gpio: add trace events for setting direction and value

This patch allows to trace gpio operations using ftrace

Signed-off-by: Uwe Kleine-König <[e-mail]>
Signed-off-by: Grant Likely <[e-mail]>

drivers/gpio/gpiolib.c

···
 #include <linux/idr.h>
 #include <linux/slab.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/gpio.h>
 
 /* Optional implementation infrastructure for GPIO interfaces.
  *
···
 	status = chip->direction_input(chip, gpio);
 	if (status == 0)
 		clear_bit(FLAG_IS_OUT, &desc->flags);
+
+	trace_gpio_direction(chip->base + gpio, 1, status);
 lose:
 	return status;
 fail:
···
 	status = chip->direction_output(chip, gpio, value);
 	if (status == 0)
 		set_bit(FLAG_IS_OUT, &desc->flags);
+	trace_gpio_value(chip->base + gpio, 0, value);
+	trace_gpio_direction(chip->base + gpio, 0, status);
 lose:
 	return status;
 fail:
···
 int __gpio_get_value(unsigned gpio)
 {
 	struct gpio_chip	*chip;
+	int value;
 
 	chip = gpio_to_chip(gpio);
 	WARN_ON(chip->can_sleep);
-	return chip->get ? chip->get(chip, gpio - chip->base) : 0;
+	value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
+	trace_gpio_value(gpio, 1, value);
+	return value;
 }
 EXPORT_SYMBOL_GPL(__gpio_get_value);
 
···
 
 	chip = gpio_to_chip(gpio);
 	WARN_ON(chip->can_sleep);
+	trace_gpio_value(gpio, 0, value);
 	chip->set(chip, gpio - chip->base, value);
 }
 EXPORT_SYMBOL_GPL(__gpio_set_value);
···
 int gpio_get_value_cansleep(unsigned gpio)
 {
 	struct gpio_chip	*chip;
+	int value;
 
 	might_sleep_if(extra_checks);
 	chip = gpio_to_chip(gpio);
-	return chip->get ? chip->get(chip, gpio - chip->base) : 0;
+	value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
+	trace_gpio_value(gpio, 1, value);
+	return value;
 }
 EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);
 
···
 
 	might_sleep_if(extra_checks);
 	chip = gpio_to_chip(gpio);
+	trace_gpio_value(gpio, 0, value);
 	chip->set(chip, gpio - chip->base, value);
 }
 EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);

include/trace/events/gpio.h

···
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM gpio
+
+#if !defined(_TRACE_GPIO_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_GPIO_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(gpio_direction,
+
+	TP_PROTO(unsigned gpio, int in, int err),
+
+	TP_ARGS(gpio, in, err),
+
+	TP_STRUCT__entry(
+		__field(unsigned, gpio)
+		__field(int, in)
+		__field(int, err)
+	),
+
+	TP_fast_assign(
+		__entry->gpio = gpio;
+		__entry->in = in;
+		__entry->err = err;
+	),
+
+	TP_printk("%u %3s (%d)", __entry->gpio,
+		__entry->in ? "in" : "out", __entry->err)
+);
+
+TRACE_EVENT(gpio_value,
+
+	TP_PROTO(unsigned gpio, int get, int value),
+
+	TP_ARGS(gpio, get, value),
+
+	TP_STRUCT__entry(
+		__field(unsigned, gpio)
+		__field(int, get)
+		__field(int, value)
+	),
+
+	TP_fast_assign(
+		__entry->gpio = gpio;
+		__entry->get = get;
+		__entry->value = value;
+	),
+
+	TP_printk("%u %3s %d", __entry->gpio,
+		__entry->get ? "get" : "set", __entry->value)
+);
+
+#endif /* if !defined(_TRACE_GPIO_H) || defined(TRACE_HEADER_MULTI_READ) */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>