- 根目录:
- drivers
- pwm
- pwm-lpc18xx-sct.c
/*
* NXP LPC18xx State Configurable Timer - Pulse Width Modulator driver
*
* Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.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.
*
* Notes
* =====
* NXP LPC18xx provides a State Configurable Timer (SCT) which can be configured
* as a Pulse Width Modulator.
*
* SCT supports 16 outputs, 16 events and 16 registers. Each event will be
* triggered when its related register matches the SCT counter value, and it
* will set or clear a selected output.
*
* One of the events is preselected to generate the period, thus the maximum
* number of simultaneous channels is limited to 15. Notice that period is
* global to all the channels, thus PWM driver will refuse setting different
* values to it, unless there's only one channel requested.
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
/* LPC18xx SCT registers */
#define LPC18XX_PWM_CONFIG 0x000
#define LPC18XX_PWM_CONFIG_UNIFY BIT(0)
#define LPC18XX_PWM_CONFIG_NORELOAD BIT(7)
#define LPC18XX_PWM_CTRL 0x004
#define LPC18XX_PWM_CTRL_HALT BIT(2)
#define LPC18XX_PWM_BIDIR BIT(4)
#define LPC18XX_PWM_PRE_SHIFT 5
#define LPC18XX_PWM_PRE_MASK (0xff << LPC18XX_PWM_PRE_SHIFT)
#define LPC18XX_PWM_PRE(x) (x << LPC18XX_PWM_PRE_SHIFT)
#define LPC18XX_PWM_LIMIT 0x008
#define LPC18XX_PWM_RES_BASE 0x058
#define LPC18XX_PWM_RES_SHIFT(_ch) (_ch * 2)
#define LPC18XX_PWM_RES(_ch, _action) (_action << LPC18XX_PWM_RES_SHIFT(_ch))
#define LPC18XX_PWM_RES_MASK(_ch) (0x3 << LPC18XX_PWM_RES_SHIFT(_ch))
#define LPC18XX_PWM_MATCH_BASE 0x100
#define LPC18XX_PWM_MATCH(_ch) (LPC18XX_PWM_MATCH_BASE + _ch * 4)
#define LPC18XX_PWM_MATCHREL_BASE 0x200
#define LPC18XX_PWM_MATCHREL(_ch) (LPC18XX_PWM_MATCHREL_BASE + _ch * 4)
#define LPC18XX_PWM_EVSTATEMSK_BASE 0x300
#define LPC18XX_PWM_EVSTATEMSK(_ch) (LPC18XX_PWM_EVSTATEMSK_BASE + _ch * 8)
#define LPC18XX_PWM_EVSTATEMSK_ALL 0xffffffff
#define LPC18XX_PWM_EVCTRL_BASE 0x304
#define LPC18XX_PWM_EVCTRL(_ev) (LPC18XX_PWM_EVCTRL_BASE + _ev * 8)
#define LPC18XX_PWM_EVCTRL_MATCH(_ch) _ch
#define LPC18XX_PWM_EVCTRL_COMB_SHIFT 12
#define LPC18XX_PWM_EVCTRL_COMB_MATCH (0x1 << LPC18XX_PWM_EVCTRL_COMB_SHIFT)
#define LPC18XX_PWM_OUTPUTSET_BASE 0x500
#define LPC18XX_PWM_OUTPUTSET(_ch) (LPC18XX_PWM_OUTPUTSET_BASE + _ch * 8)
#define LPC18XX_PWM_OUTPUTCL_BASE 0x504
#define LPC18XX_PWM_OUTPUTCL(_ch) (LPC18XX_PWM_OUTPUTCL_BASE + _ch * 8)
/* LPC18xx SCT unified counter */
#define LPC18XX_PWM_TIMER_MAX 0xffffffff
/* LPC18xx SCT events */
#define LPC18XX_PWM_EVENT_PERIOD 0
#define LPC18XX_PWM_EVENT_MAX 16
/* SCT conflict resolution */
enum lpc18xx_pwm_res_action {
LPC18XX_PWM_RES_NONE,
LPC18XX_PWM_RES_SET,
LPC18XX_PWM_RES_CLEAR,
LPC18XX_PWM_RES_TOGGLE,
};
struct lpc18xx_pwm_data {
unsigned int duty_event;
};
struct lpc18xx_pwm_chip {
struct device *dev;
struct pwm_chip chip;
void __iomem *base;
struct clk *pwm_clk;
unsigned long clk_rate;
unsigned int period_ns;
unsigned int min_period_ns;
unsigned int max_period_ns;
unsigned int period_event;
unsigned long event_map;
struct mutex res_lock;
struct mutex period_lock;
};
static inline struct lpc18xx_pwm_chip *
to_lpc18xx_pwm_chip(struct pwm_chip *chip)
{
return container_of(chip, struct lpc18xx_pwm_chip, chip);
}
static inline void lpc18xx_pwm_writel(struct lpc18xx_pwm_chip *lpc18xx_pwm,
u32 reg, u32 val)
{
writel(val, lpc18xx_pwm->base + reg);
}
static inline u32 lpc18xx_pwm_readl(struct lpc18xx_pwm_chip *lpc18xx_pwm,
u32 reg)
{
return readl(lpc18xx_pwm->base + reg);
}
static void lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip *lpc18xx_pwm,
struct pwm_device *pwm,
enum lpc18xx_pwm_res_action action)
{
u32 val;
mutex_lock(&lpc18xx_pwm->res_lock);
/*
* Simultaneous set and clear may happen on an output, that is the case
* when duty_ns == period_ns. LPC18xx SCT allows to set a conflict
* resolution action to be taken in such a case.
*/
val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_RES_BASE);
val &= ~LPC18XX_PWM_RES_MASK(pwm->hwpwm);
val |= LPC18XX_PWM_RES(pwm->hwpwm, action);
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_RES_BASE, val);
mutex_unlock(&lpc18xx_pwm->res_lock);
}
static void lpc18xx_pwm_config_period(struct pwm_chip *chip, int period_ns)
{
struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
u64 val;
val = (u64)period_ns * lpc18xx_pwm->clk_rate;
do_div(val, NSEC_PER_SEC);
lpc18xx_pwm_writel(lpc18xx_pwm,
LPC18XX_PWM_MATCH(lpc18xx_pwm->period_event),
(u32)val - 1);
lpc18xx_pwm_writel(lpc18xx_pwm,
LPC18XX_PWM_MATCHREL(lpc18xx_pwm->period_event),
(u32)val - 1);
}
static void lpc18xx_pwm_config_duty(struct pwm_chip *chip,
struct pwm_device *pwm, int duty_ns)
{
struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
u64 val;
val = (u64)duty_ns * lpc18xx_pwm->clk_rate;
do_div(val, NSEC_PER_SEC);
lpc18xx_pwm_writel(lpc18xx_pwm,
LPC18XX_PWM_MATCH(lpc18xx_data->duty_event),
(u32)val);
lpc18xx_pwm_writel(lpc18xx_pwm,
LPC18XX_PWM_MATCHREL(lpc18xx_data->duty_event),
(u32)val);
}
static int lpc18xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
int requested_events, i;
if (period_ns < lpc18xx_pwm->min_period_ns ||
period_ns > lpc18xx_pwm->max_period_ns) {
dev_err(chip->dev, "period %d not in range\n", period_ns);
return -ERANGE;
}
mutex_lock(&lpc18xx_pwm->period_lock);
requested_events = bitmap_weight(&lpc18xx_pwm->event_map,
LPC18XX_PWM_EVENT_MAX);
/*
* The PWM supports only a single period for all PWM channels.
* Once the period is set, it can only be changed if no more than one
* channel is requested at that moment.
*/
if (requested_events > 2 && lpc18xx_pwm->period_ns != period_ns &&
lpc18xx_pwm->period_ns) {
dev_err(chip->dev, "conflicting period requested for PWM %u\n",
pwm->hwpwm);
mutex_unlock(&lpc18xx_pwm->period_lock);
return -EBUSY;
}
if ((requested_events <= 2 && lpc18xx_pwm->period_ns != period_ns) ||
!lpc18xx_pwm->period_ns) {
lpc18xx_pwm->period_ns = period_ns;
for (i = 0; i < chip->npwm; i++)
pwm_set_period(&chip->pwms[i], period_ns);
lpc18xx_pwm_config_period(chip, period_ns);
}
mutex_unlock(&lpc18xx_pwm->period_lock);
lpc18xx_pwm_config_duty(chip, pwm, duty_ns);
return 0;
}
static int lpc18xx_pwm_set_polarity(struct pwm_chip *chip,
struct pwm_device *pwm,
enum pwm_polarity polarity)
{
return 0;
}
static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
enum lpc18xx_pwm_res_action res_action;
unsigned int set_event, clear_event;
lpc18xx_pwm_writel(lpc18xx_pwm,
LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event),
LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_data->duty_event) |
LPC18XX_PWM_EVCTRL_COMB_MATCH);
lpc18xx_pwm_writel(lpc18xx_pwm,
LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
LPC18XX_PWM_EVSTATEMSK_ALL);
if (pwm->polarity == PWM_POLARITY_NORMAL) {
set_event = lpc18xx_pwm->period_event;
clear_event = lpc18xx_data->duty_event;
res_action = LPC18XX_PWM_RES_SET;
} else {
set_event = lpc18xx_data->duty_event;
clear_event = lpc18xx_pwm->period_event;
res_action = LPC18XX_PWM_RES_CLEAR;
}
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm),
BIT(set_event));
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm),
BIT(clear_event));
lpc18xx_pwm_set_conflict_res(lpc18xx_pwm, pwm, res_action);
return 0;
}
static void lpc18xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
lpc18xx_pwm_writel(lpc18xx_pwm,
LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event), 0);
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm), 0);
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm), 0);
}
static int lpc18xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
unsigned long event;
event = find_first_zero_bit(&lpc18xx_pwm->event_map,
LPC18XX_PWM_EVENT_MAX);
if (event >= LPC18XX_PWM_EVENT_MAX) {
dev_err(lpc18xx_pwm->dev,
"maximum number of simultaneous channels reached\n");
return -EBUSY;
};
set_bit(event, &lpc18xx_pwm->event_map);
lpc18xx_data->duty_event = event;
lpc18xx_pwm_config_duty(chip, pwm, pwm_get_duty_cycle(pwm));
return 0;
}
static void lpc18xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
pwm_disable(pwm);
pwm_set_duty_cycle(pwm, 0);
clear_bit(lpc18xx_data->duty_event, &lpc18xx_pwm->event_map);
}
static const struct pwm_ops lpc18xx_pwm_ops = {
.config = lpc18xx_pwm_config,
.set_polarity = lpc18xx_pwm_set_polarity,
.enable = lpc18xx_pwm_enable,
.disable = lpc18xx_pwm_disable,
.request = lpc18xx_pwm_request,
.free = lpc18xx_pwm_free,
.owner = THIS_MODULE,
};
static const struct of_device_id lpc18xx_pwm_of_match[] = {
{ .compatible = "nxp,lpc1850-sct-pwm" },
{}
};
MODULE_DEVICE_TABLE(of, lpc18xx_pwm_of_match);
static int lpc18xx_pwm_probe(struct platform_device *pdev)
{
struct lpc18xx_pwm_chip *lpc18xx_pwm;
struct pwm_device *pwm;
struct resource *res;
int ret, i;
u64 val;
lpc18xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*lpc18xx_pwm),
GFP_KERNEL);
if (!lpc18xx_pwm)
return -ENOMEM;
lpc18xx_pwm->dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
lpc18xx_pwm->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(lpc18xx_pwm->base))
return PTR_ERR(lpc18xx_pwm->base);
lpc18xx_pwm->pwm_clk = devm_clk_get(&pdev->dev, "pwm");
if (IS_ERR(lpc18xx_pwm->pwm_clk)) {
dev_err(&pdev->dev, "failed to get pwm clock\n");
return PTR_ERR(lpc18xx_pwm->pwm_clk);
}
ret = clk_prepare_enable(lpc18xx_pwm->pwm_clk);
if (ret < 0) {
dev_err(&pdev->dev, "could not prepare or enable pwm clock\n");
return ret;
}
lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
mutex_init(&lpc18xx_pwm->res_lock);
mutex_init(&lpc18xx_pwm->period_lock);
val = (u64)NSEC_PER_SEC * LPC18XX_PWM_TIMER_MAX;
do_div(val, lpc18xx_pwm->clk_rate);
lpc18xx_pwm->max_period_ns = val;
lpc18xx_pwm->min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC,
lpc18xx_pwm->clk_rate);
lpc18xx_pwm->chip.dev = &pdev->dev;
lpc18xx_pwm->chip.ops = &lpc18xx_pwm_ops;
lpc18xx_pwm->chip.base = -1;
lpc18xx_pwm->chip.npwm = 16;
lpc18xx_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
lpc18xx_pwm->chip.of_pwm_n_cells = 3;
/* SCT counter must be in unify (32 bit) mode */
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CONFIG,
LPC18XX_PWM_CONFIG_UNIFY);
/*
* Everytime the timer counter reaches the period value, the related
* event will be triggered and the counter reset to 0.
*/
set_bit(LPC18XX_PWM_EVENT_PERIOD, &lpc18xx_pwm->event_map);
lpc18xx_pwm->period_event = LPC18XX_PWM_EVENT_PERIOD;
lpc18xx_pwm_writel(lpc18xx_pwm,
LPC18XX_PWM_EVSTATEMSK(lpc18xx_pwm->period_event),
LPC18XX_PWM_EVSTATEMSK_ALL);
val = LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_pwm->period_event) |
LPC18XX_PWM_EVCTRL_COMB_MATCH;
lpc18xx_pwm_writel(lpc18xx_pwm,
LPC18XX_PWM_EVCTRL(lpc18xx_pwm->period_event), val);
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_LIMIT,
BIT(lpc18xx_pwm->period_event));
ret = pwmchip_add(&lpc18xx_pwm->chip);
if (ret < 0) {
dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
goto disable_pwmclk;
}
for (i = 0; i < lpc18xx_pwm->chip.npwm; i++) {
pwm = &lpc18xx_pwm->chip.pwms[i];
pwm->chip_data = devm_kzalloc(lpc18xx_pwm->dev,
sizeof(struct lpc18xx_pwm_data),
GFP_KERNEL);
if (!pwm->chip_data) {
ret = -ENOMEM;
goto remove_pwmchip;
}
}
platform_set_drvdata(pdev, lpc18xx_pwm);
val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
val &= ~LPC18XX_PWM_BIDIR;
val &= ~LPC18XX_PWM_CTRL_HALT;
val &= ~LPC18XX_PWM_PRE_MASK;
val |= LPC18XX_PWM_PRE(0);
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL, val);
return 0;
remove_pwmchip:
pwmchip_remove(&lpc18xx_pwm->chip);
disable_pwmclk:
clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
return ret;
}
static int lpc18xx_pwm_remove(struct platform_device *pdev)
{
struct lpc18xx_pwm_chip *lpc18xx_pwm = platform_get_drvdata(pdev);
u32 val;
val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL,
val | LPC18XX_PWM_CTRL_HALT);
clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
return pwmchip_remove(&lpc18xx_pwm->chip);
}
static struct platform_driver lpc18xx_pwm_driver = {
.driver = {
.name = "lpc18xx-sct-pwm",
.of_match_table = lpc18xx_pwm_of_match,
},
.probe = lpc18xx_pwm_probe,
.remove = lpc18xx_pwm_remove,
};
module_platform_driver(lpc18xx_pwm_driver);
MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
MODULE_DESCRIPTION("NXP LPC18xx PWM driver");
MODULE_LICENSE("GPL v2");