[RFC PATCH 6/6] bluetooth: hack up ldisc to use serio

From: Rob Herring
Date: Wed Aug 24 2016 - 19:25:08 EST

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This hacks up the BT ldisc in place to work as a serio driver. It will
need refactoring into common, ldisc, and serio parts.

It is working under QEMU to the point the driver can bind to a serio
device via DT, register as a BT device, start sending out initial
packets and receive data (typed at a terminal). Now I need to find a
real device.

Still need to figure out how to plumb a few tty things like
TTY_DO_WRITE_WAKEUP bit handling and tty_unthrottle.

Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
---
drivers/bluetooth/hci_ldisc.c | 261 +++++++++++++++++-------------------------
drivers/bluetooth/hci_uart.h | 3 +
2 files changed, 109 insertions(+), 155 deletions(-)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index dda9739..8149952 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -34,7 +34,9 @@
#include <linux/poll.h>

#include <linux/slab.h>
-#include <linux/tty.h>
+#include <linux/serio.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/signal.h>
@@ -138,7 +140,7 @@ int hci_uart_tx_wakeup(struct hci_uart *hu)
static void hci_uart_write_work(struct work_struct *work)
{
struct hci_uart *hu = container_of(work, struct hci_uart, write_work);
- struct tty_struct *tty = hu->tty;
+ struct serio *serio = hu->serio;
struct hci_dev *hdev = hu->hdev;
struct sk_buff *skb;

@@ -152,8 +154,8 @@ restart:
while ((skb = hci_uart_dequeue(hu))) {
int len;

- set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
- len = tty->ops->write(tty, skb->data, skb->len);
+// set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+ len = serio_write_buf(serio, skb->data, skb->len);
hdev->stat.byte_tx += len;

skb_pull(skb, len);
@@ -215,17 +217,15 @@ static int hci_uart_open(struct hci_dev *hdev)
static int hci_uart_flush(struct hci_dev *hdev)
{
struct hci_uart *hu = hci_get_drvdata(hdev);
- struct tty_struct *tty = hu->tty;

- BT_DBG("hdev %p tty %p", hdev, tty);
+ BT_DBG("hdev %p serio %p", hdev, hu->serio);

if (hu->tx_skb) {
kfree_skb(hu->tx_skb); hu->tx_skb = NULL;
}

/* Flush any pending characters in the driver and discipline. */
- tty_ldisc_flush(tty);
- tty_driver_flush_buffer(tty);
+ serio_write_flush(hu->serio);

if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
hu->proto->flush(hu);
@@ -261,6 +261,8 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
/* Flow control or un-flow control the device */
void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
{
+ serio_set_flow_control(hu->serio, enable);
+#if 0
struct tty_struct *tty = hu->tty;
struct ktermios ktermios;
int status;
@@ -309,6 +311,7 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
BT_DBG("Enabling hardware flow control: %s",
status ? "failed" : "success");
}
+#endif
}

void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
@@ -317,7 +320,7 @@ void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
hu->init_speed = init_speed;
hu->oper_speed = oper_speed;
}
-
+#if 0
void hci_uart_init_tty(struct hci_uart *hu)
{
struct tty_struct *tty = hu->tty;
@@ -336,21 +339,13 @@ void hci_uart_init_tty(struct hci_uart *hu)
/* tty_set_termios() return not checked as it is always 0 */
tty_set_termios(tty, &ktermios);
}
-
+#endif
void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed)
{
- struct tty_struct *tty = hu->tty;
- struct ktermios ktermios;
-
- ktermios = tty->termios;
- ktermios.c_cflag &= ~CBAUD;
- tty_termios_encode_baud_rate(&ktermios, speed, speed);
-
- /* tty_set_termios() return not checked as it is always 0 */
- tty_set_termios(tty, &ktermios);
+ int out_speed = serio_set_baudrate(hu->serio, speed);

BT_DBG("%s: New tty speeds: %d/%d", hu->hdev->name,
- tty->termios.c_ispeed, tty->termios.c_ospeed);
+ speed, out_speed);
}

static int hci_uart_setup(struct hci_dev *hdev)
@@ -428,83 +423,6 @@ done:
return 0;
}

-/* ------ LDISC part ------ */
-/* hci_uart_tty_open
- *
- * Called when line discipline changed to HCI_UART.
- *
- * Arguments:
- * tty pointer to tty info structure
- * Return Value:
- * 0 if success, otherwise error code
- */
-static int hci_uart_tty_open(struct tty_struct *tty)
-{
- struct hci_uart *hu;
-
- BT_DBG("tty %p", tty);
-
- /* Error if the tty has no write op instead of leaving an exploitable
- hole */
- if (tty->ops->write == NULL)
- return -EOPNOTSUPP;
-
- hu = kzalloc(sizeof(struct hci_uart), GFP_KERNEL);
- if (!hu) {
- BT_ERR("Can't allocate control structure");
- return -ENFILE;
- }
-
- tty->disc_data = hu;
- hu->tty = tty;
- tty->receive_room = 65536;
-
- INIT_WORK(&hu->init_ready, hci_uart_init_work);
- INIT_WORK(&hu->write_work, hci_uart_write_work);
-
- /* Flush any pending characters in the driver */
- tty_driver_flush_buffer(tty);
-
- return 0;
-}
-
-/* hci_uart_tty_close()
- *
- * Called when the line discipline is changed to something
- * else, the tty is closed, or the tty detects a hangup.
- */
-static void hci_uart_tty_close(struct tty_struct *tty)
-{
- struct hci_uart *hu = tty->disc_data;
- struct hci_dev *hdev;
-
- BT_DBG("tty %p", tty);
-
- /* Detach from the tty */
- tty->disc_data = NULL;
-
- if (!hu)
- return;
-
- hdev = hu->hdev;
- if (hdev)
- hci_uart_close(hdev);
-
- cancel_work_sync(&hu->write_work);
-
- if (test_and_clear_bit(HCI_UART_PROTO_READY, &hu->flags)) {
- if (hdev) {
- if (test_bit(HCI_UART_REGISTERED, &hu->flags))
- hci_unregister_dev(hdev);
- hci_free_dev(hdev);
- }
- hu->proto->close(hu);
- }
- clear_bit(HCI_UART_PROTO_SET, &hu->flags);
-
- kfree(hu);
-}
-
/* hci_uart_tty_wakeup()
*
* Callback for transmit wakeup. Called when low level
@@ -513,18 +431,18 @@ static void hci_uart_tty_close(struct tty_struct *tty)
* Arguments: tty pointer to associated tty instance data
* Return Value: None
*/
-static void hci_uart_tty_wakeup(struct tty_struct *tty)
+static void hci_uart_serio_wakeup(struct serio *serio)
{
- struct hci_uart *hu = tty->disc_data;
+ struct hci_uart *hu = serio_get_drvdata(serio);

BT_DBG("");

if (!hu)
return;

- clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+// clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);

- if (tty != hu->tty)
+ if (serio != hu->serio)
return;

if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
@@ -543,16 +461,16 @@ static void hci_uart_tty_wakeup(struct tty_struct *tty)
*
* Return Value: None
*/
-static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
- char *flags, int count)
+static int hci_uart_serio_receive(struct serio *serio, const u8 *data,
+ size_t count)
{
- struct hci_uart *hu = tty->disc_data;
+ struct hci_uart *hu = serio_get_drvdata(serio);

- if (!hu || tty != hu->tty)
- return;
+ if (!hu || serio != hu->serio)
+ return 0;

if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
- return;
+ return 0;

/* It does not need a lock here as it is already protected by a mutex in
* tty caller
@@ -562,7 +480,8 @@ static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
if (hu->hdev)
hu->hdev->stat.byte_rx += count;

- tty_unthrottle(tty);
+// tty_unthrottle(tty);
+ return count;
}

static int hci_uart_register_dev(struct hci_uart *hu)
@@ -595,7 +514,7 @@ static int hci_uart_register_dev(struct hci_uart *hu)
hdev->flush = hci_uart_flush;
hdev->send = hci_uart_send_frame;
hdev->setup = hci_uart_setup;
- SET_HCIDEV_DEV(hdev, hu->tty->dev);
+ SET_HCIDEV_DEV(hdev, &hu->serio->dev);

if (test_bit(HCI_UART_RAW_DEVICE, &hu->hdev_flags))
set_bit(HCI_QUIRK_RAW_DEVICE, &hdev->quirks);
@@ -650,6 +569,7 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)

return 0;
}
+#if 0

static int hci_uart_set_flags(struct hci_uart *hu, unsigned long flags)
{
@@ -733,56 +653,95 @@ static int hci_uart_tty_ioctl(struct tty_struct *tty, struct file *file,

return err;
}
+#endif

-/*
- * We don't provide read/write/poll interface for user space.
- */
-static ssize_t hci_uart_tty_read(struct tty_struct *tty, struct file *file,
- unsigned char __user *buf, size_t nr)
+static int hci_uart_connect(struct serio *serio, struct serio_driver *drv)
{
- return 0;
-}
+ int id, ret;
+ struct hci_uart *hu;
+
+ BT_INFO("HCI UART driver ver %s", VERSION);
+
+ id = (int)of_device_get_match_data(&serio->dev);
+
+ hu = devm_kzalloc(&serio->dev, sizeof(struct hci_uart), GFP_KERNEL);
+ if (!hu)
+ return -ENFILE;
+
+ serio_set_drvdata(serio, hu);
+ hu->serio = serio;
+
+// tty->receive_room = 65536;
+
+ INIT_WORK(&hu->init_ready, hci_uart_init_work);
+ INIT_WORK(&hu->write_work, hci_uart_write_work);
+
+ ret = serio_open(serio, drv);
+ if (ret)
+ return ret;
+
+ set_bit(HCI_UART_PROTO_SET, &hu->flags);
+ ret = hci_uart_set_proto(hu, id);
+ if (ret) {
+ serio_close(serio);
+ return ret;
+ }
+
+ /* Flush any pending characters in the driver */
+// tty_driver_flush_buffer(tty);

-static ssize_t hci_uart_tty_write(struct tty_struct *tty, struct file *file,
- const unsigned char *data, size_t count)
-{
- return 0;
-}

-static unsigned int hci_uart_tty_poll(struct tty_struct *tty,
- struct file *filp, poll_table *wait)
-{
return 0;
}

-static int __init hci_uart_init(void)
+static void hci_uart_disconnect(struct serio *serio)
{
- static struct tty_ldisc_ops hci_uart_ldisc;
- int err;
+ struct hci_dev *hdev;
+ struct hci_uart *hu = serio_get_drvdata(serio);

- BT_INFO("HCI UART driver ver %s", VERSION);
+ hdev = hu->hdev;
+ if (hdev)
+ hci_uart_close(hdev);

- /* Register the tty discipline */
-
- memset(&hci_uart_ldisc, 0, sizeof(hci_uart_ldisc));
- hci_uart_ldisc.magic = TTY_LDISC_MAGIC;
- hci_uart_ldisc.name = "n_hci";
- hci_uart_ldisc.open = hci_uart_tty_open;
- hci_uart_ldisc.close = hci_uart_tty_close;
- hci_uart_ldisc.read = hci_uart_tty_read;
- hci_uart_ldisc.write = hci_uart_tty_write;
- hci_uart_ldisc.ioctl = hci_uart_tty_ioctl;
- hci_uart_ldisc.poll = hci_uart_tty_poll;
- hci_uart_ldisc.receive_buf = hci_uart_tty_receive;
- hci_uart_ldisc.write_wakeup = hci_uart_tty_wakeup;
- hci_uart_ldisc.owner = THIS_MODULE;
-
- err = tty_register_ldisc(N_HCI, &hci_uart_ldisc);
- if (err) {
- BT_ERR("HCI line discipline registration failed. (%d)", err);
- return err;
+ cancel_work_sync(&hu->write_work);
+
+ if (test_and_clear_bit(HCI_UART_PROTO_READY, &hu->flags)) {
+ if (hdev) {
+ if (test_bit(HCI_UART_REGISTERED, &hu->flags))
+ hci_unregister_dev(hdev);
+ hci_free_dev(hdev);
+ }
+ hu->proto->close(hu);
}
+ clear_bit(HCI_UART_PROTO_SET, &hu->flags);
+
+ pr_info("hci_uart disconnect!!!\n");
+ serio_close(serio);
+}
+
+
+static const struct of_device_id hci_uart_of_match[] = {
+ { .compatible = "loopback-uart", .data = (void *)HCI_UART_BCSP },
+ {},
+};
+MODULE_DEVICE_TABLE(of, hci_uart_of_match);
+
+static struct serio_driver serio_hci_uart_drv = {
+ .driver = {
+ .name = "hci-uart",
+ .of_match_table = of_match_ptr(hci_uart_of_match),
+ },
+ .description = "hci uart",
+ .write_wakeup = hci_uart_serio_wakeup,
+ .receive_buf = hci_uart_serio_receive,
+ .connect = hci_uart_connect,
+ .disconnect = hci_uart_disconnect,
+};

+module_serio_driver(serio_hci_uart_drv);
+
+static int __init hci_uart_init(void)
+{
#ifdef CONFIG_BT_HCIUART_H4
h4_init();
#endif
@@ -816,8 +775,6 @@ static int __init hci_uart_init(void)

static void __exit hci_uart_exit(void)
{
- int err;
-
#ifdef CONFIG_BT_HCIUART_H4
h4_deinit();
#endif
@@ -845,11 +802,6 @@ static void __exit hci_uart_exit(void)
#ifdef CONFIG_BT_HCIUART_AG6XX
ag6xx_deinit();
#endif
-
- /* Release tty registration of line discipline */
- err = tty_unregister_ldisc(N_HCI);
- if (err)
- BT_ERR("Can't unregister HCI line discipline (%d)", err);
}

module_init(hci_uart_init);
@@ -859,4 +811,3 @@ MODULE_AUTHOR("Marcel Holtmann <marcel@xxxxxxxxxxxx>");
MODULE_DESCRIPTION("Bluetooth HCI UART driver ver " VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");
-MODULE_ALIAS_LDISC(N_HCI);
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index 839bad1..c48dddc 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -73,8 +73,11 @@ struct hci_uart_proto {
struct sk_buff *(*dequeue)(struct hci_uart *hu);
};

+struct serio;
+
struct hci_uart {
struct tty_struct *tty;
+ struct serio *serio;
struct hci_dev *hdev;
unsigned long flags;
unsigned long hdev_flags;
--
2.9.3

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