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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2015-2023 Texas Instruments Incorporated - https://www.ti.com/4 * Andrew Davis <afd@ti.com>5 */6 7#include <linux/bitmap.h>8#include <linux/bitops.h>9#include <linux/delay.h>10#include <linux/gpio/consumer.h>11#include <linux/gpio/driver.h>12#include <linux/module.h>13#include <linux/mutex.h>14#include <linux/spi/spi.h>15 16#define DEFAULT_NGPIO 817 18/**19 * struct pisosr_gpio - GPIO driver data20 * @chip: GPIO controller chip21 * @spi: SPI device pointer22 * @buffer: Buffer for device reads23 * @buffer_size: Size of buffer24 * @load_gpio: GPIO pin used to load input into device25 * @lock: Protects read sequences26 */27struct pisosr_gpio {28 struct gpio_chip chip;29 struct spi_device *spi;30 u8 *buffer;31 size_t buffer_size;32 struct gpio_desc *load_gpio;33 struct mutex lock;34};35 36static int pisosr_gpio_refresh(struct pisosr_gpio *gpio)37{38 int ret;39 40 mutex_lock(&gpio->lock);41 42 if (gpio->load_gpio) {43 gpiod_set_value_cansleep(gpio->load_gpio, 1);44 udelay(1); /* registers load time (~10ns) */45 gpiod_set_value_cansleep(gpio->load_gpio, 0);46 udelay(1); /* registers recovery time (~5ns) */47 }48 49 ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size);50 51 mutex_unlock(&gpio->lock);52 53 return ret;54}55 56static int pisosr_gpio_get_direction(struct gpio_chip *chip,57 unsigned offset)58{59 /* This device always input */60 return GPIO_LINE_DIRECTION_IN;61}62 63static int pisosr_gpio_direction_input(struct gpio_chip *chip,64 unsigned offset)65{66 /* This device always input */67 return 0;68}69 70static int pisosr_gpio_direction_output(struct gpio_chip *chip,71 unsigned offset, int value)72{73 /* This device is input only */74 return -EINVAL;75}76 77static int pisosr_gpio_get(struct gpio_chip *chip, unsigned offset)78{79 struct pisosr_gpio *gpio = gpiochip_get_data(chip);80 81 /* Refresh may not always be needed */82 pisosr_gpio_refresh(gpio);83 84 return (gpio->buffer[offset / 8] >> (offset % 8)) & 0x1;85}86 87static int pisosr_gpio_get_multiple(struct gpio_chip *chip,88 unsigned long *mask, unsigned long *bits)89{90 struct pisosr_gpio *gpio = gpiochip_get_data(chip);91 unsigned long offset;92 unsigned long gpio_mask;93 unsigned long buffer_state;94 95 pisosr_gpio_refresh(gpio);96 97 bitmap_zero(bits, chip->ngpio);98 for_each_set_clump8(offset, gpio_mask, mask, chip->ngpio) {99 buffer_state = gpio->buffer[offset / 8] & gpio_mask;100 bitmap_set_value8(bits, buffer_state, offset);101 }102 103 return 0;104}105 106static const struct gpio_chip template_chip = {107 .label = "pisosr-gpio",108 .owner = THIS_MODULE,109 .get_direction = pisosr_gpio_get_direction,110 .direction_input = pisosr_gpio_direction_input,111 .direction_output = pisosr_gpio_direction_output,112 .get = pisosr_gpio_get,113 .get_multiple = pisosr_gpio_get_multiple,114 .base = -1,115 .ngpio = DEFAULT_NGPIO,116 .can_sleep = true,117};118 119static void pisosr_mutex_destroy(void *lock)120{121 mutex_destroy(lock);122}123 124static int pisosr_gpio_probe(struct spi_device *spi)125{126 struct device *dev = &spi->dev;127 struct pisosr_gpio *gpio;128 int ret;129 130 gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);131 if (!gpio)132 return -ENOMEM;133 134 gpio->chip = template_chip;135 gpio->chip.parent = dev;136 of_property_read_u16(dev->of_node, "ngpios", &gpio->chip.ngpio);137 138 gpio->spi = spi;139 140 gpio->buffer_size = DIV_ROUND_UP(gpio->chip.ngpio, 8);141 gpio->buffer = devm_kzalloc(dev, gpio->buffer_size, GFP_KERNEL);142 if (!gpio->buffer)143 return -ENOMEM;144 145 gpio->load_gpio = devm_gpiod_get_optional(dev, "load", GPIOD_OUT_LOW);146 if (IS_ERR(gpio->load_gpio))147 return dev_err_probe(dev, PTR_ERR(gpio->load_gpio),148 "Unable to allocate load GPIO\n");149 150 mutex_init(&gpio->lock);151 ret = devm_add_action_or_reset(dev, pisosr_mutex_destroy, &gpio->lock);152 if (ret)153 return ret;154 155 ret = devm_gpiochip_add_data(dev, &gpio->chip, gpio);156 if (ret < 0) {157 dev_err(dev, "Unable to register gpiochip\n");158 return ret;159 }160 161 return 0;162}163 164static const struct spi_device_id pisosr_gpio_id_table[] = {165 { "pisosr-gpio", },166 { /* sentinel */ }167};168MODULE_DEVICE_TABLE(spi, pisosr_gpio_id_table);169 170static const struct of_device_id pisosr_gpio_of_match_table[] = {171 { .compatible = "pisosr-gpio", },172 { /* sentinel */ }173};174MODULE_DEVICE_TABLE(of, pisosr_gpio_of_match_table);175 176static struct spi_driver pisosr_gpio_driver = {177 .driver = {178 .name = "pisosr-gpio",179 .of_match_table = pisosr_gpio_of_match_table,180 },181 .probe = pisosr_gpio_probe,182 .id_table = pisosr_gpio_id_table,183};184module_spi_driver(pisosr_gpio_driver);185 186MODULE_AUTHOR("Andrew Davis <afd@ti.com>");187MODULE_DESCRIPTION("SPI Compatible PISO Shift Register GPIO Driver");188MODULE_LICENSE("GPL v2");189