soc: qcom: Add Type-C alternate mode driver

The Type-C standard defines various "alternate (alt) modes" which enable
standard Type-C connectors to carry non-USB signals and data.

This driver provides an interface for Type-C alternate mode clients to
receive data such as Pin Assignment Notifications from the Type-C stack
running on a remote subsystem (e.g. DSP) via the PMIC GLINK interface.

Change-Id: Ic7eacb6901830cab181d91a1775cf02cddbccae2
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>

drivers/soc/qcom/Kconfig

@@ -248,6 +248,15 @@ config QTI_BATTERY_GLINK_DEBUG
 	  Glink from charger and gauging firmware running on a remote subsystem
 	  (e.g. DSP).
 
+config QTI_ALTMODE_GLINK
+	tristate "Type-C alternate mode over GLINK"
+	depends on QTI_PMIC_GLINK
+	help
+	  The Qualcomm Technologies, Inc. Type-C alternate mode driver provides
+	  an interface for Type-C alternate mode clients to receive data such
+	  as Pin Assignment Notifications from the Type-C stack running on a
+	  remote subsystem (e.g. DSP) via the PMIC GLINK interface.
+
 config QCOM_SECURE_BUFFER
 	tristate "Helper functions for secure buffers through TZ"
 	depends on QCOM_SCM

drivers/soc/qcom/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_QCOM_SMP2P)	+= smp2p.o
 obj-$(CONFIG_QCOM_SMSM)	+= smsm.o
 obj-$(CONFIG_QTI_PMIC_GLINK) += pmic_glink.o
 obj-$(CONFIG_QTI_BATTERY_GLINK_DEBUG) += qti_battery_debug.o
+obj-$(CONFIG_QTI_ALTMODE_GLINK) += altmode-glink.o
 obj-$(CONFIG_QCOM_SECURE_BUFFER) += secure_buffer.o
 obj-$(CONFIG_QCOM_SOCINFO)	+= socinfo.o
 obj-$(CONFIG_QCOM_SPM)		+= spm.o

drivers/soc/qcom/altmode-glink.c

@@ -0,0 +1,581 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2020 The Linux Foundation. All rights reserved.
+ */
+
+#define pr_fmt(fmt)	"altmode-glink: %s: " fmt, __func__
+
+#include <linux/device.h>
+#include <linux/idr.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/soc/qcom/altmode-glink.h>
+#include <linux/soc/qcom/pmic_glink.h>
+
+#define MSG_OWNER_USBC_PAN	32780
+#define MSG_TYPE_REQ_RESP	1
+
+#define NOTIFY_PAYLOAD_SIZE	16
+#define USBC_WRITE_BUFFER_SIZE	8
+
+#define USBC_CMD_WRITE_REQ	0x15
+#define USBC_NOTIFY_IND		0x16
+
+#define ALTMODE_NAME_MAX_LEN	10
+
+struct usbc_notify_ind_msg {
+	struct pmic_glink_hdr	hdr;
+	u8			payload[NOTIFY_PAYLOAD_SIZE];
+	u32			reserved;
+};
+
+struct usbc_write_buffer_req_msg {
+	struct pmic_glink_hdr	hdr;
+	u8			buf[USBC_WRITE_BUFFER_SIZE];
+	u32			reserved;
+};
+
+/**
+ * struct altmode_dev
+ *	Definition of an altmode device.
+ *
+ * @dev:		Altmode parent device for all client devices
+ * @name:		Short descriptive name of this altmode device
+ * @pgclient:		PMIC GLINK client to talk to remote subsystem
+ * @client_idr:		idr list for altmode clients
+ * @client_lock:	mutex protecting changes to client_idr
+ * @d_node:		Linked list node to string together multiple amdev's
+ * @client_list:	Linked list head keeping track of this device's clients
+ * @pan_en_sent:	Flag to ensure PAN Enable msg is sent only once
+ * @send_pan_en_work:	To schedule the sending of the PAN Enable message
+ * @probe_notifier:	Inform clients of altmode probe completion
+ */
+struct altmode_dev {
+	struct device			*dev;
+	char				name[ALTMODE_NAME_MAX_LEN];
+	struct pmic_glink_client	*pgclient;
+	struct idr			client_idr;
+	struct mutex			client_lock;
+	struct list_head		d_node;
+	struct list_head		client_list;
+	atomic_t			pan_en_sent;
+	struct delayed_work		send_pan_en_work;
+	struct raw_notifier_head	probe_notifier;
+};
+
+/**
+ * struct altmode_client
+ *	Definition of a client of an altmode device.
+ *
+ * @amdev:		Parent altmode device of this client
+ * @data:		Supplied by client driver during registration
+ * @c_node:		Linked list node for parent altmode device's client list
+ * @port_index:		Type-C port index assigned by remote subystem
+ */
+struct altmode_client {
+	struct altmode_dev		*amdev;
+	struct altmode_client_data	data;
+	struct list_head		c_node;
+	u8				port_index;
+};
+
+/**
+ * struct probe_notify_node
+ *	Linked list node to keep track of altmode clients who, by design,
+ *	register with the altmode framework before altmode probes.
+ *
+ * @amdev_name:		Name of the altmode device client wants to bind to
+ * @nb:			Client's notifier block
+ * @node:		Linked list node for probe_notify_list
+ */
+struct probe_notify_node {
+	char				*amdev_name;
+	struct notifier_block		*nb;
+	struct list_head		node;
+};
+
+/**
+ * struct list_head amdev_list
+ *	List of altmode devices currently using this driver.
+ */
+static LIST_HEAD(amdev_list);
+static DEFINE_MUTEX(amdev_lock);
+
+/**
+ * struct list_head probe_notify_list
+ *	List of altmode clients that register to get notified upon probe
+ *	completion. This list is traversed and clients are removed from this
+ *	list after they have been registered with the altmode device's
+ *	raw_notifier_head.
+ */
+static LIST_HEAD(probe_notify_list);
+static DEFINE_MUTEX(notify_lock);
+
+static struct altmode_dev *get_amdev_from_dev(struct device *dev)
+{
+	struct altmode_dev *pos, *tmp;
+
+	mutex_lock(&amdev_lock);
+	list_for_each_entry_safe(pos, tmp, &amdev_list, d_node) {
+		if (pos->dev == dev) {
+			mutex_unlock(&amdev_lock);
+			return pos;
+		}
+	}
+	mutex_unlock(&amdev_lock);
+
+	return NULL;
+}
+
+static int __altmode_send_data(struct altmode_dev *amdev, void *data,
+			       size_t len)
+{
+	int rc;
+	struct usbc_write_buffer_req_msg msg = { { 0 } };
+
+	if (len > sizeof(msg.buf)) {
+		pr_err("len %zu exceeds msg buf's size: %zu\n",
+				len, USBC_WRITE_BUFFER_SIZE);
+		return -EINVAL;
+	}
+
+	msg.hdr.owner = MSG_OWNER_USBC_PAN;
+	msg.hdr.type = MSG_TYPE_REQ_RESP;
+	msg.hdr.opcode = USBC_CMD_WRITE_REQ;
+
+	memcpy(msg.buf, data, len);
+
+	rc = pmic_glink_write(amdev->pgclient, &msg, sizeof(msg));
+	if (rc < 0)
+		pr_err("Error in sending message: %d\n", rc);
+
+	return rc;
+}
+
+/**
+ * altmode_register_notifier()
+ *	Register to be notified when altmode probes.
+ *
+ * @amdev_name:		The altmode device being registered with by client
+ * @nb:			Notifier block to get notified upon probe completion
+ *
+ * Returns:		0 upon success, negative upon errors.
+ */
+int altmode_register_notifier(const char *amdev_name, struct notifier_block *nb)
+{
+	struct probe_notify_node *notify_node;
+
+	if (!amdev_name || !nb)
+		return -EINVAL;
+
+	notify_node = kzalloc(sizeof(*notify_node), GFP_KERNEL);
+	if (!notify_node)
+		return -ENOMEM;
+
+	notify_node->nb = nb;
+	notify_node->amdev_name = kstrdup(amdev_name, GFP_KERNEL);
+	if (!notify_node->amdev_name) {
+		kfree(notify_node);
+		return -ENOMEM;
+	}
+
+	mutex_lock(&notify_lock);
+	list_add(&notify_node->node, &probe_notify_list);
+	mutex_unlock(&notify_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(altmode_register_notifier);
+
+/**
+ * altmode_deregister_notifier()
+ *	Deregister probe completion notifier.
+ *
+ * @client:		The altmode client obtained during registration
+ * @nb:			Notifier block used for registration
+ *
+ * Returns:		0 upon success, negative upon errors.
+ */
+int altmode_deregister_notifier(struct altmode_client *client,
+				struct notifier_block *nb)
+{
+	struct altmode_dev *amdev;
+
+	if (!client || !nb)
+		return -EINVAL;
+
+	amdev = client->amdev;
+	if (!amdev)
+		return -ENODEV;
+
+	return raw_notifier_chain_unregister(&amdev->probe_notifier, nb);
+}
+EXPORT_SYMBOL(altmode_deregister_notifier);
+
+/**
+ * altmode_send_data()
+ *	Send data from altmode client to remote subsystem.
+ *
+ * @client:		Parent altmode device of this client
+ * @data:		Data to be sent
+ * @len:		Length in bytes of the data to be sent
+ *
+ * Returns:		0 upon success, -EINVAL if len exceeds message buffer's
+ *			capacity, and other negative error codes as appropriate.
+ */
+int altmode_send_data(struct altmode_client *client, void *data,
+			     size_t len)
+{
+	struct altmode_dev *amdev = client->amdev;
+
+	return __altmode_send_data(amdev, data, len);
+}
+EXPORT_SYMBOL(altmode_send_data);
+
+/**
+ * altmode_register_client()
+ *	Register with altmode to receive PMIC GLINK messages from remote
+ *	subsystem.
+ *
+ * @dev:		Device of the parent altmode (platform) device
+ * @client_data:	Details identifying altmode client uniquely
+ *
+ * Returns:		Valid altmode client pointer upon success, ERR_PTRs
+ *			upon errors.
+ *
+ * Notes:		client_data should contain a unique SVID.
+ */
+struct altmode_client *altmode_register_client(struct device *dev,
+		const struct altmode_client_data *client_data)
+{
+	int rc;
+	struct altmode_dev *amdev;
+	struct altmode_client *amclient;
+
+	if (!dev || !dev->parent)
+		return ERR_PTR(-ENODEV);
+
+	if (!client_data->name || !client_data->priv || !client_data->callback
+			|| !client_data->svid)
+		return ERR_PTR(-EINVAL);
+
+	amdev = get_amdev_from_dev(dev);
+	if (!amdev) {
+		pr_err("No alt mode device exists for %s\n", client_data->name);
+		return ERR_PTR(-ENODEV);
+	}
+
+	amclient = kzalloc(sizeof(*amclient), GFP_KERNEL);
+	if (!amclient)
+		return ERR_PTR(-ENOMEM);
+
+	amclient->amdev = amdev;
+	amclient->port_index = U8_MAX; /* invalid */
+	amclient->data.svid = client_data->svid;
+	amclient->data.priv = client_data->priv;
+	amclient->data.callback = client_data->callback;
+	amclient->data.name = kstrdup(client_data->name, GFP_KERNEL);
+	if (!amclient->data.name) {
+		kfree(amclient);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	mutex_lock(&amdev->client_lock);
+	rc = idr_alloc(&amdev->client_idr, amclient, amclient->data.svid,
+			amclient->data.svid + 1, GFP_KERNEL);
+	if (rc < 0) {
+		pr_err("Error in allocating idr for client %s: %d\n",
+				client_data->name, rc);
+		mutex_unlock(&amdev->client_lock);
+		kfree(amclient->data.name);
+		kfree(amclient);
+		return ERR_PTR(rc);
+	}
+
+	list_add(&amclient->c_node, &amdev->client_list);
+	mutex_unlock(&amdev->client_lock);
+
+	if (!atomic_read(&amdev->pan_en_sent))
+		schedule_delayed_work(&amdev->send_pan_en_work,
+				msecs_to_jiffies(20));
+
+	return amclient;
+}
+EXPORT_SYMBOL(altmode_register_client);
+
+/**
+ * altmode_deregister_client()
+ *	Deregister altmode client to stop receiving PMIC GLINK messages
+ *	specific to its SVID from remote subsystem.
+ *
+ * @client:		Client returned by altmode_register_client()
+ *
+ * Returns:		0 upon success, negative upon errors.
+ *
+ * Notes:		This does not stop the transmission of the messages by
+ *			the remote subsystem - only the reception of them by
+ *			the client.
+ */
+int altmode_deregister_client(struct altmode_client *client)
+{
+	struct altmode_dev *amdev;
+	struct altmode_client *pos, *tmp;
+
+	if (!client || !client->amdev)
+		return -ENODEV;
+
+	amdev = client->amdev;
+
+	mutex_lock(&amdev->client_lock);
+	idr_remove(&amdev->client_idr, client->data.svid);
+
+	list_for_each_entry_safe(pos, tmp, &amdev->client_list, c_node) {
+		if (pos == client)
+			list_del(&pos->c_node);
+	}
+	mutex_unlock(&amdev->client_lock);
+
+	kfree(client->data.name);
+	kfree(client);
+
+	return 0;
+}
+EXPORT_SYMBOL(altmode_deregister_client);
+
+static void altmode_send_pan_en(struct work_struct *work)
+{
+	int rc;
+	u32 enable_msg = ALTMODE_PAN_EN;
+	struct altmode_dev *amdev = container_of(work, struct altmode_dev,
+			send_pan_en_work.work);
+
+	rc = __altmode_send_data(amdev, &enable_msg, sizeof(enable_msg));
+	if (rc < 0) {
+		pr_err("Failed to send PAN EN: %d\n", rc);
+		return;
+	}
+
+	atomic_set(&amdev->pan_en_sent, 1);
+	pr_debug("Sent PAN EN\n");
+}
+
+static int altmode_send_ack(struct altmode_dev *amdev, u8 port_index)
+{
+	int rc;
+	struct altmode_pan_ack_msg ack;
+
+	ack.cmd_type = ALTMODE_PAN_ACK;
+	ack.port_index = port_index;
+
+	rc = __altmode_send_data(amdev, &ack, sizeof(ack));
+	if (rc < 0) {
+		pr_err("port %u: Failed to send PAN ACK\n", port_index);
+		return rc;
+	}
+
+	pr_debug("port %d: Sent PAN ACK\n", port_index);
+
+	return rc;
+}
+
+#define USBC_NOTIFY_IND_MASK	GENMASK(7, 0)
+#define GET_OP(opcode)		(opcode & USBC_NOTIFY_IND_MASK)
+#define GET_SVID(opcode)	(opcode >> 16)
+
+static int altmode_callback(void *priv, void *data, size_t len)
+{
+	u16 svid, op;
+	struct usbc_notify_ind_msg *notify_msg = data;
+	struct pmic_glink_hdr *hdr = &notify_msg->hdr;
+	struct altmode_dev *amdev = priv;
+	struct altmode_client *amclient;
+	u8 port_index;
+
+	pr_debug("len: %zu owner: %u type: %u opcode %04x\n", len, hdr->owner,
+			hdr->type, hdr->opcode);
+
+	/*
+	 * For DisplayPort alt mode, the hdr->opcode is designed as follows:
+	 *
+	 *	hdr->opcode = (svid << 16) | USBC_NOTIFY_IND
+	 */
+	op = GET_OP(hdr->opcode);
+	svid = GET_SVID(hdr->opcode);
+	port_index = notify_msg->payload[0];
+
+	mutex_lock(&amdev->client_lock);
+	amclient = idr_find(&amdev->client_idr, svid);
+	mutex_unlock(&amdev->client_lock);
+
+	if (op == USBC_NOTIFY_IND) {
+		if (!amclient) {
+			pr_debug("No client associated with SVID %#x\n", svid);
+			altmode_send_ack(amdev, port_index);
+			return 0;
+		}
+
+		if (amclient->port_index == U8_MAX)
+			amclient->port_index = port_index;
+
+		pr_debug("Payload: %*ph\n", NOTIFY_PAYLOAD_SIZE,
+				notify_msg->payload);
+		amclient->data.callback(amclient->data.priv,
+					notify_msg->payload, len);
+
+	}
+
+	return 0;
+}
+
+static void altmode_gather_clients(struct altmode_dev *amdev)
+{
+	struct probe_notify_node *pos, *tmp;
+
+	mutex_lock(&notify_lock);
+	list_for_each_entry_safe(pos, tmp, &probe_notify_list, node) {
+		if (!strcmp(pos->amdev_name, amdev->name)) {
+			raw_notifier_chain_register(&amdev->probe_notifier,
+					pos->nb);
+			/*
+			 * Client's nb has been added to amdev's notifier, so
+			 * it may be removed from the global list.
+			 */
+			list_del(&pos->node);
+			kfree(pos->amdev_name);
+			kfree(pos);
+		}
+	}
+	mutex_unlock(&notify_lock);
+}
+
+static void altmode_notify_clients(struct altmode_dev *amdev,
+					  struct platform_device *pdev)
+{
+	altmode_gather_clients(amdev);
+	raw_notifier_call_chain(&amdev->probe_notifier, 0, pdev);
+}
+
+static void altmode_device_add(struct altmode_dev *amdev)
+{
+	mutex_lock(&amdev_lock);
+	list_add(&amdev->d_node, &amdev_list);
+	mutex_unlock(&amdev_lock);
+}
+
+static int altmode_probe(struct platform_device *pdev)
+{
+	int rc;
+	const char *str = NULL;
+	struct altmode_dev *amdev;
+	struct pmic_glink_client_data pgclient_data = { };
+	struct device *dev = &pdev->dev;
+
+	amdev = devm_kzalloc(&pdev->dev, sizeof(*amdev), GFP_KERNEL);
+	if (!amdev)
+		return -ENOMEM;
+
+	rc = of_property_read_string(dev->of_node, "qcom,altmode-name",
+				     &str);
+	if (rc < 0) {
+		dev_err(dev, "No altmode device name specified: %d\n", rc);
+		return rc;
+	}
+
+	if (!str || (strlen(str) >= ALTMODE_NAME_MAX_LEN) ||
+			!str_has_prefix(str, "altmode_")) {
+		dev_err(dev, "Incorrect altmode device name format\n");
+		return -EINVAL;
+	}
+
+	amdev->dev = dev;
+	strlcpy(amdev->name, str, ALTMODE_NAME_MAX_LEN);
+
+	RAW_INIT_NOTIFIER_HEAD(&amdev->probe_notifier);
+
+	pgclient_data.id = MSG_OWNER_USBC_PAN;
+	pgclient_data.name = "altmode";
+	pgclient_data.msg_cb = altmode_callback;
+	pgclient_data.priv = amdev;
+
+	amdev->pgclient = pmic_glink_register_client(amdev->dev,
+			&pgclient_data);
+	if (IS_ERR(amdev->pgclient)) {
+		rc = PTR_ERR(amdev->pgclient);
+		if (rc != -EPROBE_DEFER)
+			dev_err(dev, "Error in pmic_glink registration: %d\n",
+				rc);
+		return rc;
+	}
+
+	platform_set_drvdata(pdev, amdev);
+
+	mutex_init(&amdev->client_lock);
+	idr_init(&amdev->client_idr);
+	INIT_DELAYED_WORK(&amdev->send_pan_en_work, altmode_send_pan_en);
+	INIT_LIST_HEAD(&amdev->d_node);
+	INIT_LIST_HEAD(&amdev->client_list);
+
+	altmode_device_add(amdev);
+	altmode_notify_clients(amdev, pdev);
+
+	return 0;
+}
+
+static void altmode_device_remove(struct altmode_dev *amdev)
+{
+	struct altmode_dev *pos, *tmp;
+
+	atomic_set(&amdev->pan_en_sent, 0);
+
+	mutex_lock(&amdev_lock);
+	list_for_each_entry_safe(pos, tmp, &amdev_list, d_node) {
+		if (pos == amdev)
+			list_del(&pos->d_node);
+	}
+	mutex_unlock(&amdev_lock);
+}
+
+static int altmode_remove(struct platform_device *pdev)
+{
+	int rc;
+	struct altmode_dev *amdev = platform_get_drvdata(pdev);
+	struct altmode_client *client, *tmp;
+
+	cancel_delayed_work_sync(&amdev->send_pan_en_work);
+	idr_destroy(&amdev->client_idr);
+
+	mutex_lock(&amdev->client_lock);
+	list_for_each_entry_safe(client, tmp, &amdev->client_list, c_node)
+		list_del(&client->c_node);
+	mutex_unlock(&amdev->client_lock);
+
+	altmode_device_remove(amdev);
+
+	rc = pmic_glink_unregister_client(amdev->pgclient);
+	if (rc < 0)
+		dev_err(amdev->dev, "Error in pmic_glink de-registration: %d\n",
+				rc);
+
+	return rc;
+}
+
+static const struct of_device_id altmode_match_table[] = {
+	{ .compatible = "qcom,altmode-glink" },
+	{},
+};
+
+static struct platform_driver altmode_driver = {
+	.driver	= {
+		.name = "altmode-glink",
+		.of_match_table = altmode_match_table,
+	},
+	.probe	= altmode_probe,
+	.remove	= altmode_remove,
+};
+module_platform_driver(altmode_driver);
+
+MODULE_DESCRIPTION("QTI Type-C Alt Mode over GLINK");
+MODULE_LICENSE("GPL v2");

include/linux/soc/qcom/altmode-glink.h

@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ */
+
+#ifndef __ALTMODE_H__
+#define __ALTMODE_H__
+
+#include <linux/types.h>
+
+/**
+ * struct altmode_client_data
+ *	Uniquely define altmode client while registering with altmode framework.
+ *
+ * @svid:		Unique ID for Type-C Altmode client devices
+ * @name:		Short descriptive name to identify client
+ * @priv:		Pointer to client driver's internal top level structure
+ * @callback:		Callback function to receive PMIC GLINK message data
+ */
+struct altmode_client_data {
+	u16		svid;
+	const char	*name;
+	void		*priv;
+	int		(*callback)(void *priv, void *data, size_t len);
+};
+
+struct altmode_client;
+
+enum altmode_send_msg_type {
+	ALTMODE_PAN_EN = 0x10,
+	ALTMODE_PAN_ACK,
+};
+
+struct altmode_pan_ack_msg {
+	u32 cmd_type;
+	u8 port_index;
+};
+
+#if IS_ENABLED(CONFIG_QTI_ALTMODE_GLINK)
+
+struct notifier_block;
+struct device;
+
+int altmode_register_notifier(const char *amdev_name,
+			      struct notifier_block *nb);
+int altmode_deregister_notifier(struct altmode_client *client,
+				struct notifier_block *nb);
+struct altmode_client *altmode_register_client(struct device *dev,
+		const struct altmode_client_data *client_data);
+int altmode_deregister_client(struct altmode_client *client);
+int altmode_send_data(struct altmode_client *client, void *data, size_t len);
+
+#else
+
+static inline int altmode_register_notifier(const char *amdev_name,
+					    struct notifier_block *nb)
+{
+	return -ENODEV;
+}
+
+static inline int altmode_deregister_notifier(struct altmode_client *client,
+				struct notifier_block *nb)
+{
+	return -ENODEV;
+}
+
+static inline struct altmode_client *altmode_register_client(struct device *dev,
+		const struct altmode_client_data *client_data)
+{
+	return ERR_PTR(-ENODEV);
+}
+
+static inline int altmode_deregister_client(struct altmode_client *client)
+{
+	return -ENODEV;
+}
+
+static inline int altmode_send_data(struct altmode_client *client, void *data,
+				    size_t len)
+{
+	return -ENODEV;
+}
+
+#endif
+
+#endif