1 /* 2 * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver 3 * 4 * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org> 5 * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 12 #include <linux/init.h> 13 #include <linux/mutex.h> 14 #include <linux/spi/spi.h> 15 #include <linux/spi/74x164.h> 16 #include <linux/gpio.h> 17 #include <linux/slab.h> 18 #include <linux/module.h> 19 20 struct gen_74x164_chip { 21 struct spi_device *spi; 22 struct gpio_chip gpio_chip; 23 struct mutex lock; 24 u8 port_config; 25 }; 26 27 static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc) 28 { 29 return container_of(gc, struct gen_74x164_chip, gpio_chip); 30 } 31 32 static int __gen_74x164_write_config(struct gen_74x164_chip *chip) 33 { 34 return spi_write(chip->spi, 35 &chip->port_config, sizeof(chip->port_config)); 36 } 37 38 static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset) 39 { 40 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc); 41 int ret; 42 43 mutex_lock(&chip->lock); 44 ret = (chip->port_config >> offset) & 0x1; 45 mutex_unlock(&chip->lock); 46 47 return ret; 48 } 49 50 static void gen_74x164_set_value(struct gpio_chip *gc, 51 unsigned offset, int val) 52 { 53 struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc); 54 55 mutex_lock(&chip->lock); 56 if (val) 57 chip->port_config |= (1 << offset); 58 else 59 chip->port_config &= ~(1 << offset); 60 61 __gen_74x164_write_config(chip); 62 mutex_unlock(&chip->lock); 63 } 64 65 static int gen_74x164_direction_output(struct gpio_chip *gc, 66 unsigned offset, int val) 67 { 68 gen_74x164_set_value(gc, offset, val); 69 return 0; 70 } 71 72 static int __devinit gen_74x164_probe(struct spi_device *spi) 73 { 74 struct gen_74x164_chip *chip; 75 struct gen_74x164_chip_platform_data *pdata; 76 int ret; 77 78 pdata = spi->dev.platform_data; 79 if (!pdata || !pdata->base) { 80 dev_dbg(&spi->dev, "incorrect or missing platform data\n"); 81 return -EINVAL; 82 } 83 84 /* 85 * bits_per_word cannot be configured in platform data 86 */ 87 spi->bits_per_word = 8; 88 89 ret = spi_setup(spi); 90 if (ret < 0) 91 return ret; 92 93 chip = kzalloc(sizeof(*chip), GFP_KERNEL); 94 if (!chip) 95 return -ENOMEM; 96 97 mutex_init(&chip->lock); 98 99 dev_set_drvdata(&spi->dev, chip); 100 101 chip->spi = spi; 102 103 chip->gpio_chip.label = spi->modalias; 104 chip->gpio_chip.direction_output = gen_74x164_direction_output; 105 chip->gpio_chip.get = gen_74x164_get_value; 106 chip->gpio_chip.set = gen_74x164_set_value; 107 chip->gpio_chip.base = pdata->base; 108 chip->gpio_chip.ngpio = 8; 109 chip->gpio_chip.can_sleep = 1; 110 chip->gpio_chip.dev = &spi->dev; 111 chip->gpio_chip.owner = THIS_MODULE; 112 113 ret = __gen_74x164_write_config(chip); 114 if (ret) { 115 dev_err(&spi->dev, "Failed writing: %d\n", ret); 116 goto exit_destroy; 117 } 118 119 ret = gpiochip_add(&chip->gpio_chip); 120 if (ret) 121 goto exit_destroy; 122 123 return ret; 124 125 exit_destroy: 126 dev_set_drvdata(&spi->dev, NULL); 127 mutex_destroy(&chip->lock); 128 kfree(chip); 129 return ret; 130 } 131 132 static int __devexit gen_74x164_remove(struct spi_device *spi) 133 { 134 struct gen_74x164_chip *chip; 135 int ret; 136 137 chip = dev_get_drvdata(&spi->dev); 138 if (chip == NULL) 139 return -ENODEV; 140 141 dev_set_drvdata(&spi->dev, NULL); 142 143 ret = gpiochip_remove(&chip->gpio_chip); 144 if (!ret) { 145 mutex_destroy(&chip->lock); 146 kfree(chip); 147 } else 148 dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n", 149 ret); 150 151 return ret; 152 } 153 154 static struct spi_driver gen_74x164_driver = { 155 .driver = { 156 .name = "74x164", 157 .owner = THIS_MODULE, 158 }, 159 .probe = gen_74x164_probe, 160 .remove = __devexit_p(gen_74x164_remove), 161 }; 162 163 static int __init gen_74x164_init(void) 164 { 165 return spi_register_driver(&gen_74x164_driver); 166 } 167 subsys_initcall(gen_74x164_init); 168 169 static void __exit gen_74x164_exit(void) 170 { 171 spi_unregister_driver(&gen_74x164_driver); 172 } 173 module_exit(gen_74x164_exit); 174 175 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); 176 MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>"); 177 MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register"); 178 MODULE_LICENSE("GPL v2"); 179