Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752624AbbKPI5e (ORCPT ); Mon, 16 Nov 2015 03:57:34 -0500 Received: from down.free-electrons.com ([37.187.137.238]:34687 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752460AbbKPI5S (ORCPT ); Mon, 16 Nov 2015 03:57:18 -0500 From: Boris Brezillon To: Thierry Reding , linux-pwm@vger.kernel.org Cc: Mike Turquette , Stephen Boyd , linux-clk@vger.kernel.org, Mark Brown , Liam Girdwood , Kamil Debski , lm-sensors@lm-sensors.org, Jean Delvare , Guenter Roeck , Dmitry Torokhov , linux-input@vger.kernel.org, Bryan Wu , Richard Purdie , Jacek Anaszewski , linux-leds@vger.kernel.org, Maxime Ripard , Chen-Yu Tsai , linux-sunxi@googlegroups.com, Joachim Eastwood , Thomas Petazzoni , Heiko Stuebner , linux-rockchip@lists.infradead.org, Jingoo Han , Lee Jones , linux-fbdev@vger.kernel.org, Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Robert Jarzmik , Alexandre Belloni , Julia Lawall , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Boris Brezillon Subject: [PATCH v4 20/24] pwm: add the core infrastructure to allow atomic update Date: Mon, 16 Nov 2015 09:56:43 +0100 Message-Id: <1447664207-24370-21-git-send-email-boris.brezillon@free-electrons.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1447664207-24370-1-git-send-email-boris.brezillon@free-electrons.com> References: <1447664207-24370-1-git-send-email-boris.brezillon@free-electrons.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7547 Lines: 263 Add an ->apply() method to the pwm_ops struct to allow PWM drivers to implement atomic update. This method will be preferred over the ->enable(), ->disable() and ->config() methods if available. Add the pwm_get_state(), pwm_get_default_state() and pwm_apply_state() functions for PWM users to be able to use the atomic update feature. Note that the pwm_apply_state() does not guarantee the atomicity of the update operation, it all depends on the availability and implementation of the ->apply() method. Signed-off-by: Boris Brezillon Tested-by: Heiko Stuebner --- drivers/pwm/core.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++--- include/linux/pwm.h | 27 ++++++++++++ 2 files changed, 146 insertions(+), 5 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index ce8b373..fbc71d3 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -46,6 +46,12 @@ static struct pwm_device *pwm_to_device(unsigned int pwm) return radix_tree_lookup(&pwm_tree, pwm); } +static void pwm_set_state(struct pwm_device *pwm, + const struct pwm_state *state) +{ + pwm->state = *state; +} + static int alloc_pwms(int pwm, unsigned int count) { unsigned int from = 0; @@ -226,6 +232,19 @@ void *pwm_get_chip_data(struct pwm_device *pwm) } EXPORT_SYMBOL_GPL(pwm_get_chip_data); +static bool pwm_ops_check(const struct pwm_ops *ops) +{ + /* driver supports legacy, non-atomic operation */ + if (ops->config && ops->enable && ops->disable) + return true; + + /* driver supports atomic operation */ + if (ops->apply) + return true; + + return false; +} + /** * pwmchip_add_with_polarity() - register a new PWM chip * @chip: the PWM chip to add @@ -244,8 +263,10 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip, unsigned int i; int ret; - if (!chip || !chip->dev || !chip->ops || !chip->ops->config || - !chip->ops->enable || !chip->ops->disable || !chip->npwm) + if (!chip || !chip->dev || !chip->ops || !chip->npwm) + return -EINVAL; + + if (!pwm_ops_check(chip->ops)) return -EINVAL; mutex_lock(&pwm_lock); @@ -446,7 +467,19 @@ int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) if (!pwm || duty_ns < 0 || period_ns <= 0 || duty_ns > period_ns) return -EINVAL; - err = pwm->chip->ops->config(pwm->chip, pwm, duty_ns, period_ns); + if (pwm->chip->ops->apply) { + struct pwm_state state; + + pwm_get_state(pwm, &state); + state.period = period_ns; + state.duty_cycle = duty_ns; + + err = pwm->chip->ops->apply(pwm->chip, pwm, &state); + } else { + err = pwm->chip->ops->config(pwm->chip, pwm, duty_ns, + period_ns); + } + if (err) return err; @@ -474,6 +507,18 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity) if (!pwm || !pwm->chip->ops) return -EINVAL; + if (pwm->chip->ops->apply) { + struct pwm_state state; + + pwm_get_state(pwm, &state); + state.polarity = polarity; + err = pwm->chip->ops->apply(pwm->chip, pwm, &state); + if (!err) + pwm->state.polarity = polarity; + + return err; + } + if (!pwm->chip->ops->set_polarity) return -ENOSYS; @@ -512,7 +557,17 @@ int pwm_enable(struct pwm_device *pwm) mutex_lock(&pwm->lock); if (!pwm_is_enabled(pwm)) { - err = pwm->chip->ops->enable(pwm->chip, pwm); + if (pwm->chip->ops->apply) { + struct pwm_state state; + + pwm_get_state(pwm, &state); + state.enabled = true; + + err = pwm->chip->ops->apply(pwm->chip, pwm, &state); + } else { + err = pwm->chip->ops->enable(pwm->chip, pwm); + } + if (!err) pwm->state.enabled = true; } @@ -535,7 +590,16 @@ void pwm_disable(struct pwm_device *pwm) mutex_lock(&pwm->lock); if (pwm_is_enabled(pwm)) { - pwm->chip->ops->disable(pwm->chip, pwm); + if (pwm->chip->ops->apply) { + struct pwm_state state; + + pwm_get_state(pwm, &state); + state.enabled = false; + + pwm->chip->ops->apply(pwm->chip, pwm, &state); + } else { + pwm->chip->ops->disable(pwm->chip, pwm); + } pwm->state.enabled = false; } @@ -543,6 +607,56 @@ void pwm_disable(struct pwm_device *pwm) } EXPORT_SYMBOL_GPL(pwm_disable); +/** + * pwm_apply_state() - atomically apply a new state to a PWM device + * @pwm: PWM device + * @state: new state to apply + */ +int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state) +{ + int err = 0; + + if (!pwm) + return -EINVAL; + + if (!memcmp(state, &pwm->state, sizeof(*state))) + return 0; + + if (pwm->chip->ops->apply) { + err = pwm->chip->ops->apply(pwm->chip, pwm, state); + if (!err) + pwm_set_state(pwm, state); + } else { + /* + * FIXME: restore the initial state in case of error. + */ + if (state->polarity != pwm->state.polarity) { + pwm_disable(pwm); + err = pwm_set_polarity(pwm, state->polarity); + if (err) + goto out; + } + + if (state->period != pwm->state.period || + state->duty_cycle != pwm->state.duty_cycle) { + err = pwm_config(pwm, state->period, state->duty_cycle); + if (err) + goto out; + } + + if (state->enabled != pwm->state.enabled) { + if (state->enabled) + err = pwm_enable(pwm); + else + pwm_disable(pwm); + } + } + +out: + return err; +} +EXPORT_SYMBOL_GPL(pwm_apply_state); + static struct pwm_chip *of_node_to_pwmchip(struct device_node *np) { struct pwm_chip *chip; diff --git a/include/linux/pwm.h b/include/linux/pwm.h index caa0ffe..5e7b378 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -174,6 +174,30 @@ static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm) return pwm ? pwm->state.polarity : PWM_POLARITY_NORMAL; } +int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state); + +/** + * pwm_get_state() - retrieve the current PWM state + * @pwm: PWM device + * @state: state to fill with the current PWM state + */ +static inline void pwm_get_state(struct pwm_device *pwm, + struct pwm_state *state) +{ + *state = pwm->state; +} + +/** + * pwm_get_default_state() - retrieve the default PWM state + * @pwm: PWM device + * @state: state to fill with the default PWM state + */ +static inline void pwm_get_default_state(struct pwm_device *pwm, + struct pwm_state *state) +{ + *state = pwm->default_state; +} + /** * struct pwm_ops - PWM controller operations * @request: optional hook for requesting a PWM @@ -182,6 +206,7 @@ static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm) * @set_polarity: configure the polarity of this PWM * @enable: enable PWM output toggling * @disable: disable PWM output toggling + * @apply: atomically apply a new PWM config * @reset_state: reset the current PWM state (pwm->state) to the actual * hardware state. This function is only called once per * PWM device when the PWM chip is registered. @@ -197,6 +222,8 @@ struct pwm_ops { enum pwm_polarity polarity); int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm); void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm); + int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state); void (*reset_state)(struct pwm_chip *chip, struct pwm_device *pwm); #ifdef CONFIG_DEBUG_FS void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s); -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/