diff options
| -rw-r--r-- | Documentation/driver-api/serial/driver.rst | 3 | ||||
| -rw-r--r-- | include/linux/serial_core.h | 80 |
2 files changed, 83 insertions, 0 deletions
diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst index 23c6b956cd90..98d268555dcc 100644 --- a/Documentation/driver-api/serial/driver.rst +++ b/Documentation/driver-api/serial/driver.rst @@ -78,6 +78,9 @@ Other functions uart_get_lsr_info uart_handle_dcd_change uart_handle_cts_change uart_try_toggle_sysrq uart_get_console +.. kernel-doc:: include/linux/serial_core.h + :identifiers: uart_port_tx_limited uart_port_tx + Other notes ----------- diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index d657f2a42a7b..dbbc4408bb19 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -664,6 +664,86 @@ struct uart_driver { void uart_write_wakeup(struct uart_port *port); +#define __uart_port_tx(uport, ch, tx_ready, put_char, tx_done, for_test, \ + for_post) \ +({ \ + struct uart_port *__port = (uport); \ + struct circ_buf *xmit = &__port->state->xmit; \ + unsigned int pending; \ + \ + for (; (for_test) && (tx_ready); (for_post), __port->icount.tx++) { \ + if (__port->x_char) { \ + (ch) = __port->x_char; \ + (put_char); \ + __port->x_char = 0; \ + continue; \ + } \ + \ + if (uart_circ_empty(xmit) || uart_tx_stopped(__port)) \ + break; \ + \ + (ch) = xmit->buf[xmit->tail]; \ + (put_char); \ + xmit->tail = (xmit->tail + 1) % UART_XMIT_SIZE; \ + } \ + \ + (tx_done); \ + \ + pending = uart_circ_chars_pending(xmit); \ + if (pending < WAKEUP_CHARS) { \ + uart_write_wakeup(__port); \ + \ + if (pending == 0) \ + __port->ops->stop_tx(__port); \ + } \ + \ + pending; \ +}) + +/** + * uart_port_tx_limited -- transmit helper for uart_port with count limiting + * @port: uart port + * @ch: variable to store a character to be written to the HW + * @count: a limit of characters to send + * @tx_ready: can HW accept more data function + * @put_char: function to write a character + * @tx_done: function to call after the loop is done + * + * This helper transmits characters from the xmit buffer to the hardware using + * @put_char(). It does so until @count characters are sent and while @tx_ready + * evaluates to true. + * + * Returns: the number of characters in the xmit buffer when done. + * + * The expression in macro parameters shall be designed as follows: + * * **tx_ready:** should evaluate to true if the HW can accept more data to + * be sent. This parameter can be %true, which means the HW is always ready. + * * **put_char:** shall write @ch to the device of @port. + * * **tx_done:** when the write loop is done, this can perform arbitrary + * action before potential invocation of ops->stop_tx() happens. If the + * driver does not need to do anything, use e.g. ({}). + * + * For all of them, @port->lock is held, interrupts are locally disabled and + * the expressions must not sleep. + */ +#define uart_port_tx_limited(port, ch, count, tx_ready, put_char, tx_done) ({ \ + unsigned int __count = (count); \ + __uart_port_tx(port, ch, tx_ready, put_char, tx_done, __count, \ + __count--); \ +}) + +/** + * uart_port_tx -- transmit helper for uart_port + * @port: uart port + * @ch: variable to store a character to be written to the HW + * @tx_ready: can HW accept more data function + * @put_char: function to write a character + * + * See uart_port_tx_limited() for more details. + */ +#define uart_port_tx(port, ch, tx_ready, put_char) \ + __uart_port_tx(port, ch, tx_ready, put_char, ({}), true, ({})) + /* * Baud rate helpers. */ |