thermal: add temperature sensor support for tango SoC

The Tango thermal driver provides support for the primitive temperature
sensor embedded in Tango chips since the SMP8758.

This sensor only generates a 1-bit signal to indicate whether the die
temperature exceeds a programmable threshold.

Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

diff --git a/Documentation/devicetree/bindings/thermal/tango-thermal.txt b/Documentation/devicetree/bindings/thermal/tango-thermal.txt
new file mode 100644 (file)
index 0000000..212198d
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/tango-thermal.txt
@@ -0,0 +1,17 @@
+* Tango Thermal
+
+The SMP8758 SoC includes 3 instances of this temperature sensor
+(in the CPU, video decoder, and PCIe controller).
+
+Required properties:
+- #thermal-sensor-cells: Should be 0 (see thermal.txt)
+- compatible: "sigma,smp8758-thermal"
+- reg: Address range of the thermal registers
+
+Example:
+
+       cpu_temp: thermal@920100 {
+               #thermal-sensor-cells = <0>;
+               compatible = "sigma,smp8758-thermal";
+               reg = <0x920100 12>;
+       };

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index a6777cbf3d534d6f1145f5bc9399b588560ee815..ee02e6021c94abdf314c76accce30eeaf48a3615 100644 (file)
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -389,6 +389,15 @@ depends on ARCH_STI && OF
 source "drivers/thermal/st/Kconfig"
 endmenu
 
+config TANGO_THERMAL
+       tristate "Tango thermal management"
+       depends on ARCH_TANGO || COMPILE_TEST
+       help
+         Enable the Tango thermal driver, which supports the primitive
+         temperature sensor embedded in Tango chips since the SMP8758.
+         This sensor only generates a 1-bit signal to indicate whether
+         the die temperature exceeds a programmable threshold.
+
 source "drivers/thermal/tegra/Kconfig"
 
 config QCOM_SPMI_TEMP_ALARM

diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index d64f7f7077028594601e82daf216c6559ccfda55..998134ff3b45c566cb4f66a9a806dcfd5c019a2a 100644 (file)
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -35,6 +35,7 @@ obj-y                         += samsung/
 obj-$(CONFIG_DOVE_THERMAL)     += dove_thermal.o
 obj-$(CONFIG_DB8500_THERMAL)   += db8500_thermal.o
 obj-$(CONFIG_ARMADA_THERMAL)   += armada_thermal.o
+obj-$(CONFIG_TANGO_THERMAL)    += tango_thermal.o
 obj-$(CONFIG_IMX_THERMAL)      += imx_thermal.o
 obj-$(CONFIG_DB8500_CPUFREQ_COOLING)   += db8500_cpufreq_cooling.o
 obj-$(CONFIG_INTEL_POWERCLAMP) += intel_powerclamp.o

diff --git a/drivers/thermal/tango_thermal.c b/drivers/thermal/tango_thermal.c
new file mode 100644 (file)
index 0000000..d6592bf
--- /dev/null
+++ b/drivers/thermal/tango_thermal.c
@@ -0,0 +1,111 @@
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/thermal.h>
+#include <linux/platform_device.h>
+
+/*
+ * According to a data sheet draft, "this temperature sensor uses a bandgap
+ * type of circuit to compare a voltage which has a negative temperature
+ * coefficient with a voltage that is proportional to absolute temperature.
+ * A resistor bank allows 41 different temperature thresholds to be selected
+ * and the logic output will then indicate whether the actual die temperature
+ * lies above or below the selected threshold."
+ */
+
+#define TEMPSI_CMD     0
+#define TEMPSI_RES     4
+#define TEMPSI_CFG     8
+
+#define CMD_OFF                0
+#define CMD_ON         1
+#define CMD_READ       2
+
+#define IDX_MIN                15
+#define IDX_MAX                40
+
+struct tango_thermal_priv {
+       void __iomem *base;
+       int thresh_idx;
+};
+
+static bool temp_above_thresh(void __iomem *base, int thresh_idx)
+{
+       writel(CMD_READ | thresh_idx << 8, base + TEMPSI_CMD);
+       usleep_range(10, 20);
+       writel(CMD_READ | thresh_idx << 8, base + TEMPSI_CMD);
+
+       return readl(base + TEMPSI_RES);
+}
+
+static int tango_get_temp(void *arg, int *res)
+{
+       struct tango_thermal_priv *priv = arg;
+       int idx = priv->thresh_idx;
+
+       if (temp_above_thresh(priv->base, idx)) {
+               /* Search upward by incrementing thresh_idx */
+               while (idx < IDX_MAX && temp_above_thresh(priv->base, ++idx))
+                       cpu_relax();
+               idx = idx - 1; /* always return lower bound */
+       } else {
+               /* Search downward by decrementing thresh_idx */
+               while (idx > IDX_MIN && !temp_above_thresh(priv->base, --idx))
+                       cpu_relax();
+       }
+
+       *res = (idx * 9 / 2 - 38) * 1000; /* millidegrees Celsius */
+       priv->thresh_idx = idx;
+
+       return 0;
+}
+
+static const struct thermal_zone_of_device_ops ops = {
+       .get_temp       = tango_get_temp,
+};
+
+static int tango_thermal_probe(struct platform_device *pdev)
+{
+       struct resource *res;
+       struct tango_thermal_priv *priv;
+       struct thermal_zone_device *tzdev;
+
+       priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+       if (!priv)
+               return -ENOMEM;
+
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       priv->base = devm_ioremap_resource(&pdev->dev, res);
+       if (IS_ERR(priv->base))
+               return PTR_ERR(priv->base);
+
+       priv->thresh_idx = IDX_MIN;
+       writel(CMD_ON, priv->base + TEMPSI_CMD);
+
+       tzdev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, priv, &ops);
+       if (IS_ERR(tzdev))
+               return PTR_ERR(tzdev);
+
+       return 0;
+}
+
+static const struct of_device_id tango_sensor_ids[] = {
+       {
+               .compatible = "sigma,smp8758-thermal",
+       },
+       { /* sentinel */ }
+};
+
+static struct platform_driver tango_thermal_driver = {
+       .probe  = tango_thermal_probe,
+       .driver = {
+               .name           = "tango-thermal",
+               .of_match_table = tango_sensor_ids,
+       },
+};
+
+module_platform_driver(tango_thermal_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sigma Designs");
+MODULE_DESCRIPTION("Tango temperature sensor");