/*
 * EHRPWM PWM driver
 *
 * Copyright (C) 2012 Texas Instruments, Inc. - http://www.ti.com/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/pm_runtime.h>
#include <linux/of_device.h>

/* EHRPWM registers and bits definitions */

/* Time base module registers */
#define TBCTL                   0x00
#define TBPRD                   0x0A

#define TBCTL_RUN_MASK          (BIT(15) | BIT(14))
#define TBCTL_STOP_NEXT         0
#define TBCTL_STOP_ON_CYCLE     BIT(14)
#define TBCTL_FREE_RUN          (BIT(15) | BIT(14))
#define TBCTL_PRDLD_MASK        BIT(3)
#define TBCTL_PRDLD_SHDW        0
#define TBCTL_PRDLD_IMDT        BIT(3)
#define TBCTL_CLKDIV_MASK       (BIT(12) | BIT(11) | BIT(10) | BIT(9) | \
                                BIT(8) | BIT(7))
#define TBCTL_CTRMODE_MASK      (BIT(1) | BIT(0))
#define TBCTL_CTRMODE_UP        0
#define TBCTL_CTRMODE_DOWN      BIT(0)
#define TBCTL_CTRMODE_UPDOWN    BIT(1)
#define TBCTL_CTRMODE_FREEZE    (BIT(1) | BIT(0))

#define TBCTL_HSPCLKDIV_SHIFT   7
#define TBCTL_CLKDIV_SHIFT      10

#define CLKDIV_MAX              7
#define HSPCLKDIV_MAX           7
#define PERIOD_MAX              0xFFFF

/* compare module registers */
#define CMPA                    0x12
#define CMPB                    0x14

/* Action qualifier module registers */
#define AQCTLA                  0x16
#define AQCTLB                  0x18
#define AQSFRC                  0x1A
#define AQCSFRC                 0x1C

#define AQCTL_CBU_MASK          (BIT(9) | BIT(8))
#define AQCTL_CBU_FRCLOW        BIT(8)
#define AQCTL_CBU_FRCHIGH       BIT(9)
#define AQCTL_CBU_FRCTOGGLE     (BIT(9) | BIT(8))
#define AQCTL_CAU_MASK          (BIT(5) | BIT(4))
#define AQCTL_CAU_FRCLOW        BIT(4)
#define AQCTL_CAU_FRCHIGH       BIT(5)
#define AQCTL_CAU_FRCTOGGLE     (BIT(5) | BIT(4))
#define AQCTL_PRD_MASK          (BIT(3) | BIT(2))
#define AQCTL_PRD_FRCLOW        BIT(2)
#define AQCTL_PRD_FRCHIGH       BIT(3)
#define AQCTL_PRD_FRCTOGGLE     (BIT(3) | BIT(2))
#define AQCTL_ZRO_MASK          (BIT(1) | BIT(0))
#define AQCTL_ZRO_FRCLOW        BIT(0)
#define AQCTL_ZRO_FRCHIGH       BIT(1)
#define AQCTL_ZRO_FRCTOGGLE     (BIT(1) | BIT(0))

#define AQCTL_CHANA_POLNORMAL   (AQCTL_CAU_FRCLOW | AQCTL_PRD_FRCHIGH | \
                                AQCTL_ZRO_FRCHIGH)
#define AQCTL_CHANA_POLINVERSED (AQCTL_CAU_FRCHIGH | AQCTL_PRD_FRCLOW | \
                                AQCTL_ZRO_FRCLOW)
#define AQCTL_CHANB_POLNORMAL   (AQCTL_CBU_FRCLOW | AQCTL_PRD_FRCHIGH | \
                                AQCTL_ZRO_FRCHIGH)
#define AQCTL_CHANB_POLINVERSED (AQCTL_CBU_FRCHIGH | AQCTL_PRD_FRCLOW | \
                                AQCTL_ZRO_FRCLOW)

#define AQSFRC_RLDCSF_MASK      (BIT(7) | BIT(6))
#define AQSFRC_RLDCSF_ZRO       0
#define AQSFRC_RLDCSF_PRD       BIT(6)
#define AQSFRC_RLDCSF_ZROPRD    BIT(7)
#define AQSFRC_RLDCSF_IMDT      (BIT(7) | BIT(6))

#define AQCSFRC_CSFB_MASK       (BIT(3) | BIT(2))
#define AQCSFRC_CSFB_FRCDIS     0
#define AQCSFRC_CSFB_FRCLOW     BIT(2)
#define AQCSFRC_CSFB_FRCHIGH    BIT(3)
#define AQCSFRC_CSFB_DISSWFRC   (BIT(3) | BIT(2))
#define AQCSFRC_CSFA_MASK       (BIT(1) | BIT(0))
#define AQCSFRC_CSFA_FRCDIS     0
#define AQCSFRC_CSFA_FRCLOW     BIT(0)
#define AQCSFRC_CSFA_FRCHIGH    BIT(1)
#define AQCSFRC_CSFA_DISSWFRC   (BIT(1) | BIT(0))

#define NUM_PWM_CHANNEL         2       /* EHRPWM channels */

struct ehrpwm_context {
        u16 tbctl;
        u16 tbprd;
        u16 cmpa;
        u16 cmpb;
        u16 aqctla;
        u16 aqctlb;
        u16 aqsfrc;
        u16 aqcsfrc;
};

struct ehrpwm_pwm_chip {
        struct pwm_chip chip;
        unsigned long clk_rate;
        void __iomem *mmio_base;
        unsigned long period_cycles[NUM_PWM_CHANNEL];
        enum pwm_polarity polarity[NUM_PWM_CHANNEL];
        struct clk *tbclk;
        struct ehrpwm_context ctx;
};

static inline struct ehrpwm_pwm_chip *to_ehrpwm_pwm_chip(struct pwm_chip *chip)
{
        return container_of(chip, struct ehrpwm_pwm_chip, chip);
}

static inline u16 ehrpwm_read(void __iomem *base, unsigned int offset)
{
        return readw(base + offset);
}

static inline void ehrpwm_write(void __iomem *base, unsigned int offset,
                                u16 value)
{
        writew(value, base + offset);
}

static void ehrpwm_modify(void __iomem *base, unsigned int offset, u16 mask,
                          u16 value)
{
        unsigned short val;

        val = readw(base + offset);
        val &= ~mask;
        val |= value & mask;
        writew(val, base + offset);
}

/**
 * set_prescale_div -   Set up the prescaler divider function
 * @rqst_prescaler:     prescaler value min
 * @prescale_div:       prescaler value set
 * @tb_clk_div:         Time Base Control prescaler bits
 */
static int set_prescale_div(unsigned long rqst_prescaler, u16 *prescale_div,
                            u16 *tb_clk_div)
{
        unsigned int clkdiv, hspclkdiv;

        for (clkdiv = 0; clkdiv <= CLKDIV_MAX; clkdiv++) {
                for (hspclkdiv = 0; hspclkdiv <= HSPCLKDIV_MAX; hspclkdiv++) {
                        /*
                         * calculations for prescaler value :
                         * prescale_div = HSPCLKDIVIDER * CLKDIVIDER.
                         * HSPCLKDIVIDER =  2 ** hspclkdiv
                         * CLKDIVIDER = (1),            if clkdiv == 0 *OR*
                         *              (2 * clkdiv),   if clkdiv != 0
                         *
                         * Configure prescale_div value such that period
                         * register value is less than 65535.
                         */

                        *prescale_div = (1 << clkdiv) *
                                        (hspclkdiv ? (hspclkdiv * 2) : 1);
                        if (*prescale_div > rqst_prescaler) {
                                *tb_clk_div = (clkdiv << TBCTL_CLKDIV_SHIFT) |
                                        (hspclkdiv << TBCTL_HSPCLKDIV_SHIFT);
                                return 0;
                        }
                }
        }

        return 1;
}

static void configure_polarity(struct ehrpwm_pwm_chip *pc, int chan)
{
        u16 aqctl_val, aqctl_mask;
        unsigned int aqctl_reg;

        /*
         * Configure PWM output to HIGH/LOW level on counter
         * reaches compare register value and LOW/HIGH level
         * on counter value reaches period register value and
         * zero value on counter
         */
        if (chan == 1) {
                aqctl_reg = AQCTLB;
                aqctl_mask = AQCTL_CBU_MASK;

                if (pc->polarity[chan] == PWM_POLARITY_INVERSED)
                        aqctl_val = AQCTL_CHANB_POLINVERSED;
                else
                        aqctl_val = AQCTL_CHANB_POLNORMAL;
        } else {
                aqctl_reg = AQCTLA;
                aqctl_mask = AQCTL_CAU_MASK;

                if (pc->polarity[chan] == PWM_POLARITY_INVERSED)
                        aqctl_val = AQCTL_CHANA_POLINVERSED;
                else
                        aqctl_val = AQCTL_CHANA_POLNORMAL;
        }

        aqctl_mask |= AQCTL_PRD_MASK | AQCTL_ZRO_MASK;
        ehrpwm_modify(pc->mmio_base, aqctl_reg, aqctl_mask, aqctl_val);
}

/*
 * period_ns = 10^9 * (ps_divval * period_cycles) / PWM_CLK_RATE
 * duty_ns   = 10^9 * (ps_divval * duty_cycles) / PWM_CLK_RATE
 */
static int ehrpwm_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                             int duty_ns, int period_ns)
{
        struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
        u32 period_cycles, duty_cycles;
        u16 ps_divval, tb_divval;
        unsigned int i, cmp_reg;
        unsigned long long c;

        if (period_ns > NSEC_PER_SEC)
                return -ERANGE;

        c = pc->clk_rate;
        c = c * period_ns;
        do_div(c, NSEC_PER_SEC);
        period_cycles = (unsigned long)c;

        if (period_cycles < 1) {
                period_cycles = 1;
                duty_cycles = 1;
        } else {
                c = pc->clk_rate;
                c = c * duty_ns;
                do_div(c, NSEC_PER_SEC);
                duty_cycles = (unsigned long)c;
        }

        /*
         * Period values should be same for multiple PWM channels as IP uses
         * same period register for multiple channels.
         */
        for (i = 0; i < NUM_PWM_CHANNEL; i++) {
                if (pc->period_cycles[i] &&
                                (pc->period_cycles[i] != period_cycles)) {
                        /*
                         * Allow channel to reconfigure period if no other
                         * channels being configured.
                         */
                        if (i == pwm->hwpwm)
                                continue;

                        dev_err(chip->dev,
                                "period value conflicts with channel %u\n",
                                i);
                        return -EINVAL;
                }
        }

        pc->period_cycles[pwm->hwpwm] = period_cycles;

        /* Configure clock prescaler to support Low frequency PWM wave */
        if (set_prescale_div(period_cycles/PERIOD_MAX, &ps_divval,
                             &tb_divval)) {
                dev_err(chip->dev, "Unsupported values\n");
                return -EINVAL;
        }

        pm_runtime_get_sync(chip->dev);

        /* Update clock prescaler values */
        ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_CLKDIV_MASK, tb_divval);

        /* Update period & duty cycle with presacler division */
        period_cycles = period_cycles / ps_divval;
        duty_cycles = duty_cycles / ps_divval;

        /* Configure shadow loading on Period register */
        ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_PRDLD_MASK, TBCTL_PRDLD_SHDW);

        ehrpwm_write(pc->mmio_base, TBPRD, period_cycles);

        /* Configure ehrpwm counter for up-count mode */
        ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_CTRMODE_MASK,
                      TBCTL_CTRMODE_UP);

        if (pwm->hwpwm == 1)
                /* Channel 1 configured with compare B register */
                cmp_reg = CMPB;
        else
                /* Channel 0 configured with compare A register */
                cmp_reg = CMPA;

        ehrpwm_write(pc->mmio_base, cmp_reg, duty_cycles);

        pm_runtime_put_sync(chip->dev);

        return 0;
}

static int ehrpwm_pwm_set_polarity(struct pwm_chip *chip,
                                   struct pwm_device *pwm,
                                   enum pwm_polarity polarity)
{
        struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);

        /* Configuration of polarity in hardware delayed, do at enable */
        pc->polarity[pwm->hwpwm] = polarity;

        return 0;
}

static int ehrpwm_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
        struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
        u16 aqcsfrc_val, aqcsfrc_mask;
        int ret;

        /* Leave clock enabled on enabling PWM */
        pm_runtime_get_sync(chip->dev);

        /* Disabling Action Qualifier on PWM output */
        if (pwm->hwpwm) {
                aqcsfrc_val = AQCSFRC_CSFB_FRCDIS;
                aqcsfrc_mask = AQCSFRC_CSFB_MASK;
        } else {
                aqcsfrc_val = AQCSFRC_CSFA_FRCDIS;
                aqcsfrc_mask = AQCSFRC_CSFA_MASK;
        }

        /* Changes to shadow mode */
        ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
                      AQSFRC_RLDCSF_ZRO);

        ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);

        /* Channels polarity can be configured from action qualifier module */
        configure_polarity(pc, pwm->hwpwm);

        /* Enable TBCLK before enabling PWM device */
        ret = clk_enable(pc->tbclk);
        if (ret) {
                dev_err(chip->dev, "Failed to enable TBCLK for %s: %d\n",
                        dev_name(pc->chip.dev), ret);
                return ret;
        }

        /* Enable time counter for free_run */
        ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_RUN_MASK, TBCTL_FREE_RUN);

        return 0;
}

static void ehrpwm_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
        struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
        u16 aqcsfrc_val, aqcsfrc_mask;

        /* Action Qualifier puts PWM output low forcefully */
        if (pwm->hwpwm) {
                aqcsfrc_val = AQCSFRC_CSFB_FRCLOW;
                aqcsfrc_mask = AQCSFRC_CSFB_MASK;
        } else {
                aqcsfrc_val = AQCSFRC_CSFA_FRCLOW;
                aqcsfrc_mask = AQCSFRC_CSFA_MASK;
        }

        /*
         * Changes to immediate action on Action Qualifier. This puts
         * Action Qualifier control on PWM output from next TBCLK
         */
        ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
                      AQSFRC_RLDCSF_IMDT);

        ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);

        /* Disabling TBCLK on PWM disable */
        clk_disable(pc->tbclk);

        /* Stop Time base counter */
        ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_RUN_MASK, TBCTL_STOP_NEXT);

        /* Disable clock on PWM disable */
        pm_runtime_put_sync(chip->dev);
}

static void ehrpwm_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
        struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);

        if (pwm_is_enabled(pwm)) {
                dev_warn(chip->dev, "Removing PWM device without disabling\n");
                pm_runtime_put_sync(chip->dev);
        }

        /* set period value to zero on free */
        pc->period_cycles[pwm->hwpwm] = 0;
}

static const struct pwm_ops ehrpwm_pwm_ops = {
        .free = ehrpwm_pwm_free,
        .config = ehrpwm_pwm_config,
        .set_polarity = ehrpwm_pwm_set_polarity,
        .enable = ehrpwm_pwm_enable,
        .disable = ehrpwm_pwm_disable,
        .owner = THIS_MODULE,
};

static const struct of_device_id ehrpwm_of_match[] = {
        { .compatible = "ti,am3352-ehrpwm" },
        { .compatible = "ti,am33xx-ehrpwm" },
        {},
};
MODULE_DEVICE_TABLE(of, ehrpwm_of_match);

static int ehrpwm_pwm_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct ehrpwm_pwm_chip *pc;
        struct resource *r;
        struct clk *clk;
        int ret;

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

        clk = devm_clk_get(&pdev->dev, "fck");
        if (IS_ERR(clk)) {
                if (of_device_is_compatible(np, "ti,am33xx-ecap")) {
                        dev_warn(&pdev->dev, "Binding is obsolete.\n");
                        clk = devm_clk_get(pdev->dev.parent, "fck");
                }
        }

        if (IS_ERR(clk)) {
                dev_err(&pdev->dev, "failed to get clock\n");
                return PTR_ERR(clk);
        }

        pc->clk_rate = clk_get_rate(clk);
        if (!pc->clk_rate) {
                dev_err(&pdev->dev, "failed to get clock rate\n");
                return -EINVAL;
        }

        pc->chip.dev = &pdev->dev;
        pc->chip.ops = &ehrpwm_pwm_ops;
        pc->chip.of_xlate = of_pwm_xlate_with_flags;
        pc->chip.of_pwm_n_cells = 3;
        pc->chip.base = -1;
        pc->chip.npwm = NUM_PWM_CHANNEL;

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        pc->mmio_base = devm_ioremap_resource(&pdev->dev, r);
        if (IS_ERR(pc->mmio_base))
                return PTR_ERR(pc->mmio_base);

        /* Acquire tbclk for Time Base EHRPWM submodule */
        pc->tbclk = devm_clk_get(&pdev->dev, "tbclk");
        if (IS_ERR(pc->tbclk)) {
                dev_err(&pdev->dev, "Failed to get tbclk\n");
                return PTR_ERR(pc->tbclk);
        }

        ret = clk_prepare(pc->tbclk);
        if (ret < 0) {
                dev_err(&pdev->dev, "clk_prepare() failed: %d\n", ret);
                return ret;
        }

        ret = pwmchip_add(&pc->chip);
        if (ret < 0) {
                dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
                goto err_clk_unprepare;
        }

        platform_set_drvdata(pdev, pc);
        pm_runtime_enable(&pdev->dev);

        return 0;

err_clk_unprepare:
        clk_unprepare(pc->tbclk);

        return ret;
}

static int ehrpwm_pwm_remove(struct platform_device *pdev)
{
        struct ehrpwm_pwm_chip *pc = platform_get_drvdata(pdev);

        clk_unprepare(pc->tbclk);

        pm_runtime_disable(&pdev->dev);

        return pwmchip_remove(&pc->chip);
}

#ifdef CONFIG_PM_SLEEP
static void ehrpwm_pwm_save_context(struct ehrpwm_pwm_chip *pc)
{
        pm_runtime_get_sync(pc->chip.dev);

        pc->ctx.tbctl = ehrpwm_read(pc->mmio_base, TBCTL);
        pc->ctx.tbprd = ehrpwm_read(pc->mmio_base, TBPRD);
        pc->ctx.cmpa = ehrpwm_read(pc->mmio_base, CMPA);
        pc->ctx.cmpb = ehrpwm_read(pc->mmio_base, CMPB);
        pc->ctx.aqctla = ehrpwm_read(pc->mmio_base, AQCTLA);
        pc->ctx.aqctlb = ehrpwm_read(pc->mmio_base, AQCTLB);
        pc->ctx.aqsfrc = ehrpwm_read(pc->mmio_base, AQSFRC);
        pc->ctx.aqcsfrc = ehrpwm_read(pc->mmio_base, AQCSFRC);

        pm_runtime_put_sync(pc->chip.dev);
}

static void ehrpwm_pwm_restore_context(struct ehrpwm_pwm_chip *pc)
{
        ehrpwm_write(pc->mmio_base, TBPRD, pc->ctx.tbprd);
        ehrpwm_write(pc->mmio_base, CMPA, pc->ctx.cmpa);
        ehrpwm_write(pc->mmio_base, CMPB, pc->ctx.cmpb);
        ehrpwm_write(pc->mmio_base, AQCTLA, pc->ctx.aqctla);
        ehrpwm_write(pc->mmio_base, AQCTLB, pc->ctx.aqctlb);
        ehrpwm_write(pc->mmio_base, AQSFRC, pc->ctx.aqsfrc);
        ehrpwm_write(pc->mmio_base, AQCSFRC, pc->ctx.aqcsfrc);
        ehrpwm_write(pc->mmio_base, TBCTL, pc->ctx.tbctl);
}

static int ehrpwm_pwm_suspend(struct device *dev)
{
        struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
        unsigned int i;

        ehrpwm_pwm_save_context(pc);

        for (i = 0; i < pc->chip.npwm; i++) {
                struct pwm_device *pwm = &pc->chip.pwms[i];

                if (!pwm_is_enabled(pwm))
                        continue;

                /* Disable explicitly if PWM is running */
                pm_runtime_put_sync(dev);
        }

        return 0;
}

static int ehrpwm_pwm_resume(struct device *dev)
{
        struct ehrpwm_pwm_chip *pc = dev_get_drvdata(dev);
        unsigned int i;

        for (i = 0; i < pc->chip.npwm; i++) {
                struct pwm_device *pwm = &pc->chip.pwms[i];

                if (!pwm_is_enabled(pwm))
                        continue;

                /* Enable explicitly if PWM was running */
                pm_runtime_get_sync(dev);
        }

        ehrpwm_pwm_restore_context(pc);

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(ehrpwm_pwm_pm_ops, ehrpwm_pwm_suspend,
                         ehrpwm_pwm_resume);

static struct platform_driver ehrpwm_pwm_driver = {
        .driver = {
                .name = "ehrpwm",
                .of_match_table = ehrpwm_of_match,
                .pm = &ehrpwm_pwm_pm_ops,
        },
        .probe = ehrpwm_pwm_probe,
        .remove = ehrpwm_pwm_remove,
};
module_platform_driver(ehrpwm_pwm_driver);

MODULE_DESCRIPTION("EHRPWM PWM driver");
MODULE_AUTHOR("Texas Instruments");
MODULE_LICENSE("GPL");