[RFC 1/2] bluetooth: hci_uart: add serdev driver support library

[Rob Herring]

This adds library functions for serdev based BT drivers. This is largely
copied from hci_ldisc.c and modified to use serdev calls. There's a little
bit of duplication, but I avoided intermixing this as the ldisc code should
eventually go away.

Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
Cc: Gustavo Padovan <gustavo@xxxxxxxxxxx>
Cc: Johan Hedberg <johan.hedberg@xxxxxxxxx>
Cc: linux-bluetooth@xxxxxxxxxxxxxxx
---
 drivers/bluetooth/Makefile     |   2 +-
 drivers/bluetooth/hci_serdev.c | 370 +++++++++++++++++++++++++++++++++++++++++
 drivers/bluetooth/hci_uart.h   |   4 +
 3 files changed, 375 insertions(+), 1 deletion(-)
 create mode 100644 drivers/bluetooth/hci_serdev.c

diff --git a/drivers/bluetooth/Makefile b/drivers/bluetooth/Makefile
index 80627187c8b6..a69b18ac704a 100644
--- a/drivers/bluetooth/Makefile
+++ b/drivers/bluetooth/Makefile
@@ -28,7 +28,7 @@ obj-$(CONFIG_BT_QCA)		+= btqca.o
 btmrvl-y			:= btmrvl_main.o
 btmrvl-$(CONFIG_DEBUG_FS)	+= btmrvl_debugfs.o
 
-hci_uart-y				:= hci_ldisc.o
+hci_uart-y				:= hci_ldisc.o hci_serdev.o
 hci_uart-$(CONFIG_BT_HCIUART_H4)	+= hci_h4.o
 hci_uart-$(CONFIG_BT_HCIUART_BCSP)	+= hci_bcsp.o
 hci_uart-$(CONFIG_BT_HCIUART_LL)	+= hci_ll.o
diff --git a/drivers/bluetooth/hci_serdev.c b/drivers/bluetooth/hci_serdev.c
new file mode 100644
index 000000000000..b2f7293a3162
--- /dev/null
+++ b/drivers/bluetooth/hci_serdev.c
@@ -0,0 +1,370 @@
+/*
+ *
+ *  Bluetooth HCI serdev driver lib
+ *
+ *  Copyright (C) 2017  Linaro, Ltd., Rob Herring <robh@xxxxxxxxxx>
+ *
+ *  Based on hci_ldisc.c:
+ *
+ *  Copyright (C) 2000-2001  Qualcomm Incorporated
+ *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@xxxxxxxxxxxx>
+ *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@xxxxxxxxxxxx>
+ *
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  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.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/serdev.h>
+#include <linux/skbuff.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "hci_uart.h"
+
+struct serdev_device_ops hci_serdev_client_ops;
+
+static inline void hci_uart_tx_complete(struct hci_uart *hu, int pkt_type)
+{
+	struct hci_dev *hdev = hu->hdev;
+
+	/* Update HCI stat counters */
+	switch (pkt_type) {
+	case HCI_COMMAND_PKT:
+		hdev->stat.cmd_tx++;
+		break;
+
+	case HCI_ACLDATA_PKT:
+		hdev->stat.acl_tx++;
+		break;
+
+	case HCI_SCODATA_PKT:
+		hdev->stat.sco_tx++;
+		break;
+	}
+}
+
+static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
+{
+	struct sk_buff *skb = hu->tx_skb;
+
+	if (!skb)
+		skb = hu->proto->dequeue(hu);
+	else
+		hu->tx_skb = NULL;
+
+	return skb;
+}
+
+static void hci_uart_write_work(struct work_struct *work)
+{
+	struct hci_uart *hu = container_of(work, struct hci_uart, write_work);
+	struct serdev_device *serdev = hu->serdev;
+	struct hci_dev *hdev = hu->hdev;
+	struct sk_buff *skb;
+
+	/* REVISIT: should we cope with bad skbs or ->write() returning
+	 * and error value ?
+	 */
+
+restart:
+	clear_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
+
+	while ((skb = hci_uart_dequeue(hu))) {
+		int len;
+
+		len = serdev_device_write_buf(serdev, skb->data, skb->len);
+		hdev->stat.byte_tx += len;
+
+		skb_pull(skb, len);
+		if (skb->len) {
+			hu->tx_skb = skb;
+			break;
+		}
+
+		hci_uart_tx_complete(hu, hci_skb_pkt_type(skb));
+		kfree_skb(skb);
+	}
+
+	if (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state))
+		goto restart;
+
+	clear_bit(HCI_UART_SENDING, &hu->tx_state);
+}
+
+/* ------- Interface to HCI layer ------ */
+/* Initialize device */
+static int hci_uart_open(struct hci_dev *hdev)
+{
+	struct hci_uart *hu  = hci_get_drvdata(hdev);
+
+	BT_DBG("%s %p", hdev->name, hdev);
+
+	serdev_device_set_client_ops(hu->serdev, &hci_serdev_client_ops);
+
+	return serdev_device_open(hu->serdev);
+}
+
+/* Reset device */
+static int hci_uart_flush(struct hci_dev *hdev)
+{
+	struct hci_uart *hu  = hci_get_drvdata(hdev);
+
+	BT_DBG("hdev %p serdev %p", hdev, hu->serdev);
+
+	if (hu->tx_skb) {
+		kfree_skb(hu->tx_skb); hu->tx_skb = NULL;
+	}
+
+	/* Flush any pending characters in the driver and discipline. */
+	serdev_device_write_flush(hu->serdev);
+
+	if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
+		hu->proto->flush(hu);
+
+	return 0;
+}
+
+/* Close device */
+static int hci_uart_close(struct hci_dev *hdev)
+{
+	struct hci_uart *hu  = hci_get_drvdata(hdev);
+
+	BT_DBG("hdev %p", hdev);
+
+	hci_uart_flush(hdev);
+	hdev->flush = NULL;
+
+	serdev_device_close(hu->serdev);
+
+	return 0;
+}
+
+/* Send frames from HCI layer */
+static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+
+	BT_DBG("%s: type %d len %d", hdev->name, hci_skb_pkt_type(skb),
+	       skb->len);
+
+	hu->proto->enqueue(hu, skb);
+
+	hci_uart_tx_wakeup(hu);
+
+	return 0;
+}
+
+static int hci_uart_setup(struct hci_dev *hdev)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+	struct hci_rp_read_local_version *ver;
+	struct sk_buff *skb;
+	unsigned int speed;
+	int err;
+
+	/* Init speed if any */
+	if (hu->init_speed)
+		speed = hu->init_speed;
+	else if (hu->proto->init_speed)
+		speed = hu->proto->init_speed;
+	else
+		speed = 0;
+
+	if (speed)
+		serdev_device_set_baudrate(hu->serdev, speed);
+
+	/* Operational speed if any */
+	if (hu->oper_speed)
+		speed = hu->oper_speed;
+	else if (hu->proto->oper_speed)
+		speed = hu->proto->oper_speed;
+	else
+		speed = 0;
+
+	if (hu->proto->set_baudrate && speed) {
+		err = hu->proto->set_baudrate(hu, speed);
+		if (!err)
+			serdev_device_set_baudrate(hu->serdev, speed);
+	}
+
+	if (hu->proto->setup)
+		return hu->proto->setup(hu);
+
+	if (!test_bit(HCI_UART_VND_DETECT, &hu->hdev_flags))
+		return 0;
+
+	skb = __hci_cmd_sync(hdev, HCI_OP_READ_LOCAL_VERSION, 0, NULL,
+			     HCI_INIT_TIMEOUT);
+	if (IS_ERR(skb)) {
+		BT_ERR("%s: Reading local version information failed (%ld)",
+		       hdev->name, PTR_ERR(skb));
+		return 0;
+	}
+
+	if (skb->len != sizeof(*ver)) {
+		BT_ERR("%s: Event length mismatch for version information",
+		       hdev->name);
+		goto done;
+	}
+
+done:
+	kfree_skb(skb);
+	return 0;
+}
+
+/* hci_uart_write_wakeup()
+ *
+ *    Callback for transmit wakeup. Called when low level
+ *    device driver can accept more send data.
+ *
+ * Arguments:        tty    pointer to associated tty instance data
+ * Return Value:    None
+ */
+static void hci_uart_write_wakeup(struct serdev_device *serdev)
+{
+	struct hci_uart *hu = serdev_device_get_drvdata(serdev);
+
+	BT_DBG("");
+
+	if (!hu)
+		return;
+
+	if (serdev != hu->serdev)
+		return;
+
+	if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
+		hci_uart_tx_wakeup(hu);
+}
+
+/* hci_uart_receive_buf()
+ *
+ *     Called by tty low level driver when receive data is
+ *     available.
+ *
+ * Arguments:  tty          pointer to tty isntance data
+ *             data         pointer to received data
+ *             flags        pointer to flags for data
+ *             count        count of received data in bytes
+ *
+ * Return Value:    None
+ */
+static int hci_uart_receive_buf(struct serdev_device *serdev, const u8 *data,
+				   size_t count)
+{
+	struct hci_uart *hu = serdev_device_get_drvdata(serdev);
+
+	if (!hu || serdev != hu->serdev)
+		return 0;
+
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
+		return 0;
+
+	/* It does not need a lock here as it is already protected by a mutex in
+	 * tty caller
+	 */
+	hu->proto->recv(hu, data, count);
+
+	if (hu->hdev)
+		hu->hdev->stat.byte_rx += count;
+
+	return count;
+}
+
+struct serdev_device_ops hci_serdev_client_ops = {
+	.receive_buf = hci_uart_receive_buf,
+	.write_wakeup = hci_uart_write_wakeup,
+};
+
+int hci_uart_register_device(struct hci_uart *hu, const struct hci_uart_proto *p)
+{
+	int err;
+	struct hci_dev *hdev;
+
+	BT_DBG("");
+
+	err = p->open(hu);
+	if (err)
+		return err;
+
+	hu->proto = p;
+	set_bit(HCI_UART_PROTO_READY, &hu->flags);
+
+	/* Initialize and register HCI device */
+	hdev = hci_alloc_dev();
+	if (!hdev) {
+		BT_ERR("Can't allocate HCI device");
+		err = -ENOMEM;
+		goto err_alloc;
+	}
+
+	hu->hdev = hdev;
+
+	hdev->bus = HCI_UART;
+	hci_set_drvdata(hdev, hu);
+
+	INIT_WORK(&hu->write_work, hci_uart_write_work);
+
+	/* Only when vendor specific setup callback is provided, consider
+	 * the manufacturer information valid. This avoids filling in the
+	 * value for Ericsson when nothing is specified.
+	 */
+	if (hu->proto->setup)
+		hdev->manufacturer = hu->proto->manufacturer;
+
+	hdev->open  = hci_uart_open;
+	hdev->close = hci_uart_close;
+	hdev->flush = hci_uart_flush;
+	hdev->send  = hci_uart_send_frame;
+	hdev->setup = hci_uart_setup;
+	SET_HCIDEV_DEV(hdev, &hu->serdev->dev);
+
+	if (test_bit(HCI_UART_RAW_DEVICE, &hu->hdev_flags))
+		set_bit(HCI_QUIRK_RAW_DEVICE, &hdev->quirks);
+
+	if (test_bit(HCI_UART_EXT_CONFIG, &hu->hdev_flags))
+		set_bit(HCI_QUIRK_EXTERNAL_CONFIG, &hdev->quirks);
+
+	if (!test_bit(HCI_UART_RESET_ON_INIT, &hu->hdev_flags))
+		set_bit(HCI_QUIRK_RESET_ON_CLOSE, &hdev->quirks);
+
+	if (test_bit(HCI_UART_CREATE_AMP, &hu->hdev_flags))
+		hdev->dev_type = HCI_AMP;
+	else
+		hdev->dev_type = HCI_PRIMARY;
+
+	if (test_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
+		return 0;
+
+	if (hci_register_dev(hdev) < 0) {
+		BT_ERR("Can't register HCI device");
+		err = -ENODEV;
+		goto err_register;
+	}
+
+	set_bit(HCI_UART_REGISTERED, &hu->flags);
+
+	return 0;
+
+err_register:
+	hci_free_dev(hdev);
+err_alloc:
+	clear_bit(HCI_UART_PROTO_READY, &hu->flags);
+	p->close(hu);
+	return err;
+}
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index cb7f4b4aeca0..4796a29d575f 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -58,6 +58,7 @@
 #define HCI_UART_VND_DETECT	5
 
 struct hci_uart;
+struct serdev_device;
 
 struct hci_uart_proto {
 	unsigned int id;
@@ -77,6 +78,7 @@ struct hci_uart_proto {
 
 struct hci_uart {
 	struct tty_struct	*tty;
+	struct serdev_device	*serdev;
 	struct hci_dev		*hdev;
 	unsigned long		flags;
 	unsigned long		hdev_flags;
@@ -105,6 +107,8 @@ struct hci_uart {
 
 int hci_uart_register_proto(const struct hci_uart_proto *p);
 int hci_uart_unregister_proto(const struct hci_uart_proto *p);
+int hci_uart_register_device(struct hci_uart *hu, const struct hci_uart_proto *p);
+
 int hci_uart_tx_wakeup(struct hci_uart *hu);
 int hci_uart_init_ready(struct hci_uart *hu);
 void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed);
-- 
2.10.1