diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_ni.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_ni.c | 446 |
1 files changed, 446 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_ni.c b/drivers/tty/serial/8250/8250_ni.c new file mode 100644 index 000000000000..b0e44fb00b3a --- /dev/null +++ b/drivers/tty/serial/8250/8250_ni.c @@ -0,0 +1,446 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * NI 16550 UART Driver + * + * The National Instruments (NI) 16550 is a UART that is compatible with the + * TL16C550C and OX16C950B register interfaces, but has additional functions + * for RS-485 transceiver control. This driver implements support for the + * additional functionality on top of the standard serial8250 core. + * + * Copyright 2012-2023 National Instruments Corporation + */ + +#include <linux/bitfield.h> +#include <linux/bits.h> +#include <linux/clk.h> +#include <linux/device.h> +#include <linux/io.h> +#include <linux/init.h> +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/property.h> +#include <linux/serial_core.h> +#include <linux/types.h> + +#include "8250.h" + +/* Extra bits in UART_ACR */ +#define NI16550_ACR_AUTO_DTR_EN BIT(4) + +/* TFS - TX FIFO Size */ +#define NI16550_TFS_OFFSET 0x0C +/* RFS - RX FIFO Size */ +#define NI16550_RFS_OFFSET 0x0D + +/* PMR - Port Mode Register */ +#define NI16550_PMR_OFFSET 0x0E +/* PMR[1:0] - Port Capabilities */ +#define NI16550_PMR_CAP_MASK GENMASK(1, 0) +#define NI16550_PMR_NOT_IMPL FIELD_PREP(NI16550_PMR_CAP_MASK, 0) /* not implemented */ +#define NI16550_PMR_CAP_RS232 FIELD_PREP(NI16550_PMR_CAP_MASK, 1) /* RS-232 capable */ +#define NI16550_PMR_CAP_RS485 FIELD_PREP(NI16550_PMR_CAP_MASK, 2) /* RS-485 capable */ +#define NI16550_PMR_CAP_DUAL FIELD_PREP(NI16550_PMR_CAP_MASK, 3) /* dual-port */ +/* PMR[4] - Interface Mode */ +#define NI16550_PMR_MODE_MASK GENMASK(4, 4) +#define NI16550_PMR_MODE_RS232 FIELD_PREP(NI16550_PMR_MODE_MASK, 0) /* currently 232 */ +#define NI16550_PMR_MODE_RS485 FIELD_PREP(NI16550_PMR_MODE_MASK, 1) /* currently 485 */ + +/* PCR - Port Control Register */ +/* + * Wire Mode | Tx enabled? | Rx enabled? + * ---------------|----------------------|-------------------------- + * PCR_RS422 | Always | Always + * PCR_ECHO_RS485 | When DTR asserted | Always + * PCR_DTR_RS485 | When DTR asserted | Disabled when TX enabled + * PCR_AUTO_RS485 | When data in TX FIFO | Disabled when TX enabled + */ +#define NI16550_PCR_OFFSET 0x0F +#define NI16550_PCR_WIRE_MODE_MASK GENMASK(1, 0) +#define NI16550_PCR_RS422 FIELD_PREP(NI16550_PCR_WIRE_MODE_MASK, 0) +#define NI16550_PCR_ECHO_RS485 FIELD_PREP(NI16550_PCR_WIRE_MODE_MASK, 1) +#define NI16550_PCR_DTR_RS485 FIELD_PREP(NI16550_PCR_WIRE_MODE_MASK, 2) +#define NI16550_PCR_AUTO_RS485 FIELD_PREP(NI16550_PCR_WIRE_MODE_MASK, 3) +#define NI16550_PCR_TXVR_ENABLE_BIT BIT(3) +#define NI16550_PCR_RS485_TERMINATION_BIT BIT(6) + +/* flags for ni16550_device_info */ +#define NI_HAS_PMR BIT(0) + +struct ni16550_device_info { + u32 uartclk; + u8 prescaler; + u8 flags; +}; + +struct ni16550_data { + int line; + struct clk *clk; +}; + +static int ni16550_enable_transceivers(struct uart_port *port) +{ + u8 pcr; + + pcr = port->serial_in(port, NI16550_PCR_OFFSET); + pcr |= NI16550_PCR_TXVR_ENABLE_BIT; + dev_dbg(port->dev, "enable transceivers: write pcr: 0x%02x\n", pcr); + port->serial_out(port, NI16550_PCR_OFFSET, pcr); + + return 0; +} + +static int ni16550_disable_transceivers(struct uart_port *port) +{ + u8 pcr; + + pcr = serial_port_in(port, NI16550_PCR_OFFSET); + pcr &= ~NI16550_PCR_TXVR_ENABLE_BIT; + dev_dbg(port->dev, "disable transceivers: write pcr: 0x%02x\n", pcr); + serial_port_out(port, NI16550_PCR_OFFSET, pcr); + + return 0; +} + +static int ni16550_rs485_config(struct uart_port *port, + struct ktermios *termios, + struct serial_rs485 *rs485) +{ + struct uart_8250_port *up = container_of(port, struct uart_8250_port, port); + u8 pcr; + + pcr = serial_port_in(port, NI16550_PCR_OFFSET); + pcr &= ~NI16550_PCR_WIRE_MODE_MASK; + + if ((rs485->flags & SER_RS485_MODE_RS422) || + !(rs485->flags & SER_RS485_ENABLED)) { + /* RS-422 */ + pcr |= NI16550_PCR_RS422; + up->acr &= ~NI16550_ACR_AUTO_DTR_EN; + } else { + /* RS-485 2-wire Auto */ + pcr |= NI16550_PCR_AUTO_RS485; + up->acr |= NI16550_ACR_AUTO_DTR_EN; + } + + dev_dbg(port->dev, "config rs485: write pcr: 0x%02x, acr: %02x\n", pcr, up->acr); + serial_port_out(port, NI16550_PCR_OFFSET, pcr); + serial_icr_write(up, UART_ACR, up->acr); + + return 0; +} + +static bool is_pmr_rs232_mode(struct uart_8250_port *up) +{ + u8 pmr = serial_in(up, NI16550_PMR_OFFSET); + u8 pmr_mode = pmr & NI16550_PMR_MODE_MASK; + u8 pmr_cap = pmr & NI16550_PMR_CAP_MASK; + + /* + * If the PMR is not implemented, then by default NI UARTs are + * connected to RS-485 transceivers + */ + if (pmr_cap == NI16550_PMR_NOT_IMPL) + return false; + + if (pmr_cap == NI16550_PMR_CAP_DUAL) + /* + * If the port is dual-mode capable, then read the mode bit + * to know the current mode + */ + return pmr_mode == NI16550_PMR_MODE_RS232; + /* + * If it is not dual-mode capable, then decide based on the + * capability + */ + return pmr_cap == NI16550_PMR_CAP_RS232; +} + +static void ni16550_config_prescaler(struct uart_8250_port *up, + u8 prescaler) +{ + /* + * Page in the Enhanced Mode Registers + * Sets EFR[4] for Enhanced Mode. + */ + u8 lcr_value; + u8 efr_value; + + lcr_value = serial_in(up, UART_LCR); + serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); + + efr_value = serial_in(up, UART_EFR); + efr_value |= UART_EFR_ECB; + + serial_out(up, UART_EFR, efr_value); + + /* Page out the Enhanced Mode Registers */ + serial_out(up, UART_LCR, lcr_value); + + /* Set prescaler to CPR register. */ + serial_out(up, UART_SCR, UART_CPR); + serial_out(up, UART_ICR, prescaler); +} + +static const struct serial_rs485 ni16550_rs485_supported = { + .flags = SER_RS485_ENABLED | SER_RS485_MODE_RS422 | SER_RS485_RTS_ON_SEND | + SER_RS485_RTS_AFTER_SEND, + /* + * delay_rts_* and RX_DURING_TX are not supported. + * + * RTS_{ON,AFTER}_SEND are supported, but ignored; the transceiver + * is connected in only one way and we don't need userspace to tell + * us, but want to retain compatibility with applications that do. + */ +}; + +static void ni16550_rs485_setup(struct uart_port *port) +{ + port->rs485_config = ni16550_rs485_config; + port->rs485_supported = ni16550_rs485_supported; + /* + * The hardware comes up by default in 2-wire auto mode and we + * set the flags to represent that + */ + port->rs485.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND; +} + +static int ni16550_port_startup(struct uart_port *port) +{ + int ret; + + ret = serial8250_do_startup(port); + if (ret) + return ret; + + return ni16550_enable_transceivers(port); +} + +static void ni16550_port_shutdown(struct uart_port *port) +{ + ni16550_disable_transceivers(port); + + serial8250_do_shutdown(port); +} + +static int ni16550_get_regs(struct platform_device *pdev, + struct uart_port *port) +{ + struct resource *regs; + + regs = platform_get_mem_or_io(pdev, 0); + if (!regs) + return dev_err_probe(&pdev->dev, -EINVAL, "no registers defined\n"); + + switch (resource_type(regs)) { + case IORESOURCE_IO: + port->iotype = UPIO_PORT; + port->iobase = regs->start; + + return 0; + case IORESOURCE_MEM: + port->iotype = UPIO_MEM; + port->mapbase = regs->start; + port->mapsize = resource_size(regs); + port->flags |= UPF_IOREMAP; + + return 0; + default: + return -EINVAL; + } +} + +/* + * Very old implementations don't have the TFS or RFS registers + * defined, so we may read all-0s or all-1s. For such devices, + * assume a FIFO size of 128. + */ +static u8 ni16550_read_fifo_size(struct uart_8250_port *uart, int reg) +{ + u8 value = serial_in(uart, reg); + + if (value == 0x00 || value == 0xFF) + return 128; + + return value; +} + +static void ni16550_set_mctrl(struct uart_port *port, unsigned int mctrl) +{ + struct uart_8250_port *up = up_to_u8250p(port); + + up->mcr |= UART_MCR_CLKSEL; + serial8250_do_set_mctrl(port, mctrl); +} + +static int ni16550_probe(struct platform_device *pdev) +{ + const struct ni16550_device_info *info; + struct device *dev = &pdev->dev; + struct uart_8250_port uart = {}; + unsigned int txfifosz, rxfifosz; + unsigned int prescaler; + struct ni16550_data *data; + const char *portmode; + bool rs232_property; + int ret; + + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + spin_lock_init(&uart.port.lock); + + ret = ni16550_get_regs(pdev, &uart.port); + if (ret < 0) + return ret; + + /* early setup so that serial_in()/serial_out() work */ + serial8250_set_defaults(&uart); + + info = device_get_match_data(dev); + + uart.port.dev = dev; + uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_FIXED_TYPE; + uart.port.startup = ni16550_port_startup; + uart.port.shutdown = ni16550_port_shutdown; + + /* + * Hardware instantiation of FIFO sizes are held in registers. + */ + txfifosz = ni16550_read_fifo_size(&uart, NI16550_TFS_OFFSET); + rxfifosz = ni16550_read_fifo_size(&uart, NI16550_RFS_OFFSET); + + dev_dbg(dev, "NI 16550 has TX FIFO size %u, RX FIFO size %u\n", + txfifosz, rxfifosz); + + uart.port.type = PORT_16550A; + uart.port.fifosize = txfifosz; + uart.tx_loadsz = txfifosz; + uart.fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10; + uart.capabilities = UART_CAP_FIFO | UART_CAP_AFE | UART_CAP_EFR; + + /* + * Declaration of the base clock frequency can come from one of: + * - static declaration in this driver (for older ACPI IDs) + * - a "clock-frequency" ACPI + */ + uart.port.uartclk = info->uartclk; + + ret = uart_read_port_properties(&uart.port); + if (ret) + return ret; + + if (!uart.port.uartclk) { + data->clk = devm_clk_get_enabled(dev, NULL); + if (!IS_ERR(data->clk)) + uart.port.uartclk = clk_get_rate(data->clk); + } + + if (!uart.port.uartclk) + return dev_err_probe(dev, -ENODEV, "unable to determine clock frequency!\n"); + + prescaler = info->prescaler; + device_property_read_u32(dev, "clock-prescaler", &prescaler); + if (prescaler) { + uart.port.set_mctrl = ni16550_set_mctrl; + ni16550_config_prescaler(&uart, (u8)prescaler); + } + + /* + * The determination of whether or not this is an RS-485 or RS-232 port + * can come from the PMR (if present), otherwise we're solely an RS-485 + * port. + * + * This is a device-specific property, and there are old devices in the + * field using "transceiver" as an ACPI property, so we have to check + * for that as well. + */ + if (!device_property_read_string(dev, "transceiver", &portmode)) { + rs232_property = strncmp(portmode, "RS-232", 6) == 0; + + dev_dbg(dev, "port is in %s mode (via device property)\n", + rs232_property ? "RS-232" : "RS-485"); + } else if (info->flags & NI_HAS_PMR) { + rs232_property = is_pmr_rs232_mode(&uart); + + dev_dbg(dev, "port is in %s mode (via PMR)\n", + rs232_property ? "RS-232" : "RS-485"); + } else { + rs232_property = 0; + + dev_dbg(dev, "port is fixed as RS-485\n"); + } + + if (!rs232_property) { + /* + * Neither the 'transceiver' property nor the PMR indicate + * that this is an RS-232 port, so it must be an RS-485 one. + */ + ni16550_rs485_setup(&uart.port); + } + + ret = serial8250_register_8250_port(&uart); + if (ret < 0) + return ret; + data->line = ret; + + platform_set_drvdata(pdev, data); + return 0; +} + +static void ni16550_remove(struct platform_device *pdev) +{ + struct ni16550_data *data = platform_get_drvdata(pdev); + + serial8250_unregister_port(data->line); +} + +/* NI 16550 RS-485 Interface */ +static const struct ni16550_device_info nic7750 = { + .uartclk = 33333333, +}; + +/* NI CVS-145x RS-485 Interface */ +static const struct ni16550_device_info nic7772 = { + .uartclk = 1843200, + .flags = NI_HAS_PMR, +}; + +/* NI cRIO-904x RS-485 Interface */ +static const struct ni16550_device_info nic792b = { + /* Sets UART clock rate to 22.222 MHz with 1.125 prescale */ + .uartclk = 22222222, + .prescaler = 0x09, +}; + +/* NI sbRIO 96x8 RS-232/485 Interfaces */ +static const struct ni16550_device_info nic7a69 = { + /* Set UART clock rate to 29.629 MHz with 1.125 prescale */ + .uartclk = 29629629, + .prescaler = 0x09, +}; + +static const struct acpi_device_id ni16550_acpi_match[] = { + { "NIC7750", (kernel_ulong_t)&nic7750 }, + { "NIC7772", (kernel_ulong_t)&nic7772 }, + { "NIC792B", (kernel_ulong_t)&nic792b }, + { "NIC7A69", (kernel_ulong_t)&nic7a69 }, + { } +}; +MODULE_DEVICE_TABLE(acpi, ni16550_acpi_match); + +static struct platform_driver ni16550_driver = { + .driver = { + .name = "ni16550", + .acpi_match_table = ni16550_acpi_match, + }, + .probe = ni16550_probe, + .remove = ni16550_remove, +}; + +module_platform_driver(ni16550_driver); + +MODULE_AUTHOR("Emerson Electric Co."); +MODULE_DESCRIPTION("NI 16550 Driver"); +MODULE_LICENSE("GPL"); |