Re: [PATCH 7/8] usb: misc: eud: Handle usb role switch notifications

Elson Serrao
2024-08-01T00:51:29Z

On 7/31/2024 6:06 AM, Dmitry Baryshkov wrote:
> On Tue, Jul 30, 2024 at 03:24:38PM GMT, Elson Roy Serrao wrote:
>> Since EUD is physically present between the USB connector and
>> the USB controller, it should relay the usb role notifications
>> from the connector. Hence register a role switch handler to
>> process and relay these roles to the USB controller. This results
>> in a common framework to send both connector related events
>> and eud attach/detach events to the USB controller.
>>
>> Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
>> ---
>> drivers/usb/misc/qcom_eud.c | 91 ++++++++++++++++++++++++++++---------
>> 1 file changed, 69 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
>> index 3de7d465912c..9a49c934e8cf 100644
>> --- a/drivers/usb/misc/qcom_eud.c
>> +++ b/drivers/usb/misc/qcom_eud.c
>> @@ -10,6 +10,7 @@
>> #include <linux/iopoll.h>
>> #include <linux/kernel.h>
>> #include <linux/module.h>
>> +#include <linux/mutex.h>
>> #include <linux/of.h>
>> #include <linux/phy/phy.h>
>> #include <linux/platform_device.h>
>> @@ -35,12 +36,16 @@ struct eud_chip {
>> struct device *dev;
>> struct usb_role_switch *role_sw;
>> struct phy *usb2_phy;
>> +
>> + /* mode lock */
>> + struct mutex mutex;
>> void __iomem *base;
>> void __iomem *mode_mgr;
>> unsigned int int_status;
>> int irq;
>> bool enabled;
>> bool usb_attached;
>> + enum usb_role current_role;
>> };
>>
>> static int eud_phy_enable(struct eud_chip *chip)
>> @@ -64,6 +69,38 @@ static void eud_phy_disable(struct eud_chip *chip)
>> phy_exit(chip->usb2_phy);
>> }
>>
>> +static int eud_usb_role_set(struct eud_chip *chip, enum usb_role role)
>> +{
>> + struct usb_role_switch *sw;
>> + int ret = 0;
>> +
>> + mutex_lock(&chip->mutex);
>> +
>> + /* Avoid duplicate role handling */
>> + if (role == chip->current_role)
>> + goto err;
>> +
>> + sw = usb_role_switch_get(chip->dev);
>
> Why isn't chip->role_sw good enough? Why do you need to get it each
> time?
>

Hi Dmitry

chip->role_sw is the eud role switch handler to receive role switch notifications from the
USB connector. The 'sw' I am getting above is the role switch handler of the USB controller.
As per this design, EUD receives role switch notification from the connector
(via chip->role_sw) and then relays it to the 'sw' switch handler of the USB controller.

Thanks
Elson

>> + if (IS_ERR_OR_NULL(sw)) {
>> + dev_err(chip->dev, "failed to get usb switch\n");
>> + ret = -EINVAL;
>> + goto err;
>> + }
>> +
>> + ret = usb_role_switch_set_role(sw, role);
>> + usb_role_switch_put(sw);
>> +
>> + if (ret) {
>> + dev_err(chip->dev, "failed to set role\n");
>> + goto err;
>> + }
>> + chip->current_role = role;
>> +err:
>> + mutex_unlock(&chip->mutex);
>> +
>> + return ret;
>> +}
>> +
>> static int enable_eud(struct eud_chip *priv)
>> {
>> int ret;
>> @@ -77,7 +114,7 @@ static int enable_eud(struct eud_chip *priv)
>> priv->base + EUD_REG_INT1_EN_MASK);
>> writel(1, priv->mode_mgr + EUD_REG_EUD_EN2);
>>
>> - return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
>> + return ret;
>> }
>>
>> static void disable_eud(struct eud_chip *priv)
>> @@ -106,15 +143,20 @@ static ssize_t enable_store(struct device *dev,
>> if (kstrtobool(buf, &enable))
>> return -EINVAL;
>>
>> + /* EUD enable is applicable only in DEVICE mode */
>> + if (enable && chip->current_role != USB_ROLE_DEVICE)
>> + return -EINVAL;
>> +
>> if (enable) {
>> ret = enable_eud(chip);
>> - if (!ret)
>> - chip->enabled = enable;
>> - else
>> - disable_eud(chip);
>> + if (ret) {
>> + dev_err(chip->dev, "failed to enable eud\n");
>> + return count;
>> + }
>> } else {
>> disable_eud(chip);
>> }
>> + chip->enabled = enable;
>>
>> return count;
>> }
>> @@ -185,11 +227,9 @@ static irqreturn_t handle_eud_irq_thread(int irq, void *data)
>> int ret;
>>
>> if (chip->usb_attached)
>> - ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_DEVICE);
>> + ret = eud_usb_role_set(chip, USB_ROLE_DEVICE);
>> else
>> - ret = usb_role_switch_set_role(chip->role_sw, USB_ROLE_HOST);
>> - if (ret)
>> - dev_err(chip->dev, "failed to set role switch\n");
>> + ret = eud_usb_role_set(chip, USB_ROLE_HOST);
>>
>> /* set and clear vbus_int_clr[0] to clear interrupt */
>> writel(BIT(0), chip->base + EUD_REG_VBUS_INT_CLR);
>> @@ -198,16 +238,18 @@ static irqreturn_t handle_eud_irq_thread(int irq, void *data)
>> return IRQ_HANDLED;
>> }
>>
>> -static void eud_role_switch_release(void *data)
>> +static int eud_usb_role_switch_set(struct usb_role_switch *sw,
>> + enum usb_role role)
>> {
>> - struct eud_chip *chip = data;
>> + struct eud_chip *chip = usb_role_switch_get_drvdata(sw);
>>
>> - usb_role_switch_put(chip->role_sw);
>> + return eud_usb_role_set(chip, role);
>> }
>>
>> static int eud_probe(struct platform_device *pdev)
>> {
>> struct eud_chip *chip;
>> + struct usb_role_switch_desc eud_role_switch = {NULL};
>> int ret;
>>
>> chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
>> @@ -221,16 +263,6 @@ static int eud_probe(struct platform_device *pdev)
>> return dev_err_probe(chip->dev, PTR_ERR(chip->usb2_phy),
>> "no usb2 phy configured\n");
>>
>> - chip->role_sw = usb_role_switch_get(&pdev->dev);
>> - if (IS_ERR(chip->role_sw))
>> - return dev_err_probe(chip->dev, PTR_ERR(chip->role_sw),
>> - "failed to get role switch\n");
>> -
>> - ret = devm_add_action_or_reset(chip->dev, eud_role_switch_release, chip);
>> - if (ret)
>> - return dev_err_probe(chip->dev, ret,
>> - "failed to add role switch release action\n");
>> -
>> chip->base = devm_platform_ioremap_resource(pdev, 0);
>> if (IS_ERR(chip->base))
>> return PTR_ERR(chip->base);
>> @@ -248,6 +280,18 @@ static int eud_probe(struct platform_device *pdev)
>> if (ret)
>> return dev_err_probe(chip->dev, ret, "failed to allocate irq\n");
>>
>> + eud_role_switch.fwnode = dev_fwnode(chip->dev);
>> + eud_role_switch.set = eud_usb_role_switch_set;
>> + eud_role_switch.get = NULL;
>> + eud_role_switch.driver_data = chip;
>> + chip->role_sw = usb_role_switch_register(chip->dev, &eud_role_switch);
>> +
>> + if (IS_ERR(chip->role_sw))
>> + return dev_err_probe(chip->dev, PTR_ERR(chip->role_sw),
>> + "failed to register role switch\n");
>> +
>> + mutex_init(&chip->mutex);
>
> please move mutex_init earlier.
>

Ack
>> +
>> enable_irq_wake(chip->irq);
>>
>> platform_set_drvdata(pdev, chip);
>> @@ -262,6 +306,9 @@ static void eud_remove(struct platform_device *pdev)
>> if (chip->enabled)
>> disable_eud(chip);
>>
>> + if (chip->role_sw)
>> + usb_role_switch_unregister(chip->role_sw);
>> +
>> device_init_wakeup(&pdev->dev, false);
>> disable_irq_wake(chip->irq);
>> }
>> --
>> 2.17.1
>>
>