// SPDX-License-Identifier: GPL-2.0+
/*
* Driver for Broadcom BCM2835 SoC temperature sensor
*
* Copyright (C) 2016 Martin Sperl
*/
#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/thermal.h>
#include "../thermal_hwmon.h"
#define BCM2835_TS_TSENSCTL 0x00
#define BCM2835_TS_TSENSSTAT 0x04
#define BCM2835_TS_TSENSCTL_PRWDW BIT(0)
#define BCM2835_TS_TSENSCTL_RSTB BIT(1)
/*
* bandgap reference voltage in 6 mV increments
* 000b = 1178 mV, 001b = 1184 mV, ... 111b = 1220 mV
*/
#define BCM2835_TS_TSENSCTL_CTRL_BITS 3
#define BCM2835_TS_TSENSCTL_CTRL_SHIFT 2
#define BCM2835_TS_TSENSCTL_CTRL_MASK \
GENMASK(BCM2835_TS_TSENSCTL_CTRL_BITS + \
BCM2835_TS_TSENSCTL_CTRL_SHIFT - 1, \
BCM2835_TS_TSENSCTL_CTRL_SHIFT)
#define BCM2835_TS_TSENSCTL_CTRL_DEFAULT 1
#define BCM2835_TS_TSENSCTL_EN_INT BIT(5)
#define BCM2835_TS_TSENSCTL_DIRECT BIT(6)
#define BCM2835_TS_TSENSCTL_CLR_INT BIT(7)
#define BCM2835_TS_TSENSCTL_THOLD_SHIFT 8
#define BCM2835_TS_TSENSCTL_THOLD_BITS 10
#define BCM2835_TS_TSENSCTL_THOLD_MASK \
GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS + \
BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
BCM2835_TS_TSENSCTL_THOLD_SHIFT)
/*
* time how long the block to be asserted in reset
* which based on a clock counter (TSENS clock assumed)
*/
#define BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT 18
#define BCM2835_TS_TSENSCTL_RSTDELAY_BITS 8
#define BCM2835_TS_TSENSCTL_REGULEN BIT(26)
#define BCM2835_TS_TSENSSTAT_DATA_BITS 10
#define BCM2835_TS_TSENSSTAT_DATA_SHIFT 0
#define BCM2835_TS_TSENSSTAT_DATA_MASK \
GENMASK(BCM2835_TS_TSENSSTAT_DATA_BITS + \
BCM2835_TS_TSENSSTAT_DATA_SHIFT - 1, \
BCM2835_TS_TSENSSTAT_DATA_SHIFT)
#define BCM2835_TS_TSENSSTAT_VALID BIT(10)
#define BCM2835_TS_TSENSSTAT_INTERRUPT BIT(11)
struct bcm2835_thermal_data {
struct thermal_zone_device *tz;
void __iomem *regs;
struct clk *clk;
struct dentry *debugfsdir;
};
static int bcm2835_thermal_adc2temp(u32 adc,
int offset,
int slope)
{
return offset + slope * adc;
}
static int bcm2835_thermal_temp2adc(
int temp,
int offset,
int slope)
{
temp -= offset;
temp /= slope;
if (temp < 0)
temp = 0;
if (temp >= BIT(BCM2835_TS_TSENSSTAT_DATA_BITS))
temp = BIT(BCM2835_TS_TSENSSTAT_DATA_BITS) - 1;
return temp;
}
static int bcm2835_thermal_get_temp(
struct thermal_zone_device *tz,
int *temp)
{
struct bcm2835_thermal_data *data = thermal_zone_device_priv(tz);
u32 val = readl(data->regs + BCM2835_TS_TSENSSTAT);
if (!(val & BCM2835_TS_TSENSSTAT_VALID))
return -EIO;
val &= BCM2835_TS_TSENSSTAT_DATA_MASK;
*temp = bcm2835_thermal_adc2temp(
val,
thermal_zone_get_offset(data->tz),
thermal_zone_get_slope(data->tz));
return 0;
}
static const struct debugfs_reg32 bcm2835_thermal_regs[] = {
{
.name =
"ctl",
.offset = 0
},
{
.name =
"stat",
.offset = 4
}
};
static void bcm2835_thermal_debugfs(
struct platform_device *pdev)
{
struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
struct debugfs_regset32 *regset;
data->debugfsdir = debugfs_create_dir(
"bcm2835_thermal", NULL);
regset = devm_kzalloc(&pdev->dev,
sizeof(*regset), GFP_KERNEL);
if (!regset)
return;
regset->regs = bcm2835_thermal_regs;
regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
regset->base = data->regs;
debugfs_create_regset32(
"regset", 0444, data->debugfsdir, regset);
}
static const struct thermal_zone_device_ops bcm2835_thermal_ops = {
.get_temp = bcm2835_thermal_get_temp,
};
/*
* Note: as per Raspberry Foundation FAQ
* (https://www.raspberrypi.org/help/faqs/#performanceOperatingTemperature)
* the recommended temperature range for the SoC -40C to +85C
* so the trip limit is set to 80C.
* this applies to all the BCM283X SoC
*/
static const struct of_device_id bcm2835_thermal_of_match_table[] = {
{
.compatible =
"brcm,bcm2835-thermal",
},
{
.compatible =
"brcm,bcm2836-thermal",
},
{
.compatible =
"brcm,bcm2837-thermal",
},
{},
};
MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
static int bcm2835_thermal_probe(
struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
const struct of_device_id *match;
struct thermal_zone_device *tz;
struct bcm2835_thermal_data *data;
int err = 0;
u32 val;
unsigned long rate;
data = devm_kzalloc(dev,
sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
match = of_match_device(bcm2835_thermal_of_match_table, dev);
if (!match)
return -EINVAL;
data->regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
if (IS_ERR(data->regs)) {
err = PTR_ERR(data->regs);
return err;
}
data->clk = devm_clk_get_enabled(dev, NULL);
if (IS_ERR(data->clk))
return dev_err_probe(dev, PTR_ERR(data->clk),
"Could not get clk\n");
rate = clk_get_rate(data->clk);
if ((rate < 1920000) || (rate > 5000000))
dev_warn(dev,
"Clock %pC running at %lu Hz is outside of the recommended range: 1.92 to 5MHz\n",
data->clk, rate);
/* register of thermal sensor and get info from DT */
tz = devm_thermal_of_zone_register(dev, 0, data, &bcm2835_thermal_ops);
if (IS_ERR(tz))
return dev_err_probe(dev, PTR_ERR(tz),
"Failed to register the thermal device\n");
/*
* right now the FW does set up the HW-block, so we are not
* touching the configuration registers.
* But if the HW is not enabled, then set it up
* using "sane" values used by the firmware right now.
*/
val = readl(data->regs + BCM2835_TS_TSENSCTL);
if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
int offset, slope, crit_temp;
slope = thermal_zone_get_slope(tz);
offset = thermal_zone_get_offset(tz);
/*
* For now we deal only with critical, otherwise
* would need to iterate
*/
err = thermal_zone_get_crit_temp(tz, &crit_temp);
if (err < 0) {
dev_err(dev,
"Not able to read trip_temp: %d\n", err);
return err;
}
/* set bandgap reference voltage and enable voltage regulator */
val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
BCM2835_TS_TSENSCTL_REGULEN;
/* use the recommended reset duration */
val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
/* trip_adc value from info */
val |= bcm2835_thermal_temp2adc(crit_temp,
offset,
slope)
<< BCM2835_TS_TSENSCTL_THOLD_SHIFT;
/* write the value back to the register as 2 steps */
writel(val, data->regs + BCM2835_TS_TSENSCTL);
val |= BCM2835_TS_TSENSCTL_RSTB;
writel(val, data->regs + BCM2835_TS_TSENSCTL);
}
data->tz = tz;
platform_set_drvdata(pdev, data);
/*
* Thermal_zone doesn't enable hwmon as default,
* enable it here
*/
err = thermal_add_hwmon_sysfs(tz);
if (err)
return err;
bcm2835_thermal_debugfs(pdev);
return 0;
}
static void bcm2835_thermal_remove(
struct platform_device *pdev)
{
struct bcm2835_thermal_data *data = platform_get_drvdata(pdev);
debugfs_remove_recursive(data->debugfsdir);
}
static struct platform_driver bcm2835_thermal_driver = {
.probe = bcm2835_thermal_probe,
.remove = bcm2835_thermal_remove,
.driver = {
.name =
"bcm2835_thermal",
.of_match_table = bcm2835_thermal_of_match_table,
},
};
module_platform_driver(bcm2835_thermal_driver);
MODULE_AUTHOR(
"Martin Sperl");
MODULE_DESCRIPTION(
"Thermal driver for bcm2835 chip");
MODULE_LICENSE(
"GPL");
