1df6df93cSAndrew F. Davis /* 2df6df93cSAndrew F. Davis * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/ 3df6df93cSAndrew F. Davis * Andrew F. Davis <afd@ti.com> 4df6df93cSAndrew F. Davis * 5df6df93cSAndrew F. Davis * This program is free software; you can redistribute it and/or 6df6df93cSAndrew F. Davis * modify it under the terms of the GNU General Public License version 2 as 7df6df93cSAndrew F. Davis * published by the Free Software Foundation. 8df6df93cSAndrew F. Davis * 9df6df93cSAndrew F. Davis * This program is distributed "as is" WITHOUT ANY WARRANTY of any 10df6df93cSAndrew F. Davis * kind, whether expressed or implied; without even the implied warranty 11df6df93cSAndrew F. Davis * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12df6df93cSAndrew F. Davis * GNU General Public License version 2 for more details. 13df6df93cSAndrew F. Davis */ 14df6df93cSAndrew F. Davis 15df6df93cSAndrew F. Davis #include <linux/delay.h> 16df6df93cSAndrew F. Davis #include <linux/gpio/consumer.h> 17df6df93cSAndrew F. Davis #include <linux/gpio/driver.h> 18df6df93cSAndrew F. Davis #include <linux/module.h> 19df6df93cSAndrew F. Davis #include <linux/mutex.h> 20df6df93cSAndrew F. Davis #include <linux/spi/spi.h> 21df6df93cSAndrew F. Davis 22df6df93cSAndrew F. Davis #define DEFAULT_NGPIO 8 23df6df93cSAndrew F. Davis 24df6df93cSAndrew F. Davis /** 25df6df93cSAndrew F. Davis * struct pisosr_gpio - GPIO driver data 26df6df93cSAndrew F. Davis * @chip: GPIO controller chip 27df6df93cSAndrew F. Davis * @spi: SPI device pointer 28df6df93cSAndrew F. Davis * @buffer: Buffer for device reads 29df6df93cSAndrew F. Davis * @buffer_size: Size of buffer 30df6df93cSAndrew F. Davis * @load_gpio: GPIO pin used to load input into device 31df6df93cSAndrew F. Davis * @lock: Protects read sequences 32df6df93cSAndrew F. Davis */ 33df6df93cSAndrew F. Davis struct pisosr_gpio { 34df6df93cSAndrew F. Davis struct gpio_chip chip; 35df6df93cSAndrew F. Davis struct spi_device *spi; 36df6df93cSAndrew F. Davis u8 *buffer; 37df6df93cSAndrew F. Davis size_t buffer_size; 38df6df93cSAndrew F. Davis struct gpio_desc *load_gpio; 39df6df93cSAndrew F. Davis struct mutex lock; 40df6df93cSAndrew F. Davis }; 41df6df93cSAndrew F. Davis 42df6df93cSAndrew F. Davis static int pisosr_gpio_refresh(struct pisosr_gpio *gpio) 43df6df93cSAndrew F. Davis { 44df6df93cSAndrew F. Davis int ret; 45df6df93cSAndrew F. Davis 46df6df93cSAndrew F. Davis mutex_lock(&gpio->lock); 47df6df93cSAndrew F. Davis 48df6df93cSAndrew F. Davis if (gpio->load_gpio) { 49ea04a7caSAxel Lin gpiod_set_value_cansleep(gpio->load_gpio, 1); 50df6df93cSAndrew F. Davis udelay(1); /* registers load time (~10ns) */ 51ea04a7caSAxel Lin gpiod_set_value_cansleep(gpio->load_gpio, 0); 52df6df93cSAndrew F. Davis udelay(1); /* registers recovery time (~5ns) */ 53df6df93cSAndrew F. Davis } 54df6df93cSAndrew F. Davis 55df6df93cSAndrew F. Davis ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size); 56df6df93cSAndrew F. Davis 57df6df93cSAndrew F. Davis mutex_unlock(&gpio->lock); 58df6df93cSAndrew F. Davis 593e089d9fSSudip Mukherjee return ret; 60df6df93cSAndrew F. Davis } 61df6df93cSAndrew F. Davis 62df6df93cSAndrew F. Davis static int pisosr_gpio_get_direction(struct gpio_chip *chip, 63df6df93cSAndrew F. Davis unsigned offset) 64df6df93cSAndrew F. Davis { 65df6df93cSAndrew F. Davis /* This device always input */ 66df6df93cSAndrew F. Davis return 1; 67df6df93cSAndrew F. Davis } 68df6df93cSAndrew F. Davis 69df6df93cSAndrew F. Davis static int pisosr_gpio_direction_input(struct gpio_chip *chip, 70df6df93cSAndrew F. Davis unsigned offset) 71df6df93cSAndrew F. Davis { 72df6df93cSAndrew F. Davis /* This device always input */ 73df6df93cSAndrew F. Davis return 0; 74df6df93cSAndrew F. Davis } 75df6df93cSAndrew F. Davis 76df6df93cSAndrew F. Davis static int pisosr_gpio_direction_output(struct gpio_chip *chip, 77df6df93cSAndrew F. Davis unsigned offset, int value) 78df6df93cSAndrew F. Davis { 79df6df93cSAndrew F. Davis /* This device is input only */ 80df6df93cSAndrew F. Davis return -EINVAL; 81df6df93cSAndrew F. Davis } 82df6df93cSAndrew F. Davis 83df6df93cSAndrew F. Davis static int pisosr_gpio_get(struct gpio_chip *chip, unsigned offset) 84df6df93cSAndrew F. Davis { 85df6df93cSAndrew F. Davis struct pisosr_gpio *gpio = gpiochip_get_data(chip); 86df6df93cSAndrew F. Davis 87df6df93cSAndrew F. Davis /* Refresh may not always be needed */ 88df6df93cSAndrew F. Davis pisosr_gpio_refresh(gpio); 89df6df93cSAndrew F. Davis 90df6df93cSAndrew F. Davis return (gpio->buffer[offset / 8] >> (offset % 8)) & 0x1; 91df6df93cSAndrew F. Davis } 92df6df93cSAndrew F. Davis 93e35b5ab0SJulia Lawall static const struct gpio_chip template_chip = { 94df6df93cSAndrew F. Davis .label = "pisosr-gpio", 95df6df93cSAndrew F. Davis .owner = THIS_MODULE, 96df6df93cSAndrew F. Davis .get_direction = pisosr_gpio_get_direction, 97df6df93cSAndrew F. Davis .direction_input = pisosr_gpio_direction_input, 98df6df93cSAndrew F. Davis .direction_output = pisosr_gpio_direction_output, 99df6df93cSAndrew F. Davis .get = pisosr_gpio_get, 100df6df93cSAndrew F. Davis .base = -1, 101df6df93cSAndrew F. Davis .ngpio = DEFAULT_NGPIO, 102df6df93cSAndrew F. Davis .can_sleep = true, 103df6df93cSAndrew F. Davis }; 104df6df93cSAndrew F. Davis 105df6df93cSAndrew F. Davis static int pisosr_gpio_probe(struct spi_device *spi) 106df6df93cSAndrew F. Davis { 107df6df93cSAndrew F. Davis struct device *dev = &spi->dev; 108df6df93cSAndrew F. Davis struct pisosr_gpio *gpio; 109df6df93cSAndrew F. Davis int ret; 110df6df93cSAndrew F. Davis 111df6df93cSAndrew F. Davis gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL); 112df6df93cSAndrew F. Davis if (!gpio) 113df6df93cSAndrew F. Davis return -ENOMEM; 114df6df93cSAndrew F. Davis 115df6df93cSAndrew F. Davis spi_set_drvdata(spi, gpio); 116df6df93cSAndrew F. Davis 117df6df93cSAndrew F. Davis gpio->chip = template_chip; 118df6df93cSAndrew F. Davis gpio->chip.parent = dev; 119df6df93cSAndrew F. Davis of_property_read_u16(dev->of_node, "ngpios", &gpio->chip.ngpio); 120df6df93cSAndrew F. Davis 121df6df93cSAndrew F. Davis gpio->spi = spi; 122df6df93cSAndrew F. Davis 123df6df93cSAndrew F. Davis gpio->buffer_size = DIV_ROUND_UP(gpio->chip.ngpio, 8); 124df6df93cSAndrew F. Davis gpio->buffer = devm_kzalloc(dev, gpio->buffer_size, GFP_KERNEL); 125df6df93cSAndrew F. Davis if (!gpio->buffer) 126df6df93cSAndrew F. Davis return -ENOMEM; 127df6df93cSAndrew F. Davis 12821d08ab9SAxel Lin gpio->load_gpio = devm_gpiod_get_optional(dev, "load", GPIOD_OUT_LOW); 129df6df93cSAndrew F. Davis if (IS_ERR(gpio->load_gpio)) { 130df6df93cSAndrew F. Davis ret = PTR_ERR(gpio->load_gpio); 131df6df93cSAndrew F. Davis if (ret != -EPROBE_DEFER) 132df6df93cSAndrew F. Davis dev_err(dev, "Unable to allocate load GPIO\n"); 133df6df93cSAndrew F. Davis return ret; 134df6df93cSAndrew F. Davis } 135df6df93cSAndrew F. Davis 136df6df93cSAndrew F. Davis mutex_init(&gpio->lock); 137df6df93cSAndrew F. Davis 138df6df93cSAndrew F. Davis ret = gpiochip_add_data(&gpio->chip, gpio); 139df6df93cSAndrew F. Davis if (ret < 0) { 140df6df93cSAndrew F. Davis dev_err(dev, "Unable to register gpiochip\n"); 141df6df93cSAndrew F. Davis return ret; 142df6df93cSAndrew F. Davis } 143df6df93cSAndrew F. Davis 144df6df93cSAndrew F. Davis return 0; 145df6df93cSAndrew F. Davis } 146df6df93cSAndrew F. Davis 147df6df93cSAndrew F. Davis static int pisosr_gpio_remove(struct spi_device *spi) 148df6df93cSAndrew F. Davis { 149df6df93cSAndrew F. Davis struct pisosr_gpio *gpio = spi_get_drvdata(spi); 150df6df93cSAndrew F. Davis 151df6df93cSAndrew F. Davis gpiochip_remove(&gpio->chip); 152df6df93cSAndrew F. Davis 153df6df93cSAndrew F. Davis mutex_destroy(&gpio->lock); 154df6df93cSAndrew F. Davis 155df6df93cSAndrew F. Davis return 0; 156df6df93cSAndrew F. Davis } 157df6df93cSAndrew F. Davis 158df6df93cSAndrew F. Davis static const struct spi_device_id pisosr_gpio_id_table[] = { 159df6df93cSAndrew F. Davis { "pisosr-gpio", }, 160df6df93cSAndrew F. Davis { /* sentinel */ } 161df6df93cSAndrew F. Davis }; 162df6df93cSAndrew F. Davis MODULE_DEVICE_TABLE(spi, pisosr_gpio_id_table); 163df6df93cSAndrew F. Davis 164df6df93cSAndrew F. Davis static const struct of_device_id pisosr_gpio_of_match_table[] = { 165df6df93cSAndrew F. Davis { .compatible = "pisosr-gpio", }, 166df6df93cSAndrew F. Davis { /* sentinel */ } 167df6df93cSAndrew F. Davis }; 168df6df93cSAndrew F. Davis MODULE_DEVICE_TABLE(of, pisosr_gpio_of_match_table); 169df6df93cSAndrew F. Davis 170df6df93cSAndrew F. Davis static struct spi_driver pisosr_gpio_driver = { 171df6df93cSAndrew F. Davis .driver = { 172df6df93cSAndrew F. Davis .name = "pisosr-gpio", 173df6df93cSAndrew F. Davis .of_match_table = pisosr_gpio_of_match_table, 174df6df93cSAndrew F. Davis }, 175df6df93cSAndrew F. Davis .probe = pisosr_gpio_probe, 176df6df93cSAndrew F. Davis .remove = pisosr_gpio_remove, 177df6df93cSAndrew F. Davis .id_table = pisosr_gpio_id_table, 178df6df93cSAndrew F. Davis }; 179df6df93cSAndrew F. Davis module_spi_driver(pisosr_gpio_driver); 180df6df93cSAndrew F. Davis 181df6df93cSAndrew F. Davis MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>"); 182df6df93cSAndrew F. Davis MODULE_DESCRIPTION("SPI Compatible PISO Shift Register GPIO Driver"); 183df6df93cSAndrew F. Davis MODULE_LICENSE("GPL v2"); 184