/* * Copyright (c) 2015 Neil Armstrong * Copyright (c) 2014 Joachim Eastwood * Copyright (c) 2012 NeilBrown * Heavily based on earlier code which is: * Copyright (c) 2010 Grant Erickson * * Also based on pwm-samsung.c * * 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. * * Description: * This file is the core OMAP support for the generic, Linux * PWM driver / controller, using the OMAP's dual-mode timers. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #define DM_TIMER_LOAD_MIN 0xfffffffe #define DM_TIMER_MAX 0xffffffff struct pwm_omap_dmtimer_chip { struct pwm_chip chip; struct mutex mutex; pwm_omap_dmtimer *dm_timer; struct pwm_omap_dmtimer_pdata *pdata; struct platform_device *dm_timer_pdev; }; static inline struct pwm_omap_dmtimer_chip * to_pwm_omap_dmtimer_chip(struct pwm_chip *chip) { return container_of(chip, struct pwm_omap_dmtimer_chip, chip); } static u32 pwm_omap_dmtimer_get_clock_cycles(unsigned long clk_rate, int ns) { return DIV_ROUND_CLOSEST_ULL((u64)clk_rate * ns, NSEC_PER_SEC); } static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap) { /* * According to OMAP 4 TRM section 22.2.4.10 the counter should be * started at 0xFFFFFFFE when overflow and match is used to ensure * that the PWM line is toggled on the first event. * * Note that omap_dm_timer_enable/disable is for register access and * not the timer counter itself. */ omap->pdata->enable(omap->dm_timer); omap->pdata->write_counter(omap->dm_timer, DM_TIMER_LOAD_MIN); omap->pdata->disable(omap->dm_timer); omap->pdata->start(omap->dm_timer); } static int pwm_omap_dmtimer_enable(struct pwm_chip *chip, struct pwm_device *pwm) { struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); mutex_lock(&omap->mutex); pwm_omap_dmtimer_start(omap); mutex_unlock(&omap->mutex); return 0; } static void pwm_omap_dmtimer_disable(struct pwm_chip *chip, struct pwm_device *pwm) { struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); mutex_lock(&omap->mutex); omap->pdata->stop(omap->dm_timer); mutex_unlock(&omap->mutex); } static int pwm_omap_dmtimer_config(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns) { struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); u32 period_cycles, duty_cycles; u32 load_value, match_value; struct clk *fclk; unsigned long clk_rate; bool timer_active; dev_dbg(chip->dev, "requested duty cycle: %d ns, period: %d ns\n", duty_ns, period_ns); mutex_lock(&omap->mutex); if (duty_ns == pwm_get_duty_cycle(pwm) && period_ns == pwm_get_period(pwm)) { /* No change - don't cause any transients. */ mutex_unlock(&omap->mutex); return 0; } fclk = omap->pdata->get_fclk(omap->dm_timer); if (!fclk) { dev_err(chip->dev, "invalid pmtimer fclk\n"); goto err_einval; } clk_rate = clk_get_rate(fclk); if (!clk_rate) { dev_err(chip->dev, "invalid pmtimer fclk rate\n"); goto err_einval; } dev_dbg(chip->dev, "clk rate: %luHz\n", clk_rate); /* * Calculate the appropriate load and match values based on the * specified period and duty cycle. The load value determines the * period time and the match value determines the duty time. * * The period lasts for (DM_TIMER_MAX-load_value+1) clock cycles. * Similarly, the active time lasts (match_value-load_value+1) cycles. * The non-active time is the remainder: (DM_TIMER_MAX-match_value) * clock cycles. * * NOTE: It is required that: load_value <= match_value < DM_TIMER_MAX * * References: * OMAP4430/60/70 TRM sections 22.2.4.10 and 22.2.4.11 * AM335x Sitara TRM sections 20.1.3.5 and 20.1.3.6 */ period_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, period_ns); duty_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, duty_ns); if (period_cycles < 2) { dev_info(chip->dev, "period %d ns too short for clock rate %lu Hz\n", period_ns, clk_rate); goto err_einval; } if (duty_cycles < 1) { dev_dbg(chip->dev, "duty cycle %d ns is too short for clock rate %lu Hz\n", duty_ns, clk_rate); dev_dbg(chip->dev, "using minimum of 1 clock cycle\n"); duty_cycles = 1; } else if (duty_cycles >= period_cycles) { dev_dbg(chip->dev, "duty cycle %d ns is too long for period %d ns at clock rate %lu Hz\n", duty_ns, period_ns, clk_rate); dev_dbg(chip->dev, "using maximum of 1 clock cycle less than period\n"); duty_cycles = period_cycles - 1; } dev_dbg(chip->dev, "effective duty cycle: %lld ns, period: %lld ns\n", DIV_ROUND_CLOSEST_ULL((u64)NSEC_PER_SEC * duty_cycles, clk_rate), DIV_ROUND_CLOSEST_ULL((u64)NSEC_PER_SEC * period_cycles, clk_rate)); load_value = (DM_TIMER_MAX - period_cycles) + 1; match_value = load_value + duty_cycles - 1; /* * We MUST stop the associated dual-mode timer before attempting to * write its registers, but calls to omap_dm_timer_start/stop must * be balanced so check if timer is active before calling timer_stop. */ timer_active = pm_runtime_active(&omap->dm_timer_pdev->dev); if (timer_active) omap->pdata->stop(omap->dm_timer); omap->pdata->set_load(omap->dm_timer, true, load_value); omap->pdata->set_match(omap->dm_timer, true, match_value); dev_dbg(chip->dev, "load value: %#08x (%d), match value: %#08x (%d)\n", load_value, load_value, match_value, match_value); omap->pdata->set_pwm(omap->dm_timer, pwm->polarity == PWM_POLARITY_INVERSED, true, PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE); /* If config was called while timer was running it must be reenabled. */ if (timer_active) pwm_omap_dmtimer_start(omap); mutex_unlock(&omap->mutex); return 0; err_einval: mutex_unlock(&omap->mutex); return -EINVAL; } static int pwm_omap_dmtimer_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, enum pwm_polarity polarity) { struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); /* * PWM core will not call set_polarity while PWM is enabled so it's * safe to reconfigure the timer here without stopping it first. */ mutex_lock(&omap->mutex); omap->pdata->set_pwm(omap->dm_timer, polarity == PWM_POLARITY_INVERSED, true, PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE); mutex_unlock(&omap->mutex); return 0; } static const struct pwm_ops pwm_omap_dmtimer_ops = { .enable = pwm_omap_dmtimer_enable, .disable = pwm_omap_dmtimer_disable, .config = pwm_omap_dmtimer_config, .set_polarity = pwm_omap_dmtimer_set_polarity, .owner = THIS_MODULE, }; static int pwm_omap_dmtimer_probe(struct platform_device *pdev) { struct device_node *np = pdev->dev.of_node; struct device_node *timer; struct pwm_omap_dmtimer_chip *omap; struct pwm_omap_dmtimer_pdata *pdata; pwm_omap_dmtimer *dm_timer; u32 prescaler; int status; pdata = dev_get_platdata(&pdev->dev); if (!pdata) { dev_err(&pdev->dev, "Missing dmtimer platform data\n"); return -EINVAL; } if (!pdata->request_by_node || !pdata->free || !pdata->enable || !pdata->disable || !pdata->get_fclk || !pdata->start || !pdata->stop || !pdata->set_load || !pdata->set_match || !pdata->set_pwm || !pdata->set_prescaler || !pdata->write_counter) { dev_err(&pdev->dev, "Incomplete dmtimer pdata structure\n"); return -EINVAL; } timer = of_parse_phandle(np, "ti,timers", 0); if (!timer) return -ENODEV; if (!of_get_property(timer, "ti,timer-pwm", NULL)) { dev_err(&pdev->dev, "Missing ti,timer-pwm capability\n"); return -ENODEV; } dm_timer = pdata->request_by_node(timer); if (!dm_timer) return -EPROBE_DEFER; omap = devm_kzalloc(&pdev->dev, sizeof(*omap), GFP_KERNEL); if (!omap) { pdata->free(dm_timer); return -ENOMEM; } omap->pdata = pdata; omap->dm_timer = dm_timer; omap->dm_timer_pdev = of_find_device_by_node(timer); if (!omap->dm_timer_pdev) { dev_err(&pdev->dev, "Unable to find timer pdev\n"); omap->pdata->free(dm_timer); return -EINVAL; } /* * Ensure that the timer is stopped before we allow PWM core to call * pwm_enable. */ if (pm_runtime_active(&omap->dm_timer_pdev->dev)) omap->pdata->stop(omap->dm_timer); /* setup dmtimer prescaler */ if (!of_property_read_u32(pdev->dev.of_node, "ti,prescaler", &prescaler)) omap->pdata->set_prescaler(omap->dm_timer, prescaler); omap->chip.dev = &pdev->dev; omap->chip.ops = &pwm_omap_dmtimer_ops; omap->chip.base = -1; omap->chip.npwm = 1; omap->chip.of_xlate = of_pwm_xlate_with_flags; omap->chip.of_pwm_n_cells = 3; mutex_init(&omap->mutex); status = pwmchip_add(&omap->chip); if (status < 0) { dev_err(&pdev->dev, "failed to register PWM\n"); omap->pdata->free(omap->dm_timer); return status; } platform_set_drvdata(pdev, omap); return 0; } static int pwm_omap_dmtimer_remove(struct platform_device *pdev) { struct pwm_omap_dmtimer_chip *omap = platform_get_drvdata(pdev); if (pm_runtime_active(&omap->dm_timer_pdev->dev)) omap->pdata->stop(omap->dm_timer); omap->pdata->free(omap->dm_timer); mutex_destroy(&omap->mutex); return pwmchip_remove(&omap->chip); } static const struct of_device_id pwm_omap_dmtimer_of_match[] = { {.compatible = "ti,omap-dmtimer-pwm"}, {} }; MODULE_DEVICE_TABLE(of, pwm_omap_dmtimer_of_match); static struct platform_driver pwm_omap_dmtimer_driver = { .driver = { .name = "omap-dmtimer-pwm", .of_match_table = of_match_ptr(pwm_omap_dmtimer_of_match), }, .probe = pwm_omap_dmtimer_probe, .remove = pwm_omap_dmtimer_remove, }; module_platform_driver(pwm_omap_dmtimer_driver); MODULE_AUTHOR("Grant Erickson "); MODULE_AUTHOR("NeilBrown "); MODULE_AUTHOR("Neil Armstrong "); MODULE_LICENSE("GPL v2"); MODULE_DESCRIPTION("OMAP PWM Driver using Dual-mode Timers");