diff options
Diffstat (limited to 'drivers/pwm/pwm-lpc18xx-sct.c')
| -rw-r--r-- | drivers/pwm/pwm-lpc18xx-sct.c | 465 |
1 files changed, 465 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-lpc18xx-sct.c b/drivers/pwm/pwm-lpc18xx-sct.c new file mode 100644 index 0000000..9163085 --- /dev/null +++ b/drivers/pwm/pwm-lpc18xx-sct.c @@ -0,0 +1,465 @@ +/* + * 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"); |
