/*
 * 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/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/serial_8250.h>
#include <linux/serial_core.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 "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 */

/* Intel Low Power Subsystem specific */
#define LPSS_PRV_CLOCK_PARAMS 0x800

/* 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)


struct dw8250_data {
	int	last_lcr;
	int	line;
};

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

	if (offset == UART_LCR)
		d->last_lcr = value;

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

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

	return readb(p->membase + offset);
}

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

	if (offset == UART_LCR)
		d->last_lcr = value;

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

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

	return readl(p->membase + offset);
}

static int dw8250_handle_irq(struct uart_port *p)
{
	struct dw8250_data *d = p->private_data;
	unsigned int iir = p->serial_in(p, UART_IIR);

	if (serial8250_handle_irq(p, iir)) {
		return 1;
	} else if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
		/* Clear the USR and write the LCR again. */
		(void)p->serial_in(p, DW_UART_USR);
		p->serial_out(p, UART_LCR, d->last_lcr);

		return 1;
	}

	return 0;
}

static int dw8250_probe_of(struct uart_port *p)
{
	struct device_node	*np = p->dev->of_node;
	u32			val;

	if (!of_property_read_u32(np, "reg-io-width", &val)) {
		switch (val) {
		case 1:
			break;
		case 4:
			p->iotype = UPIO_MEM32;
			p->serial_in = dw8250_serial_in32;
			p->serial_out = dw8250_serial_out32;
			break;
		default:
			dev_err(p->dev, "unsupported reg-io-width (%u)\n", val);
			return -EINVAL;
		}
	}

	if (!of_property_read_u32(np, "reg-shift", &val))
		p->regshift = val;

	if (of_property_read_u32(np, "clock-frequency", &val)) {
		dev_err(p->dev, "no clock-frequency property set\n");
		return -EINVAL;
	}
	p->uartclk = val;

	return 0;
}

#ifdef CONFIG_ACPI
static bool dw8250_acpi_dma_filter(struct dma_chan *chan, void *parm)
{
	return chan->chan_id == *(int *)parm;
}

static acpi_status
dw8250_acpi_walk_resource(struct acpi_resource *res, void *data)
{
	struct uart_port		*p = data;
	struct uart_8250_port		*port;
	struct uart_8250_dma		*dma;
	struct acpi_resource_fixed_dma	*fixed_dma;
	struct dma_slave_config		*slave;

	port = container_of(p, struct uart_8250_port, port);

	switch (res->type) {
	case ACPI_RESOURCE_TYPE_FIXED_DMA:
		fixed_dma = &res->data.fixed_dma;

		/* TX comes first */
		if (!port->dma) {
			dma = devm_kzalloc(p->dev, sizeof(*dma), GFP_KERNEL);
			if (!dma)
				return AE_NO_MEMORY;

			port->dma = dma;
			slave = &dma->txconf;

			slave->direction	= DMA_MEM_TO_DEV;
			slave->dst_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
			slave->slave_id		= fixed_dma->request_lines;
			slave->dst_maxburst	= port->tx_loadsz / 4;

			dma->tx_chan_id		= fixed_dma->channels;
			dma->tx_param		= &dma->tx_chan_id;
			dma->fn			= dw8250_acpi_dma_filter;
		} else {
			dma = port->dma;
			slave = &dma->rxconf;

			slave->direction	= DMA_DEV_TO_MEM;
			slave->src_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
			slave->slave_id		= fixed_dma->request_lines;
			slave->src_maxburst	= p->fifosize / 4;

			dma->rx_chan_id		= fixed_dma->channels;
			dma->rx_param		= &dma->rx_chan_id;
		}

		break;
	}

	return AE_OK;
}

static int dw8250_probe_acpi(struct uart_port *p)
{
	const struct acpi_device_id *id;
	acpi_status status;
	u32 reg;

	id = acpi_match_device(p->dev->driver->acpi_match_table, p->dev);
	if (!id)
		return -ENODEV;

	p->iotype = UPIO_MEM32;
	p->serial_in = dw8250_serial_in32;
	p->serial_out = dw8250_serial_out32;
	p->regshift = 2;
	p->uartclk = (unsigned int)id->driver_data;

	status = acpi_walk_resources(ACPI_HANDLE(p->dev), METHOD_NAME__CRS,
				     dw8250_acpi_walk_resource, p);
	if (ACPI_FAILURE(status)) {
		dev_err_ratelimited(p->dev, "%s failed \"%s\"\n", __func__,
				    acpi_format_exception(status));
		return -ENODEV;
	}

	/* Fix Haswell issue where the clocks do not get enabled */
	if (!strcmp(id->id, "INT33C4") || !strcmp(id->id, "INT33C5")) {
		reg = readl(p->membase + LPSS_PRV_CLOCK_PARAMS);
		writel(reg | 1, p->membase + LPSS_PRV_CLOCK_PARAMS);
	}

	return 0;
}
#else
static inline int dw8250_probe_acpi(struct uart_port *p)
{
	return -ENODEV;
}
#endif /* CONFIG_ACPI */

static void dw8250_setup_port(struct uart_8250_port *up)
{
	struct uart_port	*p = &up->port;
	u32			reg = readl(p->membase + DW_UART_UCV);

	/*
	 * If the Component Version Register returns zero, we know that
	 * ADDITIONAL_FEATURES are not enabled. No need to go any further.
	 */
	if (!reg)
		return;

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

	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->tx_loadsz = p->fifosize;
	}
}

static int dw8250_probe(struct platform_device *pdev)
{
	struct uart_8250_port uart = {};
	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	struct dw8250_data *data;
	int err;

	if (!regs || !irq) {
		dev_err(&pdev->dev, "no registers/irq defined\n");
		return -EINVAL;
	}

	spin_lock_init(&uart.port.lock);
	uart.port.mapbase = regs->start;
	uart.port.irq = irq->start;
	uart.port.handle_irq = dw8250_handle_irq;
	uart.port.type = PORT_8250;
	uart.port.flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_FIXED_PORT;
	uart.port.dev = &pdev->dev;

	uart.port.membase = ioremap(regs->start, resource_size(regs));
	if (!uart.port.membase)
		return -ENOMEM;

	uart.port.iotype = UPIO_MEM;
	uart.port.serial_in = dw8250_serial_in;
	uart.port.serial_out = dw8250_serial_out;

	dw8250_setup_port(&uart);

	if (pdev->dev.of_node) {
		err = dw8250_probe_of(&uart.port);
		if (err)
			return err;
	} else if (ACPI_HANDLE(&pdev->dev)) {
		err = dw8250_probe_acpi(&uart.port);
		if (err)
			return err;
	} else {
		return -ENODEV;
	}

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

	uart.port.private_data = data;

	data->line = serial8250_register_8250_port(&uart);
	if (data->line < 0)
		return data->line;

	platform_set_drvdata(pdev, data);

	return 0;
}

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

	serial8250_unregister_port(data->line);

	return 0;
}

#ifdef CONFIG_PM
static int dw8250_suspend(struct platform_device *pdev, pm_message_t state)
{
	struct dw8250_data *data = platform_get_drvdata(pdev);

	serial8250_suspend_port(data->line);

	return 0;
}

static int dw8250_resume(struct platform_device *pdev)
{
	struct dw8250_data *data = platform_get_drvdata(pdev);

	serial8250_resume_port(data->line);

	return 0;
}
#else
#define dw8250_suspend NULL
#define dw8250_resume NULL
#endif /* CONFIG_PM */

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

static const struct acpi_device_id dw8250_acpi_match[] = {
	{ "INT33C4", 100000000 },
	{ "INT33C5", 100000000 },
	{ },
};
MODULE_DEVICE_TABLE(acpi, dw8250_acpi_match);

static struct platform_driver dw8250_platform_driver = {
	.driver = {
		.name		= "dw-apb-uart",
		.owner		= THIS_MODULE,
		.of_match_table	= dw8250_of_match,
		.acpi_match_table = ACPI_PTR(dw8250_acpi_match),
	},
	.probe			= dw8250_probe,
	.remove			= dw8250_remove,
	.suspend		= dw8250_suspend,
	.resume			= dw8250_resume,
};

module_platform_driver(dw8250_platform_driver);

MODULE_AUTHOR("Jamie Iles");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Synopsys DesignWare 8250 serial port driver");