[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
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