1 /* 2 * MC33880 high-side/low-side switch GPIO driver 3 * Copyright (c) 2009 Intel Corporation 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License version 2 as 7 * published by the Free Software Foundation. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 17 */ 18 19 /* Supports: 20 * Freescale MC33880 high-side/low-side switch 21 */ 22 23 #include <linux/init.h> 24 #include <linux/mutex.h> 25 #include <linux/spi/spi.h> 26 #include <linux/spi/mc33880.h> 27 #include <linux/gpio.h> 28 #include <linux/slab.h> 29 #include <linux/module.h> 30 31 #define DRIVER_NAME "mc33880" 32 33 /* 34 * Pin configurations, see MAX7301 datasheet page 6 35 */ 36 #define PIN_CONFIG_MASK 0x03 37 #define PIN_CONFIG_IN_PULLUP 0x03 38 #define PIN_CONFIG_IN_WO_PULLUP 0x02 39 #define PIN_CONFIG_OUT 0x01 40 41 #define PIN_NUMBER 8 42 43 44 /* 45 * Some registers must be read back to modify. 46 * To save time we cache them here in memory 47 */ 48 struct mc33880 { 49 struct mutex lock; /* protect from simultaneous accesses */ 50 u8 port_config; 51 struct gpio_chip chip; 52 struct spi_device *spi; 53 }; 54 55 static int mc33880_write_config(struct mc33880 *mc) 56 { 57 return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config)); 58 } 59 60 61 static int __mc33880_set(struct mc33880 *mc, unsigned offset, int value) 62 { 63 if (value) 64 mc->port_config |= 1 << offset; 65 else 66 mc->port_config &= ~(1 << offset); 67 68 return mc33880_write_config(mc); 69 } 70 71 72 static void mc33880_set(struct gpio_chip *chip, unsigned offset, int value) 73 { 74 struct mc33880 *mc = gpiochip_get_data(chip); 75 76 mutex_lock(&mc->lock); 77 78 __mc33880_set(mc, offset, value); 79 80 mutex_unlock(&mc->lock); 81 } 82 83 static int mc33880_probe(struct spi_device *spi) 84 { 85 struct mc33880 *mc; 86 struct mc33880_platform_data *pdata; 87 int ret; 88 89 pdata = dev_get_platdata(&spi->dev); 90 if (!pdata || !pdata->base) { 91 dev_dbg(&spi->dev, "incorrect or missing platform data\n"); 92 return -EINVAL; 93 } 94 95 /* 96 * bits_per_word cannot be configured in platform data 97 */ 98 spi->bits_per_word = 8; 99 100 ret = spi_setup(spi); 101 if (ret < 0) 102 return ret; 103 104 mc = devm_kzalloc(&spi->dev, sizeof(struct mc33880), GFP_KERNEL); 105 if (!mc) 106 return -ENOMEM; 107 108 mutex_init(&mc->lock); 109 110 spi_set_drvdata(spi, mc); 111 112 mc->spi = spi; 113 114 mc->chip.label = DRIVER_NAME, 115 mc->chip.set = mc33880_set; 116 mc->chip.base = pdata->base; 117 mc->chip.ngpio = PIN_NUMBER; 118 mc->chip.can_sleep = true; 119 mc->chip.parent = &spi->dev; 120 mc->chip.owner = THIS_MODULE; 121 122 mc->port_config = 0x00; 123 /* write twice, because during initialisation the first setting 124 * is just for testing SPI communication, and the second is the 125 * "real" configuration 126 */ 127 ret = mc33880_write_config(mc); 128 mc->port_config = 0x00; 129 if (!ret) 130 ret = mc33880_write_config(mc); 131 132 if (ret) { 133 dev_err(&spi->dev, "Failed writing to " DRIVER_NAME ": %d\n", 134 ret); 135 goto exit_destroy; 136 } 137 138 ret = gpiochip_add_data(&mc->chip, mc); 139 if (ret) 140 goto exit_destroy; 141 142 return ret; 143 144 exit_destroy: 145 mutex_destroy(&mc->lock); 146 return ret; 147 } 148 149 static int mc33880_remove(struct spi_device *spi) 150 { 151 struct mc33880 *mc; 152 153 mc = spi_get_drvdata(spi); 154 if (!mc) 155 return -ENODEV; 156 157 gpiochip_remove(&mc->chip); 158 mutex_destroy(&mc->lock); 159 160 return 0; 161 } 162 163 static struct spi_driver mc33880_driver = { 164 .driver = { 165 .name = DRIVER_NAME, 166 }, 167 .probe = mc33880_probe, 168 .remove = mc33880_remove, 169 }; 170 171 static int __init mc33880_init(void) 172 { 173 return spi_register_driver(&mc33880_driver); 174 } 175 /* register after spi postcore initcall and before 176 * subsys initcalls that may rely on these GPIOs 177 */ 178 subsys_initcall(mc33880_init); 179 180 static void __exit mc33880_exit(void) 181 { 182 spi_unregister_driver(&mc33880_driver); 183 } 184 module_exit(mc33880_exit); 185 186 MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>"); 187 MODULE_LICENSE("GPL v2"); 188 189