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SubjectRe: [RFC PATCH 1/1] usb: dwc3: of-simple: Add extcon support
On Fri, May 22, 2020 at 09:12:02PM -0700, Prashant Malani wrote:
> Add optional extcon notifier support to enable the hotplug / unplug of
> the underlying PHY layer devices.
>
> If supported, the Device Tree (DT) node for the device should include an
> "extcon" property which is a phandle to an extcon DT node.
>
> This patch is an effort to incorporate the equivalent support from the
> Rockchip dwc3 driver implementation from Chrome OS [1] to the mainline.
>
> [1] : https://chromium.googlesource.com/chromiumos/third_party/kernel/
> +/refs/heads/chromeos-4.4/drivers/usb/dwc3/dwc3-rockchip.c
>
> Cc: Benson Leung <bleung@chromium.org>
> Cc: Guenter Roeck <groeck@chromium.org>
> Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> Signed-off-by: Prashant Malani <pmalani@chromium.org>

Couple of nitpicks, otherwise

Reviewed-by: Guenter Roeck <groeck@chromium.org>

> ---
> drivers/usb/dwc3/dwc3-of-simple.c | 149 +++++++++++++++++++++++++++++-
> 1 file changed, 146 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/dwc3/dwc3-of-simple.c b/drivers/usb/dwc3/dwc3-of-simple.c
> index e64754be47b4..28bde27cd1f9 100644
> --- a/drivers/usb/dwc3/dwc3-of-simple.c
> +++ b/drivers/usb/dwc3/dwc3-of-simple.c
> @@ -11,6 +11,7 @@
> * by Subbaraya Sundeep Bhatta <subbaraya.sundeep.bhatta@xilinx.com>
> */
>
> +#include <linux/extcon.h>
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/slab.h>
> @@ -29,8 +30,117 @@ struct dwc3_of_simple {
> struct reset_control *resets;
> bool pulse_resets;
> bool need_reset;
> + struct extcon_dev *edev;
> + struct notifier_block nb;
> + struct work_struct work;
> + /* Denotes whether child devices have been populated. */
> + bool populated;
> + bool suspended;
> + spinlock_t suspend_lock;
> };
>
> +static int dwc3_of_simple_populate(struct dwc3_of_simple *simple)
> +{
> + struct device *dev = simple->dev;
> + struct device_node *np = dev->of_node;
> + int ret;
> +
> + ret = of_platform_populate(np, NULL, NULL, dev);
> + if (ret) {
> + dev_err(dev, "Failed to populate dwc3 devices.\n");
> + return ret;
> + }
> + simple->populated = true;
> + return 0;
> +}
> +
> +static void dwc3_of_simple_depopulate(struct dwc3_of_simple *simple)
> +{
> + if (simple->populated) {
> + of_platform_depopulate(simple->dev);
> + simple->populated = false;
> + }
> +}
> +
> +static void dwc3_of_simple_work(struct work_struct *work)
> +{
> + struct dwc3_of_simple *simple = container_of(work,
> + struct dwc3_of_simple, work);
> + struct extcon_dev *edev = simple->edev;
> +
> + if (extcon_get_state(edev, EXTCON_USB_HOST) > 0) {
> + if (simple->populated)
> + return;
> +
> + dwc3_of_simple_populate(simple);
> + } else {
> + if (!simple->populated)
> + return;
> +
> + dwc3_of_simple_depopulate(simple);
> + }
> +}
> +
> +static int dwc3_of_simple_notifier(struct notifier_block *nb,
> + unsigned long event, void *ptr)

Multi-line alignment is off.

> +{
> + struct dwc3_of_simple *simple = container_of(nb, struct dwc3_of_simple,
> + nb);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&simple->suspend_lock, flags);
> + if (!simple->suspended)
> + schedule_work(&simple->work);
> + spin_unlock_irqrestore(&simple->suspend_lock, flags);
> +
> + return NOTIFY_OK;
> +}
> +
> +static int dwc3_of_simple_extcon_register(struct dwc3_of_simple *simple)
> +{
> + struct device *dev = simple->dev;
> + struct extcon_dev *edev;
> + int ret;
> +
> + edev = extcon_get_edev_by_phandle(dev, 0);
> + if (IS_ERR(edev)) {
> + /* The extcon property is optional. */
> + if (PTR_ERR(edev) == -ENODEV)
> + return 0;
> + if (PTR_ERR(edev) != -EPROBE_DEFER)
> + dev_err(dev, "Couldn't get extcon device.\n");
> + return PTR_ERR(edev);
> + }
> +
> + INIT_WORK(&simple->work, dwc3_of_simple_work);
> +
> + simple->nb.notifier_call = dwc3_of_simple_notifier;
> + ret = devm_extcon_register_notifier(dev, edev, EXTCON_USB_HOST,
> + &simple->nb);

Same here.

> + if (ret < 0) {
> + dev_err(dev, "Failed to register notifier.\n");
> + return ret;
> + }
> +
> + simple->edev = edev;
> +
> + return 0;
> +}
> +
> +static void dwc3_of_simple_extcon_unregister(struct dwc3_of_simple *simple)
> +{
> + if (!simple->edev)
> + return;
> +
> + /*
> + * We explicitly unregister the notifier to prevent races with
> + * the of_depopulate() call in remove().
> + */
> + devm_extcon_unregister_notifier(simple->dev, simple->edev,
> + EXTCON_USB_HOST, &simple->nb);
> + cancel_work_sync(&simple->work);
> +}
> +
> static int dwc3_of_simple_probe(struct platform_device *pdev)
> {
> struct dwc3_of_simple *simple;
> @@ -47,6 +157,8 @@ static int dwc3_of_simple_probe(struct platform_device *pdev)
> platform_set_drvdata(pdev, simple);
> simple->dev = dev;
>
> + spin_lock_init(&simple->suspend_lock);
> +
> /*
> * Some controllers need to toggle the usb3-otg reset before trying to
> * initialize the PHY, otherwise the PHY times out.
> @@ -87,9 +199,24 @@ static int dwc3_of_simple_probe(struct platform_device *pdev)
> if (ret)
> goto err_resetc_assert;
>
> - ret = of_platform_populate(np, NULL, NULL, dev);
> - if (ret)
> + ret = dwc3_of_simple_extcon_register(simple);
> + if (ret < 0) {
> + dev_warn(dev, "No extcon device found, err: %d\n", ret);
> goto err_clk_put;
> + }
> +
> + if (!simple->edev) {
> + ret = dwc3_of_simple_populate(simple);
> + if (ret)
> + goto err_clk_put;
> + } else {
> + /*
> + * Populate through worker to avoid race conditions against
> + * action scheduled through notifier.
> + */
> + if (extcon_get_state(simple->edev, EXTCON_USB_HOST) > 0)
> + schedule_work(&simple->work);
> + }
>
> pm_runtime_set_active(dev);
> pm_runtime_enable(dev);
> @@ -112,7 +239,8 @@ static int dwc3_of_simple_probe(struct platform_device *pdev)
>
> static void __dwc3_of_simple_teardown(struct dwc3_of_simple *simple)
> {
> - of_platform_depopulate(simple->dev);
> + dwc3_of_simple_extcon_unregister(simple);
> + dwc3_of_simple_depopulate(simple);
>
> clk_bulk_disable_unprepare(simple->num_clocks, simple->clks);
> clk_bulk_put_all(simple->num_clocks, simple->clks);
> @@ -163,6 +291,13 @@ static int __maybe_unused dwc3_of_simple_runtime_resume(struct device *dev)
> static int __maybe_unused dwc3_of_simple_suspend(struct device *dev)
> {
> struct dwc3_of_simple *simple = dev_get_drvdata(dev);
> + unsigned long flags;
> +
> + spin_lock_irqsave(&simple->suspend_lock, flags);
> + simple->suspended = true;
> + spin_unlock_irqrestore(&simple->suspend_lock, flags);
> +
> + cancel_work_sync(&simple->work);
>
> if (simple->need_reset)
> reset_control_assert(simple->resets);
> @@ -173,10 +308,18 @@ static int __maybe_unused dwc3_of_simple_suspend(struct device *dev)
> static int __maybe_unused dwc3_of_simple_resume(struct device *dev)
> {
> struct dwc3_of_simple *simple = dev_get_drvdata(dev);
> + unsigned long flags;
>
> if (simple->need_reset)
> reset_control_deassert(simple->resets);
>
> + spin_lock_irqsave(&simple->suspend_lock, flags);
> + simple->suspended = false;
> + spin_unlock_irqrestore(&simple->suspend_lock, flags);
> +
> + if (simple->edev)
> + schedule_work(&simple->work);
> +
> return 0;
> }
>

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