// SPDX-License-Identifier: GPL-2.0-only
/*
 * SPI interface.
 *
 * Copyright (c) 2017-2020, Silicon Laboratories, Inc.
 * Copyright (c) 2011, Sagrad Inc.
 * Copyright (c) 2010, ST-Ericsson
 */
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/spi/spi.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/of.h>

#include "bus.h"
#include "wfx.h"
#include "hwio.h"
#include "main.h"
#include "bh.h"

#define SET_WRITE 0x7FFF        /* usage: and operation */
#define SET_READ 0x8000         /* usage: or operation */

#define WFX_RESET_INVERTED 1

static const struct wfx_platform_data wfx_spi_pdata = {
        .file_fw = "wfm_wf200",
        .file_pds = "wf200.pds",
        .use_rising_clk = true,
};

struct wfx_spi_priv {
        struct spi_device *func;
        struct wfx_dev *core;
        struct gpio_desc *gpio_reset;
        bool need_swab;
};

/*
 * WFx chip read data 16bits at time and place them directly into (little
 * endian) CPU register. So, chip expect byte order like "B1 B0 B3 B2" (while
 * LE is "B0 B1 B2 B3" and BE is "B3 B2 B1 B0")
 *
 * A little endian host with bits_per_word == 16 should do the right job
 * natively. The code below to support big endian host and commonly used SPI
 * 8bits.
 */
static int wfx_spi_copy_from_io(void *priv, unsigned int addr,
                                void *dst, size_t count)
{
        struct wfx_spi_priv *bus = priv;
        u16 regaddr = (addr << 12) | (count / 2) | SET_READ;
        struct spi_message      m;
        struct spi_transfer     t_addr = {
                .tx_buf         = &regaddr,
                .len            = sizeof(regaddr),
        };
        struct spi_transfer     t_msg = {
                .rx_buf         = dst,
                .len            = count,
        };
        u16 *dst16 = dst;
        int ret, i;

        WARN(count % 2, "buffer size must be a multiple of 2");

        cpu_to_le16s(&regaddr);
        if (bus->need_swab)
                swab16s(&regaddr);

        spi_message_init(&m);
        spi_message_add_tail(&t_addr, &m);
        spi_message_add_tail(&t_msg, &m);
        ret = spi_sync(bus->func, &m);

        if (bus->need_swab && addr == WFX_REG_CONFIG)
                for (i = 0; i < count / 2; i++)
                        swab16s(&dst16[i]);
        return ret;
}

static int wfx_spi_copy_to_io(void *priv, unsigned int addr,
                              const void *src, size_t count)
{
        struct wfx_spi_priv *bus = priv;
        u16 regaddr = (addr << 12) | (count / 2);
        // FIXME: use a bounce buffer
        u16 *src16 = (void *)src;
        int ret, i;
        struct spi_message      m;
        struct spi_transfer     t_addr = {
                .tx_buf         = &regaddr,
                .len            = sizeof(regaddr),
        };
        struct spi_transfer     t_msg = {
                .tx_buf         = src,
                .len            = count,
        };

        WARN(count % 2, "buffer size must be a multiple of 2");
        WARN(regaddr & SET_READ, "bad addr or size overflow");

        cpu_to_le16s(&regaddr);

        // Register address and CONFIG content always use 16bit big endian
        // ("BADC" order)
        if (bus->need_swab)
                swab16s(&regaddr);
        if (bus->need_swab && addr == WFX_REG_CONFIG)
                for (i = 0; i < count / 2; i++)
                        swab16s(&src16[i]);

        spi_message_init(&m);
        spi_message_add_tail(&t_addr, &m);
        spi_message_add_tail(&t_msg, &m);
        ret = spi_sync(bus->func, &m);

        if (bus->need_swab && addr == WFX_REG_CONFIG)
                for (i = 0; i < count / 2; i++)
                        swab16s(&src16[i]);
        return ret;
}

static void wfx_spi_lock(void *priv)
{
}

static void wfx_spi_unlock(void *priv)
{
}

static irqreturn_t wfx_spi_irq_handler(int irq, void *priv)
{
        struct wfx_spi_priv *bus = priv;

        wfx_bh_request_rx(bus->core);
        return IRQ_HANDLED;
}

static int wfx_spi_irq_subscribe(void *priv)
{
        struct wfx_spi_priv *bus = priv;
        u32 flags;

        flags = irq_get_trigger_type(bus->func->irq);
        if (!flags)
                flags = IRQF_TRIGGER_HIGH;
        flags |= IRQF_ONESHOT;
        return devm_request_threaded_irq(&bus->func->dev, bus->func->irq, NULL,
                                         wfx_spi_irq_handler, IRQF_ONESHOT,
                                         "wfx", bus);
}

static int wfx_spi_irq_unsubscribe(void *priv)
{
        struct wfx_spi_priv *bus = priv;

        devm_free_irq(&bus->func->dev, bus->func->irq, bus);
        return 0;
}

static size_t wfx_spi_align_size(void *priv, size_t size)
{
        // Most of SPI controllers avoid DMA if buffer size is not 32bit aligned
        return ALIGN(size, 4);
}

static const struct hwbus_ops wfx_spi_hwbus_ops = {
        .copy_from_io = wfx_spi_copy_from_io,
        .copy_to_io = wfx_spi_copy_to_io,
        .irq_subscribe = wfx_spi_irq_subscribe,
        .irq_unsubscribe = wfx_spi_irq_unsubscribe,
        .lock                   = wfx_spi_lock,
        .unlock                 = wfx_spi_unlock,
        .align_size             = wfx_spi_align_size,
};

static int wfx_spi_probe(struct spi_device *func)
{
        struct wfx_spi_priv *bus;
        int ret;

        if (!func->bits_per_word)
                func->bits_per_word = 16;
        ret = spi_setup(func);
        if (ret)
                return ret;
        // Trace below is also displayed by spi_setup() if compiled with DEBUG
        dev_dbg(&func->dev, "SPI params: CS=%d, mode=%d bits/word=%d speed=%d\n",
                func->chip_select, func->mode, func->bits_per_word,
                func->max_speed_hz);
        if (func->bits_per_word != 16 && func->bits_per_word != 8)
                dev_warn(&func->dev, "unusual bits/word value: %d\n",
                         func->bits_per_word);
        if (func->max_speed_hz > 50000000)
                dev_warn(&func->dev, "%dHz is a very high speed\n",
                         func->max_speed_hz);

        bus = devm_kzalloc(&func->dev, sizeof(*bus), GFP_KERNEL);
        if (!bus)
                return -ENOMEM;
        bus->func = func;
        if (func->bits_per_word == 8 || IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
                bus->need_swab = true;
        spi_set_drvdata(func, bus);

        bus->gpio_reset = devm_gpiod_get_optional(&func->dev, "reset",
                                                  GPIOD_OUT_LOW);
        if (IS_ERR(bus->gpio_reset))
                return PTR_ERR(bus->gpio_reset);
        if (!bus->gpio_reset) {
                dev_warn(&func->dev,
                         "gpio reset is not defined, trying to load firmware anyway\n");
        } else {
                gpiod_set_consumer_name(bus->gpio_reset, "wfx reset");
                if (spi_get_device_id(func)->driver_data & WFX_RESET_INVERTED)
                        gpiod_toggle_active_low(bus->gpio_reset);
                gpiod_set_value_cansleep(bus->gpio_reset, 1);
                usleep_range(100, 150);
                gpiod_set_value_cansleep(bus->gpio_reset, 0);
                usleep_range(2000, 2500);
        }

        bus->core = wfx_init_common(&func->dev, &wfx_spi_pdata,
                                    &wfx_spi_hwbus_ops, bus);
        if (!bus->core)
                return -EIO;

        return wfx_probe(bus->core);
}

static int wfx_spi_remove(struct spi_device *func)
{
        struct wfx_spi_priv *bus = spi_get_drvdata(func);

        wfx_release(bus->core);
        return 0;
}

/*
 * For dynamic driver binding, kernel does not use OF to match driver. It only
 * use modalias and modalias is a copy of 'compatible' DT node with vendor
 * stripped.
 */
static const struct spi_device_id wfx_spi_id[] = {
        { "wfx-spi", WFX_RESET_INVERTED },
        { "wf200", 0 },
        { },
};
MODULE_DEVICE_TABLE(spi, wfx_spi_id);

#ifdef CONFIG_OF
static const struct of_device_id wfx_spi_of_match[] = {
        { .compatible = "silabs,wfx-spi", .data = (void *)WFX_RESET_INVERTED },
        { .compatible = "silabs,wf200" },
        { },
};
MODULE_DEVICE_TABLE(of, wfx_spi_of_match);
#endif

struct spi_driver wfx_spi_driver = {
        .driver = {
                .name = "wfx-spi",
                .of_match_table = of_match_ptr(wfx_spi_of_match),
        },
        .id_table = wfx_spi_id,
        .probe = wfx_spi_probe,
        .remove = wfx_spi_remove,
};