// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/pwm/pwm-pxa.c
 *
 * simple driver for PWM (Pulse Width Modulator) controller
 *
 * 2008-02-13   initial version
 *              eric miao <eric.miao@marvell.com>
 *
 * Links to reference manuals for some of the supported PWM chips can be found
 * in Documentation/arch/arm/marvell.rst.
 *
 * Limitations:
 * - When PWM is stopped, the current PWM period stops abruptly at the next
 *   input clock (PWMCR_SD is set) and the output is driven to inactive.
 */

#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pwm.h>
#include <linux/of.h>
#include <linux/reset.h>

#include <asm/div64.h>

#define HAS_SECONDARY_PWM       0x10

static const struct platform_device_id pwm_id_table[] = {
        /*   PWM    has_secondary_pwm? */
        { "pxa25x-pwm", 0 },
        { "pxa27x-pwm", HAS_SECONDARY_PWM },
        { "pxa168-pwm", 0 },
        { "pxa910-pwm", 0 },
        { },
};
MODULE_DEVICE_TABLE(platform, pwm_id_table);

/* PWM registers and bits definitions */
#define PWMCR           (0x00)
#define PWMDCR          (0x04)
#define PWMPCR          (0x08)

#define PWMCR_SD        (1 << 6)
#define PWMDCR_FD       (1 << 10)

struct pxa_pwm_chip {
        struct device   *dev;

        struct clk      *clk;
        void __iomem    *mmio_base;
};

static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)
{
        return pwmchip_get_drvdata(chip);
}

/*
 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
 * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 */
static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                          u64 duty_ns, u64 period_ns)
{
        struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
        unsigned long long c;
        unsigned long period_cycles, prescale, pv, dc;
        unsigned long offset;

        offset = pwm->hwpwm ? 0x10 : 0;

        c = clk_get_rate(pc->clk);
        c = c * period_ns;
        do_div(c, 1000000000);
        period_cycles = c;

        if (period_cycles < 1)
                period_cycles = 1;
        prescale = (period_cycles - 1) / 1024;
        pv = period_cycles / (prescale + 1) - 1;

        if (prescale > 63)
                return -EINVAL;

        if (duty_ns == period_ns)
                dc = PWMDCR_FD;
        else
                dc = mul_u64_u64_div_u64(pv + 1, duty_ns, period_ns);

        writel(prescale | PWMCR_SD, pc->mmio_base + offset + PWMCR);
        writel(dc, pc->mmio_base + offset + PWMDCR);
        writel(pv, pc->mmio_base + offset + PWMPCR);

        return 0;
}

static int pxa_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
                         const struct pwm_state *state)
{
        struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
        u64 duty_cycle;
        int err;

        if (state->polarity != PWM_POLARITY_NORMAL)
                return -EINVAL;

        err = clk_prepare_enable(pc->clk);
        if (err)
                return err;

        duty_cycle = state->enabled ? state->duty_cycle : 0;

        err = pxa_pwm_config(chip, pwm, duty_cycle, state->period);
        if (err) {
                clk_disable_unprepare(pc->clk);
                return err;
        }

        if (state->enabled && !pwm->state.enabled)
                return 0;

        clk_disable_unprepare(pc->clk);

        if (!state->enabled && pwm->state.enabled)
                clk_disable_unprepare(pc->clk);

        return 0;
}

static const struct pwm_ops pxa_pwm_ops = {
        .apply = pxa_pwm_apply,
};

#ifdef CONFIG_OF
/*
 * Device tree users must create one device instance for each PWM channel.
 * Hence we dispense with the HAS_SECONDARY_PWM and "tell" the original driver
 * code that this is a single channel pxa25x-pwm.  Currently all devices are
 * supported identically.
 */
static const struct of_device_id pwm_of_match[] = {
        { .compatible = "marvell,pxa250-pwm", .data = &pwm_id_table[0]},
        { .compatible = "marvell,pxa270-pwm", .data = &pwm_id_table[0]},
        { .compatible = "marvell,pxa168-pwm", .data = &pwm_id_table[0]},
        { .compatible = "marvell,pxa910-pwm", .data = &pwm_id_table[0]},
        { }
};
MODULE_DEVICE_TABLE(of, pwm_of_match);
#else
#define pwm_of_match NULL
#endif

static int pwm_probe(struct platform_device *pdev)
{
        const struct platform_device_id *id = platform_get_device_id(pdev);
        struct pwm_chip *chip;
        struct pxa_pwm_chip *pc;
        struct device *dev = &pdev->dev;
        struct reset_control *rst;
        int ret = 0;

        if (IS_ENABLED(CONFIG_OF) && id == NULL)
                id = of_device_get_match_data(dev);

        if (id == NULL)
                return -EINVAL;

        chip = devm_pwmchip_alloc(dev, (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1,
                                  sizeof(*pc));
        if (IS_ERR(chip))
                return PTR_ERR(chip);
        pc = to_pxa_pwm_chip(chip);

        pc->clk = devm_clk_get(dev, NULL);
        if (IS_ERR(pc->clk))
                return dev_err_probe(dev, PTR_ERR(pc->clk), "Failed to get clock\n");

        rst = devm_reset_control_get_optional_exclusive_deasserted(dev, NULL);
        if (IS_ERR(rst))
                return PTR_ERR(rst);

        chip->ops = &pxa_pwm_ops;

        if (IS_ENABLED(CONFIG_OF))
                chip->of_xlate = of_pwm_single_xlate;

        pc->mmio_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(pc->mmio_base))
                return PTR_ERR(pc->mmio_base);

        ret = devm_pwmchip_add(dev, chip);
        if (ret < 0)
                return dev_err_probe(dev, ret, "pwmchip_add() failed\n");

        return 0;
}

static struct platform_driver pwm_driver = {
        .driver         = {
                .name   = "pxa25x-pwm",
                .of_match_table = pwm_of_match,
        },
        .probe          = pwm_probe,
        .id_table       = pwm_id_table,
};

module_platform_driver(pwm_driver);

MODULE_DESCRIPTION("PXA Pulse Width Modulator driver");
MODULE_LICENSE("GPL v2");