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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2006 Juergen Beisert, Pengutronix4 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix5 * Copyright (C) 2009 Wolfram Sang, Pengutronix6 *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 */19static 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 30static 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 44static 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 67static void max7301_remove(struct spi_device *spi)68{69 __max730x_remove(&spi->dev);70}71 72static const struct spi_device_id max7301_id[] = {73 { "max7301", 0 },74 { }75};76MODULE_DEVICE_TABLE(spi, max7301_id);77 78static struct spi_driver max7301_driver = {79 .driver = {80 .name = "max7301",81 },82 .probe = max7301_probe,83 .remove = max7301_remove,84 .id_table = max7301_id,85};86 87static int __init max7301_init(void)88{89 return spi_register_driver(&max7301_driver);90}91/* register after spi postcore initcall and before92 * subsys initcalls that may rely on these GPIOs93 */94subsys_initcall(max7301_init);95 96static void __exit max7301_exit(void)97{98 spi_unregister_driver(&max7301_driver);99}100module_exit(max7301_exit);101 102MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");103MODULE_LICENSE("GPL v2");104MODULE_DESCRIPTION("MAX7301 GPIO-Expander");105