From e39c0df1be5a97e0910b09af1530bdf3de057a06 Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Thu, 14 Apr 2016 21:17:21 +0200 Subject: [PATCH 1/2] pwm: Introduce the pwm_args concept Currently the PWM core mixes the current PWM state with the per-platform reference config (specified through the PWM lookup table, DT definition or directly hardcoded in PWM drivers). Create a struct pwm_args to store this reference configuration, so that PWM users can differentiate between the current and reference configurations. Patch all places where pwm->args should be initialized. We keep the pwm_set_polarity/period() calls until all PWM users are patched to use pwm_args instead of pwm_get_period/polarity(). Signed-off-by: Boris Brezillon [thierry.reding@gmail.com: reword kerneldoc comments] Signed-off-by: Thierry Reding --- drivers/pwm/core.c | 21 ++++++++++++++------- drivers/pwm/pwm-clps711x.c | 2 +- drivers/pwm/pwm-pxa.c | 2 +- include/linux/pwm.h | 33 +++++++++++++++++++++++++++++++++ 4 files changed, 49 insertions(+), 9 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 7831bc6b51dd..680fbc795a0a 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -128,6 +128,13 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label) set_bit(PWMF_REQUESTED, &pwm->flags); pwm->label = label; + /* + * FIXME: This should be removed once all PWM users properly make use + * of struct pwm_args to initialize the PWM device. As long as this is + * here, the PWM state and hardware state can get out of sync. + */ + pwm_apply_args(pwm); + return 0; } @@ -146,12 +153,12 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args) if (IS_ERR(pwm)) return pwm; - pwm_set_period(pwm, args->args[1]); + pwm->args.period = args->args[1]; if (args->args[2] & PWM_POLARITY_INVERTED) - pwm_set_polarity(pwm, PWM_POLARITY_INVERSED); + pwm->args.polarity = PWM_POLARITY_INVERSED; else - pwm_set_polarity(pwm, PWM_POLARITY_NORMAL); + pwm->args.polarity = PWM_POLARITY_NORMAL; return pwm; } @@ -172,7 +179,7 @@ of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args) if (IS_ERR(pwm)) return pwm; - pwm_set_period(pwm, args->args[1]); + pwm->args.period = args->args[1]; return pwm; } @@ -747,13 +754,13 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) if (!chip) goto out; + pwm->args.period = chosen->period; + pwm->args.polarity = chosen->polarity; + pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id); if (IS_ERR(pwm)) goto out; - pwm_set_period(pwm, chosen->period); - pwm_set_polarity(pwm, chosen->polarity); - out: mutex_unlock(&pwm_lookup_lock); return pwm; diff --git a/drivers/pwm/pwm-clps711x.c b/drivers/pwm/pwm-clps711x.c index a80c10803636..7d335422cfda 100644 --- a/drivers/pwm/pwm-clps711x.c +++ b/drivers/pwm/pwm-clps711x.c @@ -60,7 +60,7 @@ static int clps711x_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) return -EINVAL; /* Store constant period value */ - pwm_set_period(pwm, DIV_ROUND_CLOSEST(NSEC_PER_SEC, freq)); + pwm->args.period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, freq); return 0; } diff --git a/drivers/pwm/pwm-pxa.c b/drivers/pwm/pwm-pxa.c index cb2f7024cf68..58b709f29130 100644 --- a/drivers/pwm/pwm-pxa.c +++ b/drivers/pwm/pwm-pxa.c @@ -160,7 +160,7 @@ pxa_pwm_of_xlate(struct pwm_chip *pc, const struct of_phandle_args *args) if (IS_ERR(pwm)) return pwm; - pwm_set_period(pwm, args->args[0]); + pwm->args.period = args->args[0]; return pwm; } diff --git a/include/linux/pwm.h b/include/linux/pwm.h index cfc3ed46cad2..b78d27c42629 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -74,6 +74,24 @@ enum pwm_polarity { PWM_POLARITY_INVERSED, }; +/** + * struct pwm_args - board-dependent PWM arguments + * @period: reference period + * @polarity: reference polarity + * + * This structure describes board-dependent arguments attached to a PWM + * device. These arguments are usually retrieved from the PWM lookup table or + * device tree. + * + * Do not confuse this with the PWM state: PWM arguments represent the initial + * configuration that users want to use on this PWM device rather than the + * current PWM hardware state. + */ +struct pwm_args { + unsigned int period; + enum pwm_polarity polarity; +}; + enum { PWMF_REQUESTED = 1 << 0, PWMF_ENABLED = 1 << 1, @@ -92,6 +110,7 @@ enum { * @period: period of the PWM signal (in nanoseconds) * @duty_cycle: duty cycle of the PWM signal (in nanoseconds) * @polarity: polarity of the PWM signal + * @args: PWM arguments */ struct pwm_device { const char *label; @@ -105,6 +124,8 @@ struct pwm_device { unsigned int period; unsigned int duty_cycle; enum pwm_polarity polarity; + + struct pwm_args args; }; static inline bool pwm_is_enabled(const struct pwm_device *pwm) @@ -144,6 +165,18 @@ static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm) return pwm ? pwm->polarity : PWM_POLARITY_NORMAL; } +static inline void pwm_get_args(const struct pwm_device *pwm, + struct pwm_args *args) +{ + *args = pwm->args; +} + +static inline void pwm_apply_args(struct pwm_device *pwm) +{ + pwm_set_period(pwm, pwm->args.period); + pwm_set_polarity(pwm, pwm->args.polarity); +} + /** * struct pwm_ops - PWM controller operations * @request: optional hook for requesting a PWM From fbd45a12988e75a48d392feb8b0e5feb5d612513 Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Tue, 17 May 2016 14:27:25 +0200 Subject: [PATCH 2/2] pwm: Fix pwm_apply_args() call sites pwm_apply_args() is supposed to initialize a PWM device according to the arguments provided by the DT or the PWM lookup, but this function was called inside pwm_device_request(), which in turn was called before the core had a chance to initialize the pwm->args fields. Fix that by calling pwm_apply_args directly in pwm_get() and of_pwm_get() after initializing pwm->args field. This commit also fixes an invalid pointer dereference introduced by commit e39c0df1be5a ("pwm: Introduce the pwm_args concept"). Signed-off-by: Boris Brezillon Fixes: e39c0df1be5a ("pwm: Introduce the pwm_args concept") Signed-off-by: Thierry Reding --- drivers/pwm/core.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 680fbc795a0a..22cf3959041c 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -128,13 +128,6 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label) set_bit(PWMF_REQUESTED, &pwm->flags); pwm->label = label; - /* - * FIXME: This should be removed once all PWM users properly make use - * of struct pwm_args to initialize the PWM device. As long as this is - * here, the PWM state and hardware state can get out of sync. - */ - pwm_apply_args(pwm); - return 0; } @@ -627,6 +620,13 @@ struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id) pwm->label = con_id; + /* + * FIXME: This should be removed once all PWM users properly make use + * of struct pwm_args to initialize the PWM device. As long as this is + * here, the PWM state and hardware state can get out of sync. + */ + pwm_apply_args(pwm); + put: of_node_put(args.np); @@ -754,13 +754,20 @@ struct pwm_device *pwm_get(struct device *dev, const char *con_id) if (!chip) goto out; - pwm->args.period = chosen->period; - pwm->args.polarity = chosen->polarity; - pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id); if (IS_ERR(pwm)) goto out; + pwm->args.period = chosen->period; + pwm->args.polarity = chosen->polarity; + + /* + * FIXME: This should be removed once all PWM users properly make use + * of struct pwm_args to initialize the PWM device. As long as this is + * here, the PWM state and hardware state can get out of sync. + */ + pwm_apply_args(pwm); + out: mutex_unlock(&pwm_lookup_lock); return pwm;