/*
 * Platform CAN bus driver for Bosch C_CAN controller
 *
 * Copyright (C) 2010 ST Microelectronics
 * Bhupesh Sharma <bhupesh.sharma@st.com>
 *
 * Borrowed heavily from the C_CAN driver originally written by:
 * Copyright (C) 2007
 * - Sascha Hauer, Marc Kleine-Budde, Pengutronix <s.hauer@pengutronix.de>
 * - Simon Kallweit, intefo AG <simon.kallweit@intefo.ch>
 *
 * Bosch C_CAN controller is compliant to CAN protocol version 2.0 part A and B.
 * Bosch C_CAN user manual can be obtained from:
 * http://www.semiconductors.bosch.de/media/en/pdf/ipmodules_1/c_can/
 * users_manual_c_can.pdf
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/list.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/clk.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>

#include <linux/can/dev.h>

#include "c_can.h"

#define DCAN_RAM_INIT_BIT BIT(3)

static DEFINE_SPINLOCK(raminit_lock);

/* 16-bit c_can registers can be arranged differently in the memory
 * architecture of different implementations. For example: 16-bit
 * registers can be aligned to a 16-bit boundary or 32-bit boundary etc.
 * Handle the same by providing a common read/write interface.
 */
static u16 c_can_plat_read_reg_aligned_to_16bit(const struct c_can_priv *priv,
                                                enum reg index)
{
        return readw(priv->base + priv->regs[index]);
}

static void c_can_plat_write_reg_aligned_to_16bit(const struct c_can_priv *priv,
                                                  enum reg index, u16 val)
{
        writew(val, priv->base + priv->regs[index]);
}

static u16 c_can_plat_read_reg_aligned_to_32bit(const struct c_can_priv *priv,
                                                enum reg index)
{
        return readw(priv->base + 2 * priv->regs[index]);
}

static void c_can_plat_write_reg_aligned_to_32bit(const struct c_can_priv *priv,
                                                  enum reg index, u16 val)
{
        writew(val, priv->base + 2 * priv->regs[index]);
}

static void c_can_hw_raminit_wait_syscon(const struct c_can_priv *priv,
                                         u32 mask, u32 val)
{
        const struct c_can_raminit *raminit = &priv->raminit_sys;
        int timeout = 0;
        u32 ctrl = 0;

        /* We look only at the bits of our instance. */
        val &= mask;
        do {
                udelay(1);
                timeout++;

                regmap_read(raminit->syscon, raminit->reg, &ctrl);
                if (timeout == 1000) {
                        dev_err(&priv->dev->dev, "%s: time out\n", __func__);
                        break;
                }
        } while ((ctrl & mask) != val);
}

static void c_can_hw_raminit_syscon(const struct c_can_priv *priv, bool enable)
{
        const struct c_can_raminit *raminit = &priv->raminit_sys;
        u32 ctrl = 0;
        u32 mask;

        spin_lock(&raminit_lock);

        mask = 1 << raminit->bits.start | 1 << raminit->bits.done;
        regmap_read(raminit->syscon, raminit->reg, &ctrl);

        /* We clear the start bit first. The start bit is
         * looking at the 0 -> transition, but is not self clearing;
         * NOTE: DONE must be written with 1 to clear it.
         * We can't clear the DONE bit here using regmap_update_bits()
         * as it will bypass the write if initial condition is START:0 DONE:1
         * e.g. on DRA7 which needs START pulse.
         */
        ctrl &= ~mask;  /* START = 0, DONE = 0 */
        regmap_update_bits(raminit->syscon, raminit->reg, mask, ctrl);

        /* check if START bit is 0. Ignore DONE bit for now
         * as it can be either 0 or 1.
         */
        c_can_hw_raminit_wait_syscon(priv, 1 << raminit->bits.start, ctrl);

        if (enable) {
                /* Clear DONE bit & set START bit. */
                ctrl |= 1 << raminit->bits.start;
                /* DONE must be written with 1 to clear it */
                ctrl |= 1 << raminit->bits.done;
                regmap_update_bits(raminit->syscon, raminit->reg, mask, ctrl);
                /* prevent further clearing of DONE bit */
                ctrl &= ~(1 << raminit->bits.done);
                /* clear START bit if start pulse is needed */
                if (raminit->needs_pulse) {
                        ctrl &= ~(1 << raminit->bits.start);
                        regmap_update_bits(raminit->syscon, raminit->reg,
                                           mask, ctrl);
                }

                ctrl |= 1 << raminit->bits.done;
                c_can_hw_raminit_wait_syscon(priv, mask, ctrl);
        }
        spin_unlock(&raminit_lock);
}

static u32 c_can_plat_read_reg32(const struct c_can_priv *priv, enum reg index)
{
        u32 val;

        val = priv->read_reg(priv, index);
        val |= ((u32)priv->read_reg(priv, index + 1)) << 16;

        return val;
}

static void c_can_plat_write_reg32(const struct c_can_priv *priv,
                                   enum reg index, u32 val)
{
        priv->write_reg(priv, index + 1, val >> 16);
        priv->write_reg(priv, index, val);
}

static u32 d_can_plat_read_reg32(const struct c_can_priv *priv, enum reg index)
{
        return readl(priv->base + priv->regs[index]);
}

static void d_can_plat_write_reg32(const struct c_can_priv *priv,
                                   enum reg index, u32 val)
{
        writel(val, priv->base + priv->regs[index]);
}

static void c_can_hw_raminit_wait(const struct c_can_priv *priv, u32 mask)
{
        while (priv->read_reg32(priv, C_CAN_FUNCTION_REG) & mask)
                udelay(1);
}

static void c_can_hw_raminit(const struct c_can_priv *priv, bool enable)
{
        u32 ctrl;

        ctrl = priv->read_reg32(priv, C_CAN_FUNCTION_REG);
        ctrl &= ~DCAN_RAM_INIT_BIT;
        priv->write_reg32(priv, C_CAN_FUNCTION_REG, ctrl);
        c_can_hw_raminit_wait(priv, ctrl);

        if (enable) {
                ctrl |= DCAN_RAM_INIT_BIT;
                priv->write_reg32(priv, C_CAN_FUNCTION_REG, ctrl);
                c_can_hw_raminit_wait(priv, ctrl);
        }
}

static const struct c_can_driver_data c_can_drvdata = {
        .id = BOSCH_C_CAN,
        .msg_obj_num = 32,
};

static const struct c_can_driver_data d_can_drvdata = {
        .id = BOSCH_D_CAN,
        .msg_obj_num = 32,
};

static const struct raminit_bits dra7_raminit_bits[] = {
        [0] = { .start = 3, .done = 1, },
        [1] = { .start = 5, .done = 2, },
};

static const struct c_can_driver_data dra7_dcan_drvdata = {
        .id = BOSCH_D_CAN,
        .msg_obj_num = 64,
        .raminit_num = ARRAY_SIZE(dra7_raminit_bits),
        .raminit_bits = dra7_raminit_bits,
        .raminit_pulse = true,
};

static const struct raminit_bits am3352_raminit_bits[] = {
        [0] = { .start = 0, .done = 8, },
        [1] = { .start = 1, .done = 9, },
};

static const struct c_can_driver_data am3352_dcan_drvdata = {
        .id = BOSCH_D_CAN,
        .msg_obj_num = 64,
        .raminit_num = ARRAY_SIZE(am3352_raminit_bits),
        .raminit_bits = am3352_raminit_bits,
};

static const struct platform_device_id c_can_id_table[] = {
        {
                .name = KBUILD_MODNAME,
                .driver_data = (kernel_ulong_t)&c_can_drvdata,
        },
        {
                .name = "c_can",
                .driver_data = (kernel_ulong_t)&c_can_drvdata,
        },
        {
                .name = "d_can",
                .driver_data = (kernel_ulong_t)&d_can_drvdata,
        },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(platform, c_can_id_table);

static const struct of_device_id c_can_of_table[] = {
        { .compatible = "bosch,c_can", .data = &c_can_drvdata },
        { .compatible = "bosch,d_can", .data = &d_can_drvdata },
        { .compatible = "ti,dra7-d_can", .data = &dra7_dcan_drvdata },
        { .compatible = "ti,am3352-d_can", .data = &am3352_dcan_drvdata },
        { .compatible = "ti,am4372-d_can", .data = &am3352_dcan_drvdata },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, c_can_of_table);

static int c_can_plat_probe(struct platform_device *pdev)
{
        int ret;
        void __iomem *addr;
        struct net_device *dev;
        struct c_can_priv *priv;
        const struct of_device_id *match;
        struct resource *mem;
        int irq;
        struct clk *clk;
        const struct c_can_driver_data *drvdata;
        struct device_node *np = pdev->dev.of_node;

        match = of_match_device(c_can_of_table, &pdev->dev);
        if (match) {
                drvdata = match->data;
        } else if (pdev->id_entry->driver_data) {
                drvdata = (struct c_can_driver_data *)
                        platform_get_device_id(pdev)->driver_data;
        } else {
                return -ENODEV;
        }

        /* get the appropriate clk */
        clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(clk)) {
                ret = PTR_ERR(clk);
                goto exit;
        }

        /* get the platform data */
        irq = platform_get_irq(pdev, 0);
        if (irq <= 0) {
                ret = -ENODEV;
                goto exit;
        }

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        addr = devm_ioremap_resource(&pdev->dev, mem);
        if (IS_ERR(addr)) {
                ret =  PTR_ERR(addr);
                goto exit;
        }

        /* allocate the c_can device */
        dev = alloc_c_can_dev(drvdata->msg_obj_num);
        if (!dev) {
                ret = -ENOMEM;
                goto exit;
        }

        priv = netdev_priv(dev);
        switch (drvdata->id) {
        case BOSCH_C_CAN:
                priv->regs = reg_map_c_can;
                switch (mem->flags & IORESOURCE_MEM_TYPE_MASK) {
                case IORESOURCE_MEM_32BIT:
                        priv->read_reg = c_can_plat_read_reg_aligned_to_32bit;
                        priv->write_reg = c_can_plat_write_reg_aligned_to_32bit;
                        priv->read_reg32 = c_can_plat_read_reg32;
                        priv->write_reg32 = c_can_plat_write_reg32;
                        break;
                case IORESOURCE_MEM_16BIT:
                default:
                        priv->read_reg = c_can_plat_read_reg_aligned_to_16bit;
                        priv->write_reg = c_can_plat_write_reg_aligned_to_16bit;
                        priv->read_reg32 = c_can_plat_read_reg32;
                        priv->write_reg32 = c_can_plat_write_reg32;
                        break;
                }
                break;
        case BOSCH_D_CAN:
                priv->regs = reg_map_d_can;
                priv->read_reg = c_can_plat_read_reg_aligned_to_16bit;
                priv->write_reg = c_can_plat_write_reg_aligned_to_16bit;
                priv->read_reg32 = d_can_plat_read_reg32;
                priv->write_reg32 = d_can_plat_write_reg32;

                /* Check if we need custom RAMINIT via syscon. Mostly for TI
                 * platforms. Only supported with DT boot.
                 */
                if (np && of_property_read_bool(np, "syscon-raminit")) {
                        u32 id;
                        struct c_can_raminit *raminit = &priv->raminit_sys;

                        ret = -EINVAL;
                        raminit->syscon = syscon_regmap_lookup_by_phandle(np,
                                                                          "syscon-raminit");
                        if (IS_ERR(raminit->syscon)) {
                                /* can fail with -EPROBE_DEFER */
                                ret = PTR_ERR(raminit->syscon);
                                free_c_can_dev(dev);
                                return ret;
                        }

                        if (of_property_read_u32_index(np, "syscon-raminit", 1,
                                                       &raminit->reg)) {
                                dev_err(&pdev->dev,
                                        "couldn't get the RAMINIT reg. offset!\n");
                                goto exit_free_device;
                        }

                        if (of_property_read_u32_index(np, "syscon-raminit", 2,
                                                       &id)) {
                                dev_err(&pdev->dev,
                                        "couldn't get the CAN instance ID\n");
                                goto exit_free_device;
                        }

                        if (id >= drvdata->raminit_num) {
                                dev_err(&pdev->dev,
                                        "Invalid CAN instance ID\n");
                                goto exit_free_device;
                        }

                        raminit->bits = drvdata->raminit_bits[id];
                        raminit->needs_pulse = drvdata->raminit_pulse;

                        priv->raminit = c_can_hw_raminit_syscon;
                } else {
                        priv->raminit = c_can_hw_raminit;
                }
                break;
        default:
                ret = -EINVAL;
                goto exit_free_device;
        }

        dev->irq = irq;
        priv->base = addr;
        priv->device = &pdev->dev;
        priv->can.clock.freq = clk_get_rate(clk);
        priv->type = drvdata->id;

        platform_set_drvdata(pdev, dev);
        SET_NETDEV_DEV(dev, &pdev->dev);

        pm_runtime_enable(priv->device);
        ret = register_c_can_dev(dev);
        if (ret) {
                dev_err(&pdev->dev, "registering %s failed (err=%d)\n",
                        KBUILD_MODNAME, ret);
                goto exit_free_device;
        }

        dev_info(&pdev->dev, "%s device registered (regs=%p, irq=%d)\n",
                 KBUILD_MODNAME, priv->base, dev->irq);
        return 0;

exit_free_device:
        pm_runtime_disable(priv->device);
        free_c_can_dev(dev);
exit:
        dev_err(&pdev->dev, "probe failed\n");

        return ret;
}

static int c_can_plat_remove(struct platform_device *pdev)
{
        struct net_device *dev = platform_get_drvdata(pdev);
        struct c_can_priv *priv = netdev_priv(dev);

        unregister_c_can_dev(dev);
        pm_runtime_disable(priv->device);
        free_c_can_dev(dev);

        return 0;
}

#ifdef CONFIG_PM
static int c_can_suspend(struct platform_device *pdev, pm_message_t state)
{
        int ret;
        struct net_device *ndev = platform_get_drvdata(pdev);
        struct c_can_priv *priv = netdev_priv(ndev);

        if (priv->type != BOSCH_D_CAN) {
                dev_warn(&pdev->dev, "Not supported\n");
                return 0;
        }

        if (netif_running(ndev)) {
                netif_stop_queue(ndev);
                netif_device_detach(ndev);
        }

        ret = c_can_power_down(ndev);
        if (ret) {
                netdev_err(ndev, "failed to enter power down mode\n");
                return ret;
        }

        priv->can.state = CAN_STATE_SLEEPING;

        return 0;
}

static int c_can_resume(struct platform_device *pdev)
{
        int ret;
        struct net_device *ndev = platform_get_drvdata(pdev);
        struct c_can_priv *priv = netdev_priv(ndev);

        if (priv->type != BOSCH_D_CAN) {
                dev_warn(&pdev->dev, "Not supported\n");
                return 0;
        }

        ret = c_can_power_up(ndev);
        if (ret) {
                netdev_err(ndev, "Still in power down mode\n");
                return ret;
        }

        priv->can.state = CAN_STATE_ERROR_ACTIVE;

        if (netif_running(ndev)) {
                netif_device_attach(ndev);
                netif_start_queue(ndev);
        }

        return 0;
}
#else
#define c_can_suspend NULL
#define c_can_resume NULL
#endif

static struct platform_driver c_can_plat_driver = {
        .driver = {
                .name = KBUILD_MODNAME,
                .of_match_table = c_can_of_table,
        },
        .probe = c_can_plat_probe,
        .remove = c_can_plat_remove,
        .suspend = c_can_suspend,
        .resume = c_can_resume,
        .id_table = c_can_id_table,
};

module_platform_driver(c_can_plat_driver);

MODULE_AUTHOR("Bhupesh Sharma <bhupesh.sharma@st.com>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Platform CAN bus driver for Bosch C_CAN controller");