1 // SPDX-License-Identifier: GPL-2.0+
3 * Driver for Broadcom BCM2835 SoC temperature sensor
5 * Copyright (C) 2016 Martin Sperl
9 #include <linux/debugfs.h>
10 #include <linux/device.h>
11 #include <linux/err.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
16 #include <linux/of_address.h>
17 #include <linux/of_device.h>
18 #include <linux/platform_device.h>
19 #include <linux/thermal.h>
21 #define BCM2835_TS_TSENSCTL 0x00
22 #define BCM2835_TS_TSENSSTAT 0x04
24 #define BCM2835_TS_TSENSCTL_PRWDW BIT(0)
25 #define BCM2835_TS_TSENSCTL_RSTB BIT(1)
28 * bandgap reference voltage in 6 mV increments
29 * 000b = 1178 mV, 001b = 1184 mV, ... 111b = 1220 mV
31 #define BCM2835_TS_TSENSCTL_CTRL_BITS 3
32 #define BCM2835_TS_TSENSCTL_CTRL_SHIFT 2
33 #define BCM2835_TS_TSENSCTL_CTRL_MASK \
34 GENMASK(BCM2835_TS_TSENSCTL_CTRL_BITS + \
35 BCM2835_TS_TSENSCTL_CTRL_SHIFT - 1, \
36 BCM2835_TS_TSENSCTL_CTRL_SHIFT)
37 #define BCM2835_TS_TSENSCTL_CTRL_DEFAULT 1
38 #define BCM2835_TS_TSENSCTL_EN_INT BIT(5)
39 #define BCM2835_TS_TSENSCTL_DIRECT BIT(6)
40 #define BCM2835_TS_TSENSCTL_CLR_INT BIT(7)
41 #define BCM2835_TS_TSENSCTL_THOLD_SHIFT 8
42 #define BCM2835_TS_TSENSCTL_THOLD_BITS 10
43 #define BCM2835_TS_TSENSCTL_THOLD_MASK \
44 GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS + \
45 BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
46 BCM2835_TS_TSENSCTL_THOLD_SHIFT)
48 * time how long the block to be asserted in reset
49 * which based on a clock counter (TSENS clock assumed)
51 #define BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT 18
52 #define BCM2835_TS_TSENSCTL_RSTDELAY_BITS 8
53 #define BCM2835_TS_TSENSCTL_REGULEN BIT(26)
55 #define BCM2835_TS_TSENSSTAT_DATA_BITS 10
56 #define BCM2835_TS_TSENSSTAT_DATA_SHIFT 0
57 #define BCM2835_TS_TSENSSTAT_DATA_MASK \
58 GENMASK(BCM2835_TS_TSENSSTAT_DATA_BITS + \
59 BCM2835_TS_TSENSSTAT_DATA_SHIFT - 1, \
60 BCM2835_TS_TSENSSTAT_DATA_SHIFT)
61 #define BCM2835_TS_TSENSSTAT_VALID BIT(10)
62 #define BCM2835_TS_TSENSSTAT_INTERRUPT BIT(11)
64 struct bcm2835_thermal_data {
65 struct thermal_zone_device *tz;
68 struct dentry *debugfsdir;
71 static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
73 return offset + slope * adc;
76 static int bcm2835_thermal_temp2adc(int temp, int offset, int slope)
83 if (temp >= BIT(BCM2835_TS_TSENSSTAT_DATA_BITS))
84 temp = BIT(BCM2835_TS_TSENSSTAT_DATA_BITS) - 1;
89 static int bcm2835_thermal_get_temp(void *d, int *temp)
91 struct bcm2835_thermal_data *data = d;
92 u32 val = readl(data->regs + BCM2835_TS_TSENSSTAT);
94 if (!(val & BCM2835_TS_TSENSSTAT_VALID))
97 val &= BCM2835_TS_TSENSSTAT_DATA_MASK;
99 *temp = bcm2835_thermal_adc2temp(
101 thermal_zone_get_offset(data->tz),
102 thermal_zone_get_slope(data->tz));
107 static const struct debugfs_reg32 bcm2835_thermal_regs[] = {
118 static void bcm2835_thermal_debugfs(struct platform_device *pdev)
120 struct thermal_zone_device *tz = platform_get_drvdata(pdev);
121 struct bcm2835_thermal_data *data = tz->devdata;
122 struct debugfs_regset32 *regset;
124 data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);
125 if (!data->debugfsdir)
128 regset = devm_kzalloc(&pdev->dev, sizeof(*regset), GFP_KERNEL);
132 regset->regs = bcm2835_thermal_regs;
133 regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
134 regset->base = data->regs;
136 debugfs_create_regset32("regset", 0444, data->debugfsdir, regset);
139 static const struct thermal_zone_of_device_ops bcm2835_thermal_ops = {
140 .get_temp = bcm2835_thermal_get_temp,
144 * Note: as per Raspberry Foundation FAQ
145 * (https://www.raspberrypi.org/help/faqs/#performanceOperatingTemperature)
146 * the recommended temperature range for the SoC -40C to +85C
147 * so the trip limit is set to 80C.
148 * this applies to all the BCM283X SoC
151 static const struct of_device_id bcm2835_thermal_of_match_table[] = {
153 .compatible = "brcm,bcm2835-thermal",
156 .compatible = "brcm,bcm2836-thermal",
159 .compatible = "brcm,bcm2837-thermal",
163 MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
165 static int bcm2835_thermal_probe(struct platform_device *pdev)
167 const struct of_device_id *match;
168 struct thermal_zone_device *tz;
169 struct bcm2835_thermal_data *data;
170 struct resource *res;
175 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
179 match = of_match_device(bcm2835_thermal_of_match_table,
184 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
185 data->regs = devm_ioremap_resource(&pdev->dev, res);
186 if (IS_ERR(data->regs)) {
187 err = PTR_ERR(data->regs);
188 dev_err(&pdev->dev, "Could not get registers: %d\n", err);
192 data->clk = devm_clk_get(&pdev->dev, NULL);
193 if (IS_ERR(data->clk)) {
194 err = PTR_ERR(data->clk);
195 if (err != -EPROBE_DEFER)
196 dev_err(&pdev->dev, "Could not get clk: %d\n", err);
200 err = clk_prepare_enable(data->clk);
204 rate = clk_get_rate(data->clk);
205 if ((rate < 1920000) || (rate > 5000000))
207 "Clock %pCn running at %lu Hz is outside of the recommended range: 1.92 to 5MHz\n",
210 /* register of thermal sensor and get info from DT */
211 tz = thermal_zone_of_sensor_register(&pdev->dev, 0, data,
212 &bcm2835_thermal_ops);
216 "Failed to register the thermal device: %d\n",
222 * right now the FW does set up the HW-block, so we are not
223 * touching the configuration registers.
224 * But if the HW is not enabled, then set it up
225 * using "sane" values used by the firmware right now.
227 val = readl(data->regs + BCM2835_TS_TSENSCTL);
228 if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
229 int trip_temp, offset, slope;
231 slope = thermal_zone_get_slope(tz);
232 offset = thermal_zone_get_offset(tz);
234 * For now we deal only with critical, otherwise
235 * would need to iterate
237 err = tz->ops->get_trip_temp(tz, 0, &trip_temp);
240 "Not able to read trip_temp: %d\n",
245 /* set bandgap reference voltage and enable voltage regulator */
246 val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
247 BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
248 BCM2835_TS_TSENSCTL_REGULEN;
250 /* use the recommended reset duration */
251 val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
253 /* trip_adc value from info */
254 val |= bcm2835_thermal_temp2adc(trip_temp,
257 << BCM2835_TS_TSENSCTL_THOLD_SHIFT;
259 /* write the value back to the register as 2 steps */
260 writel(val, data->regs + BCM2835_TS_TSENSCTL);
261 val |= BCM2835_TS_TSENSCTL_RSTB;
262 writel(val, data->regs + BCM2835_TS_TSENSCTL);
267 platform_set_drvdata(pdev, tz);
269 bcm2835_thermal_debugfs(pdev);
273 thermal_zone_of_sensor_unregister(&pdev->dev, tz);
275 clk_disable_unprepare(data->clk);
280 static int bcm2835_thermal_remove(struct platform_device *pdev)
282 struct thermal_zone_device *tz = platform_get_drvdata(pdev);
283 struct bcm2835_thermal_data *data = tz->devdata;
285 debugfs_remove_recursive(data->debugfsdir);
286 thermal_zone_of_sensor_unregister(&pdev->dev, tz);
287 clk_disable_unprepare(data->clk);
292 static struct platform_driver bcm2835_thermal_driver = {
293 .probe = bcm2835_thermal_probe,
294 .remove = bcm2835_thermal_remove,
296 .name = "bcm2835_thermal",
297 .of_match_table = bcm2835_thermal_of_match_table,
300 module_platform_driver(bcm2835_thermal_driver);
302 MODULE_AUTHOR("Martin Sperl");
303 MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
304 MODULE_LICENSE("GPL");