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