[PATCH v7 4/7] 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>
---
 drivers/usb/mux/Kconfig               |   8 ++
 drivers/usb/mux/Makefile              |   1 +
 drivers/usb/mux/portmux-intel-drcfg.c | 171 ++++++++++++++++++++++++++++++++++
 3 files changed, 180 insertions(+)
 create mode 100644 drivers/usb/mux/portmux-intel-drcfg.c

diff --git a/drivers/usb/mux/Kconfig b/drivers/usb/mux/Kconfig
index 1dc1f33..ae3f746 100644
--- a/drivers/usb/mux/Kconfig
+++ b/drivers/usb/mux/Kconfig
@@ -19,4 +19,12 @@ 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 USB_PORTMUX
+	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 4eb5582..0f102b5 100644
--- a/drivers/usb/mux/Makefile
+++ b/drivers/usb/mux/Makefile
@@ -3,3 +3,4 @@
 #
 obj-$(CONFIG_USB_PORTMUX)		+= portmux-core.o
 obj-$(CONFIG_INTEL_MUX_GPIO)		+= portmux-intel-gpio.o
+obj-$(CONFIG_INTEL_MUX_DRCFG)		+= portmux-intel-drcfg.o
diff --git a/drivers/usb/mux/portmux-intel-drcfg.c b/drivers/usb/mux/portmux-intel-drcfg.c
new file mode 100644
index 0000000..0bb6b08
--- /dev/null
+++ b/drivers/usb/mux/portmux-intel-drcfg.c
@@ -0,0 +1,171 @@
+/**
+ * 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/platform_device.h>
+#include <linux/usb.h>
+#include <linux/usb/portmux.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_MODE		BIT(29)
+
+struct intel_mux_drcfg {
+	struct portmux_desc desc;
+	struct device *dev;
+	void __iomem *regs;
+	struct portmux_dev *pdev;
+};
+
+static inline int intel_mux_drcfg_switch(struct device *dev, bool host)
+{
+	u32 data;
+	struct intel_mux_drcfg *mux;
+
+	mux = dev_get_drvdata(dev);
+
+	/* 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);
+
+	return 0;
+}
+
+static int intel_mux_drcfg_cable_set(struct device *dev)
+{
+	dev_dbg(dev, "drcfg mux switch to HOST\n");
+
+	return intel_mux_drcfg_switch(dev, true);
+}
+
+static int intel_mux_drcfg_cable_unset(struct device *dev)
+{
+	dev_dbg(dev, "drcfg mux switch to DEVICE\n");
+
+	return intel_mux_drcfg_switch(dev, false);
+}
+
+static const struct portmux_ops drcfg_ops = {
+	.cable_set_cb = intel_mux_drcfg_cable_set,
+	.cable_unset_cb = intel_mux_drcfg_cable_unset,
+};
+
+static int intel_mux_drcfg_probe(struct platform_device *pdev)
+{
+	struct intel_mux_drcfg *mux;
+	struct device *dev = &pdev->dev;
+	const char *extcon_name = NULL;
+	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;
+
+	ret = device_property_read_string(dev, "extcon-name", &extcon_name);
+	if (!ret)
+		mux->desc.extcon_name = extcon_name;
+
+	mux->regs = devm_ioremap_nocache(dev, start, size);
+	if (!mux->regs)
+		return -ENOMEM;
+
+	mux->desc.dev = dev;
+	mux->desc.name = "intel-mux-drcfg";
+	mux->desc.ops = &drcfg_ops;
+	mux->desc.initial_state =
+			!!(readl(mux->regs + INTEL_MUX_CFG1) & CFG1_MODE);
+	dev_set_drvdata(dev, mux);
+	mux->pdev = portmux_register(&mux->desc);
+
+	return PTR_ERR_OR_ZERO(mux->pdev);
+}
+
+static int intel_mux_drcfg_remove(struct platform_device *pdev)
+{
+	struct intel_mux_drcfg *mux;
+
+	mux = platform_get_drvdata(pdev);
+	portmux_unregister(mux->pdev);
+
+	return 0;
+}
+
+#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 void intel_mux_drcfg_complete(struct device *dev)
+{
+	struct intel_mux_drcfg *mux;
+
+	mux = dev_get_drvdata(dev);
+	portmux_complete(mux->pdev);
+}
+
+static const struct dev_pm_ops intel_mux_drcfg_pm_ops = {
+	.complete = intel_mux_drcfg_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