[PATCH v3 5/7] usb: mux: add driver for Intel drcfg controlled port mux

[Lu Baolu]

Several Intel PCHs and SOCs have an internal mux that is used to
share one USB port between device controller and host controller.
The mux is handled through the Dual Role Configuration Register.

Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Signed-off-by: Wu Hao <hao.wu@xxxxxxxxx>
Reviewed-by: Felipe Balbi <balbi@xxxxxxxxxx>
---
 MAINTAINERS                       |   1 +
 drivers/usb/mux/Kconfig           |   7 ++
 drivers/usb/mux/Makefile          |   1 +
 drivers/usb/mux/intel-mux-drcfg.c | 161 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 170 insertions(+)
 create mode 100644 drivers/usb/mux/intel-mux-drcfg.c

diff --git a/MAINTAINERS b/MAINTAINERS
index ab876eb..399cefe 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11407,6 +11407,7 @@ S:	Supported
 F:	drivers/usb/mux/intel-mux.c
 F:	include/linux/usb/intel-mux.h
 F:	drivers/usb/mux/intel-mux-gpio.c
+F:	drivers/usb/mux/intel-mux-drcfg.c
 
 USB PRINTER DRIVER (usblp)
 M:	Pete Zaitcev <zaitcev@xxxxxxxxxx>
diff --git a/drivers/usb/mux/Kconfig b/drivers/usb/mux/Kconfig
index 060bf5c..775d5da 100644
--- a/drivers/usb/mux/Kconfig
+++ b/drivers/usb/mux/Kconfig
@@ -15,4 +15,11 @@ config INTEL_MUX_GPIO
 	  Say Y here to enable support for Intel dual role port mux
 	  controlled by GPIOs.
 
+config INTEL_MUX_DRCFG
+	tristate "Intel dual role port mux controlled by register"
+	depends on X86
+	select INTEL_USB_MUX
+	help
+	  Say Y here to enable support for Intel dual role port mux
+	  controlled by the Dual Role Configuration Register.
 endmenu
diff --git a/drivers/usb/mux/Makefile b/drivers/usb/mux/Makefile
index 66f765c..3179909 100644
--- a/drivers/usb/mux/Makefile
+++ b/drivers/usb/mux/Makefile
@@ -3,3 +3,4 @@
 #
 obj-$(CONFIG_INTEL_USB_MUX)		+= intel-mux.o
 obj-$(CONFIG_INTEL_MUX_GPIO)		+= intel-mux-gpio.o
+obj-$(CONFIG_INTEL_MUX_DRCFG)		+= intel-mux-drcfg.o
diff --git a/drivers/usb/mux/intel-mux-drcfg.c b/drivers/usb/mux/intel-mux-drcfg.c
new file mode 100644
index 0000000..11db826
--- /dev/null
+++ b/drivers/usb/mux/intel-mux-drcfg.c
@@ -0,0 +1,161 @@
+/**
+ * intel-mux-drcfg.c - Driver for Intel USB mux via register
+ *
+ * Copyright (C) 2016 Intel Corporation
+ * Author: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
+ * Author: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/usb/intel-mux.h>
+#include <linux/platform_device.h>
+
+#define INTEL_MUX_CFG0		0x00
+#define INTEL_MUX_CFG1		0x04
+#define CFG0_SW_IDPIN		BIT(20)
+#define CFG0_SW_IDPIN_EN	BIT(21)
+#define CFG0_SW_VBUS_VALID	BIT(24)
+#define CFG1_SW_MODE		BIT(29)
+#define CFG1_POLL_TIMEOUT	1000
+
+struct intel_usb_mux {
+	struct intel_mux_dev umdev;
+	void __iomem *regs;
+};
+
+static inline int intel_mux_drcfg_switch(struct intel_mux_dev *umdev, bool host)
+{
+	struct intel_usb_mux *mux;
+	unsigned long timeout;
+	u32 data;
+
+	mux = container_of(umdev, struct intel_usb_mux, umdev);
+
+	/* Check and set mux to SW controlled mode */
+	data = readl(mux->regs + INTEL_MUX_CFG0);
+	if (!(data & CFG0_SW_IDPIN_EN)) {
+		data |= CFG0_SW_IDPIN_EN;
+		writel(data, mux->regs + INTEL_MUX_CFG0);
+	}
+
+	/*
+	 * Configure CFG0 to switch the mux and VBUS_VALID bit is
+	 * required for device mode.
+	 */
+	data = readl(mux->regs + INTEL_MUX_CFG0);
+	if (host)
+		data &= ~(CFG0_SW_IDPIN | CFG0_SW_VBUS_VALID);
+	else
+		data |= (CFG0_SW_IDPIN | CFG0_SW_VBUS_VALID);
+	writel(data, mux->regs + INTEL_MUX_CFG0);
+
+	/*
+	 * Polling CFG1 for safety, most case it takes about 600ms
+	 * to finish mode switching, set TIMEOUT long enough.
+	 */
+	timeout = jiffies + msecs_to_jiffies(CFG1_POLL_TIMEOUT);
+
+	/* Polling on CFG1 register to confirm mode switch. */
+	while (!time_after(jiffies, timeout)) {
+		data = readl(mux->regs + INTEL_MUX_CFG1);
+		if (!(host ^ (data & CFG1_SW_MODE)))
+			return 0;
+		/* interval for polling is set to about 5ms */
+		usleep_range(5000, 5100);
+	}
+
+	return -ETIMEDOUT;
+}
+
+static int intel_mux_drcfg_cable_set(struct intel_mux_dev *umdev)
+{
+	dev_dbg(umdev->dev, "drcfg mux switch to HOST\n");
+
+	return intel_mux_drcfg_switch(umdev, true);
+}
+
+static int intel_mux_drcfg_cable_unset(struct intel_mux_dev *umdev)
+{
+	dev_dbg(umdev->dev, "drcfg mux switch to DEVICE\n");
+
+	return intel_mux_drcfg_switch(umdev, false);
+}
+
+static int intel_mux_drcfg_probe(struct platform_device *pdev)
+{
+	struct intel_usb_mux *mux;
+	struct intel_mux_dev *umdev;
+	struct device *dev = &pdev->dev;
+	u64 start, size;
+	int ret;
+
+	mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
+	if (!mux)
+		return -ENOMEM;
+
+	ret = device_property_read_u64(dev, "reg-start", &start);
+	ret |= device_property_read_u64(dev, "reg-size", &size);
+	if (ret)
+		return -ENODEV;
+
+	mux->regs = devm_ioremap_nocache(dev, start, size);
+	if (!mux->regs)
+		return -ENOMEM;
+
+	umdev = &mux->umdev;
+	umdev->dev = dev;
+	umdev->cable_name = "USB-HOST";
+	umdev->cable_set_cb = intel_mux_drcfg_cable_set;
+	umdev->cable_unset_cb = intel_mux_drcfg_cable_unset;
+
+	return intel_usb_mux_register(umdev);
+}
+
+static int intel_mux_drcfg_remove(struct platform_device *pdev)
+{
+	return intel_usb_mux_unregister(&pdev->dev);
+}
+
+#ifdef CONFIG_PM_SLEEP
+/*
+ * In case a micro A cable was plugged in while device was sleeping,
+ * we missed the interrupt. We need to poll usb id state when waking
+ * the driver to detect the missed event.
+ * We use 'complete' callback to give time to all extcon listeners to
+ * resume before we send new events.
+ */
+static const struct dev_pm_ops intel_mux_drcfg_pm_ops = {
+	.complete = intel_usb_mux_complete,
+};
+#endif
+
+static const struct platform_device_id intel_mux_drcfg_platform_ids[] = {
+	{ .name = "intel-mux-drcfg", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, intel_mux_drcfg_platform_ids);
+
+static struct platform_driver intel_mux_drcfg_driver = {
+	.probe		= intel_mux_drcfg_probe,
+	.remove		= intel_mux_drcfg_remove,
+	.driver		= {
+		.name	= "intel-mux-drcfg",
+#ifdef CONFIG_PM_SLEEP
+		.pm	= &intel_mux_drcfg_pm_ops,
+#endif
+	},
+	.id_table = intel_mux_drcfg_platform_ids,
+};
+
+module_platform_driver(intel_mux_drcfg_driver);
+
+MODULE_AUTHOR("Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Intel USB drcfg mux driver");
+MODULE_LICENSE("GPL v2");
-- 
2.1.4