diff options
Diffstat (limited to 'target/linux/ath79/patches-5.4/0061-tty-serial-ar933x-uart-rs485-gpio.patch')
| -rw-r--r-- | target/linux/ath79/patches-5.4/0061-tty-serial-ar933x-uart-rs485-gpio.patch | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/target/linux/ath79/patches-5.4/0061-tty-serial-ar933x-uart-rs485-gpio.patch b/target/linux/ath79/patches-5.4/0061-tty-serial-ar933x-uart-rs485-gpio.patch new file mode 100644 index 0000000000..54811eb4c1 --- /dev/null +++ b/target/linux/ath79/patches-5.4/0061-tty-serial-ar933x-uart-rs485-gpio.patch @@ -0,0 +1,267 @@ +From patchwork Fri Feb 21 21:23:31 2020 +Content-Type: text/plain; charset="utf-8" +MIME-Version: 1.0 +Content-Transfer-Encoding: 7bit +X-Patchwork-Submitter: Daniel Golle <daniel@makrotopia.org> +X-Patchwork-Id: 1198835 +Date: Fri, 21 Feb 2020 22:23:31 +0100 +From: Daniel Golle <daniel@makrotopia.org> +To: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org +Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, + Jiri Slaby <jslaby@suse.com>, Petr =?utf-8?q?=C5=A0tetiar?= <ynezz@true.cz>, + Chuanhong Guo <gch981213@gmail.com>, Piotr Dymacz <pepe2k@gmail.com> +Subject: [PATCH v2] serial: ar933x_uart: add RS485 support +Message-ID: <20200221212331.GA21467@makrotopia.org> +MIME-Version: 1.0 +Content-Disposition: inline +Sender: linux-kernel-owner@vger.kernel.org +Precedence: bulk +List-ID: <linux-kernel.vger.kernel.org> +X-Mailing-List: linux-kernel@vger.kernel.org + +Emulate half-duplex operation and use mctrl_gpio to add support for +RS485 tranceiver with transmit/receive switch hooked to RTS GPIO line. +This is needed to make use of the RS485 port found on Teltonika RUT955. + +Signed-off-by: Daniel Golle <daniel@makrotopia.org> +--- +v2: use bool to indicate ongoing half-duplex send, use it afterwards + to decide whether we've just been in a send operation. + + drivers/tty/serial/Kconfig | 1 + + drivers/tty/serial/ar933x_uart.c | 113 +++++++++++++++++++++++++++++-- + 2 files changed, 108 insertions(+), 6 deletions(-) + +--- a/drivers/tty/serial/Kconfig ++++ b/drivers/tty/serial/Kconfig +@@ -1279,6 +1279,7 @@ config SERIAL_AR933X + tristate "AR933X serial port support" + depends on HAVE_CLK && ATH79 + select SERIAL_CORE ++ select SERIAL_MCTRL_GPIO if GPIOLIB + help + If you have an Atheros AR933X SOC based board and want to use the + built-in UART of the SoC, say Y to this option. +--- a/drivers/tty/serial/ar933x_uart.c ++++ b/drivers/tty/serial/ar933x_uart.c +@@ -13,6 +13,7 @@ + #include <linux/console.h> + #include <linux/sysrq.h> + #include <linux/delay.h> ++#include <linux/gpio/consumer.h> + #include <linux/platform_device.h> + #include <linux/of.h> + #include <linux/of_platform.h> +@@ -29,6 +30,8 @@ + + #include <asm/mach-ath79/ar933x_uart.h> + ++#include "serial_mctrl_gpio.h" ++ + #define DRIVER_NAME "ar933x-uart" + + #define AR933X_UART_MAX_SCALE 0xff +@@ -47,6 +50,8 @@ struct ar933x_uart_port { + unsigned int min_baud; + unsigned int max_baud; + struct clk *clk; ++ struct mctrl_gpios *gpios; ++ struct gpio_desc *rts_gpiod; + }; + + static inline unsigned int ar933x_uart_read(struct ar933x_uart_port *up, +@@ -100,6 +105,18 @@ static inline void ar933x_uart_stop_tx_i + ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); + } + ++static inline void ar933x_uart_start_rx_interrupt(struct ar933x_uart_port *up) ++{ ++ up->ier |= AR933X_UART_INT_RX_VALID; ++ ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); ++} ++ ++static inline void ar933x_uart_stop_rx_interrupt(struct ar933x_uart_port *up) ++{ ++ up->ier &= ~AR933X_UART_INT_RX_VALID; ++ ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); ++} ++ + static inline void ar933x_uart_putc(struct ar933x_uart_port *up, int ch) + { + unsigned int rdata; +@@ -125,11 +142,21 @@ static unsigned int ar933x_uart_tx_empty + + static unsigned int ar933x_uart_get_mctrl(struct uart_port *port) + { +- return TIOCM_CAR; ++ struct ar933x_uart_port *up = ++ container_of(port, struct ar933x_uart_port, port); ++ int ret = TIOCM_CTS | TIOCM_DSR | TIOCM_CAR; ++ ++ mctrl_gpio_get(up->gpios, &ret); ++ ++ return ret; + } + + static void ar933x_uart_set_mctrl(struct uart_port *port, unsigned int mctrl) + { ++ struct ar933x_uart_port *up = ++ container_of(port, struct ar933x_uart_port, port); ++ ++ mctrl_gpio_set(up->gpios, mctrl); + } + + static void ar933x_uart_start_tx(struct uart_port *port) +@@ -140,6 +167,37 @@ static void ar933x_uart_start_tx(struct + ar933x_uart_start_tx_interrupt(up); + } + ++static void ar933x_uart_wait_tx_complete(struct ar933x_uart_port *up) ++{ ++ unsigned int status; ++ unsigned int timeout = 60000; ++ ++ /* Wait up to 60ms for the character(s) to be sent. */ ++ do { ++ status = ar933x_uart_read(up, AR933X_UART_CS_REG); ++ if (--timeout == 0) ++ break; ++ udelay(1); ++ } while (status & AR933X_UART_CS_TX_BUSY); ++ ++ if (timeout == 0) ++ dev_err(up->port.dev, "waiting for TX timed out\n"); ++} ++ ++static void ar933x_uart_rx_flush(struct ar933x_uart_port *up) ++{ ++ unsigned int status; ++ ++ /* clear RX_VALID interrupt */ ++ ar933x_uart_write(up, AR933X_UART_INT_REG, AR933X_UART_INT_RX_VALID); ++ ++ /* remove characters from the RX FIFO */ ++ do { ++ ar933x_uart_write(up, AR933X_UART_DATA_REG, AR933X_UART_DATA_RX_CSR); ++ status = ar933x_uart_read(up, AR933X_UART_DATA_REG); ++ } while (status & AR933X_UART_DATA_RX_CSR); ++} ++ + static void ar933x_uart_stop_tx(struct uart_port *port) + { + struct ar933x_uart_port *up = +@@ -153,8 +211,7 @@ static void ar933x_uart_stop_rx(struct u + struct ar933x_uart_port *up = + container_of(port, struct ar933x_uart_port, port); + +- up->ier &= ~AR933X_UART_INT_RX_VALID; +- ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); ++ ar933x_uart_stop_rx_interrupt(up); + } + + static void ar933x_uart_break_ctl(struct uart_port *port, int break_state) +@@ -336,11 +393,20 @@ static void ar933x_uart_rx_chars(struct + static void ar933x_uart_tx_chars(struct ar933x_uart_port *up) + { + struct circ_buf *xmit = &up->port.state->xmit; ++ struct serial_rs485 *rs485conf = &up->port.rs485; + int count; ++ bool half_duplex_send = false; + + if (uart_tx_stopped(&up->port)) + return; + ++ if ((rs485conf->flags & SER_RS485_ENABLED) && ++ (up->port.x_char || !uart_circ_empty(xmit))) { ++ ar933x_uart_stop_rx_interrupt(up); ++ gpiod_set_value(up->rts_gpiod, !!(rs485conf->flags & SER_RS485_RTS_ON_SEND)); ++ half_duplex_send = true; ++ } ++ + count = up->port.fifosize; + do { + unsigned int rdata; +@@ -368,8 +434,14 @@ static void ar933x_uart_tx_chars(struct + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) + uart_write_wakeup(&up->port); + +- if (!uart_circ_empty(xmit)) ++ if (!uart_circ_empty(xmit)) { + ar933x_uart_start_tx_interrupt(up); ++ } else if (half_duplex_send) { ++ ar933x_uart_wait_tx_complete(up); ++ ar933x_uart_rx_flush(up); ++ ar933x_uart_start_rx_interrupt(up); ++ gpiod_set_value(up->rts_gpiod, !!(rs485conf->flags & SER_RS485_RTS_AFTER_SEND)); ++ } + } + + static irqreturn_t ar933x_uart_interrupt(int irq, void *dev_id) +@@ -427,8 +499,7 @@ static int ar933x_uart_startup(struct ua + AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE); + + /* Enable RX interrupts */ +- up->ier = AR933X_UART_INT_RX_VALID; +- ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier); ++ ar933x_uart_start_rx_interrupt(up); + + spin_unlock_irqrestore(&up->port.lock, flags); + +@@ -511,6 +582,21 @@ static const struct uart_ops ar933x_uart + .verify_port = ar933x_uart_verify_port, + }; + ++static int ar933x_config_rs485(struct uart_port *port, ++ struct serial_rs485 *rs485conf) ++{ ++ struct ar933x_uart_port *up = ++ container_of(port, struct ar933x_uart_port, port); ++ ++ if ((rs485conf->flags & SER_RS485_ENABLED) && ++ !up->rts_gpiod) { ++ dev_err(port->dev, "RS485 needs rts-gpio\n"); ++ return 1; ++ } ++ port->rs485 = *rs485conf; ++ return 0; ++} ++ + #ifdef CONFIG_SERIAL_AR933X_CONSOLE + static struct ar933x_uart_port * + ar933x_console_ports[CONFIG_SERIAL_AR933X_NR_UARTS]; +@@ -680,6 +766,8 @@ static int ar933x_uart_probe(struct plat + goto err_disable_clk; + } + ++ uart_get_rs485_mode(&pdev->dev, &port->rs485); ++ + port->mapbase = mem_res->start; + port->line = id; + port->irq = irq_res->start; +@@ -690,6 +778,7 @@ static int ar933x_uart_probe(struct plat + port->regshift = 2; + port->fifosize = AR933X_UART_FIFO_SIZE; + port->ops = &ar933x_uart_ops; ++ port->rs485_config = ar933x_config_rs485; + + baud = ar933x_uart_get_baud(port->uartclk, AR933X_UART_MAX_SCALE, 1); + up->min_baud = max_t(unsigned int, baud, AR933X_UART_MIN_BAUD); +@@ -697,6 +786,18 @@ static int ar933x_uart_probe(struct plat + baud = ar933x_uart_get_baud(port->uartclk, 0, AR933X_UART_MAX_STEP); + up->max_baud = min_t(unsigned int, baud, AR933X_UART_MAX_BAUD); + ++ up->gpios = mctrl_gpio_init(port, 0); ++ if (IS_ERR(up->gpios) && PTR_ERR(up->gpios) != -ENOSYS) ++ return PTR_ERR(up->gpios); ++ ++ up->rts_gpiod = mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_RTS); ++ ++ if ((port->rs485.flags & SER_RS485_ENABLED) && ++ !up->rts_gpiod) { ++ dev_err(&pdev->dev, "lacking rts-gpio, disabling RS485\n"); ++ port->rs485.flags &= ~SER_RS485_ENABLED; ++ } ++ + #ifdef CONFIG_SERIAL_AR933X_CONSOLE + ar933x_console_ports[up->port.line] = up; + #endif |