--- /dev/null
+/*
+ * 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");
projects / users / willy / pagecache.git / commitdiff