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/*
* Intel Low Power Subsystem PWM controller driver
*
* Copyright (C) 2014, Intel Corporation
* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
* Author: Chew Kean Ho <kean.ho.chew@intel.com>
* Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
* Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
* Author: Alan Cox <alan@linux.intel.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include "pwm-lpss.h"
#define PWM 0x00000000
#define PWM_ENABLE BIT(31)
#define PWM_SW_UPDATE BIT(30)
#define PWM_BASE_UNIT_SHIFT 8
#define PWM_BASE_UNIT_MASK 0x00ffff00
#define PWM_ON_TIME_DIV_MASK 0x000000ff
#define PWM_DIVISION_CORRECTION 0x2
#define PWM_LIMIT (0x8000 + PWM_DIVISION_CORRECTION)
#define NSECS_PER_SEC 1000000000UL
struct pwm_lpss_chip {
struct pwm_chip chip;
void __iomem *regs;
unsigned long clk_rate;
};
/* BayTrail */
const struct pwm_lpss_boardinfo pwm_lpss_byt_info = {
25000000
};
EXPORT_SYMBOL_GPL(pwm_lpss_byt_info);
/* Braswell */
const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
19200000
};
EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info);
static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
{
return container_of(chip, struct pwm_lpss_chip, chip);
}
static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct pwm_lpss_chip *lpwm = to_lpwm(chip);
u8 on_time_div;
unsigned long c;
unsigned long long base_unit, freq = NSECS_PER_SEC;
u32 ctrl;
do_div(freq, period_ns);
/* The equation is: base_unit = ((freq / c) * 65536) + correction */
base_unit = freq * 65536;
c = lpwm->clk_rate;
if (!c)
return -EINVAL;
do_div(base_unit, c);
base_unit += PWM_DIVISION_CORRECTION;
if (base_unit > PWM_LIMIT)
return -EINVAL;
if (duty_ns <= 0)
duty_ns = 1;
on_time_div = 255 - (255 * duty_ns / period_ns);
ctrl = readl(lpwm->regs + PWM);
ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
ctrl |= on_time_div;
/* request PWM to update on next cycle */
ctrl |= PWM_SW_UPDATE;
writel(ctrl, lpwm->regs + PWM);
return 0;
}
static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pwm_lpss_chip *lpwm = to_lpwm(chip);
u32 ctrl;
ctrl = readl(lpwm->regs + PWM);
writel(ctrl | PWM_ENABLE, lpwm->regs + PWM);
return 0;
}
static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct pwm_lpss_chip *lpwm = to_lpwm(chip);
u32 ctrl;
ctrl = readl(lpwm->regs + PWM);
writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
}
static const struct pwm_ops pwm_lpss_ops = {
.config = pwm_lpss_config,
.enable = pwm_lpss_enable,
.disable = pwm_lpss_disable,
.owner = THIS_MODULE,
};
struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
const struct pwm_lpss_boardinfo *info)
{
struct pwm_lpss_chip *lpwm;
int ret;
lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
if (!lpwm)
return ERR_PTR(-ENOMEM);
lpwm->regs = devm_ioremap_resource(dev, r);
if (IS_ERR(lpwm->regs))
return ERR_CAST(lpwm->regs);
lpwm->clk_rate = info->clk_rate;
lpwm->chip.dev = dev;
lpwm->chip.ops = &pwm_lpss_ops;
lpwm->chip.base = -1;
lpwm->chip.npwm = 1;
ret = pwmchip_add(&lpwm->chip);
if (ret) {
dev_err(dev, "failed to add PWM chip: %d\n", ret);
return ERR_PTR(ret);
}
return lpwm;
}
EXPORT_SYMBOL_GPL(pwm_lpss_probe);
int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
{
u32 ctrl;
ctrl = readl(lpwm->regs + PWM);
writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
return pwmchip_remove(&lpwm->chip);
}
EXPORT_SYMBOL_GPL(pwm_lpss_remove);
MODULE_DESCRIPTION("PWM driver for Intel LPSS");
MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
MODULE_LICENSE("GPL v2");
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