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greybus: uart: wait for credits on shutdown 

We should try to wait until all credits are accounted
for before returning from shutdown.

For this purpose add a helper function that will
wait on completion, and call it form the shutdown.
This helper will also be useful when "wait until sent" is
implemented.

Signed-off-by: Axel Haslam <ahaslam@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
hifive-unleashed-5.1
Axel Haslam 2016-05-31 14:36:13 +02:00 committed by Greg Kroah-Hartman
parent 2b3b87f056
commit 5dad5c314b
1 changed files with 31 additions and 0 deletions
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31
drivers/staging/greybus/uart.c
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@ -29,6 +29,7 @@
#include <linux/kdev_t.h>
#include <linux/kfifo.h>
#include <linux/workqueue.h>
#include <linux/completion.h>
#include "greybus.h"
#include "gbphy.h"
@ -39,6 +40,7 @@
#define GB_UART_WRITE_FIFO_SIZE PAGE_SIZE
#define GB_UART_WRITE_ROOM_MARGIN 1 /* leave some space in fifo */
#define GB_UART_FIRMWARE_CREDITS 4096
#define GB_UART_CREDIT_WAIT_TIMEOUT_MSEC 10000
struct gb_tty_line_coding {
__le32 rate;
@ -71,6 +73,7 @@ struct gb_tty {
struct kfifo write_fifo;
bool close_pending;
unsigned int credits;
struct completion credits_complete;
};
static struct tty_driver *gb_tty_driver;
@ -197,6 +200,9 @@ static int gb_uart_receive_credits_handler(struct gb_operation *op)
*/
tty_port_tty_wakeup(&gb_tty->port);
if (gb_tty->credits == GB_UART_FIRMWARE_CREDITS)
complete(&gb_tty->credits_complete);
return ret;
}
@ -317,6 +323,24 @@ static int send_break(struct gb_tty *gb_tty, u8 state)
&request, sizeof(request), NULL, 0);
}
static int gb_uart_wait_for_all_credits(struct gb_tty *gb_tty)
{
int ret;
if (gb_tty->credits == GB_UART_FIRMWARE_CREDITS)
return 0;
ret = wait_for_completion_timeout(&gb_tty->credits_complete,
msecs_to_jiffies(GB_UART_CREDIT_WAIT_TIMEOUT_MSEC));
if (!ret) {
dev_err(&gb_tty->gbphy_dev->dev,
"time out waiting for credits\n");
return -ETIMEDOUT;
}
return 0;
}
static int gb_uart_flush(struct gb_tty *gb_tty, u8 flags)
{
struct gb_uart_serial_flush_request request;
@ -765,12 +789,18 @@ static void gb_tty_port_shutdown(struct tty_port *port)
kfifo_reset_out(&gb_tty->write_fifo);
spin_unlock_irqrestore(&gb_tty->write_lock, flags);
if (gb_tty->credits == GB_UART_FIRMWARE_CREDITS)
goto out;
ret = gb_uart_flush(gb_tty, GB_SERIAL_FLAG_FLUSH_TRANSMITTER);
if (ret) {
dev_err(&gb_tty->gbphy_dev->dev,
"error flushing transmitter: %d\n", ret);
}
gb_uart_wait_for_all_credits(gb_tty);
out:
gb_tty->close_pending = false;
}
@ -842,6 +872,7 @@ static int gb_uart_probe(struct gbphy_device *gbphy_dev,
goto exit_buf_free;
gb_tty->credits = GB_UART_FIRMWARE_CREDITS;
init_completion(&gb_tty->credits_complete);
minor = alloc_minor(gb_tty);
if (minor < 0) {