/*
 * CAN bus driver for the Freescale MPC5xxx embedded CPU.
 *
 * Copyright (C) 2004-2005 Andrey Volkov <avolkov@varma-el.com>,
 *                         Varma Electronics Oy
 * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
 * Copyright (C) 2009 Wolfram Sang, Pengutronix <w.sang@pengutronix.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the version 2 of the GNU General Public License
 * as published by the Free Software Foundation
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/netdevice.h>
#include <linux/can/dev.h>
#include <linux/of_platform.h>
#include <sysdev/fsl_soc.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <asm/mpc52xx.h>

#include "mscan.h"

#define DRV_NAME "mpc5xxx_can"

struct mpc5xxx_can_data {
        unsigned int type;
        u32 (*get_clock)(struct platform_device *ofdev, const char *clock_name,
                         int *mscan_clksrc);
        void (*put_clock)(struct platform_device *ofdev);
};

#ifdef CONFIG_PPC_MPC52xx
static const struct of_device_id mpc52xx_cdm_ids[] = {
        { .compatible = "fsl,mpc5200-cdm", },
        {}
};

static u32 mpc52xx_can_get_clock(struct platform_device *ofdev,
                                 const char *clock_name, int *mscan_clksrc)
{
        unsigned int pvr;
        struct mpc52xx_cdm  __iomem *cdm;
        struct device_node *np_cdm;
        unsigned int freq;
        u32 val;

        pvr = mfspr(SPRN_PVR);

        /*
         * Either the oscillator clock (SYS_XTAL_IN) or the IP bus clock
         * (IP_CLK) can be selected as MSCAN clock source. According to
         * the MPC5200 user's manual, the oscillator clock is the better
         * choice as it has less jitter. For this reason, it is selected
         * by default. Unfortunately, it can not be selected for the old
         * MPC5200 Rev. A chips due to a hardware bug (check errata).
         */
        if (clock_name && strcmp(clock_name, "ip") == 0)
                *mscan_clksrc = MSCAN_CLKSRC_BUS;
        else
                *mscan_clksrc = MSCAN_CLKSRC_XTAL;

        freq = mpc5xxx_get_bus_frequency(ofdev->dev.of_node);
        if (!freq)
                return 0;

        if (*mscan_clksrc == MSCAN_CLKSRC_BUS || pvr == 0x80822011)
                return freq;

        /* Determine SYS_XTAL_IN frequency from the clock domain settings */
        np_cdm = of_find_matching_node(NULL, mpc52xx_cdm_ids);
        if (!np_cdm) {
                dev_err(&ofdev->dev, "can't get clock node!\n");
                return 0;
        }
        cdm = of_iomap(np_cdm, 0);

        if (in_8(&cdm->ipb_clk_sel) & 0x1)
                freq *= 2;
        val = in_be32(&cdm->rstcfg);

        freq *= (val & (1 << 5)) ? 8 : 4;
        freq /= (val & (1 << 6)) ? 12 : 16;

        of_node_put(np_cdm);
        iounmap(cdm);

        return freq;
}
#else /* !CONFIG_PPC_MPC52xx */
static u32 mpc52xx_can_get_clock(struct platform_device *ofdev,
                                 const char *clock_name, int *mscan_clksrc)
{
        return 0;
}
#endif /* CONFIG_PPC_MPC52xx */

#ifdef CONFIG_PPC_MPC512x
static u32 mpc512x_can_get_clock(struct platform_device *ofdev,
                                 const char *clock_source, int *mscan_clksrc)
{
        struct device_node *np;
        u32 clockdiv;
        enum {
                CLK_FROM_AUTO,
                CLK_FROM_IPS,
                CLK_FROM_SYS,
                CLK_FROM_REF,
        } clk_from;
        struct clk *clk_in, *clk_can;
        unsigned long freq_calc;
        struct mscan_priv *priv;
        struct clk *clk_ipg;

        /* the caller passed in the clock source spec that was read from
         * the device tree, get the optional clock divider as well
         */
        np = ofdev->dev.of_node;
        clockdiv = 1;
        of_property_read_u32(np, "fsl,mscan-clock-divider", &clockdiv);
        dev_dbg(&ofdev->dev, "device tree specs: clk src[%s] div[%d]\n",
                clock_source ? clock_source : "<NULL>", clockdiv);

        /* when clock-source is 'ip', the CANCTL1[CLKSRC] bit needs to
         * get set, and the 'ips' clock is the input to the MSCAN
         * component
         *
         * for clock-source values of 'ref' or 'sys' the CANCTL1[CLKSRC]
         * bit needs to get cleared, an optional clock-divider may have
         * been specified (the default value is 1), the appropriate
         * MSCAN related MCLK is the input to the MSCAN component
         *
         * in the absence of a clock-source spec, first an optimal clock
         * gets determined based on the 'sys' clock, if that fails the
         * 'ref' clock is used
         */
        clk_from = CLK_FROM_AUTO;
        if (clock_source) {
                /* interpret the device tree's spec for the clock source */
                if (!strcmp(clock_source, "ip"))
                        clk_from = CLK_FROM_IPS;
                else if (!strcmp(clock_source, "sys"))
                        clk_from = CLK_FROM_SYS;
                else if (!strcmp(clock_source, "ref"))
                        clk_from = CLK_FROM_REF;
                else
                        goto err_invalid;
                dev_dbg(&ofdev->dev, "got a clk source spec[%d]\n", clk_from);
        }
        if (clk_from == CLK_FROM_AUTO) {
                /* no spec so far, try the 'sys' clock; round to the
                 * next MHz and see if we can get a multiple of 16MHz
                 */
                dev_dbg(&ofdev->dev, "no clk source spec, trying SYS\n");
                clk_in = devm_clk_get(&ofdev->dev, "sys");
                if (IS_ERR(clk_in))
                        goto err_notavail;
                freq_calc = clk_get_rate(clk_in);
                freq_calc +=  499999;
                freq_calc /= 1000000;
                freq_calc *= 1000000;
                if ((freq_calc % 16000000) == 0) {
                        clk_from = CLK_FROM_SYS;
                        clockdiv = freq_calc / 16000000;
                        dev_dbg(&ofdev->dev,
                                "clk fit, sys[%lu] div[%d] freq[%lu]\n",
                                freq_calc, clockdiv, freq_calc / clockdiv);
                }
        }
        if (clk_from == CLK_FROM_AUTO) {
                /* no spec so far, use the 'ref' clock */
                dev_dbg(&ofdev->dev, "no clk source spec, trying REF\n");
                clk_in = devm_clk_get(&ofdev->dev, "ref");
                if (IS_ERR(clk_in))
                        goto err_notavail;
                clk_from = CLK_FROM_REF;
                freq_calc = clk_get_rate(clk_in);
                dev_dbg(&ofdev->dev,
                        "clk fit, ref[%lu] (no div) freq[%lu]\n",
                        freq_calc, freq_calc);
        }

        /* select IPS or MCLK as the MSCAN input (returned to the caller),
         * setup the MCLK mux source and rate if applicable, apply the
         * optionally specified or derived above divider, and determine
         * the actual resulting clock rate to return to the caller
         */
        switch (clk_from) {
        case CLK_FROM_IPS:
                clk_can = devm_clk_get(&ofdev->dev, "ips");
                if (IS_ERR(clk_can))
                        goto err_notavail;
                priv = netdev_priv(dev_get_drvdata(&ofdev->dev));
                priv->clk_can = clk_can;
                freq_calc = clk_get_rate(clk_can);
                *mscan_clksrc = MSCAN_CLKSRC_IPS;
                dev_dbg(&ofdev->dev, "clk from IPS, clksrc[%d] freq[%lu]\n",
                        *mscan_clksrc, freq_calc);
                break;
        case CLK_FROM_SYS:
        case CLK_FROM_REF:
                clk_can = devm_clk_get(&ofdev->dev, "mclk");
                if (IS_ERR(clk_can))
                        goto err_notavail;
                priv = netdev_priv(dev_get_drvdata(&ofdev->dev));
                priv->clk_can = clk_can;
                if (clk_from == CLK_FROM_SYS)
                        clk_in = devm_clk_get(&ofdev->dev, "sys");
                if (clk_from == CLK_FROM_REF)
                        clk_in = devm_clk_get(&ofdev->dev, "ref");
                if (IS_ERR(clk_in))
                        goto err_notavail;
                clk_set_parent(clk_can, clk_in);
                freq_calc = clk_get_rate(clk_in);
                freq_calc /= clockdiv;
                clk_set_rate(clk_can, freq_calc);
                freq_calc = clk_get_rate(clk_can);
                *mscan_clksrc = MSCAN_CLKSRC_BUS;
                dev_dbg(&ofdev->dev, "clk from MCLK, clksrc[%d] freq[%lu]\n",
                        *mscan_clksrc, freq_calc);
                break;
        default:
                goto err_invalid;
        }

        /* the above clk_can item is used for the bitrate, access to
         * the peripheral's register set needs the clk_ipg item
         */
        clk_ipg = devm_clk_get(&ofdev->dev, "ipg");
        if (IS_ERR(clk_ipg))
                goto err_notavail_ipg;
        if (clk_prepare_enable(clk_ipg))
                goto err_notavail_ipg;
        priv = netdev_priv(dev_get_drvdata(&ofdev->dev));
        priv->clk_ipg = clk_ipg;

        /* return the determined clock source rate */
        return freq_calc;

err_invalid:
        dev_err(&ofdev->dev, "invalid clock source specification\n");
        /* clock source rate could not get determined */
        return 0;

err_notavail:
        dev_err(&ofdev->dev, "cannot acquire or setup bitrate clock source\n");
        /* clock source rate could not get determined */
        return 0;

err_notavail_ipg:
        dev_err(&ofdev->dev, "cannot acquire or setup register clock\n");
        /* clock source rate could not get determined */
        return 0;
}

static void mpc512x_can_put_clock(struct platform_device *ofdev)
{
        struct mscan_priv *priv;

        priv = netdev_priv(dev_get_drvdata(&ofdev->dev));
        if (priv->clk_ipg)
                clk_disable_unprepare(priv->clk_ipg);
}
#else /* !CONFIG_PPC_MPC512x */
static u32 mpc512x_can_get_clock(struct platform_device *ofdev,
                                 const char *clock_name, int *mscan_clksrc)
{
        return 0;
}
#define mpc512x_can_put_clock NULL
#endif /* CONFIG_PPC_MPC512x */

static const struct of_device_id mpc5xxx_can_table[];
static int mpc5xxx_can_probe(struct platform_device *ofdev)
{
        const struct of_device_id *match;
        const struct mpc5xxx_can_data *data;
        struct device_node *np = ofdev->dev.of_node;
        struct net_device *dev;
        struct mscan_priv *priv;
        void __iomem *base;
        const char *clock_name = NULL;
        int irq, mscan_clksrc = 0;
        int err = -ENOMEM;

        match = of_match_device(mpc5xxx_can_table, &ofdev->dev);
        if (!match)
                return -EINVAL;
        data = match->data;

        base = of_iomap(np, 0);
        if (!base) {
                dev_err(&ofdev->dev, "couldn't ioremap\n");
                return err;
        }

        irq = irq_of_parse_and_map(np, 0);
        if (!irq) {
                dev_err(&ofdev->dev, "no irq found\n");
                err = -ENODEV;
                goto exit_unmap_mem;
        }

        dev = alloc_mscandev();
        if (!dev)
                goto exit_dispose_irq;
        platform_set_drvdata(ofdev, dev);
        SET_NETDEV_DEV(dev, &ofdev->dev);

        priv = netdev_priv(dev);
        priv->reg_base = base;
        dev->irq = irq;

        clock_name = of_get_property(np, "fsl,mscan-clock-source", NULL);

        BUG_ON(!data);
        priv->type = data->type;
        priv->can.clock.freq = data->get_clock(ofdev, clock_name,
                                               &mscan_clksrc);
        if (!priv->can.clock.freq) {
                dev_err(&ofdev->dev, "couldn't get MSCAN clock properties\n");
                goto exit_free_mscan;
        }

        err = register_mscandev(dev, mscan_clksrc);
        if (err) {
                dev_err(&ofdev->dev, "registering %s failed (err=%d)\n",
                        DRV_NAME, err);
                goto exit_free_mscan;
        }

        dev_info(&ofdev->dev, "MSCAN at 0x%p, irq %d, clock %d Hz\n",
                 priv->reg_base, dev->irq, priv->can.clock.freq);

        return 0;

exit_free_mscan:
        free_candev(dev);
exit_dispose_irq:
        irq_dispose_mapping(irq);
exit_unmap_mem:
        iounmap(base);

        return err;
}

static int mpc5xxx_can_remove(struct platform_device *ofdev)
{
        const struct of_device_id *match;
        const struct mpc5xxx_can_data *data;
        struct net_device *dev = platform_get_drvdata(ofdev);
        struct mscan_priv *priv = netdev_priv(dev);

        match = of_match_device(mpc5xxx_can_table, &ofdev->dev);
        data = match ? match->data : NULL;

        unregister_mscandev(dev);
        if (data && data->put_clock)
                data->put_clock(ofdev);
        iounmap(priv->reg_base);
        irq_dispose_mapping(dev->irq);
        free_candev(dev);

        return 0;
}

#ifdef CONFIG_PM
static struct mscan_regs saved_regs;
static int mpc5xxx_can_suspend(struct platform_device *ofdev, pm_message_t state)
{
        struct net_device *dev = platform_get_drvdata(ofdev);
        struct mscan_priv *priv = netdev_priv(dev);
        struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;

        _memcpy_fromio(&saved_regs, regs, sizeof(*regs));

        return 0;
}

static int mpc5xxx_can_resume(struct platform_device *ofdev)
{
        struct net_device *dev = platform_get_drvdata(ofdev);
        struct mscan_priv *priv = netdev_priv(dev);
        struct mscan_regs *regs = (struct mscan_regs *)priv->reg_base;

        regs->canctl0 |= MSCAN_INITRQ;
        while (!(regs->canctl1 & MSCAN_INITAK))
                udelay(10);

        regs->canctl1 = saved_regs.canctl1;
        regs->canbtr0 = saved_regs.canbtr0;
        regs->canbtr1 = saved_regs.canbtr1;
        regs->canidac = saved_regs.canidac;

        /* restore masks, buffers etc. */
        _memcpy_toio(&regs->canidar1_0, (void *)&saved_regs.canidar1_0,
                     sizeof(*regs) - offsetof(struct mscan_regs, canidar1_0));

        regs->canctl0 &= ~MSCAN_INITRQ;
        regs->cantbsel = saved_regs.cantbsel;
        regs->canrier = saved_regs.canrier;
        regs->cantier = saved_regs.cantier;
        regs->canctl0 = saved_regs.canctl0;

        return 0;
}
#endif

static const struct mpc5xxx_can_data mpc5200_can_data = {
        .type = MSCAN_TYPE_MPC5200,
        .get_clock = mpc52xx_can_get_clock,
        /* .put_clock not applicable */
};

static const struct mpc5xxx_can_data mpc5121_can_data = {
        .type = MSCAN_TYPE_MPC5121,
        .get_clock = mpc512x_can_get_clock,
        .put_clock = mpc512x_can_put_clock,
};

static const struct of_device_id mpc5xxx_can_table[] = {
        { .compatible = "fsl,mpc5200-mscan", .data = &mpc5200_can_data, },
        /* Note that only MPC5121 Rev. 2 (and later) is supported */
        { .compatible = "fsl,mpc5121-mscan", .data = &mpc5121_can_data, },
        {},
};
MODULE_DEVICE_TABLE(of, mpc5xxx_can_table);

static struct platform_driver mpc5xxx_can_driver = {
        .driver = {
                .name = "mpc5xxx_can",
                .of_match_table = mpc5xxx_can_table,
        },
        .probe = mpc5xxx_can_probe,
        .remove = mpc5xxx_can_remove,
#ifdef CONFIG_PM
        .suspend = mpc5xxx_can_suspend,
        .resume = mpc5xxx_can_resume,
#endif
};

module_platform_driver(mpc5xxx_can_driver);

MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
MODULE_DESCRIPTION("Freescale MPC5xxx CAN driver");
MODULE_LICENSE("GPL v2");