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Subject[PATCH 2/2] pwm: core: Add option to config PWM duty/period with u64 data length
Date
From: Fenglin Wu <fenglinw@codeaurora.org>

Currently, PWM core driver provides interfaces for configuring PWM
period and duty length in nanoseconds with an integer data type, so
the max period can be only set to ~2.147 seconds. Add interfaces which
can set PWM period and duty with u64 data type to remove this
limitation.

Change-Id: Ic8722088510d447fc939ab6a5014711aef1b832f
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>
---
drivers/pwm/core.c | 20 ++++++---
drivers/pwm/sysfs.c | 6 +--
include/linux/pwm.h | 115 ++++++++++++++++++++++++++++++++++++++++++++++++----
3 files changed, 126 insertions(+), 15 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 960a451..02ad16b 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -526,9 +526,19 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state)

if (state->period != pwm->state.period ||
state->duty_cycle != pwm->state.duty_cycle) {
- err = pwm->chip->ops->config(pwm->chip, pwm,
- state->duty_cycle,
- state->period);
+ if (pwm->chip->ops->config_extend) {
+ err = pwm->chip->ops->config_extend(pwm->chip,
+ pwm, state->duty_cycle,
+ state->period);
+ } else {
+ if (state->period > UINT_MAX)
+ pr_warn("period %llu duty_cycle %llu will be truncated\n",
+ state->period,
+ state->duty_cycle);
+ err = pwm->chip->ops->config(pwm->chip, pwm,
+ state->duty_cycle,
+ state->period);
+ }
if (err)
return err;

@@ -1181,8 +1191,8 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
if (state.enabled)
seq_puts(s, " enabled");

- seq_printf(s, " period: %u ns", state.period);
- seq_printf(s, " duty: %u ns", state.duty_cycle);
+ seq_printf(s, " period: %llu ns", state.period);
+ seq_printf(s, " duty: %llu ns", state.duty_cycle);
seq_printf(s, " polarity: %s",
state.polarity ? "inverse" : "normal");

diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index ab703f2..ef78c40 100644
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -42,7 +42,7 @@ static ssize_t period_show(struct device *child,

pwm_get_state(pwm, &state);

- return sprintf(buf, "%u\n", state.period);
+ return sprintf(buf, "%llu\n", state.period);
}

static ssize_t period_store(struct device *child,
@@ -77,7 +77,7 @@ static ssize_t duty_cycle_show(struct device *child,

pwm_get_state(pwm, &state);

- return sprintf(buf, "%u\n", state.duty_cycle);
+ return sprintf(buf, "%llu\n", state.duty_cycle);
}

static ssize_t duty_cycle_store(struct device *child,
@@ -212,7 +212,7 @@ static ssize_t capture_show(struct device *child,
if (ret)
return ret;

- return sprintf(buf, "%u %u\n", result.period, result.duty_cycle);
+ return sprintf(buf, "%llu %llu\n", result.period, result.duty_cycle);
}

static ssize_t output_type_show(struct device *child,
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 416f08e..d714385 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -39,7 +39,7 @@ enum pwm_polarity {
* current PWM hardware state.
*/
struct pwm_args {
- unsigned int period;
+ u64 period;
enum pwm_polarity polarity;
};

@@ -66,9 +66,9 @@ enum pwm_output_type {
* @cycles_per_duty: number of PWM period cycles an entry stays at
*/
struct pwm_output_pattern {
- unsigned int *duty_pattern;
+ u64 *duty_pattern;
unsigned int num_entries;
- unsigned int cycles_per_duty;
+ u64 cycles_per_duty;
};

/*
@@ -79,8 +79,8 @@ struct pwm_output_pattern {
* @enabled: PWM enabled status
*/
struct pwm_state {
- unsigned int period;
- unsigned int duty_cycle;
+ u64 period;
+ u64 duty_cycle;
enum pwm_polarity polarity;
enum pwm_output_type output_type;
struct pwm_output_pattern *output_pattern;
@@ -136,12 +136,30 @@ static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
pwm->state.period = period;
}

+static inline void pwm_set_period_extend(struct pwm_device *pwm, u64 period)
+{
+ if (pwm)
+ pwm->state.period = period;
+}
+
static inline unsigned int pwm_get_period(const struct pwm_device *pwm)
{
struct pwm_state state;

pwm_get_state(pwm, &state);

+ if (state.period > UINT_MAX)
+ pr_warn("PWM period %llu is truncated\n", state.period);
+
+ return (unsigned int)state.period;
+}
+
+static inline u64 pwm_get_period_extend(const struct pwm_device *pwm)
+{
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
+
return state.period;
}

@@ -151,12 +169,30 @@ static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
pwm->state.duty_cycle = duty;
}

+static inline void pwm_set_duty_cycle_extend(struct pwm_device *pwm, u64 duty)
+{
+ if (pwm)
+ pwm->state.duty_cycle = duty;
+}
+
static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
{
struct pwm_state state;

pwm_get_state(pwm, &state);

+ if (state.duty_cycle > UINT_MAX)
+ pr_warn("PWM duty cycle %llu is truncated\n", state.duty_cycle);
+
+ return (unsigned int)state.duty_cycle;
+}
+
+static inline u64 pwm_get_duty_cycle_extend(const struct pwm_device *pwm)
+{
+ struct pwm_state state;
+
+ pwm_get_state(pwm, &state);
+
return state.duty_cycle;
}

@@ -300,6 +336,8 @@ static inline void pwm_init_state(const struct pwm_device *pwm,
* @set_output_pattern: set the pattern for the modulated output
* @owner: helps prevent removal of modules exporting active PWMs
* @config: configure duty cycles and period length for this PWM
+ * @config_extend: configure duty cycles and period length for this
+ * PWM with u64 data type
* @set_polarity: configure the polarity of this PWM
* @enable: enable PWM output toggling
* @disable: disable PWM output toggling
@@ -325,6 +363,8 @@ struct pwm_ops {
/* Only used by legacy drivers */
int (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns);
+ int (*config_extend)(struct pwm_chip *chip, struct pwm_device *pwm,
+ u64 duty_ns, u64 period_ns);
int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
enum pwm_polarity polarity);
int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
@@ -363,8 +403,8 @@ struct pwm_chip {
* @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
*/
struct pwm_capture {
- unsigned int period;
- unsigned int duty_cycle;
+ u64 period;
+ u64 duty_cycle;
};

#if IS_ENABLED(CONFIG_PWM)
@@ -418,6 +458,67 @@ static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
}

/**
+ * pwm_config_extend() - change PWM period and duty length with u64 data type
+ * @pwm: PWM device
+ * @duty_ns: "on" time (in nanoseconds)
+ * @period_ns: duration (in nanoseconds) of one cycle
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+static inline int pwm_config_extend(struct pwm_device *pwm, u64 duty_ns,
+ u64 period_ns)
+{
+ struct pwm_state state;
+
+ if (!pwm)
+ return -EINVAL;
+
+ pwm_get_state(pwm, &state);
+ if (state.duty_cycle == duty_ns && state.period == period_ns)
+ return 0;
+
+ state.duty_cycle = duty_ns;
+ state.period = period_ns;
+ return pwm_apply_state(pwm, &state);
+}
+
+/**
+ * pwm_set_polarity() - configure the polarity of a PWM signal
+ * @pwm: PWM device
+ * @polarity: new polarity of the PWM signal
+ *
+ * Note that the polarity cannot be configured while the PWM device is
+ * enabled.
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+static inline int pwm_set_polarity(struct pwm_device *pwm,
+ enum pwm_polarity polarity)
+{
+ struct pwm_state state;
+
+ if (!pwm)
+ return -EINVAL;
+
+ pwm_get_state(pwm, &state);
+ if (state.polarity == polarity)
+ return 0;
+
+ /*
+ * Changing the polarity of a running PWM without adjusting the
+ * dutycycle/period value is a bit risky (can introduce glitches).
+ * Return -EBUSY in this case.
+ * Note that this is allowed when using pwm_apply_state() because
+ * the user specifies all the parameters.
+ */
+ if (state.enabled)
+ return -EBUSY;
+
+ state.polarity = polarity;
+ return pwm_apply_state(pwm, &state);
+}
+
+/**
* pwm_enable() - start a PWM output toggling
* @pwm: PWM device
*
--
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a Linux Foundation Collaborative Project
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