diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250_fsl.c')
| -rw-r--r-- | drivers/tty/serial/8250/8250_fsl.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c new file mode 100644 index 000000000..fbcc90c31 --- /dev/null +++ b/drivers/tty/serial/8250/8250_fsl.c @@ -0,0 +1,175 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Freescale 16550 UART "driver", Copyright (C) 2011 Paul Gortmaker. + * Copyright 2020 NXP + * Copyright 2020 Puresoftware Ltd. + * + * This isn't a full driver; it just provides an alternate IRQ + * handler to deal with an errata and provide ACPI wrapper. + * Everything else is just using the bog standard 8250 support. + * + * We follow code flow of serial8250_default_handle_irq() but add + * a check for a break and insert a dummy read on the Rx for the + * immediately following IRQ event. + * + * We re-use the already existing "bug handling" lsr_saved_flags + * field to carry the "what we just did" information from the one + * IRQ event to the next one. + */ + +#include <linux/acpi.h> +#include <linux/serial_reg.h> +#include <linux/serial_8250.h> + +#include "8250.h" + +struct fsl8250_data { + int line; +}; + +int fsl8250_handle_irq(struct uart_port *port) +{ + unsigned char lsr, orig_lsr; + unsigned long flags; + unsigned int iir; + struct uart_8250_port *up = up_to_u8250p(port); + + spin_lock_irqsave(&up->port.lock, flags); + + iir = port->serial_in(port, UART_IIR); + if (iir & UART_IIR_NO_INT) { + spin_unlock_irqrestore(&up->port.lock, flags); + return 0; + } + + /* This is the WAR; if last event was BRK, then read and return */ + if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) { + up->lsr_saved_flags &= ~UART_LSR_BI; + port->serial_in(port, UART_RX); + spin_unlock_irqrestore(&up->port.lock, flags); + return 1; + } + + lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR); + + /* Process incoming characters first */ + if ((lsr & (UART_LSR_DR | UART_LSR_BI)) && + (up->ier & (UART_IER_RLSI | UART_IER_RDI))) { + lsr = serial8250_rx_chars(up, lsr); + } + + /* Stop processing interrupts on input overrun */ + if ((orig_lsr & UART_LSR_OE) && (up->overrun_backoff_time_ms > 0)) { + unsigned long delay; + + up->ier = port->serial_in(port, UART_IER); + if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) { + port->ops->stop_rx(port); + } else { + /* Keep restarting the timer until + * the input overrun subsides. + */ + cancel_delayed_work(&up->overrun_backoff); + } + + delay = msecs_to_jiffies(up->overrun_backoff_time_ms); + schedule_delayed_work(&up->overrun_backoff, delay); + } + + serial8250_modem_status(up); + + if ((lsr & UART_LSR_THRE) && (up->ier & UART_IER_THRI)) + serial8250_tx_chars(up); + + up->lsr_saved_flags = orig_lsr; + uart_unlock_and_check_sysrq(&up->port, flags); + return 1; +} +EXPORT_SYMBOL_GPL(fsl8250_handle_irq); + +#ifdef CONFIG_ACPI +static int fsl8250_acpi_probe(struct platform_device *pdev) +{ + struct fsl8250_data *data; + struct uart_8250_port port8250; + struct device *dev = &pdev->dev; + struct resource *regs; + + int ret, irq; + + regs = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!regs) { + dev_err(dev, "no registers defined\n"); + return -EINVAL; + } + + irq = platform_get_irq(pdev, 0); + if (irq < 0) { + if (irq != -EPROBE_DEFER) + dev_err(dev, "cannot get irq\n"); + return irq; + } + + memset(&port8250, 0, sizeof(port8250)); + + ret = device_property_read_u32(dev, "clock-frequency", + &port8250.port.uartclk); + if (ret) + return ret; + + spin_lock_init(&port8250.port.lock); + + port8250.port.mapbase = regs->start; + port8250.port.irq = irq; + port8250.port.handle_irq = fsl8250_handle_irq; + port8250.port.type = PORT_16550A; + port8250.port.flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF + | UPF_FIXED_PORT | UPF_IOREMAP + | UPF_FIXED_TYPE; + port8250.port.dev = dev; + port8250.port.mapsize = resource_size(regs); + port8250.port.iotype = UPIO_MEM; + port8250.port.irqflags = IRQF_SHARED; + + port8250.port.membase = devm_ioremap(dev, port8250.port.mapbase, + port8250.port.mapsize); + if (!port8250.port.membase) + return -ENOMEM; + + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + data->line = serial8250_register_8250_port(&port8250); + if (data->line < 0) + return data->line; + + platform_set_drvdata(pdev, data); + return 0; +} + +static int fsl8250_acpi_remove(struct platform_device *pdev) +{ + struct fsl8250_data *data = platform_get_drvdata(pdev); + + serial8250_unregister_port(data->line); + return 0; +} + +static const struct acpi_device_id fsl_8250_acpi_id[] = { + { "NXP0018", 0 }, + { }, +}; +MODULE_DEVICE_TABLE(acpi, fsl_8250_acpi_id); + +static struct platform_driver fsl8250_platform_driver = { + .driver = { + .name = "fsl-16550-uart", + .acpi_match_table = ACPI_PTR(fsl_8250_acpi_id), + }, + .probe = fsl8250_acpi_probe, + .remove = fsl8250_acpi_remove, +}; + +module_platform_driver(fsl8250_platform_driver); +#endif |