drivers/thermal/broadcom/bcm2835_thermal.c

   1 /*
   2  * Driver for Broadcom BCM2835 SoC temperature sensor
   3  *
   4  * Copyright (C) 2016 Martin Sperl
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #include <linux/clk.h>
  18 #include <linux/debugfs.h>
  19 #include <linux/device.h>
  20 #include <linux/err.h>
  21 #include <linux/io.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/of.h>
  25 #include <linux/of_address.h>
  26 #include <linux/of_device.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/thermal.h>
  29
  30 #define BCM2835_TS_TSENSCTL                     0x00
  31 #define BCM2835_TS_TSENSSTAT                    0x04
  32
  33 #define BCM2835_TS_TSENSCTL_PRWDW               BIT(0)
  34 #define BCM2835_TS_TSENSCTL_RSTB                BIT(1)
  35
  36 /*
  37  * bandgap reference voltage in 6 mV increments
  38  * 000b = 1178 mV, 001b = 1184 mV, ... 111b = 1220 mV
  39  */
  40 #define BCM2835_TS_TSENSCTL_CTRL_BITS           3
  41 #define BCM2835_TS_TSENSCTL_CTRL_SHIFT          2
  42 #define BCM2835_TS_TSENSCTL_CTRL_MASK               \
  43         GENMASK(BCM2835_TS_TSENSCTL_CTRL_BITS +     \
  44                 BCM2835_TS_TSENSCTL_CTRL_SHIFT - 1, \
  45                 BCM2835_TS_TSENSCTL_CTRL_SHIFT)
  46 #define BCM2835_TS_TSENSCTL_CTRL_DEFAULT        1
  47 #define BCM2835_TS_TSENSCTL_EN_INT              BIT(5)
  48 #define BCM2835_TS_TSENSCTL_DIRECT              BIT(6)
  49 #define BCM2835_TS_TSENSCTL_CLR_INT             BIT(7)
  50 #define BCM2835_TS_TSENSCTL_THOLD_SHIFT         8
  51 #define BCM2835_TS_TSENSCTL_THOLD_BITS          10
  52 #define BCM2835_TS_TSENSCTL_THOLD_MASK               \
  53         GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS +     \
  54                 BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
  55                 BCM2835_TS_TSENSCTL_THOLD_SHIFT)
  56 /*
  57  * time how long the block to be asserted in reset
  58  * which based on a clock counter (TSENS clock assumed)
  59  */
  60 #define BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT      18
  61 #define BCM2835_TS_TSENSCTL_RSTDELAY_BITS       8
  62 #define BCM2835_TS_TSENSCTL_REGULEN             BIT(26)
  63
  64 #define BCM2835_TS_TSENSSTAT_DATA_BITS          10
  65 #define BCM2835_TS_TSENSSTAT_DATA_SHIFT         0
  66 #define BCM2835_TS_TSENSSTAT_DATA_MASK               \
  67         GENMASK(BCM2835_TS_TSENSSTAT_DATA_BITS +     \
  68                 BCM2835_TS_TSENSSTAT_DATA_SHIFT - 1, \
  69                 BCM2835_TS_TSENSSTAT_DATA_SHIFT)
  70 #define BCM2835_TS_TSENSSTAT_VALID              BIT(10)
  71 #define BCM2835_TS_TSENSSTAT_INTERRUPT          BIT(11)
  72
  73 struct bcm2835_thermal_data {
  74         struct thermal_zone_device *tz;
  75         void __iomem *regs;
  76         struct clk *clk;
  77         struct dentry *debugfsdir;
  78 };
  79
  80 static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
  81 {
  82         return offset + slope * adc;
  83 }
  84
  85 static int bcm2835_thermal_temp2adc(int temp, int offset, int slope)
  86 {
  87         temp -= offset;
  88         temp /= slope;
  89
  90         if (temp < 0)
  91                 temp = 0;
  92         if (temp >= BIT(BCM2835_TS_TSENSSTAT_DATA_BITS))
  93                 temp = BIT(BCM2835_TS_TSENSSTAT_DATA_BITS) - 1;
  94
  95         return temp;
  96 }
  97
  98 static int bcm2835_thermal_get_temp(void *d, int *temp)
  99 {
 100         struct bcm2835_thermal_data *data = d;
 101         u32 val = readl(data->regs + BCM2835_TS_TSENSSTAT);
 102
 103         if (!(val & BCM2835_TS_TSENSSTAT_VALID))
 104                 return -EIO;
 105
 106         val &= BCM2835_TS_TSENSSTAT_DATA_MASK;
 107
 108         *temp = bcm2835_thermal_adc2temp(
 109                 val,
 110                 thermal_zone_get_offset(data->tz),
 111                 thermal_zone_get_slope(data->tz));
 112
 113         return 0;
 114 }
 115
 116 static const struct debugfs_reg32 bcm2835_thermal_regs[] = {
 117         {
 118                 .name = "ctl",
 119                 .offset = 0
 120         },
 121         {
 122                 .name = "stat",
 123                 .offset = 4
 124         }
 125 };
 126
 127 static void bcm2835_thermal_debugfs(struct platform_device *pdev)
 128 {
 129         struct thermal_zone_device *tz = platform_get_drvdata(pdev);
 130         struct bcm2835_thermal_data *data = tz->devdata;
 131         struct debugfs_regset32 *regset;
 132
 133         data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);
 134         if (!data->debugfsdir)
 135                 return;
 136
 137         regset = devm_kzalloc(&pdev->dev, sizeof(*regset), GFP_KERNEL);
 138         if (!regset)
 139                 return;
 140
 141         regset->regs = bcm2835_thermal_regs;
 142         regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
 143         regset->base = data->regs;
 144
 145         debugfs_create_regset32("regset", 0444, data->debugfsdir, regset);
 146 }
 147
 148 static struct thermal_zone_of_device_ops bcm2835_thermal_ops = {
 149         .get_temp = bcm2835_thermal_get_temp,
 150 };
 151
 152 /*
 153  * Note: as per Raspberry Foundation FAQ
 154  * (https://www.raspberrypi.org/help/faqs/#performanceOperatingTemperature)
 155  * the recommended temperature range for the SoC -40C to +85C
 156  * so the trip limit is set to 80C.
 157  * this applies to all the BCM283X SoC
 158  */
 159
 160 static const struct of_device_id bcm2835_thermal_of_match_table[] = {
 161         {
 162                 .compatible = "brcm,bcm2835-thermal",
 163         },
 164         {
 165                 .compatible = "brcm,bcm2836-thermal",
 166         },
 167         {
 168                 .compatible = "brcm,bcm2837-thermal",
 169         },
 170         {},
 171 };
 172 MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
 173
 174 static int bcm2835_thermal_probe(struct platform_device *pdev)
 175 {
 176         const struct of_device_id *match;
 177         struct thermal_zone_device *tz;
 178         struct bcm2835_thermal_data *data;
 179         struct resource *res;
 180         int err = 0;
 181         u32 val;
 182         unsigned long rate;
 183
 184         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 185         if (!data)
 186                 return -ENOMEM;
 187
 188         match = of_match_device(bcm2835_thermal_of_match_table,
 189                                 &pdev->dev);
 190         if (!match)
 191                 return -EINVAL;
 192
 193         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 194         data->regs = devm_ioremap_resource(&pdev->dev, res);
 195         if (IS_ERR(data->regs)) {
 196                 err = PTR_ERR(data->regs);
 197                 dev_err(&pdev->dev, "Could not get registers: %d\n", err);
 198                 return err;
 199         }
 200
 201         data->clk = devm_clk_get(&pdev->dev, NULL);
 202         if (IS_ERR(data->clk)) {
 203                 err = PTR_ERR(data->clk);
 204                 if (err != -EPROBE_DEFER)
 205                         dev_err(&pdev->dev, "Could not get clk: %d\n", err);
 206                 return err;
 207         }
 208
 209         err = clk_prepare_enable(data->clk);
 210         if (err)
 211                 return err;
 212
 213         rate = clk_get_rate(data->clk);
 214         if ((rate < 1920000) || (rate > 5000000))
 215                 dev_warn(&pdev->dev,
 216                          "Clock %pCn running at %pCr Hz is outside of the recommended range: 1.92 to 5MHz\n",
 217                          data->clk, data->clk);
 218
 219         /* register of thermal sensor and get info from DT */
 220         tz = thermal_zone_of_sensor_register(&pdev->dev, 0, data,
 221                                              &bcm2835_thermal_ops);
 222         if (IS_ERR(tz)) {
 223                 err = PTR_ERR(tz);
 224                 dev_err(&pdev->dev,
 225                         "Failed to register the thermal device: %d\n",
 226                         err);
 227                 goto err_clk;
 228         }
 229
 230         /*
 231          * right now the FW does set up the HW-block, so we are not
 232          * touching the configuration registers.
 233          * But if the HW is not enabled, then set it up
 234          * using "sane" values used by the firmware right now.
 235          */
 236         val = readl(data->regs + BCM2835_TS_TSENSCTL);
 237         if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
 238                 int trip_temp, offset, slope;
 239
 240                 slope = thermal_zone_get_slope(tz);
 241                 offset = thermal_zone_get_offset(tz);
 242                 /*
 243                  * For now we deal only with critical, otherwise
 244                  * would need to iterate
 245                  */
 246                 err = tz->ops->get_trip_temp(tz, 0, &trip_temp);
 247                 if (err < 0) {
 248                         dev_err(&pdev->dev,
 249                                 "Not able to read trip_temp: %d\n",
 250                                 err);
 251                         goto err_tz;
 252                 }
 253
 254                 /* set bandgap reference voltage and enable voltage regulator */
 255                 val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
 256                        BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
 257                       BCM2835_TS_TSENSCTL_REGULEN;
 258
 259                 /* use the recommended reset duration */
 260                 val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
 261
 262                 /*  trip_adc value from info */
 263                 val |= bcm2835_thermal_temp2adc(trip_temp,
 264                                                 offset,
 265                                                 slope)
 266                         << BCM2835_TS_TSENSCTL_THOLD_SHIFT;
 267
 268                 /* write the value back to the register as 2 steps */
 269                 writel(val, data->regs + BCM2835_TS_TSENSCTL);
 270                 val |= BCM2835_TS_TSENSCTL_RSTB;
 271                 writel(val, data->regs + BCM2835_TS_TSENSCTL);
 272         }
 273
 274         data->tz = tz;
 275
 276         platform_set_drvdata(pdev, tz);
 277
 278         bcm2835_thermal_debugfs(pdev);
 279
 280         return 0;
 281 err_tz:
 282         thermal_zone_of_sensor_unregister(&pdev->dev, tz);
 283 err_clk:
 284         clk_disable_unprepare(data->clk);
 285
 286         return err;
 287 }
 288
 289 static int bcm2835_thermal_remove(struct platform_device *pdev)
 290 {
 291         struct thermal_zone_device *tz = platform_get_drvdata(pdev);
 292         struct bcm2835_thermal_data *data = tz->devdata;
 293
 294         debugfs_remove_recursive(data->debugfsdir);
 295         thermal_zone_of_sensor_unregister(&pdev->dev, tz);
 296         clk_disable_unprepare(data->clk);
 297
 298         return 0;
 299 }
 300
 301 static struct platform_driver bcm2835_thermal_driver = {
 302         .probe = bcm2835_thermal_probe,
 303         .remove = bcm2835_thermal_remove,
 304         .driver = {
 305                 .name = "bcm2835_thermal",
 306                 .of_match_table = bcm2835_thermal_of_match_table,
 307         },
 308 };
 309 module_platform_driver(bcm2835_thermal_driver);
 310
 311 MODULE_AUTHOR("Martin Sperl");
 312 MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
 313 MODULE_LICENSE("GPL");