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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 | // SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/ * Andrew F. Davis <afd@ti.com> */ #include <linux/bitmap.h> #include <linux/bitops.h> #include <linux/delay.h> #include <linux/gpio/consumer.h> #include <linux/gpio/driver.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/spi/spi.h> #define DEFAULT_NGPIO 8 /** * struct pisosr_gpio - GPIO driver data * @chip: GPIO controller chip * @spi: SPI device pointer * @buffer: Buffer for device reads * @buffer_size: Size of buffer * @load_gpio: GPIO pin used to load input into device * @lock: Protects read sequences */ struct pisosr_gpio { struct gpio_chip chip; struct spi_device *spi; u8 *buffer; size_t buffer_size; struct gpio_desc *load_gpio; struct mutex lock; }; static int pisosr_gpio_refresh(struct pisosr_gpio *gpio) { int ret; mutex_lock(&gpio->lock); if (gpio->load_gpio) { gpiod_set_value_cansleep(gpio->load_gpio, 1); udelay(1); /* registers load time (~10ns) */ gpiod_set_value_cansleep(gpio->load_gpio, 0); udelay(1); /* registers recovery time (~5ns) */ } ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size); mutex_unlock(&gpio->lock); return ret; } static int pisosr_gpio_get_direction(struct gpio_chip *chip, unsigned offset) { /* This device always input */ return GPIO_LINE_DIRECTION_IN; } static int pisosr_gpio_direction_input(struct gpio_chip *chip, unsigned offset) { /* This device always input */ return 0; } static int pisosr_gpio_direction_output(struct gpio_chip *chip, unsigned offset, int value) { /* This device is input only */ return -EINVAL; } static int pisosr_gpio_get(struct gpio_chip *chip, unsigned offset) { struct pisosr_gpio *gpio = gpiochip_get_data(chip); /* Refresh may not always be needed */ pisosr_gpio_refresh(gpio); return (gpio->buffer[offset / 8] >> (offset % 8)) & 0x1; } static int pisosr_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask, unsigned long *bits) { struct pisosr_gpio *gpio = gpiochip_get_data(chip); unsigned long offset; unsigned long gpio_mask; unsigned long buffer_state; pisosr_gpio_refresh(gpio); bitmap_zero(bits, chip->ngpio); for_each_set_clump8(offset, gpio_mask, mask, chip->ngpio) { buffer_state = gpio->buffer[offset / 8] & gpio_mask; bitmap_set_value8(bits, buffer_state, offset); } return 0; } static const struct gpio_chip template_chip = { .label = "pisosr-gpio", .owner = THIS_MODULE, .get_direction = pisosr_gpio_get_direction, .direction_input = pisosr_gpio_direction_input, .direction_output = pisosr_gpio_direction_output, .get = pisosr_gpio_get, .get_multiple = pisosr_gpio_get_multiple, .base = -1, .ngpio = DEFAULT_NGPIO, .can_sleep = true, }; static int pisosr_gpio_probe(struct spi_device *spi) { struct device *dev = &spi->dev; struct pisosr_gpio *gpio; int ret; gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL); if (!gpio) return -ENOMEM; spi_set_drvdata(spi, gpio); gpio->chip = template_chip; gpio->chip.parent = dev; of_property_read_u16(dev->of_node, "ngpios", &gpio->chip.ngpio); gpio->spi = spi; gpio->buffer_size = DIV_ROUND_UP(gpio->chip.ngpio, 8); gpio->buffer = devm_kzalloc(dev, gpio->buffer_size, GFP_KERNEL); if (!gpio->buffer) return -ENOMEM; gpio->load_gpio = devm_gpiod_get_optional(dev, "load", GPIOD_OUT_LOW); if (IS_ERR(gpio->load_gpio)) return dev_err_probe(dev, PTR_ERR(gpio->load_gpio), "Unable to allocate load GPIO\n"); mutex_init(&gpio->lock); ret = gpiochip_add_data(&gpio->chip, gpio); if (ret < 0) { dev_err(dev, "Unable to register gpiochip\n"); return ret; } return 0; } static void pisosr_gpio_remove(struct spi_device *spi) { struct pisosr_gpio *gpio = spi_get_drvdata(spi); gpiochip_remove(&gpio->chip); mutex_destroy(&gpio->lock); } static const struct spi_device_id pisosr_gpio_id_table[] = { { "pisosr-gpio", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(spi, pisosr_gpio_id_table); static const struct of_device_id pisosr_gpio_of_match_table[] = { { .compatible = "pisosr-gpio", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, pisosr_gpio_of_match_table); static struct spi_driver pisosr_gpio_driver = { .driver = { .name = "pisosr-gpio", .of_match_table = pisosr_gpio_of_match_table, }, .probe = pisosr_gpio_probe, .remove = pisosr_gpio_remove, .id_table = pisosr_gpio_id_table, }; module_spi_driver(pisosr_gpio_driver); MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>"); MODULE_DESCRIPTION("SPI Compatible PISO Shift Register GPIO Driver"); MODULE_LICENSE("GPL v2"); |