| Message ID | 20231024144847.2316941-3-manikanta.guntupalli@amd.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add rs485 support to uartps driver | expand |
Manikanta Guntupalli wrote on 2023-10-24 16:48: > @@ -193,6 +196,7 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255"); > * @clk_rate_change_nb: Notifier block for clock changes > * @quirks: Flags for RXBS support. > * @cts_override: Modem control state override > + * @gpiod: Pointer to the gpio descriptor Change gpiod to gpiod_rts maybe? Later someone might want to use a gpio for cts/dtr/dsr/dcd/ri as well. > */ > struct cdns_uart { > struct uart_port *port; > @@ -203,10 +207,19 @@ struct cdns_uart { > struct notifier_block clk_rate_change_nb; > u32 quirks; > bool cts_override; > + struct gpio_desc *gpiod; > }; > struct cdns_platform_data { > u32 quirks; > }; > + > +struct serial_rs485 cdns_rs485_supported = { > + .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | > + SER_RS485_RTS_AFTER_SEND, > + .delay_rts_before_send = 1, > + .delay_rts_after_send = 1, > +}; > + > #define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \ > clk_rate_change_nb) > > @@ -305,6 +318,79 @@ static void cdns_uart_handle_rx(void *dev_id, > unsigned int isrstatus) > tty_flip_buffer_push(&port->state->port); > } > > +/** > + * cdns_rs485_config_gpio_rts_high - Configure GPIO/RTS to high > + * @cdns_uart: Handle to the cdns_uart > + */ > +static void cdns_rs485_config_gpio_rts_high(struct cdns_uart > *cdns_uart) > +{ > + u32 val; > + > + if (cdns_uart->gpiod) { > + gpiod_set_value(cdns_uart->gpiod, 1); > + } else { > + val = readl(cdns_uart->port->membase + CDNS_UART_MODEMCR); > + val &= ~CDNS_UART_MODEMCR_RTS; > + writel(val, cdns_uart->port->membase + CDNS_UART_MODEMCR); > + } > +} > + > +/** > + * cdns_rs485_config_gpio_rts_low - Configure GPIO/RTS to low > + * @cdns_uart: Handle to the cdns_uart > + */ > +static void cdns_rs485_config_gpio_rts_low(struct cdns_uart > *cdns_uart) > +{ > + u32 val; > + > + if (cdns_uart->gpiod) { > + gpiod_set_value(cdns_uart->gpiod, 0); > + } else { > + val = readl(cdns_uart->port->membase + CDNS_UART_MODEMCR); > + val |= CDNS_UART_MODEMCR_RTS; > + writel(val, cdns_uart->port->membase + CDNS_UART_MODEMCR); > + } > +} > + > +/** > + * cdns_rs485_tx_setup - Tx setup specific to rs485 > + * @cdns_uart: Handle to the cdns_uart > + */ > +static void cdns_rs485_tx_setup(struct cdns_uart *cdns_uart) > +{ > + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_ON_SEND) > + cdns_rs485_config_gpio_rts_high(cdns_uart); > + else > + cdns_rs485_config_gpio_rts_low(cdns_uart); > +} > + > +/** > + * cdns_rs485_rx_setup - Rx setup specific to rs485 > + * @cdns_uart: Handle to the cdns_uart > + */ > +static void cdns_rs485_rx_setup(struct cdns_uart *cdns_uart) > +{ > + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_AFTER_SEND) > + cdns_rs485_config_gpio_rts_high(cdns_uart); > + else > + cdns_rs485_config_gpio_rts_low(cdns_uart); > +} Why not simply create: void cdns_rs485_driver_enable(struct cdns_uart *cdns_uart, bool enable) And let it handle the rs485.flags itself? > + > +/** > + * cdns_uart_tx_empty - Check whether TX is empty > + * @port: Handle to the uart port structure > + * > + * Return: TIOCSER_TEMT on success, 0 otherwise > + */ > +static unsigned int cdns_uart_tx_empty(struct uart_port *port) > +{ > + unsigned int status; > + > + status = readl(port->membase + CDNS_UART_SR) & > + (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE); > + return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0; > +} > + > /** > * cdns_uart_handle_tx - Handle the bytes to be Txed. > * @dev_id: Id of the UART port > @@ -571,6 +657,8 @@ static int cdns_uart_clk_notifier_cb(struct > notifier_block *nb, > static void cdns_uart_start_tx(struct uart_port *port) > { > unsigned int status; > + unsigned long time_out; > + struct cdns_uart *cdns_uart = port->private_data; > > if (uart_tx_stopped(port)) > return; > @@ -589,8 +677,31 @@ static void cdns_uart_start_tx(struct uart_port > *port) > > writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR); > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { > + cdns_rs485_tx_setup(cdns_uart); > + if (cdns_uart->port->rs485.delay_rts_before_send) > + mdelay(cdns_uart->port->rs485.delay_rts_before_send); Would it not be better to start a timer here with a callback that enables the TXEMPTY interrupt? That would automatically call cdns_uart_handle_tx(). > + } > + > cdns_uart_handle_tx(port); > > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { > + time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT); > + /* Wait for tx completion */ > + while ((cdns_uart_tx_empty(cdns_uart->port) != TIOCSER_TEMT) && > + time_before(jiffies, time_out)) > + cpu_relax(); > + > + if (cdns_uart->port->rs485.delay_rts_after_send) > + mdelay(cdns_uart->port->rs485.delay_rts_after_send); > + > + /* > + * Default Rx should be setup, because RX signaling path > + * need to enable to receive data. > + */ > + cdns_rs485_rx_setup(cdns_uart); > + } I think this should be done from the TXEMPTY interrupt. And again schedule a timer to drop the DE line. You really can do this without using mdelay(). > + > /* Enable the TX Empty interrupt */ > writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER); > } > @@ -602,6 +713,14 @@ static void cdns_uart_start_tx(struct uart_port > *port) > static void cdns_uart_stop_tx(struct uart_port *port) > { > unsigned int regval; > + struct cdns_uart *cdns_uart = port->private_data; > + > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { > + if (cdns_uart->port->rs485.delay_rts_after_send) > + mdelay(cdns_uart->port->rs485.delay_rts_after_send); > + > + cdns_rs485_rx_setup(cdns_uart); > + } Again, start a timer and wait for completion? > regval = readl(port->membase + CDNS_UART_CR); > regval |= CDNS_UART_CR_TX_DIS; > @@ -626,21 +745,6 @@ static void cdns_uart_stop_rx(struct uart_port > *port) > writel(regval, port->membase + CDNS_UART_CR); > } > > -/** > - * cdns_uart_tx_empty - Check whether TX is empty > - * @port: Handle to the uart port structure > - * > - * Return: TIOCSER_TEMT on success, 0 otherwise > - */ > -static unsigned int cdns_uart_tx_empty(struct uart_port *port) > -{ > - unsigned int status; > - > - status = readl(port->membase + CDNS_UART_SR) & > - (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE); > - return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0; > -} > - > /** > * cdns_uart_break_ctl - Based on the input ctl we have to start or > stop > * transmitting char breaks > @@ -829,6 +933,9 @@ static int cdns_uart_startup(struct uart_port > *port) > (CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST)) > cpu_relax(); > > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) > + cdns_rs485_rx_setup(cdns_uart); > + > /* > * Clear the RX disable bit and then set the RX enable bit to enable > * the receiver. > @@ -1455,6 +1562,23 @@ MODULE_DEVICE_TABLE(of, cdns_uart_of_match); > /* Temporary variable for storing number of instances */ > static int instances; > > +/** > + * cdns_rs485_config - Called when an application calls TIOCSRS485 > ioctl. > + * @port: Pointer to the uart_port structure > + * @termios: Pointer to the ktermios structure > + * @rs485: Pointer to the serial_rs485 structure > + * > + * Return: 0 > + */ > +static int cdns_rs485_config(struct uart_port *port, struct ktermios > *termios, > + struct serial_rs485 *rs485) > +{ > + if (rs485->flags & SER_RS485_ENABLED) > + dev_dbg(port->dev, "Setting UART to RS485\n"); > + Shouldn't you force automatic RTS control off here? And also call cdns_rs485_rx_setup() > + return 0; > +} > + > /** > * cdns_uart_probe - Platform driver probe > * @pdev: Pointer to the platform device structure > @@ -1463,6 +1587,7 @@ static int instances; > */ > static int cdns_uart_probe(struct platform_device *pdev) > { > + u32 val; > int rc, id, irq; > struct uart_port *port; > struct resource *res; > @@ -1597,9 +1722,23 @@ static int cdns_uart_probe(struct > platform_device *pdev) > port->private_data = cdns_uart_data; > port->read_status_mask = CDNS_UART_IXR_TXEMPTY | CDNS_UART_IXR_RXTRIG > | > CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_TOUT; > + port->rs485_config = cdns_rs485_config; > + port->rs485_supported = cdns_rs485_supported; > cdns_uart_data->port = port; > platform_set_drvdata(pdev, port); > > + rc = uart_get_rs485_mode(port); > + if (rc) > + goto err_out_clk_notifier; > + > + cdns_uart_data->gpiod = devm_gpiod_get_optional(&pdev->dev, "rts", > + GPIOD_OUT_LOW); > + if (IS_ERR(cdns_uart_data->gpiod)) { > + rc = PTR_ERR(cdns_uart_data->gpiod); > + dev_err(port->dev, "xuartps: devm_gpiod_get_optional failed\n"); > + goto err_out_clk_notifier; > + } > + > pm_runtime_use_autosuspend(&pdev->dev); > pm_runtime_set_autosuspend_delay(&pdev->dev, > UART_AUTOSUSPEND_TIMEOUT); > pm_runtime_set_active(&pdev->dev); > @@ -1638,6 +1777,16 @@ static int cdns_uart_probe(struct > platform_device *pdev) > cdns_uart_data->cts_override = > of_property_read_bool(pdev->dev.of_node, > "cts-override"); > > + if (cdns_uart_data->port->rs485.flags & SER_RS485_ENABLED) { > + if (!cdns_uart_data->gpiod) { > + val = readl(cdns_uart_data->port->membase > + + CDNS_UART_MODEMCR); > + val |= CDNS_UART_MODEMCR_RTS; > + writel(val, cdns_uart_data->port->membase > + + CDNS_UART_MODEMCR); > + } > + } Simply call cdns_rs485_rx_setup() ? > + > instances++; > > return 0; > @@ -1646,6 +1795,7 @@ static int cdns_uart_probe(struct platform_device > *pdev) > pm_runtime_disable(&pdev->dev); > pm_runtime_set_suspended(&pdev->dev); > pm_runtime_dont_use_autosuspend(&pdev->dev); > +err_out_clk_notifier: > #ifdef CONFIG_COMMON_CLK > clk_notifier_unregister(cdns_uart_data->uartclk, > &cdns_uart_data->clk_rate_change_nb); Please also modify cdns_uart_[s|g]et_mctrl() so they support rts-gpios. Maarten
Hi, On 24.10.23 16:48, Manikanta Guntupalli wrote: > Add rs485 support to uartps driver. Use either rts-gpios or RTS > to control RS485 phy as driver or a receiver. > > Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com> > --- > Changes for V2: > Modify optional gpio name to xlnx,phy-ctrl-gpios. > Update commit description. > Add support for RTS, delay_rts_before_send and delay_rts_after_send in RS485 mode. > Changes for V3: > Modify optional gpio name to rts-gpios. > Update commit description. > Move cdns_uart_tx_empty function to avoid prototype statement. > Remove assignment of struct serial_rs485 to port->rs485 as > serial core performs that. > Switch to native RTS in non GPIO case. > Handle rs485 during stop tx. > Remove explicit calls to configure gpio direction and value, > as devm_gpiod_get_optional performs that by using GPIOD_OUT_LOW argument. > Update implementation to support configuration of GPIO/RTS value > based on user configuration of SER_RS485_RTS_ON_SEND and > SER_RS485_RTS_AFTER_SEND. Move implementation to start_tx from handle_tx. > --- > drivers/tty/serial/xilinx_uartps.c | 180 ++++++++++++++++++++++++++--- > 1 file changed, 165 insertions(+), 15 deletions(-) > > diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c > index 9c13dac1d4d1..32229cf5c508 100644 > --- a/drivers/tty/serial/xilinx_uartps.c > +++ b/drivers/tty/serial/xilinx_uartps.c > @@ -23,6 +23,9 @@ > #include <linux/module.h> > #include <linux/pm_runtime.h> > #include <linux/iopoll.h> > +#include <linux/gpio.h> > +#include <linux/gpio/consumer.h> > +#include <linux/delay.h> > > #define CDNS_UART_TTY_NAME "ttyPS" > #define CDNS_UART_NAME "xuartps" > @@ -193,6 +196,7 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255"); > * @clk_rate_change_nb: Notifier block for clock changes > * @quirks: Flags for RXBS support. > * @cts_override: Modem control state override > + * @gpiod: Pointer to the gpio descriptor > */ > struct cdns_uart { > struct uart_port *port; > @@ -203,10 +207,19 @@ struct cdns_uart { > struct notifier_block clk_rate_change_nb; > u32 quirks; > bool cts_override; > + struct gpio_desc *gpiod; > }; > struct cdns_platform_data { > u32 quirks; > }; > + > +struct serial_rs485 cdns_rs485_supported = { > + .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | > + SER_RS485_RTS_AFTER_SEND, > + .delay_rts_before_send = 1, > + .delay_rts_after_send = 1, > +}; > + > #define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \ > clk_rate_change_nb) > > @@ -305,6 +318,79 @@ static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus) > tty_flip_buffer_push(&port->state->port); > } > > +/** > + * cdns_rs485_config_gpio_rts_high - Configure GPIO/RTS to high > + * @cdns_uart: Handle to the cdns_uart > + */ > +static void cdns_rs485_config_gpio_rts_high(struct cdns_uart *cdns_uart) > +{ > + u32 val; > + > + if (cdns_uart->gpiod) { > + gpiod_set_value(cdns_uart->gpiod, 1); > + } else { > + val = readl(cdns_uart->port->membase + CDNS_UART_MODEMCR); > + val &= ~CDNS_UART_MODEMCR_RTS; > + writel(val, cdns_uart->port->membase + CDNS_UART_MODEMCR); > + } > +} > + > +/** > + * cdns_rs485_config_gpio_rts_low - Configure GPIO/RTS to low > + * @cdns_uart: Handle to the cdns_uart > + */ > +static void cdns_rs485_config_gpio_rts_low(struct cdns_uart *cdns_uart) > +{ > + u32 val; > + > + if (cdns_uart->gpiod) { > + gpiod_set_value(cdns_uart->gpiod, 0); > + } else { > + val = readl(cdns_uart->port->membase + CDNS_UART_MODEMCR); > + val |= CDNS_UART_MODEMCR_RTS; > + writel(val, cdns_uart->port->membase + CDNS_UART_MODEMCR); > + } > +} > + > +/** > + * cdns_rs485_tx_setup - Tx setup specific to rs485 > + * @cdns_uart: Handle to the cdns_uart > + */ > +static void cdns_rs485_tx_setup(struct cdns_uart *cdns_uart) > +{ > + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_ON_SEND) > + cdns_rs485_config_gpio_rts_high(cdns_uart); > + else > + cdns_rs485_config_gpio_rts_low(cdns_uart); > +} > + > +/** > + * cdns_rs485_rx_setup - Rx setup specific to rs485 > + * @cdns_uart: Handle to the cdns_uart > + */ > +static void cdns_rs485_rx_setup(struct cdns_uart *cdns_uart) > +{ > + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_AFTER_SEND) > + cdns_rs485_config_gpio_rts_high(cdns_uart); > + else > + cdns_rs485_config_gpio_rts_low(cdns_uart); > +} > + > +/** > + * cdns_uart_tx_empty - Check whether TX is empty > + * @port: Handle to the uart port structure > + * > + * Return: TIOCSER_TEMT on success, 0 otherwise > + */ > +static unsigned int cdns_uart_tx_empty(struct uart_port *port) > +{ > + unsigned int status; > + > + status = readl(port->membase + CDNS_UART_SR) & > + (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE); > + return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0; > +} > + > /** > * cdns_uart_handle_tx - Handle the bytes to be Txed. > * @dev_id: Id of the UART port > @@ -571,6 +657,8 @@ static int cdns_uart_clk_notifier_cb(struct notifier_block *nb, > static void cdns_uart_start_tx(struct uart_port *port) > { > unsigned int status; > + unsigned long time_out; > + struct cdns_uart *cdns_uart = port->private_data; > > if (uart_tx_stopped(port)) > return; > @@ -589,8 +677,31 @@ static void cdns_uart_start_tx(struct uart_port *port) > > writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR); > > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { > + cdns_rs485_tx_setup(cdns_uart); > + if (cdns_uart->port->rs485.delay_rts_before_send) > + mdelay(cdns_uart->port->rs485.delay_rts_before_send); So, this will be executed each time (including the rts_before_send delay) the core wants to send data? This is not how it is supposed to work: The tx setup (and the delay before send) has to be done once when transmission starts. Note that when sending a bulk of data the core may call cdns_uart_start_tx() several times before it eventually calls cdns_uart_stop_tx() to stop the transmission. > + } > + > cdns_uart_handle_tx(port); > > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { > + time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT); > + /* Wait for tx completion */ > + while ((cdns_uart_tx_empty(cdns_uart->port) != TIOCSER_TEMT) && > + time_before(jiffies, time_out)) > + cpu_relax(); > + > + if (cdns_uart->port->rs485.delay_rts_after_send) > + mdelay(cdns_uart->port->rs485.delay_rts_after_send); > + > + /* > + * Default Rx should be setup, because RX signaling path > + * need to enable to receive data. > + */ > + cdns_rs485_rx_setup(cdns_uart); > + } > + > /* Enable the TX Empty interrupt */ > writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER); > } > @@ -602,6 +713,14 @@ static void cdns_uart_start_tx(struct uart_port *port) > static void cdns_uart_stop_tx(struct uart_port *port) > { > unsigned int regval; > + struct cdns_uart *cdns_uart = port->private_data; > + > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { > + if (cdns_uart->port->rs485.delay_rts_after_send) > + mdelay(cdns_uart->port->rs485.delay_rts_after_send); > + > + cdns_rs485_rx_setup(cdns_uart); > + } > > regval = readl(port->membase + CDNS_UART_CR); > regval |= CDNS_UART_CR_TX_DIS; > @@ -626,21 +745,6 @@ static void cdns_uart_stop_rx(struct uart_port *port) > writel(regval, port->membase + CDNS_UART_CR); > } > > -/** > - * cdns_uart_tx_empty - Check whether TX is empty > - * @port: Handle to the uart port structure > - * > - * Return: TIOCSER_TEMT on success, 0 otherwise > - */ > -static unsigned int cdns_uart_tx_empty(struct uart_port *port) > -{ > - unsigned int status; > - > - status = readl(port->membase + CDNS_UART_SR) & > - (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE); > - return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0; > -} > - > /** > * cdns_uart_break_ctl - Based on the input ctl we have to start or stop > * transmitting char breaks > @@ -829,6 +933,9 @@ static int cdns_uart_startup(struct uart_port *port) > (CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST)) > cpu_relax(); > > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) > + cdns_rs485_rx_setup(cdns_uart); > + > /* > * Clear the RX disable bit and then set the RX enable bit to enable > * the receiver. > @@ -1455,6 +1562,23 @@ MODULE_DEVICE_TABLE(of, cdns_uart_of_match); > /* Temporary variable for storing number of instances */ > static int instances; > > +/** > + * cdns_rs485_config - Called when an application calls TIOCSRS485 ioctl. > + * @port: Pointer to the uart_port structure > + * @termios: Pointer to the ktermios structure > + * @rs485: Pointer to the serial_rs485 structure > + * > + * Return: 0 > + */ > +static int cdns_rs485_config(struct uart_port *port, struct ktermios *termios, > + struct serial_rs485 *rs485) > +{ > + if (rs485->flags & SER_RS485_ENABLED) > + dev_dbg(port->dev, "Setting UART to RS485\n"); > + > + return 0; > +} So what if userspace changes the RS485 configuration? When does it take effect? > + > /** > * cdns_uart_probe - Platform driver probe > * @pdev: Pointer to the platform device structure > @@ -1463,6 +1587,7 @@ static int instances; > */ > static int cdns_uart_probe(struct platform_device *pdev) > { > + u32 val; > int rc, id, irq; > struct uart_port *port; > struct resource *res; > @@ -1597,9 +1722,23 @@ static int cdns_uart_probe(struct platform_device *pdev) > port->private_data = cdns_uart_data; > port->read_status_mask = CDNS_UART_IXR_TXEMPTY | CDNS_UART_IXR_RXTRIG | > CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_TOUT; > + port->rs485_config = cdns_rs485_config; > + port->rs485_supported = cdns_rs485_supported; > cdns_uart_data->port = port; > platform_set_drvdata(pdev, port); > > + rc = uart_get_rs485_mode(port); > + if (rc) > + goto err_out_clk_notifier; > + > + cdns_uart_data->gpiod = devm_gpiod_get_optional(&pdev->dev, "rts", > + GPIOD_OUT_LOW); > + if (IS_ERR(cdns_uart_data->gpiod)) { > + rc = PTR_ERR(cdns_uart_data->gpiod); > + dev_err(port->dev, "xuartps: devm_gpiod_get_optional failed\n"); Why bail out with an error if having cdns_uart_data->gpiod is only optional? > + goto err_out_clk_notifier; > + } > + > pm_runtime_use_autosuspend(&pdev->dev); > pm_runtime_set_autosuspend_delay(&pdev->dev, UART_AUTOSUSPEND_TIMEOUT); > pm_runtime_set_active(&pdev->dev); > @@ -1638,6 +1777,16 @@ static int cdns_uart_probe(struct platform_device *pdev) > cdns_uart_data->cts_override = of_property_read_bool(pdev->dev.of_node, > "cts-override"); > > + if (cdns_uart_data->port->rs485.flags & SER_RS485_ENABLED) { > + if (!cdns_uart_data->gpiod) { > + val = readl(cdns_uart_data->port->membase > + + CDNS_UART_MODEMCR); > + val |= CDNS_UART_MODEMCR_RTS; > + writel(val, cdns_uart_data->port->membase > + + CDNS_UART_MODEMCR); > + } > + } This covers the RTS_AFTER_SEND mode. What if SER_RS485_RTS_ON_SEND is configured instead (as it is the default set by uart_get_rs485_mode())? What if cdns_uart_data->gpiod exists? Why not simply call cdns_rs485_rx_setup() which covers all these cases? Note that uart_add_one_port() will call into the serial core and eventually result in an initial call to the ports rs485_config function (see uart_rs485_config()). So maybe put the initial configuration into that function and remove the above code. However in this case cdns_uart_data->cts_override = of_property_read_bool(pdev->dev.of_node, "cts-override"); should be called before uart_add_one_port(). Regards, Lino
Hi, > -----Original Message----- > From: Lino Sanfilippo <LinoSanfilippo@gmx.de> > Sent: Monday, November 13, 2023 1:08 AM > To: Guntupalli, Manikanta <manikanta.guntupalli@amd.com>; git (AMD- > Xilinx) <git@amd.com>; Simek, Michal <michal.simek@amd.com>; > gregkh@linuxfoundation.org; robh+dt@kernel.org; > krzysztof.kozlowski+dt@linaro.org; conor+dt@kernel.org; linux- > serial@vger.kernel.org; devicetree@vger.kernel.org; linux- > kernel@vger.kernel.org; jirislaby@kernel.org; linux-arm- > kernel@lists.infradead.org > Cc: Pandey, Radhey Shyam <radhey.shyam.pandey@amd.com>; Goud, > Srinivas <srinivas.goud@amd.com>; Datta, Shubhrajyoti > <shubhrajyoti.datta@amd.com>; manion05gk@gmail.com > Subject: Re: [PATCH V3 2/2] tty: serial: uartps: Add rs485 support to uartps > driver > > Hi, > > On 24.10.23 16:48, Manikanta Guntupalli wrote: > > Add rs485 support to uartps driver. Use either rts-gpios or RTS to > > control RS485 phy as driver or a receiver. > > > > Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com> > > --- > > Changes for V2: > > Modify optional gpio name to xlnx,phy-ctrl-gpios. > > Update commit description. > > Add support for RTS, delay_rts_before_send and delay_rts_after_send in > RS485 mode. > > Changes for V3: > > Modify optional gpio name to rts-gpios. > > Update commit description. > > Move cdns_uart_tx_empty function to avoid prototype statement. > > Remove assignment of struct serial_rs485 to port->rs485 as serial core > > performs that. > > Switch to native RTS in non GPIO case. > > Handle rs485 during stop tx. > > Remove explicit calls to configure gpio direction and value, as > > devm_gpiod_get_optional performs that by using GPIOD_OUT_LOW > argument. > > Update implementation to support configuration of GPIO/RTS value based > > on user configuration of SER_RS485_RTS_ON_SEND and > > SER_RS485_RTS_AFTER_SEND. Move implementation to start_tx from > handle_tx. > > --- > > drivers/tty/serial/xilinx_uartps.c | 180 > > ++++++++++++++++++++++++++--- > > 1 file changed, 165 insertions(+), 15 deletions(-) > > > > diff --git a/drivers/tty/serial/xilinx_uartps.c > > b/drivers/tty/serial/xilinx_uartps.c > > index 9c13dac1d4d1..32229cf5c508 100644 > > --- a/drivers/tty/serial/xilinx_uartps.c > > +++ b/drivers/tty/serial/xilinx_uartps.c > > @@ -23,6 +23,9 @@ > > #include <linux/module.h> > > #include <linux/pm_runtime.h> > > #include <linux/iopoll.h> > > +#include <linux/gpio.h> > > +#include <linux/gpio/consumer.h> > > +#include <linux/delay.h> > > > > #define CDNS_UART_TTY_NAME "ttyPS" > > #define CDNS_UART_NAME "xuartps" > > @@ -193,6 +196,7 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1- > 255"); > > * @clk_rate_change_nb: Notifier block for clock changes > > * @quirks: Flags for RXBS support. > > * @cts_override: Modem control state override > > + * @gpiod: Pointer to the gpio descriptor > > */ > > struct cdns_uart { > > struct uart_port *port; > > @@ -203,10 +207,19 @@ struct cdns_uart { > > struct notifier_block clk_rate_change_nb; > > u32 quirks; > > bool cts_override; > > + struct gpio_desc *gpiod; > > }; > > struct cdns_platform_data { > > u32 quirks; > > }; > > + > > +struct serial_rs485 cdns_rs485_supported = { > > + .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | > > + SER_RS485_RTS_AFTER_SEND, > > + .delay_rts_before_send = 1, > > + .delay_rts_after_send = 1, > > +}; > > + > > #define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \ > > clk_rate_change_nb) > > > > @@ -305,6 +318,79 @@ static void cdns_uart_handle_rx(void *dev_id, > unsigned int isrstatus) > > tty_flip_buffer_push(&port->state->port); > > } > > > > +/** > > + * cdns_rs485_config_gpio_rts_high - Configure GPIO/RTS to high > > + * @cdns_uart: Handle to the cdns_uart */ static void > > +cdns_rs485_config_gpio_rts_high(struct cdns_uart *cdns_uart) { > > + u32 val; > > + > > + if (cdns_uart->gpiod) { > > + gpiod_set_value(cdns_uart->gpiod, 1); > > + } else { > > + val = readl(cdns_uart->port->membase + > CDNS_UART_MODEMCR); > > + val &= ~CDNS_UART_MODEMCR_RTS; > > + writel(val, cdns_uart->port->membase + > CDNS_UART_MODEMCR); > > + } > > +} > > + > > +/** > > + * cdns_rs485_config_gpio_rts_low - Configure GPIO/RTS to low > > + * @cdns_uart: Handle to the cdns_uart */ static void > > +cdns_rs485_config_gpio_rts_low(struct cdns_uart *cdns_uart) { > > + u32 val; > > + > > + if (cdns_uart->gpiod) { > > + gpiod_set_value(cdns_uart->gpiod, 0); > > + } else { > > + val = readl(cdns_uart->port->membase + > CDNS_UART_MODEMCR); > > + val |= CDNS_UART_MODEMCR_RTS; > > + writel(val, cdns_uart->port->membase + > CDNS_UART_MODEMCR); > > + } > > +} > > + > > +/** > > + * cdns_rs485_tx_setup - Tx setup specific to rs485 > > + * @cdns_uart: Handle to the cdns_uart */ static void > > +cdns_rs485_tx_setup(struct cdns_uart *cdns_uart) { > > + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_ON_SEND) > > + cdns_rs485_config_gpio_rts_high(cdns_uart); > > + else > > + cdns_rs485_config_gpio_rts_low(cdns_uart); > > +} > > + > > +/** > > + * cdns_rs485_rx_setup - Rx setup specific to rs485 > > + * @cdns_uart: Handle to the cdns_uart */ static void > > +cdns_rs485_rx_setup(struct cdns_uart *cdns_uart) { > > + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_AFTER_SEND) > > + cdns_rs485_config_gpio_rts_high(cdns_uart); > > + else > > + cdns_rs485_config_gpio_rts_low(cdns_uart); > > +} > > + > > +/** > > + * cdns_uart_tx_empty - Check whether TX is empty > > + * @port: Handle to the uart port structure > > + * > > + * Return: TIOCSER_TEMT on success, 0 otherwise */ static unsigned > > +int cdns_uart_tx_empty(struct uart_port *port) { > > + unsigned int status; > > + > > + status = readl(port->membase + CDNS_UART_SR) & > > + (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE); > > + return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0; } > > + > > /** > > * cdns_uart_handle_tx - Handle the bytes to be Txed. > > * @dev_id: Id of the UART port > > @@ -571,6 +657,8 @@ static int cdns_uart_clk_notifier_cb(struct > > notifier_block *nb, static void cdns_uart_start_tx(struct uart_port > > *port) { > > unsigned int status; > > + unsigned long time_out; > > + struct cdns_uart *cdns_uart = port->private_data; > > > > if (uart_tx_stopped(port)) > > return; > > @@ -589,8 +677,31 @@ static void cdns_uart_start_tx(struct uart_port > > *port) > > > > writel(CDNS_UART_IXR_TXEMPTY, port->membase + > CDNS_UART_ISR); > > > > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { > > + cdns_rs485_tx_setup(cdns_uart); > > + if (cdns_uart->port->rs485.delay_rts_before_send) > > + mdelay(cdns_uart->port- > >rs485.delay_rts_before_send); > > So, this will be executed each time (including the rts_before_send delay) the > core wants to send data? This is not how it is supposed to work: The tx setup > (and the delay before send) has to be done once when transmission starts. > Note that when sending a bulk of data the core may call cdns_uart_start_tx() > several times before it eventually calls cdns_uart_stop_tx() to stop the > transmission. We have tested bulk transfer (5000 bytes) and observed that cdns_uart_start_tx() is getting called only once. Can you please suggest how to reproduce the case where the core may call cdns_uart_start_tx() several times before it eventually calls cdns_uart_stop_tx(). > > > > + } > > + > > cdns_uart_handle_tx(port); > > > > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { > > + time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT); > > + /* Wait for tx completion */ > > + while ((cdns_uart_tx_empty(cdns_uart->port) != > TIOCSER_TEMT) && > > + time_before(jiffies, time_out)) > > + cpu_relax(); > > + > > + if (cdns_uart->port->rs485.delay_rts_after_send) > > + mdelay(cdns_uart->port- > >rs485.delay_rts_after_send); > > + > > + /* > > + * Default Rx should be setup, because RX signaling path > > + * need to enable to receive data. > > + */ > > + cdns_rs485_rx_setup(cdns_uart); > > + } > > + > > /* Enable the TX Empty interrupt */ > > writel(CDNS_UART_IXR_TXEMPTY, port->membase + > CDNS_UART_IER); } @@ > > -602,6 +713,14 @@ static void cdns_uart_start_tx(struct uart_port > > *port) static void cdns_uart_stop_tx(struct uart_port *port) { > > unsigned int regval; > > + struct cdns_uart *cdns_uart = port->private_data; > > + > > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { > > + if (cdns_uart->port->rs485.delay_rts_after_send) > > + mdelay(cdns_uart->port- > >rs485.delay_rts_after_send); > > + > > + cdns_rs485_rx_setup(cdns_uart); > > + } > > > > regval = readl(port->membase + CDNS_UART_CR); > > regval |= CDNS_UART_CR_TX_DIS; > > @@ -626,21 +745,6 @@ static void cdns_uart_stop_rx(struct uart_port > *port) > > writel(regval, port->membase + CDNS_UART_CR); } > > > > -/** > > - * cdns_uart_tx_empty - Check whether TX is empty > > - * @port: Handle to the uart port structure > > - * > > - * Return: TIOCSER_TEMT on success, 0 otherwise > > - */ > > -static unsigned int cdns_uart_tx_empty(struct uart_port *port) -{ > > - unsigned int status; > > - > > - status = readl(port->membase + CDNS_UART_SR) & > > - (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE); > > - return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0; > > -} > > - > > /** > > * cdns_uart_break_ctl - Based on the input ctl we have to start or stop > > * transmitting char breaks > > @@ -829,6 +933,9 @@ static int cdns_uart_startup(struct uart_port *port) > > (CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST)) > > cpu_relax(); > > > > + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) > > + cdns_rs485_rx_setup(cdns_uart); > > + > > /* > > * Clear the RX disable bit and then set the RX enable bit to enable > > * the receiver. > > @@ -1455,6 +1562,23 @@ MODULE_DEVICE_TABLE(of, > cdns_uart_of_match); > > /* Temporary variable for storing number of instances */ static int > > instances; > > > > +/** > > + * cdns_rs485_config - Called when an application calls TIOCSRS485 ioctl. > > + * @port: Pointer to the uart_port structure > > + * @termios: Pointer to the ktermios structure > > + * @rs485: Pointer to the serial_rs485 structure > > + * > > + * Return: 0 > > + */ > > +static int cdns_rs485_config(struct uart_port *port, struct ktermios > *termios, > > + struct serial_rs485 *rs485) > > +{ > > + if (rs485->flags & SER_RS485_ENABLED) > > + dev_dbg(port->dev, "Setting UART to RS485\n"); > > + > > + return 0; > > +} > > So what if userspace changes the RS485 configuration? When does it take > effect? We will disable auto RTS control and call cdns_uart_stop_tx() which will perform both stop tx and cdns_rs485_rx_setup() > > > + > > /** > > * cdns_uart_probe - Platform driver probe > > * @pdev: Pointer to the platform device structure @@ -1463,6 +1587,7 > > @@ static int instances; > > */ > > static int cdns_uart_probe(struct platform_device *pdev) { > > + u32 val; > > int rc, id, irq; > > struct uart_port *port; > > struct resource *res; > > @@ -1597,9 +1722,23 @@ static int cdns_uart_probe(struct > platform_device *pdev) > > port->private_data = cdns_uart_data; > > port->read_status_mask = CDNS_UART_IXR_TXEMPTY | > CDNS_UART_IXR_RXTRIG | > > CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_TOUT; > > + port->rs485_config = cdns_rs485_config; > > + port->rs485_supported = cdns_rs485_supported; > > cdns_uart_data->port = port; > > platform_set_drvdata(pdev, port); > > > > + rc = uart_get_rs485_mode(port); > > + if (rc) > > + goto err_out_clk_notifier; > > + > > + cdns_uart_data->gpiod = devm_gpiod_get_optional(&pdev->dev, > "rts", > > + GPIOD_OUT_LOW); > > + if (IS_ERR(cdns_uart_data->gpiod)) { > > + rc = PTR_ERR(cdns_uart_data->gpiod); > > + dev_err(port->dev, "xuartps: devm_gpiod_get_optional > failed\n"); > > Why bail out with an error if having cdns_uart_data->gpiod is only optional? We are using devm_gpiod_get_optional(), it will return NULL when gpio not passed, so IS_ERR() check will be false and will not bail out. > > > + goto err_out_clk_notifier; > > + } > > + > > pm_runtime_use_autosuspend(&pdev->dev); > > pm_runtime_set_autosuspend_delay(&pdev->dev, > UART_AUTOSUSPEND_TIMEOUT); > > pm_runtime_set_active(&pdev->dev); > > @@ -1638,6 +1777,16 @@ static int cdns_uart_probe(struct > platform_device *pdev) > > cdns_uart_data->cts_override = of_property_read_bool(pdev- > >dev.of_node, > > "cts-override"); > > > > + if (cdns_uart_data->port->rs485.flags & SER_RS485_ENABLED) { > > + if (!cdns_uart_data->gpiod) { > > + val = readl(cdns_uart_data->port->membase > > + + CDNS_UART_MODEMCR); > > + val |= CDNS_UART_MODEMCR_RTS; > > + writel(val, cdns_uart_data->port->membase > > + + CDNS_UART_MODEMCR); > > + } > > + } > > This covers the RTS_AFTER_SEND mode. What if SER_RS485_RTS_ON_SEND is > configured instead (as it is the default set by uart_get_rs485_mode())? What if > cdns_uart_data->gpiod exists? > Why not simply call cdns_rs485_rx_setup() which covers all these cases? > Note that uart_add_one_port() will call into the serial core and eventually > result in an initial call to the ports rs485_config function (see > uart_rs485_config()). So maybe put the initial configuration into that function > and remove the above code. However in this case > > cdns_uart_data->cts_override = of_property_read_bool(pdev->dev.of_node, > "cts-override"); > should be called before uart_add_one_port(). We will fix. Thanks, Manikanta.
Hi, On 15.11.23 07:50, Guntupalli, Manikanta wrote: >> From: Lino Sanfilippo <LinoSanfilippo@gmx.de> >> >> So, this will be executed each time (including the rts_before_send delay) the >> core wants to send data? This is not how it is supposed to work: The tx setup >> (and the delay before send) has to be done once when transmission starts. >> Note that when sending a bulk of data the core may call cdns_uart_start_tx() >> several times before it eventually calls cdns_uart_stop_tx() to stop the >> transmission. > We have tested bulk transfer (5000 bytes) and observed that cdns_uart_start_tx() is getting called only once. Can you please suggest how to reproduce the case where the core may call cdns_uart_start_tx() several times before it eventually calls cdns_uart_stop_tx(). Thats strange. Normally the uart_ports start_tx() function is called whenever there is new data in the tty circular buffer (see uart_write()) and the writing process is suspended after that (see n_tty_write() in case of N_TTY line discipline). The writing process is woken up via uart_write_wakeup() called from the uart driver and then it writes new data into the circular buffer which results in another call to the uart_ports start_tx(). There is no stop_tx() until all data from the passed userspace buffer is written. But there is a start_tx for every new bulk of data that is available in the circular buffer. This is at least what I can observe in my test setup (using a PL011 UART with the amba driver). If I write a test buffer of 9212 bytes to the tty device using one single write() I can see 10 consecutive calls of tx_start() before tx_stop() eventually is called. What does your test setup look like? Regards, Lino
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index 9c13dac1d4d1..32229cf5c508 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c @@ -23,6 +23,9 @@ #include <linux/module.h> #include <linux/pm_runtime.h> #include <linux/iopoll.h> +#include <linux/gpio.h> +#include <linux/gpio/consumer.h> +#include <linux/delay.h> #define CDNS_UART_TTY_NAME "ttyPS" #define CDNS_UART_NAME "xuartps" @@ -193,6 +196,7 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255"); * @clk_rate_change_nb: Notifier block for clock changes * @quirks: Flags for RXBS support. * @cts_override: Modem control state override + * @gpiod: Pointer to the gpio descriptor */ struct cdns_uart { struct uart_port *port; @@ -203,10 +207,19 @@ struct cdns_uart { struct notifier_block clk_rate_change_nb; u32 quirks; bool cts_override; + struct gpio_desc *gpiod; }; struct cdns_platform_data { u32 quirks; }; + +struct serial_rs485 cdns_rs485_supported = { + .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | + SER_RS485_RTS_AFTER_SEND, + .delay_rts_before_send = 1, + .delay_rts_after_send = 1, +}; + #define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \ clk_rate_change_nb) @@ -305,6 +318,79 @@ static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus) tty_flip_buffer_push(&port->state->port); } +/** + * cdns_rs485_config_gpio_rts_high - Configure GPIO/RTS to high + * @cdns_uart: Handle to the cdns_uart + */ +static void cdns_rs485_config_gpio_rts_high(struct cdns_uart *cdns_uart) +{ + u32 val; + + if (cdns_uart->gpiod) { + gpiod_set_value(cdns_uart->gpiod, 1); + } else { + val = readl(cdns_uart->port->membase + CDNS_UART_MODEMCR); + val &= ~CDNS_UART_MODEMCR_RTS; + writel(val, cdns_uart->port->membase + CDNS_UART_MODEMCR); + } +} + +/** + * cdns_rs485_config_gpio_rts_low - Configure GPIO/RTS to low + * @cdns_uart: Handle to the cdns_uart + */ +static void cdns_rs485_config_gpio_rts_low(struct cdns_uart *cdns_uart) +{ + u32 val; + + if (cdns_uart->gpiod) { + gpiod_set_value(cdns_uart->gpiod, 0); + } else { + val = readl(cdns_uart->port->membase + CDNS_UART_MODEMCR); + val |= CDNS_UART_MODEMCR_RTS; + writel(val, cdns_uart->port->membase + CDNS_UART_MODEMCR); + } +} + +/** + * cdns_rs485_tx_setup - Tx setup specific to rs485 + * @cdns_uart: Handle to the cdns_uart + */ +static void cdns_rs485_tx_setup(struct cdns_uart *cdns_uart) +{ + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_ON_SEND) + cdns_rs485_config_gpio_rts_high(cdns_uart); + else + cdns_rs485_config_gpio_rts_low(cdns_uart); +} + +/** + * cdns_rs485_rx_setup - Rx setup specific to rs485 + * @cdns_uart: Handle to the cdns_uart + */ +static void cdns_rs485_rx_setup(struct cdns_uart *cdns_uart) +{ + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_AFTER_SEND) + cdns_rs485_config_gpio_rts_high(cdns_uart); + else + cdns_rs485_config_gpio_rts_low(cdns_uart); +} + +/** + * cdns_uart_tx_empty - Check whether TX is empty + * @port: Handle to the uart port structure + * + * Return: TIOCSER_TEMT on success, 0 otherwise + */ +static unsigned int cdns_uart_tx_empty(struct uart_port *port) +{ + unsigned int status; + + status = readl(port->membase + CDNS_UART_SR) & + (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE); + return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0; +} + /** * cdns_uart_handle_tx - Handle the bytes to be Txed. * @dev_id: Id of the UART port @@ -571,6 +657,8 @@ static int cdns_uart_clk_notifier_cb(struct notifier_block *nb, static void cdns_uart_start_tx(struct uart_port *port) { unsigned int status; + unsigned long time_out; + struct cdns_uart *cdns_uart = port->private_data; if (uart_tx_stopped(port)) return; @@ -589,8 +677,31 @@ static void cdns_uart_start_tx(struct uart_port *port) writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR); + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { + cdns_rs485_tx_setup(cdns_uart); + if (cdns_uart->port->rs485.delay_rts_before_send) + mdelay(cdns_uart->port->rs485.delay_rts_before_send); + } + cdns_uart_handle_tx(port); + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { + time_out = jiffies + usecs_to_jiffies(TX_TIMEOUT); + /* Wait for tx completion */ + while ((cdns_uart_tx_empty(cdns_uart->port) != TIOCSER_TEMT) && + time_before(jiffies, time_out)) + cpu_relax(); + + if (cdns_uart->port->rs485.delay_rts_after_send) + mdelay(cdns_uart->port->rs485.delay_rts_after_send); + + /* + * Default Rx should be setup, because RX signaling path + * need to enable to receive data. + */ + cdns_rs485_rx_setup(cdns_uart); + } + /* Enable the TX Empty interrupt */ writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER); } @@ -602,6 +713,14 @@ static void cdns_uart_start_tx(struct uart_port *port) static void cdns_uart_stop_tx(struct uart_port *port) { unsigned int regval; + struct cdns_uart *cdns_uart = port->private_data; + + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { + if (cdns_uart->port->rs485.delay_rts_after_send) + mdelay(cdns_uart->port->rs485.delay_rts_after_send); + + cdns_rs485_rx_setup(cdns_uart); + } regval = readl(port->membase + CDNS_UART_CR); regval |= CDNS_UART_CR_TX_DIS; @@ -626,21 +745,6 @@ static void cdns_uart_stop_rx(struct uart_port *port) writel(regval, port->membase + CDNS_UART_CR); } -/** - * cdns_uart_tx_empty - Check whether TX is empty - * @port: Handle to the uart port structure - * - * Return: TIOCSER_TEMT on success, 0 otherwise - */ -static unsigned int cdns_uart_tx_empty(struct uart_port *port) -{ - unsigned int status; - - status = readl(port->membase + CDNS_UART_SR) & - (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE); - return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0; -} - /** * cdns_uart_break_ctl - Based on the input ctl we have to start or stop * transmitting char breaks @@ -829,6 +933,9 @@ static int cdns_uart_startup(struct uart_port *port) (CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST)) cpu_relax(); + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) + cdns_rs485_rx_setup(cdns_uart); + /* * Clear the RX disable bit and then set the RX enable bit to enable * the receiver. @@ -1455,6 +1562,23 @@ MODULE_DEVICE_TABLE(of, cdns_uart_of_match); /* Temporary variable for storing number of instances */ static int instances; +/** + * cdns_rs485_config - Called when an application calls TIOCSRS485 ioctl. + * @port: Pointer to the uart_port structure + * @termios: Pointer to the ktermios structure + * @rs485: Pointer to the serial_rs485 structure + * + * Return: 0 + */ +static int cdns_rs485_config(struct uart_port *port, struct ktermios *termios, + struct serial_rs485 *rs485) +{ + if (rs485->flags & SER_RS485_ENABLED) + dev_dbg(port->dev, "Setting UART to RS485\n"); + + return 0; +} + /** * cdns_uart_probe - Platform driver probe * @pdev: Pointer to the platform device structure @@ -1463,6 +1587,7 @@ static int instances; */ static int cdns_uart_probe(struct platform_device *pdev) { + u32 val; int rc, id, irq; struct uart_port *port; struct resource *res; @@ -1597,9 +1722,23 @@ static int cdns_uart_probe(struct platform_device *pdev) port->private_data = cdns_uart_data; port->read_status_mask = CDNS_UART_IXR_TXEMPTY | CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_TOUT; + port->rs485_config = cdns_rs485_config; + port->rs485_supported = cdns_rs485_supported; cdns_uart_data->port = port; platform_set_drvdata(pdev, port); + rc = uart_get_rs485_mode(port); + if (rc) + goto err_out_clk_notifier; + + cdns_uart_data->gpiod = devm_gpiod_get_optional(&pdev->dev, "rts", + GPIOD_OUT_LOW); + if (IS_ERR(cdns_uart_data->gpiod)) { + rc = PTR_ERR(cdns_uart_data->gpiod); + dev_err(port->dev, "xuartps: devm_gpiod_get_optional failed\n"); + goto err_out_clk_notifier; + } + pm_runtime_use_autosuspend(&pdev->dev); pm_runtime_set_autosuspend_delay(&pdev->dev, UART_AUTOSUSPEND_TIMEOUT); pm_runtime_set_active(&pdev->dev); @@ -1638,6 +1777,16 @@ static int cdns_uart_probe(struct platform_device *pdev) cdns_uart_data->cts_override = of_property_read_bool(pdev->dev.of_node, "cts-override"); + if (cdns_uart_data->port->rs485.flags & SER_RS485_ENABLED) { + if (!cdns_uart_data->gpiod) { + val = readl(cdns_uart_data->port->membase + + CDNS_UART_MODEMCR); + val |= CDNS_UART_MODEMCR_RTS; + writel(val, cdns_uart_data->port->membase + + CDNS_UART_MODEMCR); + } + } + instances++; return 0; @@ -1646,6 +1795,7 @@ static int cdns_uart_probe(struct platform_device *pdev) pm_runtime_disable(&pdev->dev); pm_runtime_set_suspended(&pdev->dev); pm_runtime_dont_use_autosuspend(&pdev->dev); +err_out_clk_notifier: #ifdef CONFIG_COMMON_CLK clk_notifier_unregister(cdns_uart_data->uartclk, &cdns_uart_data->clk_rate_change_nb);
Add rs485 support to uartps driver. Use either rts-gpios or RTS to control RS485 phy as driver or a receiver. Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com> --- Changes for V2: Modify optional gpio name to xlnx,phy-ctrl-gpios. Update commit description. Add support for RTS, delay_rts_before_send and delay_rts_after_send in RS485 mode. Changes for V3: Modify optional gpio name to rts-gpios. Update commit description. Move cdns_uart_tx_empty function to avoid prototype statement. Remove assignment of struct serial_rs485 to port->rs485 as serial core performs that. Switch to native RTS in non GPIO case. Handle rs485 during stop tx. Remove explicit calls to configure gpio direction and value, as devm_gpiod_get_optional performs that by using GPIOD_OUT_LOW argument. Update implementation to support configuration of GPIO/RTS value based on user configuration of SER_RS485_RTS_ON_SEND and SER_RS485_RTS_AFTER_SEND. Move implementation to start_tx from handle_tx. --- drivers/tty/serial/xilinx_uartps.c | 180 ++++++++++++++++++++++++++--- 1 file changed, 165 insertions(+), 15 deletions(-)