From bf9346f5d47b4506aafbc384dfb5796b0adc3f8d Mon Sep 17 00:00:00 2001 From: Janusz Krzysztofik Date: Wed, 5 Sep 2018 23:50:06 +0200 Subject: gpiolib: Identify arrays matching GPIO hardware Certain GPIO array lookup results may map directly to GPIO pins of a single GPIO chip in hardware order. If that condition is recognized and handled efficiently, significant performance gain of get/set array functions may be possible. While processing a request for an array of GPIO descriptors, identify those which represent corresponding pins of a single GPIO chip. Skip over pins which require open source or open drain special processing. Moreover, identify pins which require inversion. Pass a pointer to that information with the array to the caller so it can benefit from enhanced performance as soon as get/set array functions can accept and make efficient use of it. Cc: Jonathan Corbet Signed-off-by: Janusz Krzysztofik Signed-off-by: Linus Walleij --- drivers/gpio/gpiolib.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 71 insertions(+), 1 deletion(-) (limited to 'drivers/gpio/gpiolib.c') diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index b66b2191c5c5..141f39308a53 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -4174,7 +4174,9 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev, { struct gpio_desc *desc; struct gpio_descs *descs; - int count; + struct gpio_array *array_info = NULL; + struct gpio_chip *chip; + int count, bitmap_size; count = gpiod_count(dev, con_id); if (count < 0) @@ -4190,9 +4192,77 @@ struct gpio_descs *__must_check gpiod_get_array(struct device *dev, gpiod_put_array(descs); return ERR_CAST(desc); } + descs->desc[descs->ndescs] = desc; + + chip = gpiod_to_chip(desc); + /* + * Select a chip of first array member + * whose index matches its pin hardware number + * as a candidate for fast bitmap processing. + */ + if (!array_info && gpio_chip_hwgpio(desc) == descs->ndescs) { + struct gpio_descs *array; + + bitmap_size = BITS_TO_LONGS(chip->ngpio > count ? + chip->ngpio : count); + + array = kzalloc(struct_size(descs, desc, count) + + struct_size(array_info, invert_mask, + 3 * bitmap_size), GFP_KERNEL); + if (!array) { + gpiod_put_array(descs); + return ERR_PTR(-ENOMEM); + } + + memcpy(array, descs, + struct_size(descs, desc, descs->ndescs + 1)); + kfree(descs); + + descs = array; + array_info = (void *)(descs->desc + count); + array_info->get_mask = array_info->invert_mask + + bitmap_size; + array_info->set_mask = array_info->get_mask + + bitmap_size; + + array_info->desc = descs->desc; + array_info->size = count; + array_info->chip = chip; + bitmap_set(array_info->get_mask, descs->ndescs, + count - descs->ndescs); + bitmap_set(array_info->set_mask, descs->ndescs, + count - descs->ndescs); + descs->info = array_info; + } + /* + * Unmark members which don't qualify for fast bitmap + * processing (different chip, not in hardware order) + */ + if (array_info && (chip != array_info->chip || + gpio_chip_hwgpio(desc) != descs->ndescs)) { + __clear_bit(descs->ndescs, array_info->get_mask); + __clear_bit(descs->ndescs, array_info->set_mask); + } else if (array_info) { + /* Exclude open drain or open source from fast output */ + if (gpiochip_line_is_open_drain(chip, descs->ndescs) || + gpiochip_line_is_open_source(chip, descs->ndescs)) + __clear_bit(descs->ndescs, + array_info->set_mask); + /* Identify 'fast' pins which require invertion */ + if (gpiod_is_active_low(desc)) + __set_bit(descs->ndescs, + array_info->invert_mask); + } + descs->ndescs++; } + if (array_info) + dev_dbg(dev, + "GPIO array info: chip=%s, size=%d, get_mask=%lx, set_mask=%lx, invert_mask=%lx\n", + array_info->chip->label, array_info->size, + *array_info->get_mask, *array_info->set_mask, + *array_info->invert_mask); return descs; } EXPORT_SYMBOL_GPL(gpiod_get_array); -- cgit v1.2.3