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 const struct of_device_id *match; 167 struct thermal_zone_device *tz; 168 struct bcm2835_thermal_data *data; 169 int err = 0; 170 u32 val; 171 unsigned long rate; 172 173 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 174 if (!data) 175 return -ENOMEM; 176 177 match = of_match_device(bcm2835_thermal_of_match_table, 178 &pdev->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(&pdev->dev, NULL); 189 if (IS_ERR(data->clk)) { 190 err = PTR_ERR(data->clk); 191 if (err != -EPROBE_DEFER) 192 dev_err(&pdev->dev, "Could not get clk: %d\n", err); 193 return err; 194 } 195 196 err = clk_prepare_enable(data->clk); 197 if (err) 198 return err; 199 200 rate = clk_get_rate(data->clk); 201 if ((rate < 1920000) || (rate > 5000000)) 202 dev_warn(&pdev->dev, 203 "Clock %pCn running at %lu Hz is outside of the recommended range: 1.92 to 5MHz\n", 204 data->clk, rate); 205 206 /* register of thermal sensor and get info from DT */ 207 tz = devm_thermal_of_zone_register(&pdev->dev, 0, data, 208 &bcm2835_thermal_ops); 209 if (IS_ERR(tz)) { 210 err = PTR_ERR(tz); 211 dev_err(&pdev->dev, 212 "Failed to register the thermal device: %d\n", 213 err); 214 goto err_clk; 215 } 216 217 /* 218 * right now the FW does set up the HW-block, so we are not 219 * touching the configuration registers. 220 * But if the HW is not enabled, then set it up 221 * using "sane" values used by the firmware right now. 222 */ 223 val = readl(data->regs + BCM2835_TS_TSENSCTL); 224 if (!(val & BCM2835_TS_TSENSCTL_RSTB)) { 225 struct thermal_trip trip; 226 int offset, slope; 227 228 slope = thermal_zone_get_slope(tz); 229 offset = thermal_zone_get_offset(tz); 230 /* 231 * For now we deal only with critical, otherwise 232 * would need to iterate 233 */ 234 err = thermal_zone_get_trip(tz, 0, &trip); 235 if (err < 0) { 236 dev_err(&pdev->dev, 237 "Not able to read trip_temp: %d\n", 238 err); 239 goto err_tz; 240 } 241 242 /* set bandgap reference voltage and enable voltage regulator */ 243 val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT << 244 BCM2835_TS_TSENSCTL_CTRL_SHIFT) | 245 BCM2835_TS_TSENSCTL_REGULEN; 246 247 /* use the recommended reset duration */ 248 val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT); 249 250 /* trip_adc value from info */ 251 val |= bcm2835_thermal_temp2adc(trip.temperature, 252 offset, 253 slope) 254 << BCM2835_TS_TSENSCTL_THOLD_SHIFT; 255 256 /* write the value back to the register as 2 steps */ 257 writel(val, data->regs + BCM2835_TS_TSENSCTL); 258 val |= BCM2835_TS_TSENSCTL_RSTB; 259 writel(val, data->regs + BCM2835_TS_TSENSCTL); 260 } 261 262 data->tz = tz; 263 264 platform_set_drvdata(pdev, data); 265 266 /* 267 * Thermal_zone doesn't enable hwmon as default, 268 * enable it here 269 */ 270 err = thermal_add_hwmon_sysfs(tz); 271 if (err) 272 goto err_tz; 273 274 bcm2835_thermal_debugfs(pdev); 275 276 return 0; 277 err_tz: 278 devm_thermal_of_zone_unregister(&pdev->dev, tz); 279 err_clk: 280 clk_disable_unprepare(data->clk); 281 282 return err; 283 } 284 285 static int bcm2835_thermal_remove(struct platform_device *pdev) 286 { 287 struct bcm2835_thermal_data *data = platform_get_drvdata(pdev); 288 289 debugfs_remove_recursive(data->debugfsdir); 290 clk_disable_unprepare(data->clk); 291 292 return 0; 293 } 294 295 static struct platform_driver bcm2835_thermal_driver = { 296 .probe = bcm2835_thermal_probe, 297 .remove = bcm2835_thermal_remove, 298 .driver = { 299 .name = "bcm2835_thermal", 300 .of_match_table = bcm2835_thermal_of_match_table, 301 }, 302 }; 303 module_platform_driver(bcm2835_thermal_driver); 304 305 MODULE_AUTHOR("Martin Sperl"); 306 MODULE_DESCRIPTION("Thermal driver for bcm2835 chip"); 307 MODULE_LICENSE("GPL"); 308