dw uart

static int dw8250_probe(struct platform_device *pdev)
{
	struct uart_8250_port uart = {};
	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	int irq = platform_get_irq(pdev, 0);
	struct uart_port *p = &uart.port;
	struct device *dev = &pdev->dev;
	struct dw8250_data *data;
	int err;
	u32 val;

	if (!regs) {
		dev_err(dev, "no registers defined\n");
		return -EINVAL;
	}

	if (irq < 0) {
		if (irq != -EPROBE_DEFER)
			dev_err(dev, "cannot get irq\n");
		return irq;
	}

	spin_lock_init(&p->lock);
	p->mapbase	= regs->start;
	p->irq		= irq;
	p->handle_irq	= dw8250_handle_irq;
	p->pm		= dw8250_do_pm;
	p->type		= PORT_8250;
	p->flags	= UPF_SHARE_IRQ | UPF_FIXED_PORT;
	p->dev		= dev;
	p->iotype	= UPIO_MEM;
	p->serial_in	= dw8250_serial_in;
	p->serial_out	= dw8250_serial_out;
	p->set_ldisc	= dw8250_set_ldisc;
	p->set_termios	= dw8250_set_termios;

	p->membase = devm_ioremap(dev, regs->start, resource_size(regs));
	if (!p->membase)
		return -ENOMEM;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->dma.fn = dw8250_fallback_dma_filter;
	data->usr_reg = DW_UART_USR;
	p->private_data = data;

	data->uart_16550_compatible = device_property_read_bool(dev,
						"snps,uart-16550-compatible");

	err = device_property_read_u32(dev, "reg-shift", &val);
	if (!err)
		p->regshift = val;

	err = device_property_read_u32(dev, "reg-io-width", &val);
	if (!err && val == 4) {
		p->iotype = UPIO_MEM32;
		p->serial_in = dw8250_serial_in32;
		p->serial_out = dw8250_serial_out32;
	}

	if (device_property_read_bool(dev, "dcd-override")) {
		/* Always report DCD as active */
		data->msr_mask_on |= UART_MSR_DCD;
		data->msr_mask_off |= UART_MSR_DDCD;
	}

	if (device_property_read_bool(dev, "dsr-override")) {
		/* Always report DSR as active */
		data->msr_mask_on |= UART_MSR_DSR;
		data->msr_mask_off |= UART_MSR_DDSR;
	}

	if (device_property_read_bool(dev, "cts-override")) {
		/* Always report CTS as active */
		data->msr_mask_on |= UART_MSR_CTS;
		data->msr_mask_off |= UART_MSR_DCTS;
	}

	if (device_property_read_bool(dev, "ri-override")) {
		/* Always report Ring indicator as inactive */
		data->msr_mask_off |= UART_MSR_RI;