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[93.181.165.181]) by smtp.gmail.com with ESMTPSA id y206-v6sm1197634wmg.45.2018.08.20.16.42.52 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 20 Aug 2018 16:42:53 -0700 (PDT) From: Janusz Krzysztofik To: Linus Walleij Cc: Jonathan Corbet , Miguel Ojeda Sandonis , Peter Korsgaard , Peter Rosin , Ulf Hansson , Andrew Lunn , Florian Fainelli , "David S. Miller" , Dominik Brodowski , Kishon Vijay Abraham I , Lars-Peter Clausen , Michael Hennerich , Jonathan Cameron , Hartmut Knaack , Peter Meerwald-Stadler , Greg Kroah-Hartman , Jiri Slaby , linux-gpio@vger.kernel.org, linux-doc@vger.kernel.org, linux-i2c@vger.kernel.org, linux-mmc@vger.kernel.org, netdev@vger.kernel.org, linux-iio@vger.kernel.org, devel@driverdev.osuosl.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Janusz Krzysztofik Subject: [RFC RFT PATCH v4 2/4] gpiolib: Identify arrays matching GPIO hardware Date: Tue, 21 Aug 2018 01:43:39 +0200 Message-Id: <20180820234341.5271-3-jmkrzyszt@gmail.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20180820234341.5271-1-jmkrzyszt@gmail.com> References: <20180813223448.21316-1-jmkrzyszt@gmail.com> <20180820234341.5271-1-jmkrzyszt@gmail.com> Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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. Signed-off-by: Janusz Krzysztofik --- Documentation/driver-api/gpio/consumer.rst | 4 +- drivers/gpio/gpiolib.c | 72 +++++++++++++++++++++++++++++- drivers/gpio/gpiolib.h | 9 ++++ include/linux/gpio/consumer.h | 9 ++++ 4 files changed, 92 insertions(+), 2 deletions(-) diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst index ed68042ddccf..7e0298b9a7b9 100644 --- a/Documentation/driver-api/gpio/consumer.rst +++ b/Documentation/driver-api/gpio/consumer.rst @@ -109,9 +109,11 @@ For a function using multiple GPIOs all of those can be obtained with one call:: enum gpiod_flags flags) This function returns a struct gpio_descs which contains an array of -descriptors:: +descriptors. It also contains a pointer to a gpiolib private structure which, +if passed back to get/set array functions, may speed up I/O proocessing:: struct gpio_descs { + struct gpio_array *info; unsigned int ndescs; struct gpio_desc *desc[]; } diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index f0e9ffa8cab6..c1ed1c759345 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); diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 11e83d2eef89..b60905d558b1 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -183,6 +183,15 @@ static inline bool acpi_can_fallback_to_crs(struct acpi_device *adev, } #endif +struct gpio_array { + struct gpio_desc **desc; + unsigned int size; + struct gpio_chip *chip; + unsigned long *get_mask; + unsigned long *set_mask; + unsigned long invert_mask[]; +}; + struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip, u16 hwnum); int gpiod_get_array_value_complex(bool raw, bool can_sleep, unsigned int array_size, diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index 1b21dc7b0fad..8dede3e886af 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -17,11 +17,20 @@ struct device; */ struct gpio_desc; +/** + * Opaque descriptor for a structure of GPIO array attributes. This structure + * is attached to struct gpiod_descs obtained from gpiod_get_array() and can be + * passed back to get/set array functions in order to activate fast processing + * path if applicable. + */ +struct gpio_array; + /** * Struct containing an array of descriptors that can be obtained using * gpiod_get_array(). */ struct gpio_descs { + struct gpio_array *info; unsigned int ndescs; struct gpio_desc *desc[]; };