[PATCH V7 2/6] thermal: bcm2835: add thermal driver for bcm2835 soc
kernel at martin.sperl.org
kernel at martin.sperl.org
Wed Sep 21 01:23:43 PDT 2016
From: Martin Sperl <kernel at martin.sperl.org>
Add basic thermal driver for bcm2835 SOC.
This driver currently relies on the firmware setting up the
tsense HW block and does not set it up itself.
Signed-off-by: Martin Sperl <kernel at martin.sperl.org>
Acked-by: Eric Anholt <eric at anholt.net>
Acked-by: Stefan Wahren <stefan.wahren at i2se.com>
ChangeLog:
V1 -> V2: added specific settings depending on compatiblity
added trip point based on register
setting up ctrl-register if HW is not enabled by firmware
as per recommendation of Eric (untested)
check that clock frequency is in range
(1.9 - 5MHz - as per comment in clk-bcm2835.c)
V2 -> V4: moved back to thermal (not using bcm sub-directory)
set polling interval to 1second (was 0ms, so interrupt driven)
V5 -> V6: added correct depends in KConfig
removed defined default for RESET_DELAY
removed obvious comments
clarify HW setup comments if not set up by FW already
move clk_prepare_enable to an earlier stage and add error handling
clarify warning when TS-clock runs out of recommended range
clk_disable_unprepare added in bcm2835_thermal_remove
added comment on recommended temperature ranges for SOC
V6 -> V7: removed depends on ARCH_BCM2836 || ARCH_BCM2837 in Kconfig
---
drivers/thermal/Kconfig | 8 +
drivers/thermal/Makefile | 1 +
drivers/thermal/bcm2835_thermal.c | 340 ++++++++++++++++++++++++++++++++++++++
3 files changed, 349 insertions(+)
create mode 100644 drivers/thermal/bcm2835_thermal.c
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 2d702ca..1bc8b14 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -399,4 +399,12 @@ config GENERIC_ADC_THERMAL
to this driver. This driver reports the temperature by reading ADC
channel and converts it to temperature based on lookup table.
+config BCM2835_THERMAL
+ tristate "Thermal sensors on bcm2835 SoC"
+ depends on ARCH_BCM2835 || COMPILE_TEST
+ depends on HAS_IOMEM
+ depends on OF
+ help
+ Support for thermal sensors on Broadcom bcm2835 SoCs.
+
endif
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 10b07c1..c26343e 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -51,3 +51,4 @@ obj-$(CONFIG_TEGRA_SOCTHERM) += tegra/
obj-$(CONFIG_HISI_THERMAL) += hisi_thermal.o
obj-$(CONFIG_MTK_THERMAL) += mtk_thermal.o
obj-$(CONFIG_GENERIC_ADC_THERMAL) += thermal-generic-adc.o
+obj-$(CONFIG_BCM2835_THERMAL) += bcm2835_thermal.o
diff --git a/drivers/thermal/bcm2835_thermal.c b/drivers/thermal/bcm2835_thermal.c
new file mode 100644
index 0000000..3468c7b
--- /dev/null
+++ b/drivers/thermal/bcm2835_thermal.c
@@ -0,0 +1,340 @@
+/*
+ * 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)
+#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)
+#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_info {
+ int offset;
+ int slope;
+ int trip_temp;
+};
+
+struct bcm2835_thermal_data {
+ const struct bcm2835_thermal_info *info;
+ void __iomem *regs;
+ struct clk *clk;
+ struct dentry *debugfsdir;
+};
+
+static int bcm2835_thermal_adc2temp(
+ const struct bcm2835_thermal_info *info, u32 adc)
+{
+ return info->offset + (adc * info->slope);
+}
+
+static int bcm2835_thermal_temp2adc(
+ const struct bcm2835_thermal_info *info, int temp)
+{
+ temp -= info->offset;
+ temp /= info->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_trip_type(
+ struct thermal_zone_device *tz, int trip,
+ enum thermal_trip_type *type)
+{
+ *type = THERMAL_TRIP_CRITICAL;
+ return 0;
+}
+
+static int bcm2835_thermal_get_trip_temp(
+ struct thermal_zone_device *tz, int trip, int *temp)
+{
+ struct bcm2835_thermal_data *data = tz->devdata;
+ u32 val = readl(data->regs + BCM2835_TS_TSENSCTL);
+
+ /* get the THOLD bits */
+ val &= BCM2835_TS_TSENSCTL_THOLD_MASK;
+ val >>= BCM2835_TS_TSENSCTL_THOLD_SHIFT;
+
+ /* if it is zero then use the info value */
+ if (val)
+ *temp = bcm2835_thermal_adc2temp(data->info, val);
+ else
+ *temp = data->info->trip_temp;
+
+ return 0;
+}
+
+static int bcm2835_thermal_get_temp(struct thermal_zone_device *tz,
+ int *temp)
+{
+ struct bcm2835_thermal_data *data = tz->devdata;
+ 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(data->info, val);
+
+ 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", S_IRUGO,
+ data->debugfsdir, regset);
+}
+
+static struct thermal_zone_device_ops bcm2835_thermal_ops = {
+ .get_temp = bcm2835_thermal_get_temp,
+ .get_trip_temp = bcm2835_thermal_get_trip_temp,
+ .get_trip_type = bcm2835_thermal_get_trip_type,
+};
+
+static const struct of_device_id 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;
+ 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;
+ data->info = match->data;
+
+ 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);
+
+ /*
+ * 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)) {
+ /* the basic required flags */
+ val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
+ BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
+ BCM2835_TS_TSENSCTL_REGULEN;
+
+ /*
+ * reset delay using the current firmware value of 14
+ * - units of time are unknown.
+ */
+ val |= (14 << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
+
+ /* trip_adc value from info */
+ val |= bcm2835_thermal_temp2adc(data->info,
+ data->info->trip_temp) <<
+ 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);
+ }
+
+ /* register thermal zone with 1 trip point an 1s polling */
+ tz = thermal_zone_device_register("bcm2835_thermal",
+ 1, 0, data,
+ &bcm2835_thermal_ops,
+ NULL,
+ 0, 1000);
+ if (IS_ERR(tz)) {
+ clk_disable_unprepare(data->clk);
+ err = PTR_ERR(tz);
+ dev_err(&pdev->dev,
+ "Failed to register the thermal device: %d\n",
+ err);
+ return err;
+ }
+
+ platform_set_drvdata(pdev, tz);
+
+ bcm2835_thermal_debugfs(pdev);
+
+ return 0;
+}
+
+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_device_unregister(tz);
+ clk_disable_unprepare(data->clk);
+
+ return 0;
+}
+
+/*
+ * 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",
+ .data = &(struct bcm2835_thermal_info) {
+ .offset = 407000,
+ .slope = -538,
+ .trip_temp = 80000
+ }
+ },
+ {
+ .compatible = "brcm,bcm2836-thermal",
+ .data = &(struct bcm2835_thermal_info) {
+ .offset = 407000,
+ .slope = -538,
+ .trip_temp = 80000
+ }
+ },
+ {
+ .compatible = "brcm,bcm2837-thermal",
+ .data = &(struct bcm2835_thermal_info) {
+ /* the bcm2837 needs adjustment of +5C */
+ .offset = 407000 + 5000,
+ .slope = -538,
+ .trip_temp = 80000
+ }
+ },
+ {},
+};
+MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
+
+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");
--
2.1.4
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