i2c/busses/i2c-pasemi-platform.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2021 The Asahi Linux Contributors
0004  *
0005  * PA Semi PWRficient SMBus host driver for Apple SoCs
0006  */
0007
0008 #include <linux/clk.h>
0009 #include <linux/i2c.h>
0010 #include <linux/io.h>
0011 #include <linux/kernel.h>
0012 #include <linux/module.h>
0013 #include <linux/platform_device.h>
0014 #include <linux/types.h>
0015
0016 #include "i2c-pasemi-core.h"
0017
0018 struct pasemi_platform_i2c_data {
0019     struct pasemi_smbus smbus;
0020     struct clk *clk_ref;
0021 };
0022
0023 static int
0024 pasemi_platform_i2c_calc_clk_div(struct pasemi_platform_i2c_data *data,
0025                  u32 frequency)
0026 {
0027     unsigned long clk_rate = clk_get_rate(data->clk_ref);
0028
0029     if (!clk_rate)
0030         return -EINVAL;
0031
0032     data->smbus.clk_div = DIV_ROUND_UP(clk_rate, 16 * frequency);
0033     if (data->smbus.clk_div < 4)
0034         return dev_err_probe(data->smbus.dev, -EINVAL,
0035                      "Bus frequency %d is too fast.\n",
0036                      frequency);
0037     if (data->smbus.clk_div > 0xff)
0038         return dev_err_probe(data->smbus.dev, -EINVAL,
0039                      "Bus frequency %d is too slow.\n",
0040                      frequency);
0041
0042     return 0;
0043 }
0044
0045 static int pasemi_platform_i2c_probe(struct platform_device *pdev)
0046 {
0047     struct device *dev = &pdev->dev;
0048     struct pasemi_platform_i2c_data *data;
0049     struct pasemi_smbus *smbus;
0050     u32 frequency;
0051     int error;
0052
0053     data = devm_kzalloc(dev, sizeof(struct pasemi_platform_i2c_data),
0054                 GFP_KERNEL);
0055     if (!data)
0056         return -ENOMEM;
0057
0058     smbus = &data->smbus;
0059     smbus->dev = dev;
0060
0061     smbus->ioaddr = devm_platform_ioremap_resource(pdev, 0);
0062     if (IS_ERR(smbus->ioaddr))
0063         return PTR_ERR(smbus->ioaddr);
0064
0065     if (of_property_read_u32(dev->of_node, "clock-frequency", &frequency))
0066         frequency = I2C_MAX_STANDARD_MODE_FREQ;
0067
0068     data->clk_ref = devm_clk_get(dev, NULL);
0069     if (IS_ERR(data->clk_ref))
0070         return PTR_ERR(data->clk_ref);
0071
0072     error = clk_prepare_enable(data->clk_ref);
0073     if (error)
0074         return error;
0075
0076     error = pasemi_platform_i2c_calc_clk_div(data, frequency);
0077     if (error)
0078         goto out_clk_disable;
0079
0080     smbus->adapter.dev.of_node = pdev->dev.of_node;
0081     error = pasemi_i2c_common_probe(smbus);
0082     if (error)
0083         goto out_clk_disable;
0084
0085     platform_set_drvdata(pdev, data);
0086
0087     return 0;
0088
0089 out_clk_disable:
0090     clk_disable_unprepare(data->clk_ref);
0091
0092     return error;
0093 }
0094
0095 static int pasemi_platform_i2c_remove(struct platform_device *pdev)
0096 {
0097     struct pasemi_platform_i2c_data *data = platform_get_drvdata(pdev);
0098
0099     clk_disable_unprepare(data->clk_ref);
0100     return 0;
0101 }
0102
0103 static const struct of_device_id pasemi_platform_i2c_of_match[] = {
0104     { .compatible = "apple,t8103-i2c" },
0105     { .compatible = "apple,i2c" },
0106     {},
0107 };
0108 MODULE_DEVICE_TABLE(of, pasemi_platform_i2c_of_match);
0109
0110 static struct platform_driver pasemi_platform_i2c_driver = {
0111     .driver = {
0112         .name           = "i2c-apple",
0113         .of_match_table     = pasemi_platform_i2c_of_match,
0114     },
0115     .probe  = pasemi_platform_i2c_probe,
0116     .remove = pasemi_platform_i2c_remove,
0117 };
0118 module_platform_driver(pasemi_platform_i2c_driver);
0119
0120 MODULE_LICENSE("GPL");
0121 MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
0122 MODULE_DESCRIPTION("Apple/PASemi SMBus platform driver");