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![Lars Povlsen](/assets/img/avatar_default.png)
If the temperature is read before the internal calibration is completed, the driver returns -EIO. Instead it should return -EAGAIN to encourage repeating the operation. Note (groeck): Returning -EAGAIN to userspace may result in hard loops; some userspace code interprets -EAGAIN as request to retry immediately. I would prefer -ENODATA, but it turns out that the thermal subsystem only handles -EAGAIN silently, so we'll have to stick with that. Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com> Link: https://lore.kernel.org/r/20200903134704.8949-1-lars.povlsen@microchip.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
168 lines
3.6 KiB
C
168 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Sparx5 SoC temperature sensor driver
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*
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* Copyright (C) 2020 Lars Povlsen <lars.povlsen@microchip.com>
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*/
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#include <linux/bitfield.h>
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#include <linux/clk.h>
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#include <linux/hwmon.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#define TEMP_CTRL 0
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#define TEMP_CFG 4
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#define TEMP_CFG_CYCLES GENMASK(24, 15)
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#define TEMP_CFG_ENA BIT(0)
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#define TEMP_STAT 8
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#define TEMP_STAT_VALID BIT(12)
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#define TEMP_STAT_TEMP GENMASK(11, 0)
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struct s5_hwmon {
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void __iomem *base;
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struct clk *clk;
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};
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static void s5_temp_clk_disable(void *data)
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{
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struct clk *clk = data;
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clk_disable_unprepare(clk);
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}
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static void s5_temp_enable(struct s5_hwmon *hwmon)
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{
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u32 val = readl(hwmon->base + TEMP_CFG);
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u32 clk = clk_get_rate(hwmon->clk) / USEC_PER_SEC;
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val &= ~TEMP_CFG_CYCLES;
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val |= FIELD_PREP(TEMP_CFG_CYCLES, clk);
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val |= TEMP_CFG_ENA;
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writel(val, hwmon->base + TEMP_CFG);
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}
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static int s5_read(struct device *dev, enum hwmon_sensor_types type,
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u32 attr, int channel, long *temp)
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{
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struct s5_hwmon *hwmon = dev_get_drvdata(dev);
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int rc = 0, value;
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u32 stat;
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switch (attr) {
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case hwmon_temp_input:
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stat = readl_relaxed(hwmon->base + TEMP_STAT);
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if (!(stat & TEMP_STAT_VALID))
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return -EAGAIN;
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value = stat & TEMP_STAT_TEMP;
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/*
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* From register documentation:
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* Temp(C) = TEMP_SENSOR_STAT.TEMP / 4096 * 352.2 - 109.4
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*/
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value = DIV_ROUND_CLOSEST(value * 3522, 4096) - 1094;
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/*
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* Scale down by 10 from above and multiply by 1000 to
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* have millidegrees as specified by the hwmon sysfs
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* interface.
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*/
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value *= 100;
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*temp = value;
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break;
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default:
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rc = -EOPNOTSUPP;
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break;
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}
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return rc;
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}
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static umode_t s5_is_visible(const void *_data, enum hwmon_sensor_types type,
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u32 attr, int channel)
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{
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if (type != hwmon_temp)
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return 0;
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switch (attr) {
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case hwmon_temp_input:
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return 0444;
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default:
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return 0;
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}
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}
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static const struct hwmon_channel_info *s5_info[] = {
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HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
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HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
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NULL
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};
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static const struct hwmon_ops s5_hwmon_ops = {
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.is_visible = s5_is_visible,
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.read = s5_read,
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};
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static const struct hwmon_chip_info s5_chip_info = {
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.ops = &s5_hwmon_ops,
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.info = s5_info,
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};
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static int s5_temp_probe(struct platform_device *pdev)
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{
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struct device *hwmon_dev;
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struct s5_hwmon *hwmon;
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int ret;
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hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
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if (!hwmon)
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return -ENOMEM;
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hwmon->base = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(hwmon->base))
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return PTR_ERR(hwmon->base);
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hwmon->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(hwmon->clk))
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return PTR_ERR(hwmon->clk);
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ret = clk_prepare_enable(hwmon->clk);
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if (ret)
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return ret;
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ret = devm_add_action_or_reset(&pdev->dev, s5_temp_clk_disable,
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hwmon->clk);
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if (ret)
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return ret;
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s5_temp_enable(hwmon);
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hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
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"s5_temp",
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hwmon,
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&s5_chip_info,
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NULL);
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return PTR_ERR_OR_ZERO(hwmon_dev);
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}
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static const struct of_device_id s5_temp_match[] = {
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{ .compatible = "microchip,sparx5-temp" },
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{},
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};
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MODULE_DEVICE_TABLE(of, s5_temp_match);
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static struct platform_driver s5_temp_driver = {
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.probe = s5_temp_probe,
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.driver = {
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.name = "sparx5-temp",
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.of_match_table = s5_temp_match,
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},
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};
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module_platform_driver(s5_temp_driver);
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MODULE_AUTHOR("Lars Povlsen <lars.povlsen@microchip.com>");
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MODULE_DESCRIPTION("Sparx5 SoC temperature sensor driver");
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MODULE_LICENSE("GPL");
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