/* * Copyright (C) 2006 Juergen Beisert, Pengutronix * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix * Copyright (C) 2009 Wolfram Sang, Pengutronix * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * Check max730x.c for further details. */ #include <linux/module.h> #include <linux/init.h> #include <linux/platform_device.h> #include <linux/mutex.h> #include <linux/slab.h> #include <linux/spi/spi.h> #include <linux/spi/max7301.h> /* A write to the MAX7301 means one message with one transfer */ static int max7301_spi_write(struct device *dev, unsigned int reg, unsigned int val) { struct spi_device *spi = to_spi_device(dev); u16 word = ((reg & 0x7F) << 8) | (val & 0xFF); return spi_write(spi, (const u8 *)&word, sizeof(word)); } /* A read from the MAX7301 means two transfers; here, one message each */ static int max7301_spi_read(struct device *dev, unsigned int reg) { int ret; u16 word; struct spi_device *spi = to_spi_device(dev); word = 0x8000 | (reg << 8); ret = spi_write(spi, (const u8 *)&word, sizeof(word)); if (ret) return ret; /* * This relies on the fact, that a transfer with NULL tx_buf shifts out * zero bytes (=NOOP for MAX7301) */ ret = spi_read(spi, (u8 *)&word, sizeof(word)); if (ret) return ret; return word & 0xff; } static int max7301_probe(struct spi_device *spi) { struct max7301 *ts; int ret; /* bits_per_word cannot be configured in platform data */ spi->bits_per_word = 16; ret = spi_setup(spi); if (ret < 0) return ret; ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL); if (!ts) return -ENOMEM; ts->read = max7301_spi_read; ts->write = max7301_spi_write; ts->dev = &spi->dev; ret = __max730x_probe(ts); return ret; } static int max7301_remove(struct spi_device *spi) { return __max730x_remove(&spi->dev); } static const struct spi_device_id max7301_id[] = { { "max7301", 0 }, { } }; MODULE_DEVICE_TABLE(spi, max7301_id); static struct spi_driver max7301_driver = { .driver = { .name = "max7301", .owner = THIS_MODULE, }, .probe = max7301_probe, .remove = max7301_remove, .id_table = max7301_id, }; static int __init max7301_init(void) { return spi_register_driver(&max7301_driver); } /* register after spi postcore initcall and before * subsys initcalls that may rely on these GPIOs */ subsys_initcall(max7301_init); static void __exit max7301_exit(void) { spi_unregister_driver(&max7301_driver); } module_exit(max7301_exit); MODULE_AUTHOR("Juergen Beisert, Wolfram Sang"); MODULE_LICENSE("GPL v2"); MODULE_DESCRIPTION("MAX7301 GPIO-Expander");