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202 lines
5.0 KiB
202 lines
5.0 KiB
/* |
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* Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/ |
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* Andrew F. Davis <[email protected]> |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public License version 2 as |
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* published by the Free Software Foundation. |
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* |
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* This program is distributed "as is" WITHOUT ANY WARRANTY of any |
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* kind, whether expressed or implied; without even the implied warranty |
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License version 2 for more details. |
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*/ |
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#include <linux/bitmap.h> |
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#include <linux/bitops.h> |
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#include <linux/delay.h> |
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#include <linux/gpio/consumer.h> |
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#include <linux/gpio/driver.h> |
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#include <linux/module.h> |
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#include <linux/mutex.h> |
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#include <linux/spi/spi.h> |
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#define DEFAULT_NGPIO 8 |
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/** |
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* struct pisosr_gpio - GPIO driver data |
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* @chip: GPIO controller chip |
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* @spi: SPI device pointer |
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* @buffer: Buffer for device reads |
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* @buffer_size: Size of buffer |
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* @load_gpio: GPIO pin used to load input into device |
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* @lock: Protects read sequences |
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*/ |
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struct pisosr_gpio { |
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struct gpio_chip chip; |
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struct spi_device *spi; |
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u8 *buffer; |
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size_t buffer_size; |
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struct gpio_desc *load_gpio; |
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struct mutex lock; |
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}; |
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static int pisosr_gpio_refresh(struct pisosr_gpio *gpio) |
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{ |
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int ret; |
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mutex_lock(&gpio->lock); |
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if (gpio->load_gpio) { |
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gpiod_set_value_cansleep(gpio->load_gpio, 1); |
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udelay(1); /* registers load time (~10ns) */ |
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gpiod_set_value_cansleep(gpio->load_gpio, 0); |
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udelay(1); /* registers recovery time (~5ns) */ |
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} |
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ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size); |
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mutex_unlock(&gpio->lock); |
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return ret; |
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} |
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static int pisosr_gpio_get_direction(struct gpio_chip *chip, |
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unsigned offset) |
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{ |
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/* This device always input */ |
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return GPIO_LINE_DIRECTION_IN; |
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} |
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static int pisosr_gpio_direction_input(struct gpio_chip *chip, |
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unsigned offset) |
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{ |
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/* This device always input */ |
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return 0; |
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} |
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static int pisosr_gpio_direction_output(struct gpio_chip *chip, |
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unsigned offset, int value) |
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{ |
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/* This device is input only */ |
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return -EINVAL; |
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} |
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static int pisosr_gpio_get(struct gpio_chip *chip, unsigned offset) |
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{ |
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struct pisosr_gpio *gpio = gpiochip_get_data(chip); |
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/* Refresh may not always be needed */ |
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pisosr_gpio_refresh(gpio); |
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return (gpio->buffer[offset / 8] >> (offset % 8)) & 0x1; |
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} |
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static int pisosr_gpio_get_multiple(struct gpio_chip *chip, |
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unsigned long *mask, unsigned long *bits) |
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{ |
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struct pisosr_gpio *gpio = gpiochip_get_data(chip); |
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unsigned long offset; |
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unsigned long gpio_mask; |
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unsigned long buffer_state; |
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pisosr_gpio_refresh(gpio); |
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bitmap_zero(bits, chip->ngpio); |
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for_each_set_clump8(offset, gpio_mask, mask, chip->ngpio) { |
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buffer_state = gpio->buffer[offset / 8] & gpio_mask; |
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bitmap_set_value8(bits, buffer_state, offset); |
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} |
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return 0; |
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} |
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static const struct gpio_chip template_chip = { |
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.label = "pisosr-gpio", |
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.owner = THIS_MODULE, |
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.get_direction = pisosr_gpio_get_direction, |
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.direction_input = pisosr_gpio_direction_input, |
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.direction_output = pisosr_gpio_direction_output, |
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.get = pisosr_gpio_get, |
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.get_multiple = pisosr_gpio_get_multiple, |
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.base = -1, |
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.ngpio = DEFAULT_NGPIO, |
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.can_sleep = true, |
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}; |
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static int pisosr_gpio_probe(struct spi_device *spi) |
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{ |
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struct device *dev = &spi->dev; |
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struct pisosr_gpio *gpio; |
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int ret; |
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gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL); |
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if (!gpio) |
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return -ENOMEM; |
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spi_set_drvdata(spi, gpio); |
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gpio->chip = template_chip; |
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gpio->chip.parent = dev; |
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of_property_read_u16(dev->of_node, "ngpios", &gpio->chip.ngpio); |
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gpio->spi = spi; |
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gpio->buffer_size = DIV_ROUND_UP(gpio->chip.ngpio, 8); |
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gpio->buffer = devm_kzalloc(dev, gpio->buffer_size, GFP_KERNEL); |
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if (!gpio->buffer) |
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return -ENOMEM; |
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gpio->load_gpio = devm_gpiod_get_optional(dev, "load", GPIOD_OUT_LOW); |
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if (IS_ERR(gpio->load_gpio)) |
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return dev_err_probe(dev, PTR_ERR(gpio->load_gpio), |
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"Unable to allocate load GPIO\n"); |
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mutex_init(&gpio->lock); |
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ret = gpiochip_add_data(&gpio->chip, gpio); |
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if (ret < 0) { |
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dev_err(dev, "Unable to register gpiochip\n"); |
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return ret; |
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} |
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return 0; |
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} |
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static int pisosr_gpio_remove(struct spi_device *spi) |
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{ |
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struct pisosr_gpio *gpio = spi_get_drvdata(spi); |
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gpiochip_remove(&gpio->chip); |
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mutex_destroy(&gpio->lock); |
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return 0; |
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} |
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static const struct spi_device_id pisosr_gpio_id_table[] = { |
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{ "pisosr-gpio", }, |
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{ /* sentinel */ } |
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}; |
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MODULE_DEVICE_TABLE(spi, pisosr_gpio_id_table); |
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static const struct of_device_id pisosr_gpio_of_match_table[] = { |
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{ .compatible = "pisosr-gpio", }, |
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{ /* sentinel */ } |
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}; |
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MODULE_DEVICE_TABLE(of, pisosr_gpio_of_match_table); |
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static struct spi_driver pisosr_gpio_driver = { |
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.driver = { |
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.name = "pisosr-gpio", |
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.of_match_table = pisosr_gpio_of_match_table, |
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}, |
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.probe = pisosr_gpio_probe, |
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.remove = pisosr_gpio_remove, |
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.id_table = pisosr_gpio_id_table, |
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}; |
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module_spi_driver(pisosr_gpio_driver); |
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MODULE_AUTHOR("Andrew F. Davis <[email protected]>"); |
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MODULE_DESCRIPTION("SPI Compatible PISO Shift Register GPIO Driver"); |
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MODULE_LICENSE("GPL v2");
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