drivers/tty/serial/8250/8250_dw.c - linux - Git at Google

 /*
  * Synopsys DesignWare 8250 driver.
  *
  * Copyright 2011 Picochip, Jamie Iles.
  * Copyright 2013 Intel Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * The Synopsys DesignWare 8250 has an extra feature whereby it detects if the
  * LCR is written whilst busy.  If it is, then a busy detect interrupt is
  * raised, the LCR needs to be rewritten and the uart status register read.
  */
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/serial_8250.h>
 #include <linux/serial_reg.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/acpi.h>
 #include <linux/clk.h>
 #include <linux/reset.h>
 #include <linux/pm_runtime.h>

 #include <asm/byteorder.h>

 #include "8250.h"

 /* Offsets for the DesignWare specific registers */
 #define DW_UART_USR	0x1f /* UART Status Register */
 #define DW_UART_CPR	0xf4 /* Component Parameter Register */
 #define DW_UART_UCV	0xf8 /* UART Component Version */

 /* Component Parameter Register bits */
 #define DW_UART_CPR_ABP_DATA_WIDTH	(3 << 0)
 #define DW_UART_CPR_AFCE_MODE		(1 << 4)
 #define DW_UART_CPR_THRE_MODE		(1 << 5)
 #define DW_UART_CPR_SIR_MODE		(1 << 6)
 #define DW_UART_CPR_SIR_LP_MODE		(1 << 7)
 #define DW_UART_CPR_ADDITIONAL_FEATURES	(1 << 8)
 #define DW_UART_CPR_FIFO_ACCESS		(1 << 9)
 #define DW_UART_CPR_FIFO_STAT		(1 << 10)
 #define DW_UART_CPR_SHADOW		(1 << 11)
 #define DW_UART_CPR_ENCODED_PARMS	(1 << 12)
 #define DW_UART_CPR_DMA_EXTRA		(1 << 13)
 #define DW_UART_CPR_FIFO_MODE		(0xff << 16)
 /* Helper for fifo size calculation */
 #define DW_UART_CPR_FIFO_SIZE(a)	(((a >> 16) & 0xff) * 16)

 /* DesignWare specific register fields */
 #define DW_UART_MCR_SIRE		BIT(6)

 struct dw8250_data {
 	u8			usr_reg;
 	int			line;
 	int			msr_mask_on;
 	int			msr_mask_off;
 	struct clk		*clk;
 	struct clk		*pclk;
 	struct reset_control	*rst;
 	struct uart_8250_dma	dma;

 	unsigned int		skip_autocfg:1;
 	unsigned int		uart_16550_compatible:1;
 };

 static inline int dw8250_modify_msr(struct uart_port *p, int offset, int value)
 {
 	struct dw8250_data *d = p->private_data;

 	/* Override any modem control signals if needed */
 	if (offset == UART_MSR) {
 		value |= d->msr_mask_on;
 		value &= ~d->msr_mask_off;
 	}

 	return value;
 }

 static void dw8250_force_idle(struct uart_port *p)
 {
 	struct uart_8250_port *up = up_to_u8250p(p);

 	serial8250_clear_and_reinit_fifos(up);
 	(void)p->serial_in(p, UART_RX);
 }

 static void dw8250_check_lcr(struct uart_port *p, int value)
 {
 	void __iomem *offset = p->membase + (UART_LCR << p->regshift);
 	int tries = 1000;

 	/* Make sure LCR write wasn't ignored */
 	while (tries--) {
 		unsigned int lcr = p->serial_in(p, UART_LCR);

 		if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
 			return;

 		dw8250_force_idle(p);

 #ifdef CONFIG_64BIT
 		if (p->type == PORT_OCTEON)
 			__raw_writeq(value & 0xff, offset);
 		else
 #endif
 		if (p->iotype == UPIO_MEM32)
 			writel(value, offset);
 		else if (p->iotype == UPIO_MEM32BE)
 			iowrite32be(value, offset);
 		else
 			writeb(value, offset);
 	}
 	/*
 	 * FIXME: this deadlocks if port->lock is already held
 	 * dev_err(p->dev, "Couldn't set LCR to %d\n", value);
 	 */
 }

 static void dw8250_serial_out(struct uart_port *p, int offset, int value)
 {
 	struct dw8250_data *d = p->private_data;

 	writeb(value, p->membase + (offset << p->regshift));

 	if (offset == UART_LCR && !d->uart_16550_compatible)
 		dw8250_check_lcr(p, value);
 }

 static unsigned int dw8250_serial_in(struct uart_port *p, int offset)
 {
 	unsigned int value = readb(p->membase + (offset << p->regshift));

 	return dw8250_modify_msr(p, offset, value);
 }

 #ifdef CONFIG_64BIT
 static unsigned int dw8250_serial_inq(struct uart_port *p, int offset)
 {
 	unsigned int value;

 	value = (u8)__raw_readq(p->membase + (offset << p->regshift));

 	return dw8250_modify_msr(p, offset, value);
 }

 static void dw8250_serial_outq(struct uart_port *p, int offset, int value)
 {
 	struct dw8250_data *d = p->private_data;

 	value &= 0xff;
 	__raw_writeq(value, p->membase + (offset << p->regshift));
 	/* Read back to ensure register write ordering. */
 	__raw_readq(p->membase + (UART_LCR << p->regshift));

 	if (offset == UART_LCR && !d->uart_16550_compatible)
 		dw8250_check_lcr(p, value);
 }
 #endif /* CONFIG_64BIT */

 static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
 {
 	struct dw8250_data *d = p->private_data;

 	writel(value, p->membase + (offset << p->regshift));

 	if (offset == UART_LCR && !d->uart_16550_compatible)
 		dw8250_check_lcr(p, value);
 }

 static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)
 {
 	unsigned int value = readl(p->membase + (offset << p->regshift));

 	return dw8250_modify_msr(p, offset, value);
 }

 static void dw8250_serial_out32be(struct uart_port *p, int offset, int value)
 {
 	struct dw8250_data *d = p->private_data;

 	iowrite32be(value, p->membase + (offset << p->regshift));

 	if (offset == UART_LCR && !d->uart_16550_compatible)
 		dw8250_check_lcr(p, value);
 }

 static unsigned int dw8250_serial_in32be(struct uart_port *p, int offset)
 {
        unsigned int value = ioread32be(p->membase + (offset << p->regshift));

        return dw8250_modify_msr(p, offset, value);
 }


 static int dw8250_handle_irq(struct uart_port *p)
 {
 	struct uart_8250_port *up = up_to_u8250p(p);
 	struct dw8250_data *d = p->private_data;
 	unsigned int iir = p->serial_in(p, UART_IIR);
 	unsigned int status;
 	unsigned long flags;

 	/*
 	 * There are ways to get Designware-based UARTs into a state where
 	 * they are asserting UART_IIR_RX_TIMEOUT but there is no actual
 	 * data available.  If we see such a case then we'll do a bogus
 	 * read.  If we don't do this then the "RX TIMEOUT" interrupt will
 	 * fire forever.
 	 *
 	 * This problem has only been observed so far when not in DMA mode
 	 * so we limit the workaround only to non-DMA mode.
 	 */
 	if (!up->dma && ((iir & 0x3f) == UART_IIR_RX_TIMEOUT)) {
 		spin_lock_irqsave(&p->lock, flags);
 		status = p->serial_in(p, UART_LSR);

 		if (!(status & (UART_LSR_DR | UART_LSR_BI)))
 			(void) p->serial_in(p, UART_RX);

 		spin_unlock_irqrestore(&p->lock, flags);
 	}

 	if (serial8250_handle_irq(p, iir))
 		return 1;

 	if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
 		/* Clear the USR */
 		(void)p->serial_in(p, d->usr_reg);

 		return 1;
 	}

 	return 0;
 }

 static void
 dw8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old)
 {
 	if (!state)
 		pm_runtime_get_sync(port->dev);

 	serial8250_do_pm(port, state, old);

 	if (state)
 		pm_runtime_put_sync_suspend(port->dev);
 }

 static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
 			       struct ktermios *old)
 {
 	unsigned int baud = tty_termios_baud_rate(termios);
 	struct dw8250_data *d = p->private_data;
 	long rate;
 	int ret;

 	if (IS_ERR(d->clk) || !old)
 		goto out;

 	clk_disable_unprepare(d->clk);
 	rate = clk_round_rate(d->clk, baud * 16);
 	if (rate < 0)
 		ret = rate;
 	else if (rate == 0)
 		ret = -ENOENT;
 	else
 		ret = clk_set_rate(d->clk, rate);
 	clk_prepare_enable(d->clk);

 	if (!ret)
 		p->uartclk = rate;

 out:
 	p->status &= ~UPSTAT_AUTOCTS;
 	if (termios->c_cflag & CRTSCTS)
 		p->status |= UPSTAT_AUTOCTS;

 	serial8250_do_set_termios(p, termios, old);
 }

 static void dw8250_set_ldisc(struct uart_port *p, struct ktermios *termios)
 {
 	struct uart_8250_port *up = up_to_u8250p(p);
 	unsigned int mcr = p->serial_in(p, UART_MCR);

 	if (up->capabilities & UART_CAP_IRDA) {
 		if (termios->c_line == N_IRDA)
 			mcr |= DW_UART_MCR_SIRE;
 		else
 			mcr &= ~DW_UART_MCR_SIRE;

 		p->serial_out(p, UART_MCR, mcr);
 	}
 	serial8250_do_set_ldisc(p, termios);
 }

 /*
  * dw8250_fallback_dma_filter will prevent the UART from getting just any free
  * channel on platforms that have DMA engines, but don't have any channels
  * assigned to the UART.
  *
  * REVISIT: This is a work around for limitation in the DMA Engine API. Once the
  * core problem is fixed, this function is no longer needed.
  */
 static bool dw8250_fallback_dma_filter(struct dma_chan *chan, void *param)
 {
 	return false;
 }

 static bool dw8250_idma_filter(struct dma_chan *chan, void *param)
 {
 	return param == chan->device->dev->parent;
 }

 static void dw8250_quirks(struct uart_port *p, struct dw8250_data *data)
 {
 	if (p->dev->of_node) {
 		struct device_node *np = p->dev->of_node;
 		int id;

 		/* get index of serial line, if found in DT aliases */
 		id = of_alias_get_id(np, "serial");
 		if (id >= 0)
 			p->line = id;
 #ifdef CONFIG_64BIT
 		if (of_device_is_compatible(np, "cavium,octeon-3860-uart")) {
 			p->serial_in = dw8250_serial_inq;
 			p->serial_out = dw8250_serial_outq;
 			p->flags = UPF_SKIP_TEST | UPF_SHARE_IRQ | UPF_FIXED_TYPE;
 			p->type = PORT_OCTEON;
 			data->usr_reg = 0x27;
 			data->skip_autocfg = true;
 		}
 #endif
 		if (of_device_is_big_endian(p->dev->of_node)) {
 			p->iotype = UPIO_MEM32BE;
 			p->serial_in = dw8250_serial_in32be;
 			p->serial_out = dw8250_serial_out32be;
 		}
 	} else if (has_acpi_companion(p->dev)) {
 		const struct acpi_device_id *id;

 		id = acpi_match_device(p->dev->driver->acpi_match_table,
 				       p->dev);
 		if (id && !strcmp(id->id, "APMC0D08")) {
 			p->iotype = UPIO_MEM32;
 			p->regshift = 2;
 			p->serial_in = dw8250_serial_in32;
 			data->uart_16550_compatible = true;
 		}
 	}

 	/* Platforms with iDMA */
 	if (platform_get_resource_byname(to_platform_device(p->dev),
 					 IORESOURCE_MEM, "lpss_priv")) {
 		data->dma.rx_param = p->dev->parent;
 		data->dma.tx_param = p->dev->parent;
 		data->dma.fn = dw8250_idma_filter;
 	}
 }

 static void dw8250_setup_port(struct uart_port *p)
 {
 	struct uart_8250_port *up = up_to_u8250p(p);
 	u32 reg;

 	/*
 	 * If the Component Version Register returns zero, we know that
 	 * ADDITIONAL_FEATURES are not enabled. No need to go any further.
 	 */
 	if (p->iotype == UPIO_MEM32BE)
 		reg = ioread32be(p->membase + DW_UART_UCV);
 	else
 		reg = readl(p->membase + DW_UART_UCV);
 	if (!reg)
 		return;

 	dev_dbg(p->dev, "Designware UART version %c.%c%c\n",
 		(reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff);

 	if (p->iotype == UPIO_MEM32BE)
 		reg = ioread32be(p->membase + DW_UART_CPR);
 	else
 		reg = readl(p->membase + DW_UART_CPR);
 	if (!reg)
 		return;

 	/* Select the type based on fifo */
 	if (reg & DW_UART_CPR_FIFO_MODE) {
 		p->type = PORT_16550A;
 		p->flags |= UPF_FIXED_TYPE;
 		p->fifosize = DW_UART_CPR_FIFO_SIZE(reg);
 		up->capabilities = UART_CAP_FIFO;
 	}

 	if (reg & DW_UART_CPR_AFCE_MODE)
 		up->capabilities |= UART_CAP_AFE;

 	if (reg & DW_UART_CPR_SIR_MODE)
 		up->capabilities |= UART_CAP_IRDA;
 }

 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;
 		data->msr_mask_off |= UART_MSR_TERI;
 	}

 	/* Always ask for fixed clock rate from a property. */
 	device_property_read_u32(dev, "clock-frequency", &p->uartclk);

 	/* If there is separate baudclk, get the rate from it. */
 	data->clk = devm_clk_get(dev, "baudclk");
 	if (IS_ERR(data->clk) && PTR_ERR(data->clk) != -EPROBE_DEFER)
 		data->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(data->clk) && PTR_ERR(data->clk) == -EPROBE_DEFER)
 		return -EPROBE_DEFER;
 	if (!IS_ERR_OR_NULL(data->clk)) {
 		err = clk_prepare_enable(data->clk);
 		if (err)
 			dev_warn(dev, "could not enable optional baudclk: %d\n",
 				 err);
 		else
 			p->uartclk = clk_get_rate(data->clk);
 	}

 	/* If no clock rate is defined, fail. */
 	if (!p->uartclk) {
 		dev_err(dev, "clock rate not defined\n");
 		return -EINVAL;
 	}

 	data->pclk = devm_clk_get(dev, "apb_pclk");
 	if (IS_ERR(data->pclk) && PTR_ERR(data->pclk) == -EPROBE_DEFER) {
 		err = -EPROBE_DEFER;
 		goto err_clk;
 	}
 	if (!IS_ERR(data->pclk)) {
 		err = clk_prepare_enable(data->pclk);
 		if (err) {
 			dev_err(dev, "could not enable apb_pclk\n");
 			goto err_clk;
 		}
 	}

 	data->rst = devm_reset_control_get_optional(dev, NULL);
 	if (IS_ERR(data->rst)) {
 		err = PTR_ERR(data->rst);
 		goto err_pclk;
 	}
 	reset_control_deassert(data->rst);

 	dw8250_quirks(p, data);

 	/* If the Busy Functionality is not implemented, don't handle it */
 	if (data->uart_16550_compatible)
 		p->handle_irq = NULL;

 	if (!data->skip_autocfg)
 		dw8250_setup_port(p);

 	/* If we have a valid fifosize, try hooking up DMA */
 	if (p->fifosize) {
 		data->dma.rxconf.src_maxburst = p->fifosize / 4;
 		data->dma.txconf.dst_maxburst = p->fifosize / 4;
 		uart.dma = &data->dma;
 	}

 	data->line = serial8250_register_8250_port(&uart);
 	if (data->line < 0) {
 		err = data->line;
 		goto err_reset;
 	}

 	platform_set_drvdata(pdev, data);

 	pm_runtime_set_active(dev);
 	pm_runtime_enable(dev);

 	return 0;

 err_reset:
 	reset_control_assert(data->rst);

 err_pclk:
 	if (!IS_ERR(data->pclk))
 		clk_disable_unprepare(data->pclk);

 err_clk:
 	if (!IS_ERR(data->clk))
 		clk_disable_unprepare(data->clk);

 	return err;
 }

 static int dw8250_remove(struct platform_device *pdev)
 {
 	struct dw8250_data *data = platform_get_drvdata(pdev);

 	pm_runtime_get_sync(&pdev->dev);

 	serial8250_unregister_port(data->line);

 	reset_control_assert(data->rst);

 	if (!IS_ERR(data->pclk))
 		clk_disable_unprepare(data->pclk);

 	if (!IS_ERR(data->clk))
 		clk_disable_unprepare(data->clk);

 	pm_runtime_disable(&pdev->dev);
 	pm_runtime_put_noidle(&pdev->dev);

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int dw8250_suspend(struct device *dev)
 {
 	struct dw8250_data *data = dev_get_drvdata(dev);

 	serial8250_suspend_port(data->line);

 	return 0;
 }

 static int dw8250_resume(struct device *dev)
 {
 	struct dw8250_data *data = dev_get_drvdata(dev);

 	serial8250_resume_port(data->line);

 	return 0;
 }
 #endif /* CONFIG_PM_SLEEP */

 #ifdef CONFIG_PM
 static int dw8250_runtime_suspend(struct device *dev)
 {
 	struct dw8250_data *data = dev_get_drvdata(dev);

 	if (!IS_ERR(data->clk))
 		clk_disable_unprepare(data->clk);

 	if (!IS_ERR(data->pclk))
 		clk_disable_unprepare(data->pclk);

 	return 0;
 }

 static int dw8250_runtime_resume(struct device *dev)
 {
 	struct dw8250_data *data = dev_get_drvdata(dev);

 	if (!IS_ERR(data->pclk))
 		clk_prepare_enable(data->pclk);

 	if (!IS_ERR(data->clk))
 		clk_prepare_enable(data->clk);

 	return 0;
 }
 #endif

 static const struct dev_pm_ops dw8250_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(dw8250_suspend, dw8250_resume)
 	SET_RUNTIME_PM_OPS(dw8250_runtime_suspend, dw8250_runtime_resume, NULL)
 };

 static const struct of_device_id dw8250_of_match[] = {
 	{ .compatible = "snps,dw-apb-uart" },
 	{ .compatible = "cavium,octeon-3860-uart" },
 	{ /* Sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, dw8250_of_match);

 static const struct acpi_device_id dw8250_acpi_match[] = {
 	{ "INT33C4", 0 },
 	{ "INT33C5", 0 },
 	{ "INT3434", 0 },
 	{ "INT3435", 0 },
 	{ "80860F0A", 0 },
 	{ "8086228A", 0 },
 	{ "APMC0D08", 0},
 	{ "AMD0020", 0 },
 	{ "AMDI0020", 0 },
 	{ "HISI0031", 0 },
 	{ },
 };
 MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match);

 static struct platform_driver dw8250_platform_driver = {
 	.driver = {
 		.name		= "dw-apb-uart",
 		.pm		= &dw8250_pm_ops,
 		.of_match_table	= dw8250_of_match,
 		.acpi_match_table = ACPI_PTR(dw8250_acpi_match),
 	},
 	.probe			= dw8250_probe,
 	.remove			= dw8250_remove,
 };

 module_platform_driver(dw8250_platform_driver);

 MODULE_AUTHOR("Jamie Iles");
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Synopsys DesignWare 8250 serial port driver");
 MODULE_ALIAS("platform:dw-apb-uart");
	/*
	* Synopsys DesignWare 8250 driver.
	*
	* Copyright 2011 Picochip, Jamie Iles.
	* Copyright 2013 Intel Corporation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* The Synopsys DesignWare 8250 has an extra feature whereby it detects if the
	* LCR is written whilst busy. If it is, then a busy detect interrupt is
	* raised, the LCR needs to be rewritten and the uart status register read.
	*/
	#include <linux/device.h>
	#include <linux/io.h>
	#include <linux/module.h>
	#include <linux/serial_8250.h>
	#include <linux/serial_reg.h>
	#include <linux/of.h>
	#include <linux/of_irq.h>
	#include <linux/of_platform.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>
	#include <linux/acpi.h>
	#include <linux/clk.h>
	#include <linux/reset.h>
	#include <linux/pm_runtime.h>

	#include <asm/byteorder.h>

	#include "8250.h"

	/* Offsets for the DesignWare specific registers */
	#define DW_UART_USR 0x1f /* UART Status Register */
	#define DW_UART_CPR 0xf4 /* Component Parameter Register */
	#define DW_UART_UCV 0xf8 /* UART Component Version */

	/* Component Parameter Register bits */
	#define DW_UART_CPR_ABP_DATA_WIDTH (3 << 0)
	#define DW_UART_CPR_AFCE_MODE (1 << 4)
	#define DW_UART_CPR_THRE_MODE (1 << 5)
	#define DW_UART_CPR_SIR_MODE (1 << 6)
	#define DW_UART_CPR_SIR_LP_MODE (1 << 7)
	#define DW_UART_CPR_ADDITIONAL_FEATURES (1 << 8)
	#define DW_UART_CPR_FIFO_ACCESS (1 << 9)
	#define DW_UART_CPR_FIFO_STAT (1 << 10)
	#define DW_UART_CPR_SHADOW (1 << 11)
	#define DW_UART_CPR_ENCODED_PARMS (1 << 12)
	#define DW_UART_CPR_DMA_EXTRA (1 << 13)
	#define DW_UART_CPR_FIFO_MODE (0xff << 16)
	/* Helper for fifo size calculation */
	#define DW_UART_CPR_FIFO_SIZE(a) (((a >> 16) & 0xff) * 16)

	/* DesignWare specific register fields */
	#define DW_UART_MCR_SIRE BIT(6)

	struct dw8250_data {
	u8 usr_reg;
	int line;
	int msr_mask_on;
	int msr_mask_off;
	struct clk *clk;
	struct clk *pclk;
	struct reset_control *rst;
	struct uart_8250_dma dma;

	unsigned int skip_autocfg:1;
	unsigned int uart_16550_compatible:1;
	};

	static inline int dw8250_modify_msr(struct uart_port *p, int offset, int value)
	{
	struct dw8250_data *d = p->private_data;

	/* Override any modem control signals if needed */
	if (offset == UART_MSR) {
	value \|= d->msr_mask_on;
	value &= ~d->msr_mask_off;
	}

	return value;
	}

	static void dw8250_force_idle(struct uart_port *p)
	{
	struct uart_8250_port *up = up_to_u8250p(p);

	serial8250_clear_and_reinit_fifos(up);
	(void)p->serial_in(p, UART_RX);
	}

	static void dw8250_check_lcr(struct uart_port *p, int value)
	{
	void __iomem *offset = p->membase + (UART_LCR << p->regshift);
	int tries = 1000;

	/* Make sure LCR write wasn't ignored */
	while (tries--) {
	unsigned int lcr = p->serial_in(p, UART_LCR);

	if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR))
	return;

	dw8250_force_idle(p);

	#ifdef CONFIG_64BIT
	if (p->type == PORT_OCTEON)
	__raw_writeq(value & 0xff, offset);
	else
	#endif
	if (p->iotype == UPIO_MEM32)
	writel(value, offset);
	else if (p->iotype == UPIO_MEM32BE)
	iowrite32be(value, offset);
	else
	writeb(value, offset);
	}
	/*
	* FIXME: this deadlocks if port->lock is already held
	* dev_err(p->dev, "Couldn't set LCR to %d\n", value);
	*/
	}

	static void dw8250_serial_out(struct uart_port *p, int offset, int value)
	{
	struct dw8250_data *d = p->private_data;

	writeb(value, p->membase + (offset << p->regshift));

	if (offset == UART_LCR && !d->uart_16550_compatible)
	dw8250_check_lcr(p, value);
	}

	static unsigned int dw8250_serial_in(struct uart_port *p, int offset)
	{
	unsigned int value = readb(p->membase + (offset << p->regshift));

	return dw8250_modify_msr(p, offset, value);
	}

	#ifdef CONFIG_64BIT
	static unsigned int dw8250_serial_inq(struct uart_port *p, int offset)
	{
	unsigned int value;

	value = (u8)__raw_readq(p->membase + (offset << p->regshift));

	return dw8250_modify_msr(p, offset, value);
	}

	static void dw8250_serial_outq(struct uart_port *p, int offset, int value)
	{
	struct dw8250_data *d = p->private_data;

	value &= 0xff;
	__raw_writeq(value, p->membase + (offset << p->regshift));
	/* Read back to ensure register write ordering. */
	__raw_readq(p->membase + (UART_LCR << p->regshift));

	if (offset == UART_LCR && !d->uart_16550_compatible)
	dw8250_check_lcr(p, value);
	}
	#endif /* CONFIG_64BIT */

	static void dw8250_serial_out32(struct uart_port *p, int offset, int value)
	{
	struct dw8250_data *d = p->private_data;

	writel(value, p->membase + (offset << p->regshift));

	if (offset == UART_LCR && !d->uart_16550_compatible)
	dw8250_check_lcr(p, value);
	}

	static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)
	{
	unsigned int value = readl(p->membase + (offset << p->regshift));

	return dw8250_modify_msr(p, offset, value);
	}

	static void dw8250_serial_out32be(struct uart_port *p, int offset, int value)
	{
	struct dw8250_data *d = p->private_data;

	iowrite32be(value, p->membase + (offset << p->regshift));

	if (offset == UART_LCR && !d->uart_16550_compatible)
	dw8250_check_lcr(p, value);
	}

	static unsigned int dw8250_serial_in32be(struct uart_port *p, int offset)
	{
	unsigned int value = ioread32be(p->membase + (offset << p->regshift));

	return dw8250_modify_msr(p, offset, value);
	}


	static int dw8250_handle_irq(struct uart_port *p)
	{
	struct uart_8250_port *up = up_to_u8250p(p);
	struct dw8250_data *d = p->private_data;
	unsigned int iir = p->serial_in(p, UART_IIR);
	unsigned int status;
	unsigned long flags;

	/*
	* There are ways to get Designware-based UARTs into a state where
	* they are asserting UART_IIR_RX_TIMEOUT but there is no actual
	* data available. If we see such a case then we'll do a bogus
	* read. If we don't do this then the "RX TIMEOUT" interrupt will
	* fire forever.
	*
	* This problem has only been observed so far when not in DMA mode
	* so we limit the workaround only to non-DMA mode.
	*/
	if (!up->dma && ((iir & 0x3f) == UART_IIR_RX_TIMEOUT)) {
	spin_lock_irqsave(&p->lock, flags);
	status = p->serial_in(p, UART_LSR);

	if (!(status & (UART_LSR_DR \| UART_LSR_BI)))
	(void) p->serial_in(p, UART_RX);

	spin_unlock_irqrestore(&p->lock, flags);
	}

	if (serial8250_handle_irq(p, iir))
	return 1;

	if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
	/* Clear the USR */
	(void)p->serial_in(p, d->usr_reg);

	return 1;
	}

	return 0;
	}

	static void
	dw8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old)
	{
	if (!state)
	pm_runtime_get_sync(port->dev);

	serial8250_do_pm(port, state, old);

	if (state)
	pm_runtime_put_sync_suspend(port->dev);
	}

	static void dw8250_set_termios(struct uart_port p, struct ktermios termios,
	struct ktermios *old)
	{
	unsigned int baud = tty_termios_baud_rate(termios);
	struct dw8250_data *d = p->private_data;
	long rate;
	int ret;

	if (IS_ERR(d->clk) \|\| !old)
	goto out;

	clk_disable_unprepare(d->clk);
	rate = clk_round_rate(d->clk, baud * 16);
	if (rate < 0)
	ret = rate;
	else if (rate == 0)
	ret = -ENOENT;
	else
	ret = clk_set_rate(d->clk, rate);
	clk_prepare_enable(d->clk);

	if (!ret)
	p->uartclk = rate;

	out:
	p->status &= ~UPSTAT_AUTOCTS;
	if (termios->c_cflag & CRTSCTS)
	p->status \|= UPSTAT_AUTOCTS;

	serial8250_do_set_termios(p, termios, old);
	}

	static void dw8250_set_ldisc(struct uart_port p, struct ktermios termios)
	{
	struct uart_8250_port *up = up_to_u8250p(p);
	unsigned int mcr = p->serial_in(p, UART_MCR);

	if (up->capabilities & UART_CAP_IRDA) {
	if (termios->c_line == N_IRDA)
	mcr \|= DW_UART_MCR_SIRE;
	else
	mcr &= ~DW_UART_MCR_SIRE;

	p->serial_out(p, UART_MCR, mcr);
	}
	serial8250_do_set_ldisc(p, termios);
	}

	/*
	* dw8250_fallback_dma_filter will prevent the UART from getting just any free
	* channel on platforms that have DMA engines, but don't have any channels
	* assigned to the UART.
	*
	* REVISIT: This is a work around for limitation in the DMA Engine API. Once the
	* core problem is fixed, this function is no longer needed.
	*/
	static bool dw8250_fallback_dma_filter(struct dma_chan chan, void param)
	{
	return false;
	}

	static bool dw8250_idma_filter(struct dma_chan chan, void param)
	{
	return param == chan->device->dev->parent;
	}

	static void dw8250_quirks(struct uart_port p, struct dw8250_data data)
	{
	if (p->dev->of_node) {
	struct device_node *np = p->dev->of_node;
	int id;

	/* get index of serial line, if found in DT aliases */
	id = of_alias_get_id(np, "serial");
	if (id >= 0)
	p->line = id;
	#ifdef CONFIG_64BIT
	if (of_device_is_compatible(np, "cavium,octeon-3860-uart")) {
	p->serial_in = dw8250_serial_inq;
	p->serial_out = dw8250_serial_outq;
	p->flags = UPF_SKIP_TEST \| UPF_SHARE_IRQ \| UPF_FIXED_TYPE;
	p->type = PORT_OCTEON;
	data->usr_reg = 0x27;
	data->skip_autocfg = true;
	}
	#endif
	if (of_device_is_big_endian(p->dev->of_node)) {
	p->iotype = UPIO_MEM32BE;
	p->serial_in = dw8250_serial_in32be;
	p->serial_out = dw8250_serial_out32be;
	}
	} else if (has_acpi_companion(p->dev)) {
	const struct acpi_device_id *id;

	id = acpi_match_device(p->dev->driver->acpi_match_table,
	p->dev);
	if (id && !strcmp(id->id, "APMC0D08")) {
	p->iotype = UPIO_MEM32;
	p->regshift = 2;
	p->serial_in = dw8250_serial_in32;
	data->uart_16550_compatible = true;
	}
	}

	/* Platforms with iDMA */
	if (platform_get_resource_byname(to_platform_device(p->dev),
	IORESOURCE_MEM, "lpss_priv")) {
	data->dma.rx_param = p->dev->parent;
	data->dma.tx_param = p->dev->parent;
	data->dma.fn = dw8250_idma_filter;
	}
	}

	static void dw8250_setup_port(struct uart_port *p)
	{
	struct uart_8250_port *up = up_to_u8250p(p);
	u32 reg;

	/*
	* If the Component Version Register returns zero, we know that
	* ADDITIONAL_FEATURES are not enabled. No need to go any further.
	*/
	if (p->iotype == UPIO_MEM32BE)
	reg = ioread32be(p->membase + DW_UART_UCV);
	else
	reg = readl(p->membase + DW_UART_UCV);
	if (!reg)
	return;

	dev_dbg(p->dev, "Designware UART version %c.%c%c\n",
	(reg >> 24) & 0xff, (reg >> 16) & 0xff, (reg >> 8) & 0xff);

	if (p->iotype == UPIO_MEM32BE)
	reg = ioread32be(p->membase + DW_UART_CPR);
	else
	reg = readl(p->membase + DW_UART_CPR);
	if (!reg)
	return;

	/* Select the type based on fifo */
	if (reg & DW_UART_CPR_FIFO_MODE) {
	p->type = PORT_16550A;
	p->flags \|= UPF_FIXED_TYPE;
	p->fifosize = DW_UART_CPR_FIFO_SIZE(reg);
	up->capabilities = UART_CAP_FIFO;
	}

	if (reg & DW_UART_CPR_AFCE_MODE)
	up->capabilities \|= UART_CAP_AFE;

	if (reg & DW_UART_CPR_SIR_MODE)
	up->capabilities \|= UART_CAP_IRDA;
	}

	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;
	data->msr_mask_off \|= UART_MSR_TERI;
	}

	/* Always ask for fixed clock rate from a property. */
	device_property_read_u32(dev, "clock-frequency", &p->uartclk);

	/* If there is separate baudclk, get the rate from it. */
	data->clk = devm_clk_get(dev, "baudclk");
	if (IS_ERR(data->clk) && PTR_ERR(data->clk) != -EPROBE_DEFER)
	data->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(data->clk) && PTR_ERR(data->clk) == -EPROBE_DEFER)
	return -EPROBE_DEFER;
	if (!IS_ERR_OR_NULL(data->clk)) {
	err = clk_prepare_enable(data->clk);
	if (err)
	dev_warn(dev, "could not enable optional baudclk: %d\n",
	err);
	else
	p->uartclk = clk_get_rate(data->clk);
	}

	/* If no clock rate is defined, fail. */
	if (!p->uartclk) {
	dev_err(dev, "clock rate not defined\n");
	return -EINVAL;
	}

	data->pclk = devm_clk_get(dev, "apb_pclk");
	if (IS_ERR(data->pclk) && PTR_ERR(data->pclk) == -EPROBE_DEFER) {
	err = -EPROBE_DEFER;
	goto err_clk;
	}
	if (!IS_ERR(data->pclk)) {
	err = clk_prepare_enable(data->pclk);
	if (err) {
	dev_err(dev, "could not enable apb_pclk\n");
	goto err_clk;
	}
	}

	data->rst = devm_reset_control_get_optional(dev, NULL);
	if (IS_ERR(data->rst)) {
	err = PTR_ERR(data->rst);
	goto err_pclk;
	}
	reset_control_deassert(data->rst);

	dw8250_quirks(p, data);

	/* If the Busy Functionality is not implemented, don't handle it */
	if (data->uart_16550_compatible)
	p->handle_irq = NULL;

	if (!data->skip_autocfg)
	dw8250_setup_port(p);

	/* If we have a valid fifosize, try hooking up DMA */
	if (p->fifosize) {
	data->dma.rxconf.src_maxburst = p->fifosize / 4;
	data->dma.txconf.dst_maxburst = p->fifosize / 4;
	uart.dma = &data->dma;
	}

	data->line = serial8250_register_8250_port(&uart);
	if (data->line < 0) {
	err = data->line;
	goto err_reset;
	}

	platform_set_drvdata(pdev, data);

	pm_runtime_set_active(dev);
	pm_runtime_enable(dev);

	return 0;

	err_reset:
	reset_control_assert(data->rst);

	err_pclk:
	if (!IS_ERR(data->pclk))
	clk_disable_unprepare(data->pclk);

	err_clk:
	if (!IS_ERR(data->clk))
	clk_disable_unprepare(data->clk);

	return err;
	}

	static int dw8250_remove(struct platform_device *pdev)
	{
	struct dw8250_data *data = platform_get_drvdata(pdev);

	pm_runtime_get_sync(&pdev->dev);

	serial8250_unregister_port(data->line);

	reset_control_assert(data->rst);

	if (!IS_ERR(data->pclk))
	clk_disable_unprepare(data->pclk);

	if (!IS_ERR(data->clk))
	clk_disable_unprepare(data->clk);

	pm_runtime_disable(&pdev->dev);
	pm_runtime_put_noidle(&pdev->dev);

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int dw8250_suspend(struct device *dev)
	{
	struct dw8250_data *data = dev_get_drvdata(dev);

	serial8250_suspend_port(data->line);

	return 0;
	}

	static int dw8250_resume(struct device *dev)
	{
	struct dw8250_data *data = dev_get_drvdata(dev);

	serial8250_resume_port(data->line);

	return 0;
	}
	#endif /* CONFIG_PM_SLEEP */

	#ifdef CONFIG_PM
	static int dw8250_runtime_suspend(struct device *dev)
	{
	struct dw8250_data *data = dev_get_drvdata(dev);

	if (!IS_ERR(data->clk))
	clk_disable_unprepare(data->clk);

	if (!IS_ERR(data->pclk))
	clk_disable_unprepare(data->pclk);

	return 0;
	}

	static int dw8250_runtime_resume(struct device *dev)
	{
	struct dw8250_data *data = dev_get_drvdata(dev);

	if (!IS_ERR(data->pclk))
	clk_prepare_enable(data->pclk);

	if (!IS_ERR(data->clk))
	clk_prepare_enable(data->clk);

	return 0;
	}
	#endif

	static const struct dev_pm_ops dw8250_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(dw8250_suspend, dw8250_resume)
	SET_RUNTIME_PM_OPS(dw8250_runtime_suspend, dw8250_runtime_resume, NULL)
	};

	static const struct of_device_id dw8250_of_match[] = {
	{ .compatible = "snps,dw-apb-uart" },
	{ .compatible = "cavium,octeon-3860-uart" },
	{ /* Sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, dw8250_of_match);

	static const struct acpi_device_id dw8250_acpi_match[] = {
	{ "INT33C4", 0 },
	{ "INT33C5", 0 },
	{ "INT3434", 0 },
	{ "INT3435", 0 },
	{ "80860F0A", 0 },
	{ "8086228A", 0 },
	{ "APMC0D08", 0},
	{ "AMD0020", 0 },
	{ "AMDI0020", 0 },
	{ "HISI0031", 0 },
	{ },
	};
	MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match);

	static struct platform_driver dw8250_platform_driver = {
	.driver = {
	.name = "dw-apb-uart",
	.pm = &dw8250_pm_ops,
	.of_match_table = dw8250_of_match,
	.acpi_match_table = ACPI_PTR(dw8250_acpi_match),
	},
	.probe = dw8250_probe,
	.remove = dw8250_remove,
	};

	module_platform_driver(dw8250_platform_driver);

	MODULE_AUTHOR("Jamie Iles");
	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("Synopsys DesignWare 8250 serial port driver");
	MODULE_ALIAS("platform:dw-apb-uart");