linux-imx

/*

 * Marvell Berlin PWM driver

 *

 * Copyright (C) 2015 Marvell Technology Group Ltd.

 *

 * Author: Antoine Tenart <antoine.tenart@free-electrons.com>

 *

 * 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/clk.h>

#include <linux/io.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/pwm.h>

#include <linux/slab.h>

​

#define BERLIN_PWM_EN           0x0

#define  BERLIN_PWM_ENABLE      BIT(0)

#define BERLIN_PWM_CONTROL      0x4

/*

 * The prescaler claims to support 8 different moduli, configured using the

 * low three bits of PWM_CONTROL. (Sequentially, they are 1, 4, 8, 16, 64,

 * 256, 1024, and 4096.)  However, the moduli from 4 to 1024 appear to be

 * implemented by internally shifting TCNT left without adding additional

 * bits. So, the max TCNT that actually works for a modulus of 4 is 0x3fff;

 * for 8, 0x1fff; and so on. This means that those moduli are entirely

 * useless, as we could just do the shift ourselves. The 4096 modulus is

 * implemented with a real prescaler, so we do use that, but we treat it

 * as a flag instead of pretending the modulus is actually configurable.

 */

#define  BERLIN_PWM_PRESCALE_4096   0x7

#define  BERLIN_PWM_INVERT_POLARITY BIT(3)

#define BERLIN_PWM_DUTY         0x8

#define BERLIN_PWM_TCNT         0xc

#define  BERLIN_PWM_MAX_TCNT        65535

​

struct berlin_pwm_channel {

    u32 enable;

    u32 ctrl;

    u32 duty;

    u32 tcnt;

};

​

struct berlin_pwm_chip {

    struct pwm_chip chip;

    struct clk *clk;

    void __iomem *base;

};

​

static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip)

{

    return container_of(chip, struct berlin_pwm_chip, chip);

}

​

static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *chip,

                   unsigned int channel, unsigned long offset)

{

    return readl_relaxed(chip->base + channel * 0x10 + offset);

}

​

static inline void berlin_pwm_writel(struct berlin_pwm_chip *chip,

                     unsigned int channel, u32 value,

                     unsigned long offset)

{

    writel_relaxed(value, chip->base + channel * 0x10 + offset);

}

​

static int berlin_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)

{

    struct berlin_pwm_channel *channel;

​

    channel = kzalloc(sizeof(*channel), GFP_KERNEL);

    if (!channel)

        return -ENOMEM;

​

    return pwm_set_chip_data(pwm, channel);

}

​

static void berlin_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)

{

    struct berlin_pwm_channel *channel = pwm_get_chip_data(pwm);

​

    pwm_set_chip_data(pwm, NULL);

    kfree(channel);

}

​

static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev,

                 int duty_ns, int period_ns)