drivers/hwmon/sparx5-temp.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Sparx5 SoC temperature sensor driver
   3  *
   4  * Copyright (C) 2020 Lars Povlsen <lars.povlsen@microchip.com>
   5  */
   6
   7 #include <linux/bitfield.h>
   8 #include <linux/clk.h>
   9 #include <linux/hwmon.h>
  10 #include <linux/init.h>
  11 #include <linux/io.h>
  12 #include <linux/mod_devicetable.h>
  13 #include <linux/module.h>
  14 #include <linux/platform_device.h>
  15
  16 #define TEMP_CTRL               0
  17 #define TEMP_CFG                4
  18 #define  TEMP_CFG_CYCLES        GENMASK(24, 15)
  19 #define  TEMP_CFG_ENA           BIT(0)
  20 #define TEMP_STAT               8
  21 #define  TEMP_STAT_VALID        BIT(12)
  22 #define  TEMP_STAT_TEMP         GENMASK(11, 0)
  23
  24 struct s5_hwmon {
  25         void __iomem *base;
  26         struct clk *clk;
  27 };
  28
  29 static void s5_temp_enable(struct s5_hwmon *hwmon)
  30 {
  31         u32 val = readl(hwmon->base + TEMP_CFG);
  32         u32 clk = clk_get_rate(hwmon->clk) / USEC_PER_SEC;
  33
  34         val &= ~TEMP_CFG_CYCLES;
  35         val |= FIELD_PREP(TEMP_CFG_CYCLES, clk);
  36         val |= TEMP_CFG_ENA;
  37
  38         writel(val, hwmon->base + TEMP_CFG);
  39 }
  40
  41 static int s5_read(struct device *dev, enum hwmon_sensor_types type,
  42                    u32 attr, int channel, long *temp)
  43 {
  44         struct s5_hwmon *hwmon = dev_get_drvdata(dev);
  45         int rc = 0, value;
  46         u32 stat;
  47
  48         switch (attr) {
  49         case hwmon_temp_input:
  50                 stat = readl_relaxed(hwmon->base + TEMP_STAT);
  51                 if (!(stat & TEMP_STAT_VALID))
  52                         return -EAGAIN;
  53                 value = stat & TEMP_STAT_TEMP;
  54                 /*
  55                  * From register documentation:
  56                  * Temp(C) = TEMP_SENSOR_STAT.TEMP / 4096 * 352.2 - 109.4
  57                  */
  58                 value = DIV_ROUND_CLOSEST(value * 3522, 4096) - 1094;
  59                 /*
  60                  * Scale down by 10 from above and multiply by 1000 to
  61                  * have millidegrees as specified by the hwmon sysfs
  62                  * interface.
  63                  */
  64                 value *= 100;
  65                 *temp = value;
  66                 break;
  67         default:
  68                 rc = -EOPNOTSUPP;
  69                 break;
  70         }
  71
  72         return rc;
  73 }
  74
  75 static umode_t s5_is_visible(const void *_data, enum hwmon_sensor_types type,
  76                              u32 attr, int channel)
  77 {
  78         if (type != hwmon_temp)
  79                 return 0;
  80
  81         switch (attr) {
  82         case hwmon_temp_input:
  83                 return 0444;
  84         default:
  85                 return 0;
  86         }
  87 }
  88
  89 static const struct hwmon_channel_info * const s5_info[] = {
  90         HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
  91         HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
  92         NULL
  93 };
  94
  95 static const struct hwmon_ops s5_hwmon_ops = {
  96         .is_visible = s5_is_visible,
  97         .read = s5_read,
  98 };
  99
 100 static const struct hwmon_chip_info s5_chip_info = {
 101         .ops = &s5_hwmon_ops,
 102         .info = s5_info,
 103 };
 104
 105 static int s5_temp_probe(struct platform_device *pdev)
 106 {
 107         struct device *hwmon_dev;
 108         struct s5_hwmon *hwmon;
 109
 110         hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
 111         if (!hwmon)
 112                 return -ENOMEM;
 113
 114         hwmon->base = devm_platform_ioremap_resource(pdev, 0);
 115         if (IS_ERR(hwmon->base))
 116                 return PTR_ERR(hwmon->base);
 117
 118         hwmon->clk = devm_clk_get_enabled(&pdev->dev, NULL);
 119         if (IS_ERR(hwmon->clk))
 120                 return PTR_ERR(hwmon->clk);
 121
 122         s5_temp_enable(hwmon);
 123
 124         hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
 125                                                          "s5_temp",
 126                                                          hwmon,
 127                                                          &s5_chip_info,
 128                                                          NULL);
 129
 130         return PTR_ERR_OR_ZERO(hwmon_dev);
 131 }
 132
 133 static const struct of_device_id s5_temp_match[] = {
 134         { .compatible = "microchip,sparx5-temp" },
 135         {},
 136 };
 137 MODULE_DEVICE_TABLE(of, s5_temp_match);
 138
 139 static struct platform_driver s5_temp_driver = {
 140         .probe = s5_temp_probe,
 141         .driver = {
 142                 .name = "sparx5-temp",
 143                 .of_match_table = s5_temp_match,
 144         },
 145 };
 146
 147 module_platform_driver(s5_temp_driver);
 148
 149 MODULE_AUTHOR("Lars Povlsen <lars.povlsen@microchip.com>");
 150 MODULE_DESCRIPTION("Sparx5 SoC temperature sensor driver");
 151 MODULE_LICENSE("GPL");