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	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;
277err_tz:
278	devm_thermal_of_zone_unregister(&pdev->dev, tz);
279err_clk:
280	clk_disable_unprepare(data->clk);
281
282	return err;
283}
284
285static void 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
293static struct platform_driver bcm2835_thermal_driver = {
294	.probe = bcm2835_thermal_probe,
295	.remove_new = bcm2835_thermal_remove,
296	.driver = {
297		.name = "bcm2835_thermal",
298		.of_match_table = bcm2835_thermal_of_match_table,
299	},
300};
301module_platform_driver(bcm2835_thermal_driver);
302
303MODULE_AUTHOR("Martin Sperl");
304MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
305MODULE_LICENSE("GPL");
306