drivers/platform/chrome/chromeos_of_hw_prober.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * ChromeOS Device Tree Hardware Prober
   4  *
   5  * Copyright (c) 2024 Google LLC
   6  */
   7
   8 #include <linux/array_size.h>
   9 #include <linux/errno.h>
  10 #include <linux/i2c-of-prober.h>
  11 #include <linux/module.h>
  12 #include <linux/of.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/stddef.h>
  15
  16 #define DRV_NAME        "chromeos_of_hw_prober"
  17
  18 /**
  19  * struct hw_prober_entry - Holds an entry for the hardware prober
  20  *
  21  * @compatible: compatible string to match against the machine
  22  * @prober:     prober function to call when machine matches
  23  * @data:       extra data for the prober function
  24  */
  25 struct hw_prober_entry {
  26         const char *compatible;
  27         int (*prober)(struct device *dev, const void *data);
  28         const void *data;
  29 };
  30
  31 struct chromeos_i2c_probe_data {
  32         const struct i2c_of_probe_cfg *cfg;
  33         const struct i2c_of_probe_simple_opts *opts;
  34 };
  35
  36 static int chromeos_i2c_component_prober(struct device *dev, const void *_data)
  37 {
  38         const struct chromeos_i2c_probe_data *data = _data;
  39         struct i2c_of_probe_simple_ctx ctx = {
  40                 .opts = data->opts,
  41         };
  42
  43         return i2c_of_probe_component(dev, data->cfg, &ctx);
  44 }
  45
  46 #define DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(_type)                                     \
  47         static const struct i2c_of_probe_cfg chromeos_i2c_probe_simple_ ## _type ## _cfg = {    \
  48                 .type = #_type,                                                                 \
  49                 .ops = &i2c_of_probe_simple_ops,                                                \
  50         }
  51
  52 #define DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(_type)                                      \
  53         static const struct chromeos_i2c_probe_data chromeos_i2c_probe_dumb_ ## _type = {       \
  54                 .cfg = &(const struct i2c_of_probe_cfg) {                                       \
  55                         .type = #_type,                                                         \
  56                 },                                                                              \
  57         }
  58
  59 DEFINE_CHROMEOS_I2C_PROBE_DATA_DUMB_BY_TYPE(touchscreen);
  60
  61 DEFINE_CHROMEOS_I2C_PROBE_CFG_SIMPLE_BY_TYPE(trackpad);
  62
  63 static const struct chromeos_i2c_probe_data chromeos_i2c_probe_hana_trackpad = {
  64         .cfg = &chromeos_i2c_probe_simple_trackpad_cfg,
  65         .opts = &(const struct i2c_of_probe_simple_opts) {
  66                 .res_node_compatible = "elan,ekth3000",
  67                 .supply_name = "vcc",
  68                 /*
  69                  * ELAN trackpad needs 2 ms for H/W init and 100 ms for F/W init.
  70                  * Synaptics trackpad needs 100 ms.
  71                  * However, the regulator is set to "always-on", presumably to
  72                  * avoid this delay. The ELAN driver is also missing delays.
  73                  */
  74                 .post_power_on_delay_ms = 0,
  75         },
  76 };
  77
  78 static const struct hw_prober_entry hw_prober_platforms[] = {
  79         {
  80                 .compatible = "google,hana",
  81                 .prober = chromeos_i2c_component_prober,
  82                 .data = &chromeos_i2c_probe_dumb_touchscreen,
  83         }, {
  84                 .compatible = "google,hana",
  85                 .prober = chromeos_i2c_component_prober,
  86                 .data = &chromeos_i2c_probe_hana_trackpad,
  87         },
  88 };
  89
  90 static int chromeos_of_hw_prober_probe(struct platform_device *pdev)
  91 {
  92         for (size_t i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++) {
  93                 int ret;
  94
  95                 if (!of_machine_is_compatible(hw_prober_platforms[i].compatible))
  96                         continue;
  97
  98                 ret = hw_prober_platforms[i].prober(&pdev->dev, hw_prober_platforms[i].data);
  99                 /* Ignore unrecoverable errors and keep going through other probers */
 100                 if (ret == -EPROBE_DEFER)
 101                         return ret;
 102         }
 103
 104         return 0;
 105 }
 106
 107 static struct platform_driver chromeos_of_hw_prober_driver = {
 108         .probe  = chromeos_of_hw_prober_probe,
 109         .driver = {
 110                 .name = DRV_NAME,
 111         },
 112 };
 113
 114 static struct platform_device *chromeos_of_hw_prober_pdev;
 115
 116 static int chromeos_of_hw_prober_driver_init(void)
 117 {
 118         size_t i;
 119         int ret;
 120
 121         for (i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++)
 122                 if (of_machine_is_compatible(hw_prober_platforms[i].compatible))
 123                         break;
 124         if (i == ARRAY_SIZE(hw_prober_platforms))
 125                 return -ENODEV;
 126
 127         ret = platform_driver_register(&chromeos_of_hw_prober_driver);
 128         if (ret)
 129                 return ret;
 130
 131         chromeos_of_hw_prober_pdev =
 132                         platform_device_register_simple(DRV_NAME, PLATFORM_DEVID_NONE, NULL, 0);
 133         if (IS_ERR(chromeos_of_hw_prober_pdev))
 134                 goto err;
 135
 136         return 0;
 137
 138 err:
 139         platform_driver_unregister(&chromeos_of_hw_prober_driver);
 140
 141         return PTR_ERR(chromeos_of_hw_prober_pdev);
 142 }
 143 module_init(chromeos_of_hw_prober_driver_init);
 144
 145 static void chromeos_of_hw_prober_driver_exit(void)
 146 {
 147         platform_device_unregister(chromeos_of_hw_prober_pdev);
 148         platform_driver_unregister(&chromeos_of_hw_prober_driver);
 149 }
 150 module_exit(chromeos_of_hw_prober_driver_exit);
 151
 152 MODULE_LICENSE("GPL");
 153 MODULE_DESCRIPTION("ChromeOS device tree hardware prober");
 154 MODULE_IMPORT_NS("I2C_OF_PROBER");