drivers/thermal/broadcom/bcm2835_thermal.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Driver for Broadcom BCM2835 SoC temperature sensor
   4  *
   5  * Copyright (C) 2016 Martin Sperl
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/debugfs.h>
  10 #include <linux/device.h>
  11 #include <linux/err.h>
  12 #include <linux/io.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/of_address.h>
  17 #include <linux/of_device.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/thermal.h>
  20
  21 #include "../thermal_hwmon.h"
  22
  23 #define BCM2835_TS_TSENSCTL                     0x00
  24 #define BCM2835_TS_TSENSSTAT                    0x04
  25
  26 #define BCM2835_TS_TSENSCTL_PRWDW               BIT(0)
  27 #define BCM2835_TS_TSENSCTL_RSTB                BIT(1)
  28
  29 /*
  30  * bandgap reference voltage in 6 mV increments
  31  * 000b = 1178 mV, 001b = 1184 mV, ... 111b = 1220 mV
  32  */
  33 #define BCM2835_TS_TSENSCTL_CTRL_BITS           3
  34 #define BCM2835_TS_TSENSCTL_CTRL_SHIFT          2
  35 #define BCM2835_TS_TSENSCTL_CTRL_MASK               \
  36         GENMASK(BCM2835_TS_TSENSCTL_CTRL_BITS +     \
  37                 BCM2835_TS_TSENSCTL_CTRL_SHIFT - 1, \
  38                 BCM2835_TS_TSENSCTL_CTRL_SHIFT)
  39 #define BCM2835_TS_TSENSCTL_CTRL_DEFAULT        1
  40 #define BCM2835_TS_TSENSCTL_EN_INT              BIT(5)
  41 #define BCM2835_TS_TSENSCTL_DIRECT              BIT(6)
  42 #define BCM2835_TS_TSENSCTL_CLR_INT             BIT(7)
  43 #define BCM2835_TS_TSENSCTL_THOLD_SHIFT         8
  44 #define BCM2835_TS_TSENSCTL_THOLD_BITS          10
  45 #define BCM2835_TS_TSENSCTL_THOLD_MASK               \
  46         GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS +     \
  47                 BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
  48                 BCM2835_TS_TSENSCTL_THOLD_SHIFT)
  49 /*
  50  * time how long the block to be asserted in reset
  51  * which based on a clock counter (TSENS clock assumed)
  52  */
  53 #define BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT      18
  54 #define BCM2835_TS_TSENSCTL_RSTDELAY_BITS       8
  55 #define BCM2835_TS_TSENSCTL_REGULEN             BIT(26)
  56
  57 #define BCM2835_TS_TSENSSTAT_DATA_BITS          10
  58 #define BCM2835_TS_TSENSSTAT_DATA_SHIFT         0
  59 #define BCM2835_TS_TSENSSTAT_DATA_MASK               \
  60         GENMASK(BCM2835_TS_TSENSSTAT_DATA_BITS +     \
  61                 BCM2835_TS_TSENSSTAT_DATA_SHIFT - 1, \
  62                 BCM2835_TS_TSENSSTAT_DATA_SHIFT)
  63 #define BCM2835_TS_TSENSSTAT_VALID              BIT(10)
  64 #define BCM2835_TS_TSENSSTAT_INTERRUPT          BIT(11)
  65
  66 struct bcm2835_thermal_data {
  67         struct thermal_zone_device *tz;
  68         void __iomem *regs;
  69         struct clk *clk;
  70         struct dentry *debugfsdir;
  71 };
  72
  73 static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
  74 {
  75         return offset + slope * adc;
  76 }
  77
  78 static int bcm2835_thermal_temp2adc(int temp, int offset, int slope)
  79 {
  80         temp -= offset;
  81         temp /= slope;
  82
  83         if (temp < 0)
  84                 temp = 0;
  85         if (temp >= BIT(BCM2835_TS_TSENSSTAT_DATA_BITS))
  86                 temp = BIT(BCM2835_TS_TSENSSTAT_DATA_BITS) - 1;
  87
  88         return temp;
  89 }
  90
  91 static int bcm2835_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
  92 {
  93         struct bcm2835_thermal_data *data = thermal_zone_device_priv(tz);
  94         u32 val = readl(data->regs + BCM2835_TS_TSENSSTAT);
  95
  96         if (!(val & BCM2835_TS_TSENSSTAT_VALID))
  97                 return -EIO;
  98
  99         val &= BCM2835_TS_TSENSSTAT_DATA_MASK;
 100
 101         *temp = bcm2835_thermal_adc2temp(
 102                 val,
 103                 thermal_zone_get_offset(data->tz),
 104                 thermal_zone_get_slope(data->tz));
 105
 106         return 0;
 107 }
 108
 109 static const struct debugfs_reg32 bcm2835_thermal_regs[] = {
 110         {
 111                 .name = "ctl",
 112                 .offset = 0
 113         },
 114         {
 115                 .name = "stat",
 116                 .offset = 4
 117         }
 118 };
 119
 120 static void bcm2835_thermal_debugfs(struct platform_device *pdev)
 121 {
 122         struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
 123         struct debugfs_regset32 *regset;
 124
 125         data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);
 126
 127         regset = devm_kzalloc(&pdev->dev, sizeof(*regset), GFP_KERNEL);
 128         if (!regset)
 129                 return;
 130
 131         regset->regs = bcm2835_thermal_regs;
 132         regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
 133         regset->base = data->regs;
 134
 135         debugfs_create_regset32("regset", 0444, data->debugfsdir, regset);
 136 }
 137
 138 static const struct thermal_zone_device_ops bcm2835_thermal_ops = {
 139         .get_temp = bcm2835_thermal_get_temp,
 140 };
 141
 142 /*
 143  * Note: as per Raspberry Foundation FAQ
 144  * (https://www.raspberrypi.org/help/faqs/#performanceOperatingTemperature)
 145  * the recommended temperature range for the SoC -40C to +85C
 146  * so the trip limit is set to 80C.
 147  * this applies to all the BCM283X SoC
 148  */
 149
 150 static const struct of_device_id bcm2835_thermal_of_match_table[] = {
 151         {
 152                 .compatible = "brcm,bcm2835-thermal",
 153         },
 154         {
 155                 .compatible = "brcm,bcm2836-thermal",
 156         },
 157         {
 158                 .compatible = "brcm,bcm2837-thermal",
 159         },
 160         {},
 161 };
 162 MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
 163
 164 static int bcm2835_thermal_probe(struct platform_device *pdev)
 165 {
 166         struct device *dev = &pdev->dev;
 167         const struct of_device_id *match;
 168         struct thermal_zone_device *tz;
 169         struct bcm2835_thermal_data *data;
 170         int err = 0;
 171         u32 val;
 172         unsigned long rate;
 173
 174         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 175         if (!data)
 176                 return -ENOMEM;
 177
 178         match = of_match_device(bcm2835_thermal_of_match_table, dev);
 179         if (!match)
 180                 return -EINVAL;
 181
 182         data->regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
 183         if (IS_ERR(data->regs)) {
 184                 err = PTR_ERR(data->regs);
 185                 return err;
 186         }
 187
 188         data->clk = devm_clk_get_enabled(dev, NULL);
 189         if (IS_ERR(data->clk))
 190                 return dev_err_probe(dev, PTR_ERR(data->clk), "Could not get clk\n");
 191
 192         rate = clk_get_rate(data->clk);
 193         if ((rate < 1920000) || (rate > 5000000))
 194                 dev_warn(dev,
 195                          "Clock %pCn running at %lu Hz is outside of the recommended range: 1.92 to 5MHz\n",
 196                          data->clk, rate);
 197
 198         /* register of thermal sensor and get info from DT */
 199         tz = devm_thermal_of_zone_register(dev, 0, data, &bcm2835_thermal_ops);
 200         if (IS_ERR(tz))
 201                 return dev_err_probe(dev, PTR_ERR(tz), "Failed to register the thermal device\n");
 202
 203         /*
 204          * right now the FW does set up the HW-block, so we are not
 205          * touching the configuration registers.
 206          * But if the HW is not enabled, then set it up
 207          * using "sane" values used by the firmware right now.
 208          */
 209         val = readl(data->regs + BCM2835_TS_TSENSCTL);
 210         if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
 211                 int offset, slope, crit_temp;
 212
 213                 slope = thermal_zone_get_slope(tz);
 214                 offset = thermal_zone_get_offset(tz);
 215                 /*
 216                  * For now we deal only with critical, otherwise
 217                  * would need to iterate
 218                  */
 219                 err = thermal_zone_get_crit_temp(tz, &crit_temp);
 220                 if (err < 0) {
 221                         dev_err(dev, "Not able to read trip_temp: %d\n", err);
 222                         return err;
 223                 }
 224
 225                 /* set bandgap reference voltage and enable voltage regulator */
 226                 val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
 227                        BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
 228                       BCM2835_TS_TSENSCTL_REGULEN;
 229
 230                 /* use the recommended reset duration */
 231                 val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
 232
 233                 /*  trip_adc value from info */
 234                 val |= bcm2835_thermal_temp2adc(crit_temp,
 235                                                 offset,
 236                                                 slope)
 237                         << BCM2835_TS_TSENSCTL_THOLD_SHIFT;
 238
 239                 /* write the value back to the register as 2 steps */
 240                 writel(val, data->regs + BCM2835_TS_TSENSCTL);
 241                 val |= BCM2835_TS_TSENSCTL_RSTB;
 242                 writel(val, data->regs + BCM2835_TS_TSENSCTL);
 243         }
 244
 245         data->tz = tz;
 246
 247         platform_set_drvdata(pdev, data);
 248
 249         /*
 250          * Thermal_zone doesn't enable hwmon as default,
 251          * enable it here
 252          */
 253         err = thermal_add_hwmon_sysfs(tz);
 254         if (err)
 255                 return err;
 256
 257         bcm2835_thermal_debugfs(pdev);
 258
 259         return 0;
 260 }
 261
 262 static void bcm2835_thermal_remove(struct platform_device *pdev)
 263 {
 264         struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
 265
 266         debugfs_remove_recursive(data->debugfsdir);
 267 }
 268
 269 static struct platform_driver bcm2835_thermal_driver = {
 270         .probe = bcm2835_thermal_probe,
 271         .remove = bcm2835_thermal_remove,
 272         .driver = {
 273                 .name = "bcm2835_thermal",
 274                 .of_match_table = bcm2835_thermal_of_match_table,
 275         },
 276 };
 277 module_platform_driver(bcm2835_thermal_driver);
 278
 279 MODULE_AUTHOR("Martin Sperl");
 280 MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
 281 MODULE_LICENSE("GPL");