[PATCH 2/4] thermal: bcm2835: add thermal driver for bcm2835 soc

kernel at martin.sperl.org kernel at martin.sperl.org
Thu May 12 07:35:36 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>
---
 drivers/thermal/Kconfig               |   5 +
 drivers/thermal/Makefile              |   1 +
 drivers/thermal/bcm/Kconfig           |   4 +
 drivers/thermal/bcm/Makefile          |   1 +
 drivers/thermal/bcm/bcm2835_thermal.c | 205 ++++++++++++++++++++++++++++++++++
 5 files changed, 216 insertions(+)
 create mode 100644 drivers/thermal/bcm/Kconfig
 create mode 100644 drivers/thermal/bcm/Makefile
 create mode 100644 drivers/thermal/bcm/bcm2835_thermal.c

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index c37eedc..10f92c6 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -381,6 +381,11 @@ config MTK_THERMAL
 	  Enable this option if you want to have support for thermal management
 	  controller present in Mediatek SoCs
 
+menu "Broadcom thermal drivers"
+depends on ARCH_BCM || COMPILE_TEST
+source "drivers/thermal/bcm/Kconfig"
+endmenu
+
 menu "Texas Instruments thermal drivers"
 depends on ARCH_HAS_BANDGAP || COMPILE_TEST
 depends on HAS_IOMEM
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 8e9cbc3..6df1aa3 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -49,3 +49,4 @@ obj-$(CONFIG_ST_THERMAL)	+= st/
 obj-$(CONFIG_TEGRA_SOCTHERM)	+= tegra_soctherm.o
 obj-$(CONFIG_HISI_THERMAL)     += hisi_thermal.o
 obj-$(CONFIG_MTK_THERMAL)	+= mtk_thermal.o
+obj-y				+= bcm/
diff --git a/drivers/thermal/bcm/Kconfig b/drivers/thermal/bcm/Kconfig
new file mode 100644
index 0000000..62245ae
--- /dev/null
+++ b/drivers/thermal/bcm/Kconfig
@@ -0,0 +1,4 @@
+config BCM2835_THERMAL
+       tristate "Thermal sensors on bcm2835 SoC"
+       help
+         Support for thermal sensors on Broadcom bcm2835 SoCs.
diff --git a/drivers/thermal/bcm/Makefile b/drivers/thermal/bcm/Makefile
new file mode 100644
index 0000000..13456d2
--- /dev/null
+++ b/drivers/thermal/bcm/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_BCM2835_THERMAL)		:= bcm2835_thermal.o
diff --git a/drivers/thermal/bcm/bcm2835_thermal.c b/drivers/thermal/bcm/bcm2835_thermal.c
new file mode 100644
index 0000000..a1fdc84
--- /dev/null
+++ b/drivers/thermal/bcm/bcm2835_thermal.c
@@ -0,0 +1,205 @@
+/*
+ * Driver for Broadcom BCM2835 soc temperature sensor
+ *
+ * Copyright (C) 2015 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/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		BIT(0)
+#define BCM2835_TS_TSENSCTL_EN_INT		BIT(0)
+#define BCM2835_TS_TSENSCTL_DIRECT		BIT(0)
+#define BCM2835_TS_TSENSCTL_CLR_INT		BIT(0)
+#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)
+
+/* empirical linear approximation for conversion to temperature */
+#define BCM2835_TS_VALUE_OFFSET			407000
+#define BCM2835_TS_VALUE_SLOPE			-538
+
+struct bcm2835_thermal_data {
+	void __iomem *regs;
+	struct clk *clk;
+	struct dentry *debugfsdir;
+};
+
+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);
+
+	/* mask the relevant bits */
+	val &= BCM2835_TS_TSENSSTAT_DATA_MASK;
+
+	/* linear approximation */
+	*temp = BCM2835_TS_VALUE_OFFSET +
+		(val * BCM2835_TS_VALUE_SLOPE);
+
+	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,
+};
+
+static int bcm2835_thermal_probe(struct platform_device *pdev)
+{
+	struct thermal_zone_device *tz;
+	struct bcm2835_thermal_data *data;
+	struct resource *res;
+	int err;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	/* get registers */
+	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;
+	}
+
+	/* get clock */
+	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;
+	}
+
+	/*
+	 * for now we assume the firmware sets up the device,
+	 * so we will not write to ctl, we just prepare the clock
+	 */
+	clk_prepare_enable(data->clk);
+
+	/* register it */
+	tz = thermal_zone_device_register("bcm2835_thermal",
+					  0, 0, data,
+					  &bcm2835_thermal_ops,
+					  NULL, 0, 0);
+	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);
+
+	return 0;
+}
+
+static const struct of_device_id bcm2835_thermal_of_match_table[] = {
+	{ .compatible = "brcm,bcm2835-thermal", },
+	{},
+};
+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




More information about the linux-rpi-kernel mailing list