usb: mtu3: dual-role mode support

support dual-role mode; there are two ways to switch between
host and device modes, one is by idpin, another is by debugfs
which depends on user input.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 379 insertions, 0 deletions

diff --git a/drivers/usb/mtu3/mtu3_dr.c b/drivers/usb/mtu3/mtu3_dr.c
new file mode 100644
index 000000000000..1a8987e7c5b0
--- /dev/null
+++ b/drivers/usb/mtu3/mtu3_dr.c
@@ -0,0 +1,379 @@
+/*
+ * mtu3_dr.c - dual role switch and host glue layer
+ *
+ * Copyright (C) 2016 MediaTek Inc.
+ *
+ * Author: Chunfeng Yun <chunfeng.yun@mediatek.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/debugfs.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/of_device.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+
+#include "mtu3.h"
+#include "mtu3_dr.h"
+
+#define USB2_PORT 2
+#define USB3_PORT 3
+
+enum mtu3_vbus_id_state {
+	MTU3_ID_FLOAT = 1,
+	MTU3_ID_GROUND,
+	MTU3_VBUS_OFF,
+	MTU3_VBUS_VALID,
+};
+
+static void toggle_opstate(struct ssusb_mtk *ssusb)
+{
+	if (!ssusb->otg_switch.is_u3_drd) {
+		mtu3_setbits(ssusb->mac_base, U3D_DEVICE_CONTROL, DC_SESSION);
+		mtu3_setbits(ssusb->mac_base, U3D_POWER_MANAGEMENT, SOFT_CONN);
+	}
+}
+
+/* only port0 supports dual-role mode */
+static int ssusb_port0_switch(struct ssusb_mtk *ssusb,
+	int version, bool tohost)
+{
+	void __iomem *ibase = ssusb->ippc_base;
+	u32 value;
+
+	dev_dbg(ssusb->dev, "%s (switch u%d port0 to %s)\n", __func__,
+		version, tohost ? "host" : "device");
+
+	if (version == USB2_PORT) {
+		/* 1. power off and disable u2 port0 */
+		value = mtu3_readl(ibase, SSUSB_U2_CTRL(0));
+		value |= SSUSB_U2_PORT_PDN | SSUSB_U2_PORT_DIS;
+		mtu3_writel(ibase, SSUSB_U2_CTRL(0), value);
+
+		/* 2. power on, enable u2 port0 and select its mode */
+		value = mtu3_readl(ibase, SSUSB_U2_CTRL(0));
+		value &= ~(SSUSB_U2_PORT_PDN | SSUSB_U2_PORT_DIS);
+		value = tohost ? (value | SSUSB_U2_PORT_HOST_SEL) :
+			(value & (~SSUSB_U2_PORT_HOST_SEL));
+		mtu3_writel(ibase, SSUSB_U2_CTRL(0), value);
+	} else {
+		/* 1. power off and disable u3 port0 */
+		value = mtu3_readl(ibase, SSUSB_U3_CTRL(0));
+		value |= SSUSB_U3_PORT_PDN | SSUSB_U3_PORT_DIS;
+		mtu3_writel(ibase, SSUSB_U3_CTRL(0), value);
+
+		/* 2. power on, enable u3 port0 and select its mode */
+		value = mtu3_readl(ibase, SSUSB_U3_CTRL(0));
+		value &= ~(SSUSB_U3_PORT_PDN | SSUSB_U3_PORT_DIS);
+		value = tohost ? (value | SSUSB_U3_PORT_HOST_SEL) :
+			(value & (~SSUSB_U3_PORT_HOST_SEL));
+		mtu3_writel(ibase, SSUSB_U3_CTRL(0), value);
+	}
+
+	return 0;
+}
+
+static void switch_port_to_host(struct ssusb_mtk *ssusb)
+{
+	u32 check_clk = 0;
+
+	dev_dbg(ssusb->dev, "%s\n", __func__);
+
+	ssusb_port0_switch(ssusb, USB2_PORT, true);
+
+	if (ssusb->otg_switch.is_u3_drd) {
+		ssusb_port0_switch(ssusb, USB3_PORT, true);
+		check_clk = SSUSB_U3_MAC_RST_B_STS;
+	}
+
+	ssusb_check_clocks(ssusb, check_clk);
+
+	/* after all clocks are stable */
+	toggle_opstate(ssusb);
+}
+
+static void switch_port_to_device(struct ssusb_mtk *ssusb)
+{
+	u32 check_clk = 0;
+
+	dev_dbg(ssusb->dev, "%s\n", __func__);
+
+	ssusb_port0_switch(ssusb, USB2_PORT, false);
+
+	if (ssusb->otg_switch.is_u3_drd) {
+		ssusb_port0_switch(ssusb, USB3_PORT, false);
+		check_clk = SSUSB_U3_MAC_RST_B_STS;
+	}
+
+	ssusb_check_clocks(ssusb, check_clk);
+}
+
+int ssusb_set_vbus(struct otg_switch_mtk *otg_sx, int is_on)
+{
+	struct ssusb_mtk *ssusb =
+		container_of(otg_sx, struct ssusb_mtk, otg_switch);
+	struct regulator *vbus = otg_sx->vbus;
+	int ret;
+
+	/* vbus is optional */
+	if (!vbus)
+		return 0;
+
+	dev_dbg(ssusb->dev, "%s: turn %s\n", __func__, is_on ? "on" : "off");
+
+	if (is_on) {
+		ret = regulator_enable(vbus);
+		if (ret) {
+			dev_err(ssusb->dev, "vbus regulator enable failed\n");
+			return ret;
+		}
+	} else {
+		regulator_disable(vbus);
+	}
+
+	return 0;
+}
+
+/*
+ * switch to host: -> MTU3_VBUS_OFF --> MTU3_ID_GROUND
+ * switch to device: -> MTU3_ID_FLOAT --> MTU3_VBUS_VALID
+ */
+static void ssusb_set_mailbox(struct otg_switch_mtk *otg_sx,
+	enum mtu3_vbus_id_state status)
+{
+	struct ssusb_mtk *ssusb =
+		container_of(otg_sx, struct ssusb_mtk, otg_switch);
+	struct mtu3 *mtu = ssusb->u3d;
+
+	dev_dbg(ssusb->dev, "mailbox state(%d)\n", status);
+
+	switch (status) {
+	case MTU3_ID_GROUND:
+		switch_port_to_host(ssusb);
+		ssusb_set_vbus(otg_sx, 1);
+		ssusb->is_host = true;
+		break;
+	case MTU3_ID_FLOAT:
+		ssusb->is_host = false;
+		ssusb_set_vbus(otg_sx, 0);
+		switch_port_to_device(ssusb);
+		break;
+	case MTU3_VBUS_OFF:
+		mtu3_stop(mtu);
+		pm_relax(ssusb->dev);
+		break;
+	case MTU3_VBUS_VALID:
+		/* avoid suspend when works as device */
+		pm_stay_awake(ssusb->dev);
+		mtu3_start(mtu);
+		break;
+	default:
+		dev_err(ssusb->dev, "invalid state\n");
+	}
+}
+
+static int ssusb_id_notifier(struct notifier_block *nb,
+	unsigned long event, void *ptr)
+{
+	struct otg_switch_mtk *otg_sx =
+		container_of(nb, struct otg_switch_mtk, id_nb);
+
+	if (event)
+		ssusb_set_mailbox(otg_sx, MTU3_ID_GROUND);
+	else
+		ssusb_set_mailbox(otg_sx, MTU3_ID_FLOAT);
+
+	return NOTIFY_DONE;
+}
+
+static int ssusb_vbus_notifier(struct notifier_block *nb,
+	unsigned long event, void *ptr)
+{
+	struct otg_switch_mtk *otg_sx =
+		container_of(nb, struct otg_switch_mtk, vbus_nb);
+
+	if (event)
+		ssusb_set_mailbox(otg_sx, MTU3_VBUS_VALID);
+	else
+		ssusb_set_mailbox(otg_sx, MTU3_VBUS_OFF);
+
+	return NOTIFY_DONE;
+}
+
+static int ssusb_extcon_register(struct otg_switch_mtk *otg_sx)
+{
+	struct ssusb_mtk *ssusb =
+		container_of(otg_sx, struct ssusb_mtk, otg_switch);
+	struct extcon_dev *edev = otg_sx->edev;
+	int ret;
+
+	/* extcon is optional */
+	if (!edev)
+		return 0;
+
+	otg_sx->vbus_nb.notifier_call = ssusb_vbus_notifier;
+	ret = extcon_register_notifier(edev, EXTCON_USB,
+					&otg_sx->vbus_nb);
+	if (ret < 0)
+		dev_err(ssusb->dev, "failed to register notifier for USB\n");
+
+	otg_sx->id_nb.notifier_call = ssusb_id_notifier;
+	ret = extcon_register_notifier(edev, EXTCON_USB_HOST,
+					&otg_sx->id_nb);
+	if (ret < 0)
+		dev_err(ssusb->dev, "failed to register notifier for USB-HOST\n");
+
+	dev_dbg(ssusb->dev, "EXTCON_USB: %d, EXTCON_USB_HOST: %d\n",
+		extcon_get_cable_state_(edev, EXTCON_USB),
+		extcon_get_cable_state_(edev, EXTCON_USB_HOST));
+
+	/* default as host, switch to device mode if needed */
+	if (extcon_get_cable_state_(edev, EXTCON_USB_HOST) == false)
+		ssusb_set_mailbox(otg_sx, MTU3_ID_FLOAT);
+	if (extcon_get_cable_state_(edev, EXTCON_USB) == true)
+		ssusb_set_mailbox(otg_sx, MTU3_VBUS_VALID);
+
+	return 0;
+}
+
+static void extcon_register_dwork(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct otg_switch_mtk *otg_sx =
+	    container_of(dwork, struct otg_switch_mtk, extcon_reg_dwork);
+
+	ssusb_extcon_register(otg_sx);
+}
+
+/*
+ * We provide an interface via debugfs to switch between host and device modes
+ * depending on user input.
+ * This is useful in special cases, such as uses TYPE-A receptacle but also
+ * wants to support dual-role mode.
+ * It generates cable state changes by pulling up/down IDPIN and
+ * notifies driver to switch mode by "extcon-usb-gpio".
+ * NOTE: when use MICRO receptacle, should not enable this interface.
+ */
+static void ssusb_mode_manual_switch(struct ssusb_mtk *ssusb, int to_host)
+{
+	struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;
+
+	if (to_host)
+		pinctrl_select_state(otg_sx->id_pinctrl, otg_sx->id_ground);
+	else
+		pinctrl_select_state(otg_sx->id_pinctrl, otg_sx->id_float);
+}
+
+
+static int ssusb_mode_show(struct seq_file *sf, void *unused)
+{
+	struct ssusb_mtk *ssusb = sf->private;
+
+	seq_printf(sf, "current mode: %s(%s drd)\n(echo device/host)\n",
+		ssusb->is_host ? "host" : "device",
+		ssusb->otg_switch.manual_drd_enabled ? "manual" : "auto");
+
+	return 0;
+}
+
+static int ssusb_mode_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, ssusb_mode_show, inode->i_private);
+}
+
+static ssize_t ssusb_mode_write(struct file *file,
+	const char __user *ubuf, size_t count, loff_t *ppos)
+{
+	struct seq_file *sf = file->private_data;
+	struct ssusb_mtk *ssusb = sf->private;
+	char buf[16];
+
+	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
+		return -EFAULT;
+
+	if (!strncmp(buf, "host", 4) && !ssusb->is_host) {
+		ssusb_mode_manual_switch(ssusb, 1);
+	} else if (!strncmp(buf, "device", 6) && ssusb->is_host) {
+		ssusb_mode_manual_switch(ssusb, 0);
+	} else {
+		dev_err(ssusb->dev, "wrong or duplicated setting\n");
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+static const struct file_operations ssusb_mode_fops = {
+	.open = ssusb_mode_open,
+	.write = ssusb_mode_write,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static void ssusb_debugfs_init(struct ssusb_mtk *ssusb)
+{
+	struct dentry *root;
+	struct dentry *file;
+
+	root = debugfs_create_dir(dev_name(ssusb->dev), usb_debug_root);
+	if (IS_ERR_OR_NULL(root)) {
+		if (!root)
+			dev_err(ssusb->dev, "create debugfs root failed\n");
+		return;
+	}
+	ssusb->dbgfs_root = root;
+
+	file = debugfs_create_file("mode", S_IRUGO | S_IWUSR, root,
+			ssusb, &ssusb_mode_fops);
+	if (!file)
+		dev_dbg(ssusb->dev, "create debugfs mode failed\n");
+}
+
+static void ssusb_debugfs_exit(struct ssusb_mtk *ssusb)
+{
+	debugfs_remove_recursive(ssusb->dbgfs_root);
+}
+
+int ssusb_otg_switch_init(struct ssusb_mtk *ssusb)
+{
+	struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;
+
+	INIT_DELAYED_WORK(&otg_sx->extcon_reg_dwork, extcon_register_dwork);
+
+	if (otg_sx->manual_drd_enabled)
+		ssusb_debugfs_init(ssusb);
+
+	/* It is enough to delay 1s for waiting for host initialization */
+	schedule_delayed_work(&otg_sx->extcon_reg_dwork, HZ);
+
+	return 0;
+}
+
+void ssusb_otg_switch_exit(struct ssusb_mtk *ssusb)
+{
+	struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;
+
+	cancel_delayed_work(&otg_sx->extcon_reg_dwork);
+
+	if (otg_sx->edev) {
+		extcon_unregister_notifier(otg_sx->edev,
+			EXTCON_USB, &otg_sx->vbus_nb);
+		extcon_unregister_notifier(otg_sx->edev,
+			EXTCON_USB_HOST, &otg_sx->id_nb);
+	}
+
+	if (otg_sx->manual_drd_enabled)
+		ssusb_debugfs_exit(ssusb);
+}