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126 lines
3.2 KiB
126 lines
3.2 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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#include <linux/io.h> |
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#include <linux/delay.h> |
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#include <linux/module.h> |
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#include <linux/thermal.h> |
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#include <linux/platform_device.h> |
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/* |
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* According to a data sheet draft, "this temperature sensor uses a bandgap |
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* type of circuit to compare a voltage which has a negative temperature |
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* coefficient with a voltage that is proportional to absolute temperature. |
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* A resistor bank allows 41 different temperature thresholds to be selected |
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* and the logic output will then indicate whether the actual die temperature |
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* lies above or below the selected threshold." |
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*/ |
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#define TEMPSI_CMD 0 |
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#define TEMPSI_RES 4 |
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#define TEMPSI_CFG 8 |
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#define CMD_OFF 0 |
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#define CMD_ON 1 |
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#define CMD_READ 2 |
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#define IDX_MIN 15 |
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#define IDX_MAX 40 |
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struct tango_thermal_priv { |
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void __iomem *base; |
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int thresh_idx; |
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}; |
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static bool temp_above_thresh(void __iomem *base, int thresh_idx) |
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{ |
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writel(CMD_READ | thresh_idx << 8, base + TEMPSI_CMD); |
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usleep_range(10, 20); |
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writel(CMD_READ | thresh_idx << 8, base + TEMPSI_CMD); |
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return readl(base + TEMPSI_RES); |
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} |
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static int tango_get_temp(void *arg, int *res) |
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{ |
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struct tango_thermal_priv *priv = arg; |
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int idx = priv->thresh_idx; |
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if (temp_above_thresh(priv->base, idx)) { |
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/* Search upward by incrementing thresh_idx */ |
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while (idx < IDX_MAX && temp_above_thresh(priv->base, ++idx)) |
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cpu_relax(); |
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idx = idx - 1; /* always return lower bound */ |
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} else { |
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/* Search downward by decrementing thresh_idx */ |
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while (idx > IDX_MIN && !temp_above_thresh(priv->base, --idx)) |
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cpu_relax(); |
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} |
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*res = (idx * 9 / 2 - 38) * 1000; /* millidegrees Celsius */ |
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priv->thresh_idx = idx; |
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return 0; |
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} |
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static const struct thermal_zone_of_device_ops ops = { |
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.get_temp = tango_get_temp, |
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}; |
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static void tango_thermal_init(struct tango_thermal_priv *priv) |
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{ |
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writel(0, priv->base + TEMPSI_CFG); |
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writel(CMD_ON, priv->base + TEMPSI_CMD); |
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} |
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static int tango_thermal_probe(struct platform_device *pdev) |
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{ |
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struct resource *res; |
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struct tango_thermal_priv *priv; |
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struct thermal_zone_device *tzdev; |
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priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); |
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if (!priv) |
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return -ENOMEM; |
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
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priv->base = devm_ioremap_resource(&pdev->dev, res); |
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if (IS_ERR(priv->base)) |
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return PTR_ERR(priv->base); |
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platform_set_drvdata(pdev, priv); |
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priv->thresh_idx = IDX_MIN; |
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tango_thermal_init(priv); |
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tzdev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, priv, &ops); |
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return PTR_ERR_OR_ZERO(tzdev); |
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} |
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static int __maybe_unused tango_thermal_resume(struct device *dev) |
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{ |
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tango_thermal_init(dev_get_drvdata(dev)); |
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return 0; |
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} |
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static SIMPLE_DEV_PM_OPS(tango_thermal_pm, NULL, tango_thermal_resume); |
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static const struct of_device_id tango_sensor_ids[] = { |
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{ |
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.compatible = "sigma,smp8758-thermal", |
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}, |
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{ /* sentinel */ } |
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}; |
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MODULE_DEVICE_TABLE(of, tango_sensor_ids); |
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static struct platform_driver tango_thermal_driver = { |
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.probe = tango_thermal_probe, |
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.driver = { |
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.name = "tango-thermal", |
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.of_match_table = tango_sensor_ids, |
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.pm = &tango_thermal_pm, |
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}, |
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}; |
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module_platform_driver(tango_thermal_driver); |
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MODULE_LICENSE("GPL"); |
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MODULE_AUTHOR("Sigma Designs"); |
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MODULE_DESCRIPTION("Tango temperature sensor");
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