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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>
*
* 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/acpi.h>
#include <linux/clk.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pwm.h>
#include <linux/platform_device.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;
struct clk *clk;
};
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 = clk_get_rate(lpwm->clk);
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;
int ret;
ret = clk_prepare_enable(lpwm->clk);
if (ret)
return ret;
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);
clk_disable_unprepare(lpwm->clk);
}
static const struct pwm_ops pwm_lpss_ops = {
.config = pwm_lpss_config,
.enable = pwm_lpss_enable,
.disable = pwm_lpss_disable,
.owner = THIS_MODULE,
};
static const struct acpi_device_id pwm_lpss_acpi_match[] = {
{ "80860F09", 0 },
{ },
};
MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match);
static int pwm_lpss_probe(struct platform_device *pdev)
{
struct pwm_lpss_chip *lpwm;
struct resource *r;
int ret;
lpwm = devm_kzalloc(&pdev->dev, sizeof(*lpwm), GFP_KERNEL);
if (!lpwm)
return -ENOMEM;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
lpwm->regs = devm_ioremap_resource(&pdev->dev, r);
if (IS_ERR(lpwm->regs))
return PTR_ERR(lpwm->regs);
lpwm->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(lpwm->clk)) {
dev_err(&pdev->dev, "failed to get PWM clock\n");
return PTR_ERR(lpwm->clk);
}
lpwm->chip.dev = &pdev->dev;
lpwm->chip.ops = &pwm_lpss_ops;
lpwm->chip.base = -1;
lpwm->chip.npwm = 1;
ret = pwmchip_add(&lpwm->chip);
if (ret) {
dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
return ret;
}
platform_set_drvdata(pdev, lpwm);
return 0;
}
static int pwm_lpss_remove(struct platform_device *pdev)
{
struct pwm_lpss_chip *lpwm = platform_get_drvdata(pdev);
u32 ctrl;
ctrl = readl(lpwm->regs + PWM);
writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
return pwmchip_remove(&lpwm->chip);
}
static struct platform_driver pwm_lpss_driver = {
.driver = {
.name = "pwm-lpss",
.acpi_match_table = pwm_lpss_acpi_match,
},
.probe = pwm_lpss_probe,
.remove = pwm_lpss_remove,
};
module_platform_driver(pwm_lpss_driver);
MODULE_DESCRIPTION("PWM driver for Intel LPSS");
MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:pwm-lpss");
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