// SPDX-License-Identifier: GPL-2.0
/*
 * 8250_lpss.c - Driver for UART on Intel Braswell and various other Intel SoCs
 *
 * Copyright (C) 2016 Intel Corporation
 * Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
 */

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

#include <linux/dmaengine.h>
#include <linux/dma/dw.h>

#include "8250_dwlib.h"

#define PCI_DEVICE_ID_INTEL_QRK_UARTx   0x0936

#define PCI_DEVICE_ID_INTEL_BYT_UART1   0x0f0a
#define PCI_DEVICE_ID_INTEL_BYT_UART2   0x0f0c

#define PCI_DEVICE_ID_INTEL_BSW_UART1   0x228a
#define PCI_DEVICE_ID_INTEL_BSW_UART2   0x228c

#define PCI_DEVICE_ID_INTEL_EHL_UART0   0x4b96
#define PCI_DEVICE_ID_INTEL_EHL_UART1   0x4b97
#define PCI_DEVICE_ID_INTEL_EHL_UART2   0x4b98
#define PCI_DEVICE_ID_INTEL_EHL_UART3   0x4b99
#define PCI_DEVICE_ID_INTEL_EHL_UART4   0x4b9a
#define PCI_DEVICE_ID_INTEL_EHL_UART5   0x4b9b

#define PCI_DEVICE_ID_INTEL_BDW_UART1   0x9ce3
#define PCI_DEVICE_ID_INTEL_BDW_UART2   0x9ce4

/* Intel LPSS specific registers */

#define BYT_PRV_CLK                     0x800
#define BYT_PRV_CLK_EN                  BIT(0)
#define BYT_PRV_CLK_M_VAL_SHIFT         1
#define BYT_PRV_CLK_N_VAL_SHIFT         16
#define BYT_PRV_CLK_UPDATE              BIT(31)

#define BYT_TX_OVF_INT                  0x820
#define BYT_TX_OVF_INT_MASK             BIT(1)

struct lpss8250;

struct lpss8250_board {
        unsigned long freq;
        unsigned int base_baud;
        int (*setup)(struct lpss8250 *, struct uart_port *p);
        void (*exit)(struct lpss8250 *);
};

struct lpss8250 {
        struct dw8250_port_data data;
        struct lpss8250_board *board;

        /* DMA parameters */
        struct dw_dma_chip dma_chip;
        struct dw_dma_slave dma_param;
        u8 dma_maxburst;
};

static inline struct lpss8250 *to_lpss8250(struct dw8250_port_data *data)
{
        return container_of(data, struct lpss8250, data);
}

static void byt_set_termios(struct uart_port *p, struct ktermios *termios,
                            const struct ktermios *old)
{
        unsigned int baud = tty_termios_baud_rate(termios);
        struct lpss8250 *lpss = to_lpss8250(p->private_data);
        unsigned long fref = lpss->board->freq, fuart = baud * 16;
        unsigned long w = BIT(15) - 1;
        unsigned long m, n;
        u32 reg;

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

        /* Get Fuart closer to Fref */
        fuart *= rounddown_pow_of_two(fref / fuart);

        /*
         * For baud rates 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M and 4M the
         * dividers must be adjusted.
         *
         * uartclk = (m / n) * 100 MHz, where m <= n
         */
        rational_best_approximation(fuart, fref, w, w, &m, &n);
        p->uartclk = fuart;

        /* Reset the clock */
        reg = (m << BYT_PRV_CLK_M_VAL_SHIFT) | (n << BYT_PRV_CLK_N_VAL_SHIFT);
        writel(reg, p->membase + BYT_PRV_CLK);
        reg |= BYT_PRV_CLK_EN | BYT_PRV_CLK_UPDATE;
        writel(reg, p->membase + BYT_PRV_CLK);

        dw8250_do_set_termios(p, termios, old);
}

static unsigned int byt_get_mctrl(struct uart_port *port)
{
        unsigned int ret = serial8250_do_get_mctrl(port);

        /* Force DCD and DSR signals to permanently be reported as active */
        ret |= TIOCM_CAR | TIOCM_DSR;

        return ret;
}

static int byt_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
{
        struct dw_dma_slave *param = &lpss->dma_param;
        struct pci_dev *pdev = to_pci_dev(port->dev);
        struct pci_dev *dma_dev;

        switch (pdev->device) {
        case PCI_DEVICE_ID_INTEL_BYT_UART1:
        case PCI_DEVICE_ID_INTEL_BSW_UART1:
        case PCI_DEVICE_ID_INTEL_BDW_UART1:
                param->src_id = 3;
                param->dst_id = 2;
                break;
        case PCI_DEVICE_ID_INTEL_BYT_UART2:
        case PCI_DEVICE_ID_INTEL_BSW_UART2:
        case PCI_DEVICE_ID_INTEL_BDW_UART2:
                param->src_id = 5;
                param->dst_id = 4;
                break;
        default:
                return -EINVAL;
        }

        dma_dev = pci_get_slot(pdev->bus, PCI_DEVFN(PCI_SLOT(pdev->devfn), 0));

        param->dma_dev = &dma_dev->dev;
        param->m_master = 0;
        param->p_master = 1;

        lpss->dma_maxburst = 16;

        port->set_termios = byt_set_termios;
        port->get_mctrl = byt_get_mctrl;

        /* Disable TX counter interrupts */
        writel(BYT_TX_OVF_INT_MASK, port->membase + BYT_TX_OVF_INT);

        return 0;
}

static void byt_serial_exit(struct lpss8250 *lpss)
{
        struct dw_dma_slave *param = &lpss->dma_param;

        /* Paired with pci_get_slot() in the byt_serial_setup() above */
        put_device(param->dma_dev);
}

static int ehl_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
{
        struct uart_8250_dma *dma = &lpss->data.dma;
        struct uart_8250_port *up = up_to_u8250p(port);

        /*
         * This simply makes the checks in the 8250_port to try the DMA
         * channel request which in turn uses the magic of ACPI tables
         * parsing (see drivers/dma/acpi-dma.c for the details) and
         * matching with the registered General Purpose DMA controllers.
         */
        up->dma = dma;

        lpss->dma_maxburst = 16;

        port->set_termios = dw8250_do_set_termios;

        return 0;
}

static void ehl_serial_exit(struct lpss8250 *lpss)
{
        struct uart_8250_port *up = serial8250_get_port(lpss->data.line);

        up->dma = NULL;
}

#ifdef CONFIG_SERIAL_8250_DMA
static const struct dw_dma_platform_data qrk_serial_dma_pdata = {
        .nr_channels = 2,
        .chan_allocation_order = CHAN_ALLOCATION_ASCENDING,
        .chan_priority = CHAN_PRIORITY_ASCENDING,
        .block_size = 4095,
        .nr_masters = 1,
        .data_width = {4},
        .multi_block = {0},
};

static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
{
        struct uart_8250_dma *dma = &lpss->data.dma;
        struct dw_dma_chip *chip = &lpss->dma_chip;
        struct dw_dma_slave *param = &lpss->dma_param;
        struct pci_dev *pdev = to_pci_dev(port->dev);
        int ret;

        chip->pdata = &qrk_serial_dma_pdata;
        chip->dev = &pdev->dev;
        chip->id = pdev->devfn;
        chip->irq = pci_irq_vector(pdev, 0);
        chip->regs = pci_ioremap_bar(pdev, 1);
        if (!chip->regs)
                return;

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

        pci_try_set_mwi(pdev);

        /* Special DMA address for UART */
        dma->rx_dma_addr = 0xfffff000;
        dma->tx_dma_addr = 0xfffff000;

        param->dma_dev = &pdev->dev;
        param->src_id = 0;
        param->dst_id = 1;
        param->hs_polarity = true;

        lpss->dma_maxburst = 8;
}

static void qrk_serial_exit_dma(struct lpss8250 *lpss)
{
        struct dw_dma_chip *chip = &lpss->dma_chip;
        struct dw_dma_slave *param = &lpss->dma_param;

        if (!param->dma_dev)
                return;

        dw_dma_remove(chip);

        pci_iounmap(to_pci_dev(chip->dev), chip->regs);
}
#else   /* CONFIG_SERIAL_8250_DMA */
static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port) {}
static void qrk_serial_exit_dma(struct lpss8250 *lpss) {}
#endif  /* !CONFIG_SERIAL_8250_DMA */

static int qrk_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
{
        qrk_serial_setup_dma(lpss, port);
        return 0;
}

static void qrk_serial_exit(struct lpss8250 *lpss)
{
        qrk_serial_exit_dma(lpss);
}

static bool lpss8250_dma_filter(struct dma_chan *chan, void *param)
{
        struct dw_dma_slave *dws = param;

        if (dws->dma_dev != chan->device->dev)
                return false;

        chan->private = dws;
        return true;
}

static int lpss8250_dma_setup(struct lpss8250 *lpss, struct uart_8250_port *port)
{
        struct uart_8250_dma *dma = &lpss->data.dma;
        struct dw_dma_slave *rx_param, *tx_param;
        struct device *dev = port->port.dev;

        if (!lpss->dma_param.dma_dev) {
                dma = port->dma;
                if (dma)
                        goto out_configuration_only;

                return 0;
        }

        rx_param = devm_kmemdup(dev, &lpss->dma_param, sizeof(*rx_param), GFP_KERNEL);
        if (!rx_param)
                return -ENOMEM;

        tx_param = devm_kmemdup(dev, &lpss->dma_param, sizeof(*tx_param), GFP_KERNEL);
        if (!tx_param)
                return -ENOMEM;

        dma->fn = lpss8250_dma_filter;
        dma->rx_param = rx_param;
        dma->tx_param = tx_param;

        port->dma = dma;

out_configuration_only:
        dma->rxconf.src_maxburst = lpss->dma_maxburst;
        dma->txconf.dst_maxburst = lpss->dma_maxburst;

        return 0;
}

static int lpss8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        struct uart_8250_port uart;
        struct lpss8250 *lpss;
        int ret;

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

        pci_set_master(pdev);

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

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

        lpss->board = (struct lpss8250_board *)id->driver_data;

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

        uart.port.dev = &pdev->dev;
        uart.port.irq = pci_irq_vector(pdev, 0);
        uart.port.private_data = &lpss->data;
        uart.port.type = PORT_16550A;
        uart.port.iotype = UPIO_MEM32;
        uart.port.regshift = 2;
        uart.port.uartclk = lpss->board->base_baud * 16;
        uart.port.flags = UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE;
        uart.capabilities = UART_CAP_FIFO | UART_CAP_AFE;
        uart.port.mapbase = pci_resource_start(pdev, 0);
        uart.port.membase = pcim_iomap(pdev, 0, 0);
        if (!uart.port.membase)
                return -ENOMEM;

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

        dw8250_setup_port(&uart.port);

        ret = lpss8250_dma_setup(lpss, &uart);
        if (ret)
                goto err_exit;

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

        lpss->data.line = ret;

        pci_set_drvdata(pdev, lpss);
        return 0;

err_exit:
        lpss->board->exit(lpss);
        pci_free_irq_vectors(pdev);
        return ret;
}

static void lpss8250_remove(struct pci_dev *pdev)
{
        struct lpss8250 *lpss = pci_get_drvdata(pdev);

        serial8250_unregister_port(lpss->data.line);

        lpss->board->exit(lpss);
        pci_free_irq_vectors(pdev);
}

static const struct lpss8250_board byt_board = {
        .freq = 100000000,
        .base_baud = 2764800,
        .setup = byt_serial_setup,
        .exit = byt_serial_exit,
};

static const struct lpss8250_board ehl_board = {
        .freq = 200000000,
        .base_baud = 12500000,
        .setup = ehl_serial_setup,
        .exit = ehl_serial_exit,
};

static const struct lpss8250_board qrk_board = {
        .freq = 44236800,
        .base_baud = 2764800,
        .setup = qrk_serial_setup,
        .exit = qrk_serial_exit,
};

static const struct pci_device_id pci_ids[] = {
        { PCI_DEVICE_DATA(INTEL, QRK_UARTx, &qrk_board) },
        { PCI_DEVICE_DATA(INTEL, EHL_UART0, &ehl_board) },
        { PCI_DEVICE_DATA(INTEL, EHL_UART1, &ehl_board) },
        { PCI_DEVICE_DATA(INTEL, EHL_UART2, &ehl_board) },
        { PCI_DEVICE_DATA(INTEL, EHL_UART3, &ehl_board) },
        { PCI_DEVICE_DATA(INTEL, EHL_UART4, &ehl_board) },
        { PCI_DEVICE_DATA(INTEL, EHL_UART5, &ehl_board) },
        { PCI_DEVICE_DATA(INTEL, BYT_UART1, &byt_board) },
        { PCI_DEVICE_DATA(INTEL, BYT_UART2, &byt_board) },
        { PCI_DEVICE_DATA(INTEL, BSW_UART1, &byt_board) },
        { PCI_DEVICE_DATA(INTEL, BSW_UART2, &byt_board) },
        { PCI_DEVICE_DATA(INTEL, BDW_UART1, &byt_board) },
        { PCI_DEVICE_DATA(INTEL, BDW_UART2, &byt_board) },
        { }
};
MODULE_DEVICE_TABLE(pci, pci_ids);

static struct pci_driver lpss8250_pci_driver = {
        .name           = "8250_lpss",
        .id_table       = pci_ids,
        .probe          = lpss8250_probe,
        .remove         = lpss8250_remove,
};

module_pci_driver(lpss8250_pci_driver);

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