i2c/busses/i2c-simtec.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2005 Simtec Electronics
0004  *  Ben Dooks <ben@simtec.co.uk>
0005  *
0006  * Simtec Generic I2C Controller
0007 */
0008
0009 #include <linux/kernel.h>
0010 #include <linux/module.h>
0011 #include <linux/delay.h>
0012 #include <linux/platform_device.h>
0013 #include <linux/slab.h>
0014 #include <linux/io.h>
0015
0016 #include <linux/i2c.h>
0017 #include <linux/i2c-algo-bit.h>
0018
0019 struct simtec_i2c_data {
0020     struct resource     *ioarea;
0021     void __iomem        *reg;
0022     struct i2c_adapter   adap;
0023     struct i2c_algo_bit_data bit;
0024 };
0025
0026 #define CMD_SET_SDA (1<<2)
0027 #define CMD_SET_SCL (1<<3)
0028
0029 #define STATE_SDA   (1<<0)
0030 #define STATE_SCL   (1<<1)
0031
0032 /* i2c bit-bus functions */
0033
0034 static void simtec_i2c_setsda(void *pw, int state)
0035 {
0036     struct simtec_i2c_data *pd = pw;
0037     writeb(CMD_SET_SDA | (state ? STATE_SDA : 0), pd->reg);
0038 }
0039
0040 static void simtec_i2c_setscl(void *pw, int state)
0041 {
0042     struct simtec_i2c_data *pd = pw;
0043     writeb(CMD_SET_SCL | (state ? STATE_SCL : 0), pd->reg);
0044 }
0045
0046 static int simtec_i2c_getsda(void *pw)
0047 {
0048     struct simtec_i2c_data *pd = pw;
0049     return readb(pd->reg) & STATE_SDA ? 1 : 0;
0050 }
0051
0052 static int simtec_i2c_getscl(void *pw)
0053 {
0054     struct simtec_i2c_data *pd = pw;
0055     return readb(pd->reg) & STATE_SCL ? 1 : 0;
0056 }
0057
0058 /* device registration */
0059
0060 static int simtec_i2c_probe(struct platform_device *dev)
0061 {
0062     struct simtec_i2c_data *pd;
0063     struct resource *res;
0064     int size;
0065     int ret;
0066
0067     pd = kzalloc(sizeof(struct simtec_i2c_data), GFP_KERNEL);
0068     if (pd == NULL)
0069         return -ENOMEM;
0070
0071     platform_set_drvdata(dev, pd);
0072
0073     res = platform_get_resource(dev, IORESOURCE_MEM, 0);
0074     if (res == NULL) {
0075         dev_err(&dev->dev, "cannot find IO resource\n");
0076         ret = -ENOENT;
0077         goto err;
0078     }
0079
0080     size = resource_size(res);
0081
0082     pd->ioarea = request_mem_region(res->start, size, dev->name);
0083     if (pd->ioarea == NULL) {
0084         dev_err(&dev->dev, "cannot request IO\n");
0085         ret = -ENXIO;
0086         goto err;
0087     }
0088
0089     pd->reg = ioremap(res->start, size);
0090     if (pd->reg == NULL) {
0091         dev_err(&dev->dev, "cannot map IO\n");
0092         ret = -ENXIO;
0093         goto err_res;
0094     }
0095
0096     /* setup the private data */
0097
0098     pd->adap.owner = THIS_MODULE;
0099     pd->adap.algo_data = &pd->bit;
0100     pd->adap.dev.parent = &dev->dev;
0101
0102     strscpy(pd->adap.name, "Simtec I2C", sizeof(pd->adap.name));
0103
0104     pd->bit.data = pd;
0105     pd->bit.setsda = simtec_i2c_setsda;
0106     pd->bit.setscl = simtec_i2c_setscl;
0107     pd->bit.getsda = simtec_i2c_getsda;
0108     pd->bit.getscl = simtec_i2c_getscl;
0109     pd->bit.timeout = HZ;
0110     pd->bit.udelay = 20;
0111
0112     ret = i2c_bit_add_bus(&pd->adap);
0113     if (ret)
0114         goto err_all;
0115
0116     return 0;
0117
0118  err_all:
0119     iounmap(pd->reg);
0120
0121  err_res:
0122     release_mem_region(pd->ioarea->start, size);
0123
0124  err:
0125     kfree(pd);
0126     return ret;
0127 }
0128
0129 static int simtec_i2c_remove(struct platform_device *dev)
0130 {
0131     struct simtec_i2c_data *pd = platform_get_drvdata(dev);
0132
0133     i2c_del_adapter(&pd->adap);
0134
0135     iounmap(pd->reg);
0136     release_mem_region(pd->ioarea->start, resource_size(pd->ioarea));
0137     kfree(pd);
0138
0139     return 0;
0140 }
0141
0142 /* device driver */
0143
0144 static struct platform_driver simtec_i2c_driver = {
0145     .driver     = {
0146         .name       = "simtec-i2c",
0147     },
0148     .probe      = simtec_i2c_probe,
0149     .remove     = simtec_i2c_remove,
0150 };
0151
0152 module_platform_driver(simtec_i2c_driver);
0153
0154 MODULE_DESCRIPTION("Simtec Generic I2C Bus driver");
0155 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
0156 MODULE_LICENSE("GPL");
0157 MODULE_ALIAS("platform:simtec-i2c");