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Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by CY4PEPF0000EDD7.mail.protection.outlook.com (10.167.241.211) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.7113.14 via Frontend Transport; Fri, 15 Dec 2023 12:57:24 +0000 Received: from SATLEXMB04.amd.com (10.181.40.145) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.34; Fri, 15 Dec 2023 06:56:58 -0600 Received: from xhdsgoud40.xilinx.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server id 15.1.2507.34 via Frontend Transport; Fri, 15 Dec 2023 06:56:54 -0600 From: Manikanta Guntupalli To: , , , , , , , , , , CC: , , , , Manikanta Guntupalli Subject: [PATCH V6 3/3] tty: serial: uartps: Add rs485 support to uartps driver Date: Fri, 15 Dec 2023 18:26:27 +0530 Message-ID: <20231215125627.1691573-4-manikanta.guntupalli@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20231215125627.1691573-1-manikanta.guntupalli@amd.com> References: <20231215125627.1691573-1-manikanta.guntupalli@amd.com> MIME-Version: 1.0 X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY4PEPF0000EDD7:EE_|MW3PR12MB4393:EE_ X-MS-Office365-Filtering-Correlation-Id: a79ac0a2-162b-4dab-564d-08dbfd6d6273 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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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(). --- drivers/tty/serial/xilinx_uartps.c | 222 +++++++++++++++++++++++++++-- 1 file changed, 213 insertions(+), 9 deletions(-) diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c index aafcc2179e0e..04cc23deebdf 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 +195,10 @@ 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 + * @timer: Timer for tx and rx + * @stop_tx_timer: Timer for stop tx */ struct cdns_uart { struct uart_port *port; @@ -203,10 +209,22 @@ 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 timer_list timer; + struct timer_list stop_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 +323,55 @@ 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) +{ + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_ON_SEND) + cdns_rts_gpio_enable(cdns_uart, 1); + else + cdns_rts_gpio_enable(cdns_uart, 0); + + 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) +{ + if (cdns_uart->port->rs485.flags & SER_RS485_RTS_AFTER_SEND) + cdns_rts_gpio_enable(cdns_uart, 1); + else + cdns_rts_gpio_enable(cdns_uart, 0); + + cdns_uart->rs485_tx_started = false; +} + /** * cdns_uart_tx_empty - Check whether TX is empty * @port: Handle to the uart port structure @@ -579,6 +646,44 @@ static int cdns_uart_clk_notifier_cb(struct notifier_block *nb, } #endif +/** + * cdns_rs485_rx_callback - Timer rx callback handler for rs485. + * @t: Handle to the timer list structure + */ +static void cdns_rs485_rx_callback(struct timer_list *t) +{ + struct cdns_uart *cdns_uart = from_timer(cdns_uart, t, timer); + + /* + * Default Rx should be setup, because Rx signaling path + * need to enable to receive data. + */ + cdns_rs485_rx_setup(cdns_uart); +} + +/** + * cdns_rs485_tx_callback - Timer tx callback handler for rs485. + * @t: Handle to the timer list structure + */ +static void cdns_rs485_tx_callback(struct timer_list *t) +{ + struct cdns_uart *cdns_uart = from_timer(cdns_uart, t, timer); + + uart_port_lock(cdns_uart->port); + cdns_uart_handle_tx(cdns_uart->port); + + /* Enable the TX Empty interrupt */ + writel(CDNS_UART_IXR_TXEMPTY, cdns_uart->port->membase + CDNS_UART_IER); + uart_port_unlock(cdns_uart->port); + + if (uart_circ_empty(&cdns_uart->port->state->xmit) || + uart_tx_stopped(cdns_uart->port)) { + timer_setup(&cdns_uart->timer, cdns_rs485_rx_callback, 0); + mod_timer(&cdns_uart->timer, jiffies + + msecs_to_jiffies(cdns_uart->port->rs485.delay_rts_after_send)); + } +} + /** * cdns_uart_start_tx - Start transmitting bytes * @port: Handle to the uart port structure @@ -586,6 +691,7 @@ 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; @@ -604,10 +710,40 @@ static void cdns_uart_start_tx(struct uart_port *port) writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR); - cdns_uart_handle_tx(port); + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { + if (!cdns_uart->rs485_tx_started) { + timer_setup(&cdns_uart->timer, + cdns_rs485_tx_callback, 0); + cdns_rs485_tx_setup(cdns_uart); + mod_timer(&cdns_uart->timer, jiffies + + msecs_to_jiffies(port->rs485.delay_rts_before_send)); + } else { + if (!timer_pending(&cdns_uart->timer)) + mod_timer(&cdns_uart->timer, jiffies); + } + } else { + cdns_uart_handle_tx(port); - /* Enable the TX Empty interrupt */ - writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER); + /* Enable the TX Empty interrupt */ + writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER); + } +} + +/** + * cdns_rs485_stop_tx_callback - Timer stop tx callback handler for rs485. + * @t: Handle to the timer list structure + */ +static void cdns_rs485_stop_tx_callback(struct timer_list *t) +{ + unsigned int regval; + struct cdns_uart *cdns_uart = from_timer(cdns_uart, t, stop_tx_timer); + + cdns_rs485_rx_setup(cdns_uart); + + regval = readl(cdns_uart->port->membase + CDNS_UART_CR); + regval |= CDNS_UART_CR_TX_DIS; + /* Disable the transmitter */ + writel(regval, cdns_uart->port->membase + CDNS_UART_CR); } /** @@ -617,11 +753,19 @@ 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; - regval = readl(port->membase + CDNS_UART_CR); - regval |= CDNS_UART_CR_TX_DIS; - /* Disable the transmitter */ - writel(regval, port->membase + CDNS_UART_CR); + if ((cdns_uart->port->rs485.flags & SER_RS485_ENABLED) && + !timer_pending(&cdns_uart->stop_tx_timer) && + cdns_uart->rs485_tx_started) { + mod_timer(&cdns_uart->stop_tx_timer, jiffies + + msecs_to_jiffies(cdns_uart->port->rs485.delay_rts_after_send)); + } else { + regval = readl(port->membase + CDNS_UART_CR); + regval |= CDNS_UART_CR_TX_DIS; + /* Disable the transmitter */ + writel(regval, port->membase + CDNS_UART_CR); + } } /** @@ -829,6 +973,12 @@ 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) { + timer_setup(&cdns_uart->stop_tx_timer, + cdns_rs485_stop_tx_callback, 0); + cdns_rs485_rx_setup(cdns_uart); + } + /* * Clear the RX disable bit and then set the RX enable bit to enable * the receiver. @@ -888,6 +1038,7 @@ static void cdns_uart_shutdown(struct uart_port *port) { int status; unsigned long flags; + struct cdns_uart *cdns_uart = port->private_data; uart_port_lock_irqsave(port, &flags); @@ -903,6 +1054,11 @@ static void cdns_uart_shutdown(struct uart_port *port) uart_port_unlock_irqrestore(port, flags); free_irq(port->irq, port); + + if (cdns_uart->port->rs485.flags & SER_RS485_ENABLED) { + del_timer_sync(&cdns_uart->timer); + del_timer_sync(&cdns_uart->stop_tx_timer); + } } /** @@ -1032,7 +1188,7 @@ static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl) mode_reg &= ~CDNS_UART_MR_CHMODE_MASK; if (mctrl & TIOCM_RTS) - val |= CDNS_UART_MODEMCR_RTS; + cdns_rts_gpio_enable(cdns_uart_data, 1); if (mctrl & TIOCM_DTR) val |= CDNS_UART_MODEMCR_DTR; if (mctrl & TIOCM_LOOP) @@ -1455,6 +1611,37 @@ 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; + unsigned int ctrl_reg; + + 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); + /* Disable transmitter and make Rx setup*/ + cdns_uart_stop_tx(port); + } else { + /* Disable the TX and RX */ + ctrl_reg = readl(port->membase + CDNS_UART_CR); + ctrl_reg |= CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS; + writel(ctrl_reg, port->membase + CDNS_UART_CR); + } + return 0; +} + /** * cdns_uart_probe - Platform driver probe * @pdev: Pointer to the platform device structure @@ -1597,9 +1784,23 @@ 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); @@ -1618,6 +1819,8 @@ 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) { @@ -1646,6 +1849,7 @@ 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);