1 /* 2 * Copyright (C) 2006 Juergen Beisert, Pengutronix 3 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix 4 * Copyright (C) 2009 Wolfram Sang, Pengutronix 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * Check max730x.c for further details. 11 */ 12 13 #include <linux/module.h> 14 #include <linux/init.h> 15 #include <linux/platform_device.h> 16 #include <linux/mutex.h> 17 #include <linux/slab.h> 18 #include <linux/spi/spi.h> 19 #include <linux/spi/max7301.h> 20 21 /* A write to the MAX7301 means one message with one transfer */ 22 static int max7301_spi_write(struct device *dev, unsigned int reg, 23 unsigned int val) 24 { 25 struct spi_device *spi = to_spi_device(dev); 26 u16 word = ((reg & 0x7F) << 8) | (val & 0xFF); 27 28 return spi_write_then_read(spi, &word, sizeof(word), NULL, 0); 29 } 30 31 /* A read from the MAX7301 means two transfers; here, one message each */ 32 33 static int max7301_spi_read(struct device *dev, unsigned int reg) 34 { 35 int ret; 36 u16 word; 37 struct spi_device *spi = to_spi_device(dev); 38 39 word = 0x8000 | (reg << 8); 40 ret = spi_write_then_read(spi, &word, sizeof(word), &word, 41 sizeof(word)); 42 if (ret) 43 return ret; 44 return word & 0xff; 45 } 46 47 static int max7301_probe(struct spi_device *spi) 48 { 49 struct max7301 *ts; 50 int ret; 51 52 /* bits_per_word cannot be configured in platform data */ 53 spi->bits_per_word = 16; 54 ret = spi_setup(spi); 55 if (ret < 0) 56 return ret; 57 58 ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL); 59 if (!ts) 60 return -ENOMEM; 61 62 ts->read = max7301_spi_read; 63 ts->write = max7301_spi_write; 64 ts->dev = &spi->dev; 65 66 ret = __max730x_probe(ts); 67 return ret; 68 } 69 70 static int max7301_remove(struct spi_device *spi) 71 { 72 return __max730x_remove(&spi->dev); 73 } 74 75 static const struct spi_device_id max7301_id[] = { 76 { "max7301", 0 }, 77 { } 78 }; 79 MODULE_DEVICE_TABLE(spi, max7301_id); 80 81 static struct spi_driver max7301_driver = { 82 .driver = { 83 .name = "max7301", 84 }, 85 .probe = max7301_probe, 86 .remove = max7301_remove, 87 .id_table = max7301_id, 88 }; 89 90 static int __init max7301_init(void) 91 { 92 return spi_register_driver(&max7301_driver); 93 } 94 /* register after spi postcore initcall and before 95 * subsys initcalls that may rely on these GPIOs 96 */ 97 subsys_initcall(max7301_init); 98 99 static void __exit max7301_exit(void) 100 { 101 spi_unregister_driver(&max7301_driver); 102 } 103 module_exit(max7301_exit); 104 105 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang"); 106 MODULE_LICENSE("GPL v2"); 107 MODULE_DESCRIPTION("MAX7301 GPIO-Expander"); 108