[PATCH 5/6] tty: serial: 8250-core: add rs485 support
From: One Thousand Gnomes <hidden>
Date: 2014-07-10 14:53:17
Also in:
linux-omap, linux-serial, lkml
static inline void __stop_tx(struct uart_8250_port *p)
{
+ if (p->rs485.flags & SER_RS485_ENABLED) {
+ int ret;
+
+ ret = (p->rs485.flags & SER_RS485_RTS_AFTER_SEND) ? 1 : 0;
+ if (gpio_get_value(p->rts_gpio) != ret) {
+ if (p->rs485.delay_rts_after_send > 0)
+ mdelay(p->rs485.delay_rts_after_send);
+ gpio_set_value(p->rts_gpio, ret);
+ }RTS is not normally a GPIO. We should be controlling the UART RTS here, and if the UART has a magic special case RTS wired to a GPIO then really the hardware specific part should handle that gunge. I don't care whether the drive does it via serial_out magic or a more explicit hook but it doesn't belong here in core code. Likewise the mdelay probably should be in the device specific bits or controlled by a flag as not all hardware is so braindead.
quoted hunk ↗ jump to hunk
@@ -1330,6 +1356,20 @@ static void serial8250_start_tx(struct uart_port *port) if (up->dma && !serial8250_tx_dma(up)) {
Ditto
+int serial8250_probe_rs485(struct uart_8250_port *up,
+ struct device *dev)
+{
+ struct serial_rs485 *rs485conf = &up->rs485;
+ struct device_node *np = dev->of_node;
+ u32 rs485_delay[2];
+ enum of_gpio_flags flags;
+ int ret;
+
+ rs485conf->flags = 0;
+ if (!np)
+ return 0;
+
+ /* check for tx enable gpio */
+ up->rts_gpio = of_get_named_gpio_flags(np, "rts-gpio", 0, &flags);No of_ dependencies in core 8250.c either please. That looks a perfectly good implementation of serial8250_of_probe_rs485 however, just belongs in the right place.
+static int serial8250_ioctl(struct uart_port *port, unsigned int cmd,
+ unsigned long arg)
+{
+ struct serial_rs485 rs485conf;
+ struct uart_8250_port *up;
+
+ up = container_of(port, struct uart_8250_port, port);
+ switch (cmd) {
+ case TIOCSRS485:
+ if (!gpio_is_valid(up->rts_gpio))
+ return -ENODEV;GPIO assumption again needs to go
quoted hunk ↗ jump to hunk
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h index 0ec21ec..056a73f 100644 --- a/include/linux/serial_8250.h +++ b/include/linux/serial_8250.h@@ -78,6 +78,7 @@ struct uart_8250_port { unsigned char acr; unsigned char ier; unsigned char lcr; + unsigned char fcr; unsigned char mcr; unsigned char mcr_mask; /* mask of user bits */ unsigned char mcr_force; /* mask of forced bits */@@ -94,6 +95,9 @@ struct uart_8250_port { unsigned char msr_saved_flags; struct uart_8250_dma *dma; + struct serial_rs485 rs485; + int rts_gpio; + bool rts_gpio_valid;
Keeping the gpio here doesn't look unreasonable if one is in use. Alan