1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2006 Juergen Beisert, Pengutronix 4 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix 5 * Copyright (C) 2009 Wolfram Sang, Pengutronix 6 * 7 * Check max730x.c for further details. 8 */ 9 10 #include <linux/module.h> 11 #include <linux/init.h> 12 #include <linux/platform_device.h> 13 #include <linux/mutex.h> 14 #include <linux/slab.h> 15 #include <linux/spi/spi.h> 16 #include <linux/spi/max7301.h> 17 18 /* A write to the MAX7301 means one message with one transfer */ 19 static int max7301_spi_write(struct device *dev, unsigned int reg, 20 unsigned int val) 21 { 22 struct spi_device *spi = to_spi_device(dev); 23 u16 word = ((reg & 0x7F) << 8) | (val & 0xFF); 24 25 return spi_write_then_read(spi, &word, sizeof(word), NULL, 0); 26 } 27 28 /* A read from the MAX7301 means two transfers; here, one message each */ 29 30 static int max7301_spi_read(struct device *dev, unsigned int reg) 31 { 32 int ret; 33 u16 word; 34 struct spi_device *spi = to_spi_device(dev); 35 36 word = 0x8000 | (reg << 8); 37 ret = spi_write_then_read(spi, &word, sizeof(word), &word, 38 sizeof(word)); 39 if (ret) 40 return ret; 41 return word & 0xff; 42 } 43 44 static int max7301_probe(struct spi_device *spi) 45 { 46 struct max7301 *ts; 47 int ret; 48 49 /* bits_per_word cannot be configured in platform data */ 50 spi->bits_per_word = 16; 51 ret = spi_setup(spi); 52 if (ret < 0) 53 return ret; 54 55 ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL); 56 if (!ts) 57 return -ENOMEM; 58 59 ts->read = max7301_spi_read; 60 ts->write = max7301_spi_write; 61 ts->dev = &spi->dev; 62 63 ret = __max730x_probe(ts); 64 return ret; 65 } 66 67 static int max7301_remove(struct spi_device *spi) 68 { 69 __max730x_remove(&spi->dev); 70 71 return 0; 72 } 73 74 static const struct spi_device_id max7301_id[] = { 75 { "max7301", 0 }, 76 { } 77 }; 78 MODULE_DEVICE_TABLE(spi, max7301_id); 79 80 static struct spi_driver max7301_driver = { 81 .driver = { 82 .name = "max7301", 83 }, 84 .probe = max7301_probe, 85 .remove = max7301_remove, 86 .id_table = max7301_id, 87 }; 88 89 static int __init max7301_init(void) 90 { 91 return spi_register_driver(&max7301_driver); 92 } 93 /* register after spi postcore initcall and before 94 * subsys initcalls that may rely on these GPIOs 95 */ 96 subsys_initcall(max7301_init); 97 98 static void __exit max7301_exit(void) 99 { 100 spi_unregister_driver(&max7301_driver); 101 } 102 module_exit(max7301_exit); 103 104 MODULE_AUTHOR("Juergen Beisert, Wolfram Sang"); 105 MODULE_LICENSE("GPL v2"); 106 MODULE_DESCRIPTION("MAX7301 GPIO-Expander"); 107