diff options
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/pwm/pwm-omap-dmtimer.c | 180 |
1 files changed, 129 insertions, 51 deletions
diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c index c56e7256e923..0d31833db2e2 100644 --- a/drivers/pwm/pwm-omap-dmtimer.c +++ b/drivers/pwm/pwm-omap-dmtimer.c @@ -26,6 +26,11 @@ * can get updated as below based on the current timer counter: * - period for current cycle = current_period + new period * - duty_cycle for current period = current period + new duty_cycle. + * - PWM OMAP DM timer cannot change the polarity when pwm is active. When + * user requests a change in polarity when in active state: + * - PWM is stopped abruptly(without completing the current cycle) + * - Polarity is changed + * - A fresh cycle is started. */ #include <linux/clk.h> @@ -46,8 +51,18 @@ #define DM_TIMER_LOAD_MIN 0xfffffffe #define DM_TIMER_MAX 0xffffffff +/** + * struct pwm_omap_dmtimer_chip - Structure representing a pwm chip + * corresponding to omap dmtimer. + * @chip: PWM chip structure representing PWM controller + * @mutex: Mutex to protect pwm apply state + * @dm_timer: Pointer to omap dm timer. + * @pdata: Pointer to omap dm timer ops. + * dm_timer_pdev: Pointer to omap dm timer platform device + */ struct pwm_omap_dmtimer_chip { struct pwm_chip chip; + /* Mutex to protect pwm apply state */ struct mutex mutex; struct omap_dm_timer *dm_timer; const struct omap_dm_timer_ops *pdata; @@ -60,11 +75,22 @@ to_pwm_omap_dmtimer_chip(struct pwm_chip *chip) return container_of(chip, struct pwm_omap_dmtimer_chip, chip); } +/** + * pwm_omap_dmtimer_get_clock_cycles() - Get clock cycles in a time frame + * @clk_rate: pwm timer clock rate + * @ns: time frame in nano seconds. + * + * Return number of clock cycles in a given period(ins ns). + */ 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); } +/** + * pwm_omap_dmtimer_start() - Start the pwm omap dm timer in pwm mode + * @omap: Pointer to pwm omap dm timer chip + */ static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap) { /* @@ -82,33 +108,46 @@ static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap) omap->pdata->start(omap->dm_timer); } -static int pwm_omap_dmtimer_enable(struct pwm_chip *chip, - struct pwm_device *pwm) +/** + * pwm_omap_dmtimer_is_enabled() - Detect if the pwm is enabled. + * @omap: Pointer to pwm omap dm timer chip + * + * Return true if pwm is enabled else false. + */ +static bool pwm_omap_dmtimer_is_enabled(struct pwm_omap_dmtimer_chip *omap) { - struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); + u32 status; - mutex_lock(&omap->mutex); - omap->pdata->set_pwm(omap->dm_timer, - pwm_get_polarity(pwm) == PWM_POLARITY_INVERSED, - true, OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE, - true); - - pwm_omap_dmtimer_start(omap); - mutex_unlock(&omap->mutex); + status = omap->pdata->get_pwm_status(omap->dm_timer); - return 0; + return !!(status & OMAP_TIMER_CTRL_ST); } -static void pwm_omap_dmtimer_disable(struct pwm_chip *chip, - struct pwm_device *pwm) +/** + * pwm_omap_dmtimer_polarity() - Detect the polarity of pwm. + * @omap: Pointer to pwm omap dm timer chip + * + * Return the polarity of pwm. + */ +static int pwm_omap_dmtimer_polarity(struct pwm_omap_dmtimer_chip *omap) { - struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); + u32 status; - mutex_lock(&omap->mutex); - omap->pdata->stop(omap->dm_timer); - mutex_unlock(&omap->mutex); + status = omap->pdata->get_pwm_status(omap->dm_timer); + + return !!(status & OMAP_TIMER_CTRL_SCPWM); } +/** + * pwm_omap_dmtimer_config() - Update the configuration of pwm omap dm timer + * @chip: Pointer to PWM controller + * @pwm: Pointer to PWM channel + * @duty_ns: New duty cycle in nano seconds + * @period_ns: New period in nano seconds + * + * Return 0 if successfully changed the period/duty_cycle else appropriate + * error. + */ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns) @@ -116,30 +155,26 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, 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; + struct clk *fclk; 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); + period_ns == pwm_get_period(pwm)) return 0; - } fclk = omap->pdata->get_fclk(omap->dm_timer); if (!fclk) { dev_err(chip->dev, "invalid pmtimer fclk\n"); - goto err_einval; + return -EINVAL; } clk_rate = clk_get_rate(fclk); if (!clk_rate) { dev_err(chip->dev, "invalid pmtimer fclk rate\n"); - goto err_einval; + return -EINVAL; } dev_dbg(chip->dev, "clk rate: %luHz\n", clk_rate); @@ -167,7 +202,7 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, dev_info(chip->dev, "period %d ns too short for clock rate %lu Hz\n", period_ns, clk_rate); - goto err_einval; + return -EINVAL; } if (duty_cycles < 1) { @@ -199,55 +234,97 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, dev_dbg(chip->dev, "load value: %#08x (%d), match value: %#08x (%d)\n", load_value, load_value, match_value, match_value); - 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) +/** + * pwm_omap_dmtimer_set_polarity() - Changes the polarity of the pwm dm timer. + * @chip: Pointer to PWM controller + * @pwm: Pointer to PWM channel + * @polarity: New pwm polarity to be set + */ +static void 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); + bool enabled; + + /* Disable the PWM before changing the polarity. */ + enabled = pwm_omap_dmtimer_is_enabled(omap); + if (enabled) + omap->pdata->stop(omap->dm_timer); - /* - * 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, OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE, true); + + if (enabled) + pwm_omap_dmtimer_start(omap); +} + +/** + * pwm_omap_dmtimer_apply() - Changes the state of the pwm omap dm timer. + * @chip: Pointer to PWM controller + * @pwm: Pointer to PWM channel + * @state: New state to apply + * + * Return 0 if successfully changed the state else appropriate error. + */ +static int pwm_omap_dmtimer_apply(struct pwm_chip *chip, + struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip); + int ret = 0; + + mutex_lock(&omap->mutex); + + if (pwm_omap_dmtimer_is_enabled(omap) && !state->enabled) { + omap->pdata->stop(omap->dm_timer); + goto unlock_mutex; + } + + if (pwm_omap_dmtimer_polarity(omap) != state->polarity) + pwm_omap_dmtimer_set_polarity(chip, pwm, state->polarity); + + ret = pwm_omap_dmtimer_config(chip, pwm, state->duty_cycle, + state->period); + if (ret) + goto unlock_mutex; + + if (!pwm_omap_dmtimer_is_enabled(omap) && state->enabled) { + omap->pdata->set_pwm(omap->dm_timer, + state->polarity == PWM_POLARITY_INVERSED, + true, + OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE, + true); + pwm_omap_dmtimer_start(omap); + } + +unlock_mutex: mutex_unlock(&omap->mutex); - return 0; + return ret; } 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, + .apply = pwm_omap_dmtimer_apply, .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 platform_device *timer_pdev; - struct pwm_omap_dmtimer_chip *omap; struct dmtimer_platform_data *timer_pdata; const struct omap_dm_timer_ops *pdata; + struct platform_device *timer_pdev; + struct pwm_omap_dmtimer_chip *omap; struct omap_dm_timer *dm_timer; - u32 v; + struct device_node *timer; int ret = 0; + u32 v; timer = of_parse_phandle(np, "ti,timers", 0); if (!timer) @@ -280,6 +357,7 @@ static int pwm_omap_dmtimer_probe(struct platform_device *pdev) !pdata->set_load || !pdata->set_match || !pdata->set_pwm || + !pdata->get_pwm_status || !pdata->set_prescaler || !pdata->write_counter) { dev_err(&pdev->dev, "Incomplete dmtimer pdata structure\n"); 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