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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jan 2024 07:41:15.3724 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 11ff1455-7ea0-49e0-aa57-08dc17f8d9ea X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB03.amd.com] X-MS-Exchange-CrossTenant-AuthSource: MWH0EPF000989E6.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB7790 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240117_234138_884516_E53138AB X-CRM114-Status: GOOD ( 24.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 --- 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. Changes for V4: Create separate patch for cdns_uart_tx_empty relocation. Call cdns_rs485_rx_setup() before uart_add_one_port() in probe. Update gpio descriptor name to gpiod_rts. Instead of cdns_rs485_config_gpio_rts_high() and cdns_rs485_config_gpio_rts_low() functions for RTS/GPIO value configuration implement cdns_rts_gpio_enable(). Disable auto rts and call cdns_uart_stop_tx() from cdns_rs485_config. Use timer instead of mdelay for delay_rts_before_send and delay_rts_after_send. Update cdns_uart_set_mctrl to support GPIO/RTS. Changes for V5: None. Changes for V6: Disable the TX and RX in cdns_rs485_config() when rs485 disabled. Hold lock for cdns_uart_handle_tx() in cdns_rs485_tx_callback(). Changes for V7: None. Changes for V8: Use hrtimer instead of timer list. Simplify cdns_rs485_tx_setup() and cdns_rs485_rx_setup(). Update argument of cdns_rts_gpio_enable() in cdns_uart_set_mctrl(). Add cdns_calc_after_tx_delay() to calculate required delay after tx. Add hrtimer setup in cdns_rs485_config(). Move enable TX Empty interrupt and rs485 rx callback scheduling part to cdns_uart_handle_tx(). Changes for V9: Remove stop tx timer. Remove hrtimer_cancel() call from cdns_uart_start_tx(). Handle gpio case separately in cdns_uart_set_mctrl(). Move hrtimer_cancel() call from below to above in cdns_uart_shutdown(). --- drivers/tty/serial/xilinx_uartps.c | 200 ++++++++++++++++++++++++++++- 1 file changed, 196 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index 787c7cbc6600..c44c77b3e54f 100644 --- a/drivers/tty/serial/xilinx_uartps.c +++ b/drivers/tty/serial/xilinx_uartps.c @@ -22,7 +22,9 @@ #include #include #include -#include +#include +#include +#include #define CDNS_UART_TTY_NAME "ttyPS" #define CDNS_UART_NAME "xuartps" @@ -193,6 +195,9 @@ 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_rts: Pointer to the gpio descriptor + * @rs485_tx_started: RS485 tx state + * @tx_timer: Timer for tx */ struct cdns_uart { struct uart_port *port; @@ -203,10 +208,21 @@ struct cdns_uart { struct notifier_block clk_rate_change_nb; u32 quirks; bool cts_override; + struct gpio_desc *gpiod_rts; + bool rs485_tx_started; + struct hrtimer tx_timer; }; 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 +321,55 @@ static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus) tty_flip_buffer_push(&port->state->port); } +/** + * cdns_rts_gpio_enable - Configure RTS/GPIO to high/low + * @cdns_uart: Handle to the cdns_uart + * @enable: Value to be set to RTS/GPIO + */ +static void cdns_rts_gpio_enable(struct cdns_uart *cdns_uart, bool enable) +{ + u32 val; + + if (cdns_uart->gpiod_rts) { + gpiod_set_value(cdns_uart->gpiod_rts, enable); + } else { + val = readl(cdns_uart->port->membase + CDNS_UART_MODEMCR); + if (enable) + val |= CDNS_UART_MODEMCR_RTS; + else + 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) +{ + bool enable; + + enable = cdns_uart->port->rs485.flags & SER_RS485_RTS_ON_SEND; + cdns_rts_gpio_enable(cdns_uart, enable); + + cdns_uart->rs485_tx_started = true; +} + +/** + * 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) +{ + bool enable; + + enable = cdns_uart->port->rs485.flags & SER_RS485_RTS_AFTER_SEND; + cdns_rts_gpio_enable(cdns_uart, enable); + + cdns_uart->rs485_tx_started = false; +} + /** * cdns_uart_tx_empty - Check whether TX is empty * @port: Handle to the uart port structure @@ -320,6 +385,37 @@ static unsigned int cdns_uart_tx_empty(struct uart_port *port) return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0; } +/** + * cdns_rs485_rx_callback - Timer rx callback handler for rs485. + * @t: Handle to the hrtimer structure + */ +static enum hrtimer_restart cdns_rs485_rx_callback(struct hrtimer *t) +{ + struct cdns_uart *cdns_uart = container_of(t, struct cdns_uart, tx_timer); + + /* + * Default Rx should be setup, because Rx signaling path + * need to enable to receive data. + */ + cdns_rs485_rx_setup(cdns_uart); + + return HRTIMER_NORESTART; +} + +/** + * cdns_calc_after_tx_delay - calculate delay required for after tx. + * @cdns_uart: Handle to the cdns_uart + */ +static u64 cdns_calc_after_tx_delay(struct cdns_uart *cdns_uart) +{ + /* + * Frame time + stop bit time + rs485.delay_rts_after_send + */ + return cdns_uart->port->frame_time + + DIV_ROUND_UP(cdns_uart->port->frame_time, 7) + + (u64)cdns_uart->port->rs485.delay_rts_after_send * NSEC_PER_MSEC; +} + /** * cdns_uart_handle_tx - Handle the bytes to be transmitted. * @dev_id: Id of the UART port @@ -328,6 +424,7 @@ static unsigned int cdns_uart_tx_empty(struct uart_port *port) static void cdns_uart_handle_tx(void *dev_id) { struct uart_port *port = (struct uart_port *)dev_id; + struct cdns_uart *cdns_uart = port->private_data; struct circ_buf *xmit = &port->state->xmit; unsigned int numbytes; @@ -347,6 +444,16 @@ static void cdns_uart_handle_tx(void *dev_id) if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(port); + + /* Enable the TX Empty interrupt */ + writel(CDNS_UART_IXR_TXEMPTY, cdns_uart->port->membase + CDNS_UART_IER); + + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED && + (uart_circ_empty(xmit) || uart_tx_stopped(port))) { + cdns_uart->tx_timer.function = &cdns_rs485_rx_callback; + hrtimer_start(&cdns_uart->tx_timer, + ns_to_ktime(cdns_calc_after_tx_delay(cdns_uart)), HRTIMER_MODE_REL); + } } /** @@ -579,6 +686,21 @@ static int cdns_uart_clk_notifier_cb(struct notifier_block *nb, } #endif +/** + * cdns_rs485_tx_callback - Timer tx callback handler for rs485. + * @t: Handle to the hrtimer structure + */ +static enum hrtimer_restart cdns_rs485_tx_callback(struct hrtimer *t) +{ + struct cdns_uart *cdns_uart = container_of(t, struct cdns_uart, tx_timer); + + uart_port_lock(cdns_uart->port); + cdns_uart_handle_tx(cdns_uart->port); + uart_port_unlock(cdns_uart->port); + + return HRTIMER_NORESTART; +} + /** * cdns_uart_start_tx - Start transmitting bytes * @port: Handle to the uart port structure @@ -586,6 +708,7 @@ static int cdns_uart_clk_notifier_cb(struct notifier_block *nb, static void cdns_uart_start_tx(struct uart_port *port) { unsigned int status; + struct cdns_uart *cdns_uart = port->private_data; if (uart_tx_stopped(port)) return; @@ -605,10 +728,16 @@ static void cdns_uart_start_tx(struct uart_port *port) /* Clear the TX Empty interrupt */ writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR); + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { + if (!cdns_uart->rs485_tx_started) { + cdns_uart->tx_timer.function = &cdns_rs485_tx_callback; + cdns_rs485_tx_setup(cdns_uart); + return hrtimer_start(&cdns_uart->tx_timer, + ms_to_ktime(port->rs485.delay_rts_before_send), + HRTIMER_MODE_REL); + } + } cdns_uart_handle_tx(port); - - /* Enable the TX Empty interrupt */ - writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER); } /** @@ -618,6 +747,10 @@ 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) + cdns_rs485_rx_setup(cdns_uart); regval = readl(port->membase + CDNS_UART_CR); regval |= CDNS_UART_CR_TX_DIS; @@ -830,6 +963,9 @@ 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. @@ -889,6 +1025,10 @@ static void cdns_uart_shutdown(struct uart_port *port) { int status; unsigned long flags; + struct cdns_uart *cdns_uart = port->private_data; + + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) + hrtimer_cancel(&cdns_uart->tx_timer); uart_port_lock_irqsave(port, &flags); @@ -1034,6 +1174,8 @@ static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl) if (mctrl & TIOCM_RTS) val |= CDNS_UART_MODEMCR_RTS; + if (cdns_uart_data->gpiod_rts) + gpiod_set_value(cdns_uart_data->gpiod_rts, !(mctrl & TIOCM_RTS)); if (mctrl & TIOCM_DTR) val |= CDNS_UART_MODEMCR_DTR; if (mctrl & TIOCM_LOOP) @@ -1456,6 +1598,39 @@ 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) +{ + u32 val; + struct cdns_uart *cdns_uart = port->private_data; + + if (rs485->flags & SER_RS485_ENABLED) { + dev_dbg(port->dev, "Setting UART to RS485\n"); + /* Make sure auto RTS is disabled */ + val = readl(port->membase + CDNS_UART_MODEMCR); + val &= ~CDNS_UART_MODEMCR_FCM; + writel(val, port->membase + CDNS_UART_MODEMCR); + + /* Timer setup */ + hrtimer_init(&cdns_uart->tx_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + cdns_uart->tx_timer.function = &cdns_rs485_tx_callback; + + /* Disable transmitter and make Rx setup*/ + cdns_uart_stop_tx(port); + } else { + hrtimer_cancel(&cdns_uart->tx_timer); + } + return 0; +} + /** * cdns_uart_probe - Platform driver probe * @pdev: Pointer to the platform device structure @@ -1598,9 +1773,23 @@ 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_rts = devm_gpiod_get_optional(&pdev->dev, "rts", + GPIOD_OUT_LOW); + if (IS_ERR(cdns_uart_data->gpiod_rts)) { + rc = PTR_ERR(cdns_uart_data->gpiod_rts); + 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); @@ -1619,6 +1808,8 @@ static int cdns_uart_probe(struct platform_device *pdev) console_port = port; } #endif + if (cdns_uart_data->port->rs485.flags & SER_RS485_ENABLED) + cdns_rs485_rx_setup(cdns_uart_data); rc = uart_add_one_port(&cdns_uart_uart_driver, port); if (rc) { @@ -1647,6 +1838,7 @@ 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);