drivers/i2c/busses/i2c-pasemi-platform.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2021 The Asahi Linux Contributors
   4  *
   5  * PA Semi PWRficient SMBus host driver for Apple SoCs
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/i2c.h>
  10 #include <linux/io.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/types.h>
  15
  16 #include "i2c-pasemi-core.h"
  17
  18 struct pasemi_platform_i2c_data {
  19         struct pasemi_smbus smbus;
  20         struct clk *clk_ref;
  21 };
  22
  23 static int
  24 pasemi_platform_i2c_calc_clk_div(struct pasemi_platform_i2c_data *data,
  25                                  u32 frequency)
  26 {
  27         unsigned long clk_rate = clk_get_rate(data->clk_ref);
  28
  29         if (!clk_rate)
  30                 return -EINVAL;
  31
  32         data->smbus.clk_div = DIV_ROUND_UP(clk_rate, 16 * frequency);
  33         if (data->smbus.clk_div < 4)
  34                 return dev_err_probe(data->smbus.dev, -EINVAL,
  35                                      "Bus frequency %d is too fast.\n",
  36                                      frequency);
  37         if (data->smbus.clk_div > 0xff)
  38                 return dev_err_probe(data->smbus.dev, -EINVAL,
  39                                      "Bus frequency %d is too slow.\n",
  40                                      frequency);
  41
  42         return 0;
  43 }
  44
  45 static int pasemi_platform_i2c_probe(struct platform_device *pdev)
  46 {
  47         struct device *dev = &pdev->dev;
  48         struct pasemi_platform_i2c_data *data;
  49         struct pasemi_smbus *smbus;
  50         u32 frequency;
  51         int error;
  52
  53         data = devm_kzalloc(dev, sizeof(struct pasemi_platform_i2c_data),
  54                             GFP_KERNEL);
  55         if (!data)
  56                 return -ENOMEM;
  57
  58         smbus = &data->smbus;
  59         smbus->dev = dev;
  60
  61         smbus->ioaddr = devm_platform_ioremap_resource(pdev, 0);
  62         if (IS_ERR(smbus->ioaddr))
  63                 return PTR_ERR(smbus->ioaddr);
  64
  65         if (of_property_read_u32(dev->of_node, "clock-frequency", &frequency))
  66                 frequency = I2C_MAX_STANDARD_MODE_FREQ;
  67
  68         data->clk_ref = devm_clk_get(dev, NULL);
  69         if (IS_ERR(data->clk_ref))
  70                 return PTR_ERR(data->clk_ref);
  71
  72         error = clk_prepare_enable(data->clk_ref);
  73         if (error)
  74                 return error;
  75
  76         error = pasemi_platform_i2c_calc_clk_div(data, frequency);
  77         if (error)
  78                 goto out_clk_disable;
  79
  80         smbus->adapter.dev.of_node = pdev->dev.of_node;
  81         error = pasemi_i2c_common_probe(smbus);
  82         if (error)
  83                 goto out_clk_disable;
  84
  85         platform_set_drvdata(pdev, data);
  86
  87         return 0;
  88
  89 out_clk_disable:
  90         clk_disable_unprepare(data->clk_ref);
  91
  92         return error;
  93 }
  94
  95 static int pasemi_platform_i2c_remove(struct platform_device *pdev)
  96 {
  97         struct pasemi_platform_i2c_data *data = platform_get_drvdata(pdev);
  98
  99         clk_disable_unprepare(data->clk_ref);
 100         return 0;
 101 }
 102
 103 static const struct of_device_id pasemi_platform_i2c_of_match[] = {
 104         { .compatible = "apple,t8103-i2c" },
 105         { .compatible = "apple,i2c" },
 106         {},
 107 };
 108 MODULE_DEVICE_TABLE(of, pasemi_platform_i2c_of_match);
 109
 110 static struct platform_driver pasemi_platform_i2c_driver = {
 111         .driver = {
 112                 .name                   = "i2c-apple",
 113                 .of_match_table         = pasemi_platform_i2c_of_match,
 114         },
 115         .probe  = pasemi_platform_i2c_probe,
 116         .remove = pasemi_platform_i2c_remove,
 117 };
 118 module_platform_driver(pasemi_platform_i2c_driver);
 119
 120 MODULE_LICENSE("GPL");
 121 MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>");
 122 MODULE_DESCRIPTION("Apple/PASemi SMBus platform driver");