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Subject[PATCH v8 1/6] pwm: extend PWM framework with PWM modes
Date
From: Claudiu Beznea <claudiu.beznea@microchip.com>

Add basic PWM modes: normal and complementary. These modes should
differentiate the single output PWM channels from two outputs PWM
channels. These modes could be set as follow:
1. PWM channels with one output per channel:
- normal mode
2. PWM channels with two outputs per channel:
- normal mode
- complementary mode
Since users could use a PWM channel with two output as one output PWM
channel, the PWM normal mode is allowed to be set for PWM channels with
two outputs; in fact PWM normal mode should be supported by all PWMs.

The PWM capabilities were implemented per PWM channel. Every PWM controller
will register a function to get PWM capabilities. If this is not explicitly
set by the driver a default function will be used to retrieve the PWM
capabilities (in this case the PWM capabilities will contain only PWM
normal mode). To retrieve capabilities the pwm_get_caps() function could
be used.

Every PWM channel have associated a mode in the PWM state. Proper
support was added to get/set PWM mode. Only modes supported by PWM channel
could be set.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
drivers/pwm/core.c | 91 ++++++++++++++++++++++++++++++++++++++++++++-
drivers/pwm/sysfs.c | 61 ++++++++++++++++++++++++++++++
include/linux/pwm.h | 104 +++++++++++++++++++++++++++++++++++-----------------
3 files changed, 222 insertions(+), 34 deletions(-)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index 1581f6ab1b1f..eb444ee8d486 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -249,6 +249,88 @@ static bool pwm_ops_check(const struct pwm_ops *ops)
return false;
}

+static int pwm_get_default_caps(struct pwm_caps *caps)
+{
+ static const struct pwm_caps default_caps = {
+ .modes_msk = PWM_MODE_BIT(NORMAL),
+ };
+
+ if (!caps)
+ return -EINVAL;
+
+ *caps = default_caps;
+
+ return 0;
+}
+
+/**
+ * pwm_get_caps() - get PWM capabilities of a PWM device
+ * @pwm: PWM device to get the capabilities for
+ * @caps: returned capabilities
+ *
+ * Returns: 0 on success or a negative error code on failure
+ */
+int pwm_get_caps(const struct pwm_device *pwm, struct pwm_caps *caps)
+{
+ if (!pwm || !caps)
+ return -EINVAL;
+
+ if (pwm->chip->ops->get_caps)
+ return pwm->chip->ops->get_caps(pwm->chip, pwm, caps);
+
+ return pwm_get_default_caps(caps);
+}
+EXPORT_SYMBOL_GPL(pwm_get_caps);
+
+/**
+ * pwm_get_default_modebit() - get the default mode for PWM (as a bit mask)
+ * @pwm: PWM device to get the default mode for
+ *
+ * Returns: the default PWM mode (as a bit mask) for PWM device
+ */
+unsigned long pwm_get_default_modebit(const struct pwm_device *pwm)
+{
+ struct pwm_caps caps;
+
+ if (pwm_get_caps(pwm, &caps))
+ return PWM_MODE_BIT(NORMAL);
+
+ return BIT(ffs(caps.modes_msk) - 1);
+}
+EXPORT_SYMBOL_GPL(pwm_get_default_modebit);
+
+/**
+ * pwm_supports_mode() - check if PWM mode is supported by PWM device
+ * @pwm: PWM device
+ * @modebit: PWM mode bit mask to be checked (see PWM_MODE_BIT())
+ *
+ * Returns: true if PWM mode is supported, false otherwise
+ */
+bool pwm_supports_mode(const struct pwm_device *pwm, unsigned long modebit)
+{
+ struct pwm_caps caps;
+
+ if (!pwm || !modebit)
+ return false;
+
+ if (hweight_long(modebit) != 1 || ffs(modebit) - 1 >= PWM_MODE_CNT)
+ return false;
+
+ if (pwm_get_caps(pwm, &caps))
+ return false;
+
+ return !!(caps.modes_msk & modebit);
+}
+EXPORT_SYMBOL_GPL(pwm_supports_mode);
+
+const char *pwm_get_mode_name(unsigned long modebit)
+{
+ if (modebit == PWM_MODE_BIT(COMPLEMENTARY))
+ return "complementary";
+
+ return "normal";
+}
+
/**
* pwmchip_add_with_polarity() - register a new PWM chip
* @chip: the PWM chip to add
@@ -294,6 +376,7 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip,
pwm->pwm = chip->base + i;
pwm->hwpwm = i;
pwm->state.polarity = polarity;
+ pwm->state.modebit = pwm_get_default_modebit(pwm);

if (chip->ops->get_state)
chip->ops->get_state(chip, pwm, &pwm->state);
@@ -469,7 +552,8 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state)
int err;

if (!pwm || !state || !state->period ||
- state->duty_cycle > state->period)
+ state->duty_cycle > state->period ||
+ !pwm_supports_mode(pwm, state->modebit))
return -EINVAL;

if (!memcmp(state, &pwm->state, sizeof(*state)))
@@ -530,6 +614,8 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state)

pwm->state.enabled = state->enabled;
}
+
+ pwm->state.modebit = state->modebit;
}

return 0;
@@ -579,6 +665,8 @@ int pwm_adjust_config(struct pwm_device *pwm)
pwm_get_args(pwm, &pargs);
pwm_get_state(pwm, &state);

+ state.modebit = pwm_get_default_modebit(pwm);
+
/*
* If the current period is zero it means that either the PWM driver
* does not support initial state retrieval or the PWM has not yet
@@ -999,6 +1087,7 @@ static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
seq_printf(s, " duty: %u ns", state.duty_cycle);
seq_printf(s, " polarity: %s",
state.polarity ? "inverse" : "normal");
+ seq_printf(s, " mode: %s", pwm_get_mode_name(state.modebit));

seq_puts(s, "\n");
}
diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index ceb233dd6048..7865fbafbeb4 100644
--- a/drivers/pwm/sysfs.c
+++ b/drivers/pwm/sysfs.c
@@ -223,11 +223,71 @@ static ssize_t capture_show(struct device *child,
return sprintf(buf, "%u %u\n", result.period, result.duty_cycle);
}

+static ssize_t mode_show(struct device *child,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct pwm_device *pwm = child_to_pwm_device(child);
+ struct pwm_state state;
+ unsigned long modebit;
+ enum pwm_mode mode;
+ int len = 0;
+
+ pwm_get_state(pwm, &state);
+
+ for (mode = PWM_MODE_NORMAL; mode < PWM_MODE_CNT; mode++) {
+ modebit = BIT(mode);
+ if (pwm_supports_mode(pwm, modebit)) {
+ if (state.modebit == modebit)
+ len += scnprintf(buf + len,
+ PAGE_SIZE - len, "[%s] ",
+ pwm_get_mode_name(modebit));
+ else
+ len += scnprintf(buf + len,
+ PAGE_SIZE - len, "%s ",
+ pwm_get_mode_name(modebit));
+ }
+ }
+
+ len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
+ return len;
+}
+
+static ssize_t mode_store(struct device *child,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct pwm_export *export = child_to_pwm_export(child);
+ struct pwm_device *pwm = export->pwm;
+ struct pwm_state state;
+ unsigned long modebit;
+ enum pwm_mode mode;
+ int ret;
+
+ for (mode = PWM_MODE_NORMAL; mode < PWM_MODE_CNT; mode++) {
+ modebit = BIT(mode);
+ if (sysfs_streq(buf, pwm_get_mode_name(modebit)))
+ break;
+ }
+
+ if (mode == PWM_MODE_CNT)
+ return -EINVAL;
+
+ mutex_lock(&export->lock);
+ pwm_get_state(pwm, &state);
+ state.modebit = modebit;
+ ret = pwm_apply_state(pwm, &state);
+ mutex_unlock(&export->lock);
+
+ return ret ? : size;
+}
+
static DEVICE_ATTR_RW(period);
static DEVICE_ATTR_RW(duty_cycle);
static DEVICE_ATTR_RW(enable);
static DEVICE_ATTR_RW(polarity);
static DEVICE_ATTR_RO(capture);
+static DEVICE_ATTR_RW(mode);

static struct attribute *pwm_attrs[] = {
&dev_attr_period.attr,
@@ -235,6 +295,7 @@ static struct attribute *pwm_attrs[] = {
&dev_attr_enable.attr,
&dev_attr_polarity.attr,
&dev_attr_capture.attr,
+ &dev_attr_mode.attr,
NULL
};
ATTRIBUTE_GROUPS(pwm);
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index d5199b507d79..3d89343bc405 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -26,6 +26,28 @@ enum pwm_polarity {
};

/**
+ * PWM modes capabilities
+ * @PWM_MODE_NORMAL: PWM has one output
+ * @PWM_MODE_COMPLEMENTARY: PWM has 2 outputs with opposite polarities
+ * @PWM_MODE_CNT: PWM modes count
+ */
+enum pwm_mode {
+ PWM_MODE_NORMAL,
+ PWM_MODE_COMPLEMENTARY,
+ PWM_MODE_CNT,
+};
+
+#define PWM_MODE_BIT(name) BIT(PWM_MODE_##name)
+
+/**
+ * struct pwm_caps - PWM capabilities
+ * @modes_msk: bitmask of supported modes (see PWM_MODE_*)
+ */
+struct pwm_caps {
+ unsigned long modes_msk;
+};
+
+/**
* struct pwm_args - board-dependent PWM arguments
* @period: reference period
* @polarity: reference polarity
@@ -53,12 +75,14 @@ enum {
* @period: PWM period (in nanoseconds)
* @duty_cycle: PWM duty cycle (in nanoseconds)
* @polarity: PWM polarity
+ * @modebit: PWM mode bit
* @enabled: PWM enabled status
*/
struct pwm_state {
unsigned int period;
unsigned int duty_cycle;
enum pwm_polarity polarity;
+ unsigned long modebit;
bool enabled;
};

@@ -151,39 +175,6 @@ static inline void pwm_get_args(const struct pwm_device *pwm,
}

/**
- * pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
- * @pwm: PWM device
- * @state: state to fill with the prepared PWM state
- *
- * This functions prepares a state that can later be tweaked and applied
- * to the PWM device with pwm_apply_state(). This is a convenient function
- * that first retrieves the current PWM state and the replaces the period
- * and polarity fields with the reference values defined in pwm->args.
- * Once the function returns, you can adjust the ->enabled and ->duty_cycle
- * fields according to your needs before calling pwm_apply_state().
- *
- * ->duty_cycle is initially set to zero to avoid cases where the current
- * ->duty_cycle value exceed the pwm_args->period one, which would trigger
- * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
- * first.
- */
-static inline void pwm_init_state(const struct pwm_device *pwm,
- struct pwm_state *state)
-{
- struct pwm_args args;
-
- /* First get the current state. */
- pwm_get_state(pwm, state);
-
- /* Then fill it with the reference config */
- pwm_get_args(pwm, &args);
-
- state->period = args.period;
- state->polarity = args.polarity;
- state->duty_cycle = 0;
-}
-
-/**
* pwm_get_relative_duty_cycle() - Get a relative duty cycle value
* @state: PWM state to extract the duty cycle from
* @scale: target scale of the relative duty cycle
@@ -254,6 +245,7 @@ pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
* @get_state: get the current PWM state. This function is only
* called once per PWM device when the PWM chip is
* registered.
+ * @get_caps: get PWM capabilities.
* @dbg_show: optional routine to show contents in debugfs
* @owner: helps prevent removal of modules exporting active PWMs
*/
@@ -272,6 +264,8 @@ struct pwm_ops {
struct pwm_state *state);
void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state);
+ int (*get_caps)(const struct pwm_chip *chip,
+ const struct pwm_device *pwm, struct pwm_caps *caps);
#ifdef CONFIG_DEBUG_FS
void (*dbg_show)(struct pwm_chip *chip, struct seq_file *s);
#endif
@@ -402,6 +396,10 @@ struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
unsigned int index,
const char *label);

+int pwm_get_caps(const struct pwm_device *pwm, struct pwm_caps *caps);
+bool pwm_supports_mode(const struct pwm_device *pwm, unsigned long modebit);
+unsigned long pwm_get_default_modebit(const struct pwm_device *pwm);
+const char *pwm_get_mode_name(unsigned long modebit);
struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
const struct of_phandle_args *args);

@@ -488,6 +486,11 @@ static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
return ERR_PTR(-ENODEV);
}

+static inline unsigned long pwm_get_default_modebit(const struct pwm_device *pwm)
+{
+ return 0;
+}
+
static inline struct pwm_device *pwm_get(struct device *dev,
const char *consumer)
{
@@ -522,6 +525,40 @@ static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
}
#endif

+/**
+ * pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
+ * @pwm: PWM device
+ * @state: state to fill with the prepared PWM state
+ *
+ * This functions prepares a state that can later be tweaked and applied
+ * to the PWM device with pwm_apply_state(). This is a convenient function
+ * that first retrieves the current PWM state and the replaces the period
+ * and polarity fields with the reference values defined in pwm->args.
+ * Once the function returns, you can adjust the ->enabled and ->duty_cycle
+ * fields according to your needs before calling pwm_apply_state().
+ *
+ * ->duty_cycle is initially set to zero to avoid cases where the current
+ * ->duty_cycle value exceed the pwm_args->period one, which would trigger
+ * an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
+ * first.
+ */
+static inline void pwm_init_state(const struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct pwm_args args;
+
+ /* First get the current state. */
+ pwm_get_state(pwm, state);
+
+ /* Then fill it with the reference config */
+ pwm_get_args(pwm, &args);
+
+ state->period = args.period;
+ state->polarity = args.polarity;
+ state->duty_cycle = 0;
+ state->modebit = pwm_get_default_modebit(pwm);
+}
+
static inline void pwm_apply_args(struct pwm_device *pwm)
{
struct pwm_state state = { };
@@ -550,6 +587,7 @@ static inline void pwm_apply_args(struct pwm_device *pwm)
state.enabled = false;
state.polarity = pwm->args.polarity;
state.period = pwm->args.period;
+ state.modebit = pwm_get_default_modebit(pwm);

pwm_apply_state(pwm, &state);
}
--
2.7.4
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