/*
 * 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");