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