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
 66struct bcm2835_thermal_data {
 67	struct thermal_zone_device *tz;
 68	void __iomem *regs;
 69	struct clk *clk;
 70	struct dentry *debugfsdir;
 71};
 72
 73static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
 74{
 75	return offset + slope * adc;
 76}
 77
 78static 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
 91static 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
109static 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
120static 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
138static 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
150static 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};
162MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
163
164static 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 %pC 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
262static 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
269static 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};
277module_platform_driver(bcm2835_thermal_driver);
278
279MODULE_AUTHOR("Martin Sperl");
280MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
281MODULE_LICENSE("GPL");