-12-04 11:46    [W:0.171 / U:10.780 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site