// SPDX-License-Identifier: GPL-2.0
/*
 * 8250_mid.c - Driver for UART on Intel Penwell and various other Intel SOCs
 *
 * Copyright (C) 2015 Intel Corporation
 * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
 */

#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/rational.h>
#include <linux/util_macros.h>

#include <linux/dma/hsu.h>

#include "8250.h"

#define PCI_DEVICE_ID_INTEL_PNW_UART1   0x081b
#define PCI_DEVICE_ID_INTEL_PNW_UART2   0x081c
#define PCI_DEVICE_ID_INTEL_PNW_UART3   0x081d
#define PCI_DEVICE_ID_INTEL_TNG_UART    0x1191
#define PCI_DEVICE_ID_INTEL_CDF_UART    0x18d8
#define PCI_DEVICE_ID_INTEL_DNV_UART    0x19d8

/* Intel MID Specific registers */
#define INTEL_MID_UART_FISR             0x08
#define INTEL_MID_UART_PS               0x30
#define INTEL_MID_UART_MUL              0x34
#define INTEL_MID_UART_DIV              0x38

struct mid8250;

struct mid8250_board {
        unsigned long freq;
        unsigned int base_baud;
        unsigned int bar;
        int (*setup)(struct mid8250 *, struct uart_port *p);
        void (*exit)(struct mid8250 *);
};

struct mid8250 {
        int line;
        int dma_index;
        struct pci_dev *dma_dev;
        struct uart_8250_dma dma;
        struct mid8250_board *board;
        struct hsu_dma_chip dma_chip;
};

/*****************************************************************************/

static int pnw_setup(struct mid8250 *mid, struct uart_port *p)
{
        struct pci_dev *pdev = to_pci_dev(p->dev);

        switch (pdev->device) {
        case PCI_DEVICE_ID_INTEL_PNW_UART1:
                mid->dma_index = 0;
                break;
        case PCI_DEVICE_ID_INTEL_PNW_UART2:
                mid->dma_index = 1;
                break;
        case PCI_DEVICE_ID_INTEL_PNW_UART3:
                mid->dma_index = 2;
                break;
        default:
                return -EINVAL;
        }

        mid->dma_dev = pci_get_slot(pdev->bus,
                                    PCI_DEVFN(PCI_SLOT(pdev->devfn), 3));
        return 0;
}

static void pnw_exit(struct mid8250 *mid)
{
        pci_dev_put(mid->dma_dev);
}

static int tng_handle_irq(struct uart_port *p)
{
        struct mid8250 *mid = p->private_data;
        struct uart_8250_port *up = up_to_u8250p(p);
        struct hsu_dma_chip *chip;
        u32 status;
        int ret = 0;
        int err;

        chip = pci_get_drvdata(mid->dma_dev);

        /* Rx DMA */
        err = hsu_dma_get_status(chip, mid->dma_index * 2 + 1, &status);
        if (err > 0) {
                serial8250_rx_dma_flush(up);
                ret |= 1;
        } else if (err == 0)
                ret |= hsu_dma_do_irq(chip, mid->dma_index * 2 + 1, status);

        /* Tx DMA */
        err = hsu_dma_get_status(chip, mid->dma_index * 2, &status);
        if (err > 0)
                ret |= 1;
        else if (err == 0)
                ret |= hsu_dma_do_irq(chip, mid->dma_index * 2, status);

        /* UART */
        ret |= serial8250_handle_irq(p, serial_port_in(p, UART_IIR));
        return IRQ_RETVAL(ret);
}

static int tng_setup(struct mid8250 *mid, struct uart_port *p)
{
        struct pci_dev *pdev = to_pci_dev(p->dev);
        int index = PCI_FUNC(pdev->devfn);

        /*
         * Device 0000:00:04.0 is not a real HSU port. It provides a global
         * register set for all HSU ports, although it has the same PCI ID.
         * Skip it here.
         */
        if (index-- == 0)
                return -ENODEV;

        mid->dma_index = index;
        mid->dma_dev = pci_get_slot(pdev->bus, PCI_DEVFN(5, 0));

        p->handle_irq = tng_handle_irq;
        return 0;
}

static void tng_exit(struct mid8250 *mid)
{
        pci_dev_put(mid->dma_dev);
}

static int dnv_handle_irq(struct uart_port *p)
{
        struct mid8250 *mid = p->private_data;
        struct uart_8250_port *up = up_to_u8250p(p);
        unsigned int fisr = serial_port_in(p, INTEL_MID_UART_FISR);
        u32 status;
        int ret = 0;
        int err;

        if (fisr & BIT(2)) {
                err = hsu_dma_get_status(&mid->dma_chip, 1, &status);
                if (err > 0) {
                        serial8250_rx_dma_flush(up);
                        ret |= 1;
                } else if (err == 0)
                        ret |= hsu_dma_do_irq(&mid->dma_chip, 1, status);
        }
        if (fisr & BIT(1)) {
                err = hsu_dma_get_status(&mid->dma_chip, 0, &status);
                if (err > 0)
                        ret |= 1;
                else if (err == 0)
                        ret |= hsu_dma_do_irq(&mid->dma_chip, 0, status);
        }
        if (fisr & BIT(0))
                ret |= serial8250_handle_irq(p, serial_port_in(p, UART_IIR));
        return IRQ_RETVAL(ret);
}

#define DNV_DMA_CHAN_OFFSET 0x80

static int dnv_setup(struct mid8250 *mid, struct uart_port *p)
{
        struct hsu_dma_chip *chip = &mid->dma_chip;
        struct pci_dev *pdev = to_pci_dev(p->dev);
        int ret;

        pci_set_master(pdev);

        ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
        if (ret < 0)
                return ret;

        p->irq = pci_irq_vector(pdev, 0);

        chip->dev = &pdev->dev;
        chip->irq = pci_irq_vector(pdev, 0);
        chip->regs = p->membase;
        chip->length = pci_resource_len(pdev, mid->board->bar);
        chip->offset = DNV_DMA_CHAN_OFFSET;

        /* Falling back to PIO mode if DMA probing fails */
        ret = hsu_dma_probe(chip);
        if (ret)
                return 0;

        mid->dma_dev = pdev;

        p->handle_irq = dnv_handle_irq;
        return 0;
}

static void dnv_exit(struct mid8250 *mid)
{
        if (!mid->dma_dev)
                return;
        hsu_dma_remove(&mid->dma_chip);
}

/*****************************************************************************/

static void mid8250_set_termios(struct uart_port *p, struct ktermios *termios,
                                const struct ktermios *old)
{
        unsigned int baud = tty_termios_baud_rate(termios);
        struct mid8250 *mid = p->private_data;
        unsigned short ps = 16;
        unsigned long fuart = baud * ps;
        unsigned long w = BIT(24) - 1;
        unsigned long mul, div;

        /* Gracefully handle the B0 case: fall back to B9600 */
        fuart = fuart ? fuart : 9600 * 16;

        if (mid->board->freq < fuart) {
                /* Find prescaler value that satisfies Fuart < Fref */
                if (mid->board->freq > baud)
                        ps = mid->board->freq / baud;   /* baud rate too high */
                else
                        ps = 1;                         /* PLL case */
                fuart = baud * ps;
        } else {
                /* Get Fuart closer to Fref */
                fuart *= rounddown_pow_of_two(mid->board->freq / fuart);
        }

        rational_best_approximation(fuart, mid->board->freq, w, w, &mul, &div);
        p->uartclk = fuart * 16 / ps;           /* core uses ps = 16 always */

        writel(ps, p->membase + INTEL_MID_UART_PS);             /* set PS */
        writel(mul, p->membase + INTEL_MID_UART_MUL);           /* set MUL */
        writel(div, p->membase + INTEL_MID_UART_DIV);

        serial8250_do_set_termios(p, termios, old);
}

static bool mid8250_dma_filter(struct dma_chan *chan, void *param)
{
        struct hsu_dma_slave *s = param;

        if (s->dma_dev != chan->device->dev || s->chan_id != chan->chan_id)
                return false;

        chan->private = s;
        return true;
}

static int mid8250_dma_setup(struct mid8250 *mid, struct uart_8250_port *port)
{
        struct uart_8250_dma *dma = &mid->dma;
        struct device *dev = port->port.dev;
        struct hsu_dma_slave *rx_param;
        struct hsu_dma_slave *tx_param;

        if (!mid->dma_dev)
                return 0;

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

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

        rx_param->chan_id = mid->dma_index * 2 + 1;
        tx_param->chan_id = mid->dma_index * 2;

        dma->rxconf.src_maxburst = 64;
        dma->txconf.dst_maxburst = 64;

        rx_param->dma_dev = &mid->dma_dev->dev;
        tx_param->dma_dev = &mid->dma_dev->dev;

        dma->fn = mid8250_dma_filter;
        dma->rx_param = rx_param;
        dma->tx_param = tx_param;

        port->dma = dma;
        return 0;
}

static int mid8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        struct uart_8250_port uart;
        struct mid8250 *mid;
        int ret;

        ret = pcim_enable_device(pdev);
        if (ret)
                return ret;

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

        mid->board = (struct mid8250_board *)id->driver_data;

        memset(&uart, 0, sizeof(struct uart_8250_port));

        uart.port.dev = &pdev->dev;
        uart.port.irq = pdev->irq;
        uart.port.private_data = mid;
        uart.port.type = PORT_16750;
        uart.port.iotype = UPIO_MEM;
        uart.port.uartclk = mid->board->base_baud * 16;
        uart.port.flags = UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE;
        uart.port.set_termios = mid8250_set_termios;

        uart.port.mapbase = pci_resource_start(pdev, mid->board->bar);
        uart.port.membase = pcim_iomap(pdev, mid->board->bar, 0);
        if (!uart.port.membase)
                return -ENOMEM;

        if (mid->board->setup) {
                ret = mid->board->setup(mid, &uart.port);
                if (ret)
                        return ret;
        }

        ret = mid8250_dma_setup(mid, &uart);
        if (ret)
                goto err;

        ret = serial8250_register_8250_port(&uart);
        if (ret < 0)
                goto err;

        mid->line = ret;

        pci_set_drvdata(pdev, mid);
        return 0;

err:
        if (mid->board->exit)
                mid->board->exit(mid);
        return ret;
}

static void mid8250_remove(struct pci_dev *pdev)
{
        struct mid8250 *mid = pci_get_drvdata(pdev);

        serial8250_unregister_port(mid->line);

        if (mid->board->exit)
                mid->board->exit(mid);
}

static const struct mid8250_board pnw_board = {
        .freq = 50000000,
        .base_baud = 115200,
        .bar = 0,
        .setup = pnw_setup,
        .exit = pnw_exit,
};

static const struct mid8250_board tng_board = {
        .freq = 38400000,
        .base_baud = 1843200,
        .bar = 0,
        .setup = tng_setup,
        .exit = tng_exit,
};

static const struct mid8250_board dnv_board = {
        .freq = 133333333,
        .base_baud = 115200,
        .bar = 1,
        /*
         * Errata:
         * HSUART May Stop Functioning when DMA is Active.
         *
         * - Denverton document #572409, rev 3.4, DNV60
         * - Ice Lake Xeon D document #714070, ICXD65
         * - Snowridge document #731931, SNR44
         */
        .setup = PTR_IF(false, dnv_setup),
        .exit = PTR_IF(false, dnv_exit),
};

static const struct pci_device_id pci_ids[] = {
        { PCI_DEVICE_DATA(INTEL, PNW_UART1, &pnw_board) },
        { PCI_DEVICE_DATA(INTEL, PNW_UART2, &pnw_board) },
        { PCI_DEVICE_DATA(INTEL, PNW_UART3, &pnw_board) },
        { PCI_DEVICE_DATA(INTEL, TNG_UART, &tng_board) },
        { PCI_DEVICE_DATA(INTEL, CDF_UART, &dnv_board) },
        { PCI_DEVICE_DATA(INTEL, DNV_UART, &dnv_board) },
        { }
};
MODULE_DEVICE_TABLE(pci, pci_ids);

static struct pci_driver mid8250_pci_driver = {
        .name           = "8250_mid",
        .id_table       = pci_ids,
        .probe          = mid8250_probe,
        .remove         = mid8250_remove,
};

module_pci_driver(mid8250_pci_driver);

MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Intel MID UART driver");