[RFC 06/11] gpiolib: Add HTE support

@@ -2361,6 +2361,98 @@ int gpiod_direction_output(struct gpio_desc *desc, int value)
 }
 EXPORT_SYMBOL_GPL(gpiod_direction_output);
 
+/**
+ * gpiod_hw_timestamp_control - set the hardware assisted timestamp control.
+ * @desc:	GPIO to set
+ * @enable:	Set true to enable the hardware timestamp, false otherwise.
+ *
+ * Certain GPIO chip can rely on hardware assisted timestamp engines which can
+ * record timestamp at the occurance of the configured events on selected GPIO
+ * lines. This is helper API to control such engine.
+ *
+ * Return 0 in case of success, else an error code.
+ */
+int gpiod_hw_timestamp_control(struct gpio_desc *desc, bool enable)
+{
+	struct gpio_chip	*gc;
+	int			ret = 0;
+
+	VALIDATE_DESC(desc);
+	gc = desc->gdev->chip;
+
+	if (!gc->timestamp_control) {
+		gpiod_warn(desc,
+			   "%s: Hardware assisted ts not supported\n",
+			   __func__);
+		return -ENOTSUPP;
+	}
+
+	ret = gc->timestamp_control(gc, gpio_chip_hwgpio(desc),
+				    &desc->hdesc, enable);
+
+	if (ret) {
+		gpiod_warn(desc,
+			   "%s: ts control operation failed\n", __func__);
+		return ret;
+	}
+
+	if (!enable)
+		desc->hdesc = NULL;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gpiod_hw_timestamp_control);
+
+/**
+ * gpiod_is_hw_timestamp_enabled - check if hardware assisted timestamp is
+ * enabled.
+ * @desc:	GPIO to check
+ *
+ * Return true in case of success, false otherwise.
+ */
+bool gpiod_is_hw_timestamp_enabled(const struct gpio_desc *desc)
+{
+	if (!desc)
+		return false;
+
+	return (desc->hdesc) ? true : false;
+}
+EXPORT_SYMBOL_GPL(gpiod_is_hw_timestamp_enabled);
+
+/**
+ * gpiod_get_hw_timestamp - Get hardware timestamp in nano seconds.
+ * @desc:	GPIO to get the timestamp.
+ * @block:	Set true to block until data is available.
+ *
+ * Return non-zero on success, else 0.
+ */
+u64 gpiod_get_hw_timestamp(struct gpio_desc *desc, bool block)
+{
+	struct gpio_chip	*gc;
+	int			ret = 0;
+	u64 ts;
+
+	VALIDATE_DESC(desc);
+	gc = desc->gdev->chip;
+
+	if (!gc->get_hw_timestamp) {
+		gpiod_warn(desc,
+			   "%s: Hardware assisted ts not supported\n",
+			   __func__);
+		return -ENOTSUPP;
+	}
+
+	ret = gc->get_hw_timestamp(gc, block, desc->hdesc, &ts);
+	if (ret) {
+		gpiod_warn(desc,
+			   "%s: get timestamp operation failed\n", __func__);
+		return 0;
+	}
+
+	return ts;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_hw_timestamp);
+
 /**
  * gpiod_set_config - sets @config for a GPIO
  * @desc: descriptor of the GPIO for which to set the configuration

@@ -15,6 +15,7 @@
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/cdev.h>
+#include <linux/hte.h>
 
 #define GPIOCHIP_NAME	"gpiochip"
 

@@ -117,6 +118,7 @@ struct gpio_desc {
 #define FLAG_EDGE_RISING     16	/* GPIO CDEV detects rising edge events */
 #define FLAG_EDGE_FALLING    17	/* GPIO CDEV detects falling edge events */
 #define FLAG_EVENT_CLOCK_REALTIME	18 /* GPIO CDEV reports REALTIME timestamps in events */
+#define FLAG_EVENT_CLOCK_HARDWARE	19 /* GPIO CDEV reports hardware timestamps in events */
 
 	/* Connection label */
 	const char		*label;

@@ -129,6 +131,15 @@ struct gpio_desc {
 	/* debounce period in microseconds */
 	unsigned int		debounce_period_us;
 #endif
+	/*
+	 * Hardware timestamp engine related internal data structure.
+	 * This gets set when the consumer calls gpiod_hw_timestamp_control to enable
+	 * hardware timestamping on the specified GPIO line. The API calls into HTE
+	 * subsystem, in turns HTE subsystem return the HTE descriptor for the GPIO
+	 * line. The hdesc will be later used with gpiod_is_hw_timestamp_enabled
+	 * and gpiod_get_hw_timestamp API calls.
+	 */
+	struct hte_ts_desc *hdesc;
 };
 
 #define gpiod_not_found(desc)		(IS_ERR(desc) && PTR_ERR(desc) == -ENOENT)

@@ -112,6 +112,9 @@ int gpiod_get_direction(struct gpio_desc *desc);
 int gpiod_direction_input(struct gpio_desc *desc);
 int gpiod_direction_output(struct gpio_desc *desc, int value);
 int gpiod_direction_output_raw(struct gpio_desc *desc, int value);
+int gpiod_hw_timestamp_control(struct gpio_desc *desc, bool enable);
+bool gpiod_is_hw_timestamp_enabled(const struct gpio_desc *desc);
+u64 gpiod_get_hw_timestamp(struct gpio_desc *desc, bool block);
 
 /* Value get/set from non-sleeping context */
 int gpiod_get_value(const struct gpio_desc *desc);

@@ -353,8 +356,22 @@ static inline int gpiod_direction_output_raw(struct gpio_desc *desc, int value)
 	WARN_ON(desc);
 	return -ENOSYS;
 }
-
-
+static inline int gpiod_hw_timestamp_control(struct gpio_desc *desc,
+					     bool enable)
+{
+	WARN_ON(desc);
+	return -ENOSYS;
+}
+static inline bool gpiod_is_hw_timestamp_enabled(const struct gpio_desc *desc)
+{
+	WARN_ON(desc);
+	return false;
+}
+static inline u64 gpiod_get_hw_timestamp(struct gpio_desc *desc, bool block)
+{
+	WARN_ON(desc);
+	return 0;
+}
 static inline int gpiod_get_value(const struct gpio_desc *desc)
 {
 	/* GPIO can never have been requested */

@@ -10,6 +10,7 @@
 #include <linux/lockdep.h>
 #include <linux/pinctrl/pinctrl.h>
 #include <linux/pinctrl/pinconf-generic.h>
+#include <linux/hte.h> /* For hardware timestamping */
 
 struct gpio_desc;
 struct of_phandle_args;

@@ -304,6 +305,10 @@ struct gpio_irq_chip {
  * @add_pin_ranges: optional routine to initialize pin ranges, to be used when
  *	requires special mapping of the pins that provides GPIO functionality.
  *	It is called after adding GPIO chip and before adding IRQ chip.
+ * @timestamp_control: Dependent on GPIO chip, an optional routine to
+ * 	enable/disable hardware assisted timestamp.
+ * @get_hw_timestamp: Retrieves hardware timestamp. The consumer can specify
+ * 	block parameter if it wishes to block till timestamp is available. 
  * @base: identifies the first GPIO number handled by this chip;
  *	or, if negative during registration, requests dynamic ID allocation.
  *	DEPRECATION: providing anything non-negative and nailing the base

@@ -396,6 +401,14 @@ struct gpio_chip {
 
 	int			(*add_pin_ranges)(struct gpio_chip *gc);
 
+	int			(*timestamp_control)(struct gpio_chip *gc,
+						     unsigned int offset,
+						     struct hte_ts_desc **hdesc,
+						     bool enable);
+	int			(*get_hw_timestamp)(struct gpio_chip *gc,
+						    bool block,
+						    struct hte_ts_desc *hdesc,
+						    u64 *ts);
 	int			base;
 	u16			ngpio;
 	const char		*const *names;