diff options
Diffstat (limited to 'drivers/thermal/bcm2835_thermal.c')
| -rw-r--r-- | drivers/thermal/bcm2835_thermal.c | 314 |
1 files changed, 314 insertions, 0 deletions
diff --git a/drivers/thermal/bcm2835_thermal.c b/drivers/thermal/bcm2835_thermal.c new file mode 100644 index 000000000000..0ecf80890c84 --- /dev/null +++ b/drivers/thermal/bcm2835_thermal.c @@ -0,0 +1,314 @@ +/* + * Driver for Broadcom BCM2835 SoC temperature sensor + * + * Copyright (C) 2016 Martin Sperl + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#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> + +#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(void *d, int *temp) +{ + struct bcm2835_thermal_data *data = d; + 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 thermal_zone_device *tz = platform_get_drvdata(pdev); + struct bcm2835_thermal_data *data = tz->devdata; + struct debugfs_regset32 *regset; + + data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL); + if (!data->debugfsdir) + return; + + 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 struct thermal_zone_of_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) +{ + const struct of_device_id *match; + struct thermal_zone_device *tz; + struct bcm2835_thermal_data *data; + struct resource *res; + int err = 0; + u32 val; + unsigned long rate; + + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + match = of_match_device(bcm2835_thermal_of_match_table, + &pdev->dev); + if (!match) + return -EINVAL; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + data->regs = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(data->regs)) { + err = PTR_ERR(data->regs); + dev_err(&pdev->dev, "Could not get registers: %d\n", err); + return err; + } + + data->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(data->clk)) { + err = PTR_ERR(data->clk); + if (err != -EPROBE_DEFER) + dev_err(&pdev->dev, "Could not get clk: %d\n", err); + return err; + } + + err = clk_prepare_enable(data->clk); + if (err) + return err; + + rate = clk_get_rate(data->clk); + if ((rate < 1920000) || (rate > 5000000)) + dev_warn(&pdev->dev, + "Clock %pCn running at %pCr Hz is outside of the recommended range: 1.92 to 5MHz\n", + data->clk, data->clk); + + /* register of thermal sensor and get info from DT */ + tz = thermal_zone_of_sensor_register(&pdev->dev, 0, data, + &bcm2835_thermal_ops); + if (IS_ERR(tz)) { + err = PTR_ERR(tz); + dev_err(&pdev->dev, + "Failed to register the thermal device: %d\n", + err); + goto err_clk; + } + + /* + * 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 trip_temp, offset, slope; + + 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 = tz->ops->get_trip_temp(tz, 0, &trip_temp); + if (err < 0) { + err = PTR_ERR(tz); + dev_err(&pdev->dev, + "Not able to read trip_temp: %d\n", + err); + goto err_tz; + } + + /* 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(trip_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, tz); + + bcm2835_thermal_debugfs(pdev); + + return 0; +err_tz: + thermal_zone_of_sensor_unregister(&pdev->dev, tz); +err_clk: + clk_disable_unprepare(data->clk); + + return err; +} + +static int bcm2835_thermal_remove(struct platform_device *pdev) +{ + struct thermal_zone_device *tz = platform_get_drvdata(pdev); + struct bcm2835_thermal_data *data = tz->devdata; + + debugfs_remove_recursive(data->debugfsdir); + thermal_zone_of_sensor_unregister(&pdev->dev, tz); + clk_disable_unprepare(data->clk); + + return 0; +} + +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"); |