[RFC 16/19] dwc3: exynos: add software role switching code

[Robert Baldyga]

Exynos platform doesn't have hardware OTG support in DWC3 block, so we
need to supply custom mechanism of notification about cable change. For
this purpose we use extcon framework - it would allow to use this code
with each Exynos board equipped with cable detecting hardware which has
its extcon driver.

Signed-off-by: Robert Baldyga <r.baldyga@xxxxxxxxxxx>
---
 .../devicetree/bindings/usb/exynos-usb.txt         |   4 +
 drivers/usb/dwc3/dwc3-exynos.c                     | 162 +++++++++++++++++++++
 drivers/usb/dwc3/otg.c                             |  25 ++++
 drivers/usb/dwc3/otg.h                             |   9 ++
 4 files changed, 200 insertions(+)

diff --git a/Documentation/devicetree/bindings/usb/exynos-usb.txt b/Documentation/devicetree/bindings/usb/exynos-usb.txt
index 9b4dbe3..34b049f 100644
--- a/Documentation/devicetree/bindings/usb/exynos-usb.txt
+++ b/Documentation/devicetree/bindings/usb/exynos-usb.txt
@@ -93,6 +93,10 @@ Required properties:
  - clocks: Clock IDs array as required by the controller.
  - clock-names: names of clocks correseponding to IDs in the clock property
 
+Optional properties:
+ - extcon: Phandle to extcon device which notifies about USB cable changes.
+	   It's used in OTG mode.
+
 Sub-nodes:
 The dwc3 core should be added as subnode to Exynos dwc3 glue.
 - dwc3 :
diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
index 7bd0a95..30a0560 100644
--- a/drivers/usb/dwc3/dwc3-exynos.c
+++ b/drivers/usb/dwc3/dwc3-exynos.c
@@ -27,6 +27,10 @@
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/regulator/consumer.h>
+#include <linux/extcon.h>
+#include <linux/workqueue.h>
+
+#include "otg.h"
 
 struct dwc3_exynos {
 	struct platform_device	*usb2_phy;
@@ -39,8 +43,107 @@ struct dwc3_exynos {
 
 	struct regulator	*vdd33;
 	struct regulator	*vdd10;
+
+	struct otg_fsm          *fsm;
+
+	struct extcon_dev       *extcon;
+	struct extcon_specific_cable_nb extcon_usb_dev;
+	struct extcon_specific_cable_nb extcon_usb_host_dev;
+	struct notifier_block   usb_nb;
+	struct notifier_block   usb_host_nb;
+	struct work_struct	work;
 };
 
+static int dwc3_exynos_usb_notifier(struct notifier_block *nb,
+		unsigned long event, void *ptr);
+
+static int dwc3_exynos_usb_host_notifier(struct notifier_block *nb,
+		unsigned long event, void *ptr);
+
+int dwc3_exynos_rsw_start(struct device *dev)
+{
+	struct dwc3_exynos *exynos = dev_get_drvdata(dev);
+	int ret;
+
+	dev_dbg(dev, "%s\n", __func__);
+
+	if (!exynos->extcon)
+		return -ENODEV;
+
+	exynos->usb_nb.notifier_call = dwc3_exynos_usb_notifier;
+	exynos->usb_host_nb.notifier_call = dwc3_exynos_usb_host_notifier;
+
+	ret = extcon_register_interest(&exynos->extcon_usb_dev,
+			exynos->extcon->name, "USB", &exynos->usb_nb);
+	if (ret < 0) {
+		dev_dbg(dev, "failed to register notifier for USB");
+		return -ENODEV;
+	}
+
+	ret = extcon_register_interest(&exynos->extcon_usb_host_dev,
+			exynos->extcon->name, "USB-HOST", &exynos->usb_host_nb);
+	if (ret < 0) {
+		dev_dbg(dev, "failed to register notifier for USB HOST");
+		extcon_unregister_interest(&exynos->extcon_usb_dev);
+		return -ENODEV;
+	}
+
+	if (extcon_get_cable_state(exynos->extcon, "USB")) {
+		exynos->fsm->b_sess_vld = 1;
+		exynos->fsm->id = 1;
+	} else if (extcon_get_cable_state(exynos->extcon, "USB-HOST")) {
+		exynos->fsm->b_sess_vld = 0;
+		exynos->fsm->id = 0;
+	} else {
+		exynos->fsm->b_sess_vld = 0;
+		exynos->fsm->id = 1;
+	}
+
+	dwc3_otg_run_sm(exynos->fsm);
+
+	return 0;
+}
+
+void dwc3_exynos_rsw_stop(struct device *dev)
+{
+	struct dwc3_exynos *exynos = dev_get_drvdata(dev);
+
+	dev_dbg(dev, "%s\n", __func__);
+
+	if (exynos->extcon_usb_dev.edev)
+		extcon_unregister_interest(&exynos->extcon_usb_dev);
+	if (exynos->extcon_usb_host_dev.edev)
+		extcon_unregister_interest(&exynos->extcon_usb_host_dev);
+}
+
+int dwc3_exynos_rsw_setup(struct device *dev, struct otg_fsm *fsm)
+{
+	struct dwc3_exynos *exynos = dev_get_drvdata(dev);
+
+	dev_dbg(dev, "%s\n", __func__);
+
+	exynos->fsm = fsm;
+
+	return 0;
+}
+
+void dwc3_exynos_rsw_exit(struct device *dev)
+{
+	struct dwc3_exynos	*exynos = dev_get_drvdata(dev);
+
+	dev_dbg(dev, "%s\n", __func__);
+
+	exynos->fsm = NULL;
+}
+
+bool dwc3_exynos_rsw_available(struct device *dev)
+{
+	if (of_property_read_bool(dev->of_node, "extcon"))
+		return true;
+
+	return false;
+}
+
 static int dwc3_exynos_register_phys(struct dwc3_exynos *exynos)
 {
 	struct usb_phy_generic_platform_data pdata;
@@ -105,18 +208,77 @@ static int dwc3_exynos_remove_child(struct device *dev, void *unused)
 	return 0;
 }
 
+static void dwc3_exynos_worker(struct work_struct *work)
+{
+	struct dwc3_exynos *exynos =
+		container_of(work, struct dwc3_exynos, work);
+
+	dwc3_otg_run_sm(exynos->fsm);
+}
+
+static int dwc3_exynos_usb_notifier(struct notifier_block *nb,
+		unsigned long event, void *ptr)
+{
+	struct dwc3_exynos *exynos =
+		container_of(nb, struct dwc3_exynos, usb_nb);
+
+	if (event) {
+		exynos->fsm->b_sess_vld = 1;
+		exynos->fsm->id = 1;
+	} else {
+		exynos->fsm->b_sess_vld = 0;
+		exynos->fsm->id = 1;
+	}
+
+	schedule_work(&exynos->work);
+
+	return 0;
+}
+
+static int dwc3_exynos_usb_host_notifier(struct notifier_block *nb,
+		unsigned long event, void *ptr)
+{
+	struct dwc3_exynos *exynos =
+		container_of(nb, struct dwc3_exynos, usb_host_nb);
+
+	if (event) {
+		exynos->fsm->b_sess_vld = 0;
+		exynos->fsm->id = 0;
+	} else {
+		exynos->fsm->b_sess_vld = 0;
+		exynos->fsm->id = 1;
+	}
+
+	schedule_work(&exynos->work);
+
+	return 0;
+}
+
 static int dwc3_exynos_probe(struct platform_device *pdev)
 {
 	struct dwc3_exynos	*exynos;
 	struct device		*dev = &pdev->dev;
 	struct device_node	*node = dev->of_node;
+	struct extcon_dev       *extcon = NULL;
 
 	int			ret;
 
+	if (of_property_read_bool(node, "extcon")) {
+		extcon = extcon_get_edev_by_phandle(dev, 0);
+		if (IS_ERR(extcon)) {
+			dev_vdbg(dev, "couldn't get extcon device\n");
+			return -EPROBE_DEFER;
+		}
+	}
+
 	exynos = devm_kzalloc(dev, sizeof(*exynos), GFP_KERNEL);
 	if (!exynos)
 		return -ENOMEM;
 
+	exynos->extcon = extcon;
+
+	INIT_WORK(&exynos->work, dwc3_exynos_worker);
+
 	/*
 	 * Right now device-tree probed devices don't get dma_mask set.
 	 * Since shared usb code relies on it, set it here for now.
diff --git a/drivers/usb/dwc3/otg.c b/drivers/usb/dwc3/otg.c
index 99dfd2c..507bade 100644
--- a/drivers/usb/dwc3/otg.c
+++ b/drivers/usb/dwc3/otg.c
@@ -29,10 +29,35 @@
 #include "otg.h"
 #include "io.h"
 
+#if IS_ENABLED(CONFIG_USB_DWC3_EXYNOS)
+static struct dwc3_ext_otg_ops *dwc3_otg_rsw_probe(struct dwc3 *dwc)
+{
+	struct dwc3_ext_otg_ops *ops;
+	bool                    ext_otg;
+
+	ext_otg = dwc3_exynos_rsw_available(dwc->dev->parent);
+	if (!ext_otg)
+		return NULL;
+
+	/* Allocate and init otg instance */
+	ops = devm_kzalloc(dwc->dev, sizeof(struct dwc3_ext_otg_ops),
+			GFP_KERNEL);
+	if (!ops)
+		return NULL;
+
+	ops->setup = dwc3_exynos_rsw_setup;
+	ops->exit = dwc3_exynos_rsw_exit;
+	ops->start = dwc3_exynos_rsw_start;
+	ops->stop = dwc3_exynos_rsw_stop;
+
+	return ops;
+}
+#else
 static struct dwc3_ext_otg_ops *dwc3_otg_rsw_probe(struct dwc3 *dwc)
 {
 	return NULL;
 }
+#endif
 
 static void dwc3_otg_set_host_mode(struct dwc3_otg *dotg)
 {
diff --git a/drivers/usb/dwc3/otg.h b/drivers/usb/dwc3/otg.h
index 4be7165..efed700 100644
--- a/drivers/usb/dwc3/otg.h
+++ b/drivers/usb/dwc3/otg.h
@@ -101,4 +101,13 @@ void dwc3_otg_exit(struct dwc3 *dwc);
 
 void dwc3_otg_run_sm(struct otg_fsm *fsm);
 
+/* prototypes */
+#if IS_ENABLED(CONFIG_USB_DWC3_EXYNOS)
+bool dwc3_exynos_rsw_available(struct device *dev);
+int dwc3_exynos_rsw_setup(struct device *dev, struct otg_fsm *fsm);
+void dwc3_exynos_rsw_exit(struct device *dev);
+int dwc3_exynos_rsw_start(struct device *dev);
+void dwc3_exynos_rsw_stop(struct device *dev);
+#endif
+
 #endif /* __LINUX_USB_DWC3_OTG_H */
-- 
1.9.1

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