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gpiolib: Use seq_file's iterator interface

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When dumping a collection of items via seq_file, it is recommended to
use the iterator interface. For the gpiolib debugfs interface this can
be done to dump each GPIO chip in turn.

Note that for gpiolib this is a little cumbersome because it does not
provide a list of registered GPIO chips and the only way to iterate is
over each GPIO individually. Once a chip is found, the number of GPIOs
it provides can be skipped as a small optimization.

This patch was requested by Arnd Bergmann here:

	http://article.gmane.org/gmane.linux.ports.tegra/3535

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Thierry Reding 2012-04-12 13:26:01 +02:00 committed by Linus Walleij
parent d9875690d9
commit f9c4a31f61
1 changed files with 74 additions and 28 deletions
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74
drivers/gpio/gpiolib.c
View File

@ -1773,30 +1773,69 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
}
}
static int gpiolib_show(struct seq_file *s, void *unused)
static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
{
struct gpio_chip *chip = NULL;
unsigned gpio;
int started = 0;
unsigned int gpio;
void *ret = NULL;
loff_t index = 0;
/* REVISIT this isn't locked against gpio_chip removal ... */
for (gpio = 0; gpio_is_valid(gpio); gpio++) {
struct device *dev;
if (chip == gpio_desc[gpio].chip)
if (gpio_desc[gpio].chip == chip)
continue;
chip = gpio_desc[gpio].chip;
if (!chip)
continue;
seq_printf(s, "%sGPIOs %d-%d",
started ? "\n" : "",
if (index++ >= *pos) {
ret = chip;
break;
}
}
s->private = "";
return ret;
}
static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
struct gpio_chip *chip = v;
unsigned int gpio;
void *ret = NULL;
/* skip GPIOs provided by the current chip */
for (gpio = chip->base + chip->ngpio; gpio_is_valid(gpio); gpio++) {
chip = gpio_desc[gpio].chip;
if (chip) {
ret = chip;
break;
}
}
s->private = "\n";
++*pos;
return ret;
}
static void gpiolib_seq_stop(struct seq_file *s, void *v)
{
}
static int gpiolib_seq_show(struct seq_file *s, void *v)
{
struct gpio_chip *chip = v;
struct device *dev;
seq_printf(s, "%sGPIOs %d-%d", (char *)s->private,
chip->base, chip->base + chip->ngpio - 1);
dev = chip->dev;
if (dev)
seq_printf(s, ", %s/%s",
dev->bus ? dev->bus->name : "no-bus",
seq_printf(s, ", %s/%s", dev->bus ? dev->bus->name : "no-bus",
dev_name(dev));
if (chip->label)
seq_printf(s, ", %s", chip->label);
@ -1804,25 +1843,32 @@ static int gpiolib_show(struct seq_file *s, void *unused)
seq_printf(s, ", can sleep");
seq_printf(s, ":\n");
started = 1;
if (chip->dbg_show)
chip->dbg_show(s, chip);
else
gpiolib_dbg_show(s, chip);
}
return 0;
}
static const struct seq_operations gpiolib_seq_ops = {
.start = gpiolib_seq_start,
.next = gpiolib_seq_next,
.stop = gpiolib_seq_stop,
.show = gpiolib_seq_show,
};
static int gpiolib_open(struct inode *inode, struct file *file)
{
return single_open(file, gpiolib_show, NULL);
return seq_open(file, &gpiolib_seq_ops);
}
static const struct file_operations gpiolib_operations = {
.owner = THIS_MODULE,
.open = gpiolib_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
.release = seq_release,
};
static int __init gpiolib_debugfs_init(void)