314 lines
8.2 KiB
C
314 lines
8.2 KiB
C
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/*
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* Driver for Broadcom BCM2835 SoC temperature sensor
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*
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* Copyright (C) 2016 Martin Sperl
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/clk.h>
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#include <linux/debugfs.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/io.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/thermal.h>
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#define BCM2835_TS_TSENSCTL 0x00
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#define BCM2835_TS_TSENSSTAT 0x04
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#define BCM2835_TS_TSENSCTL_PRWDW BIT(0)
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#define BCM2835_TS_TSENSCTL_RSTB BIT(1)
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/*
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* bandgap reference voltage in 6 mV increments
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* 000b = 1178 mV, 001b = 1184 mV, ... 111b = 1220 mV
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*/
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#define BCM2835_TS_TSENSCTL_CTRL_BITS 3
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#define BCM2835_TS_TSENSCTL_CTRL_SHIFT 2
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#define BCM2835_TS_TSENSCTL_CTRL_MASK \
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GENMASK(BCM2835_TS_TSENSCTL_CTRL_BITS + \
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BCM2835_TS_TSENSCTL_CTRL_SHIFT - 1, \
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BCM2835_TS_TSENSCTL_CTRL_SHIFT)
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#define BCM2835_TS_TSENSCTL_CTRL_DEFAULT 1
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#define BCM2835_TS_TSENSCTL_EN_INT BIT(5)
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#define BCM2835_TS_TSENSCTL_DIRECT BIT(6)
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#define BCM2835_TS_TSENSCTL_CLR_INT BIT(7)
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#define BCM2835_TS_TSENSCTL_THOLD_SHIFT 8
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#define BCM2835_TS_TSENSCTL_THOLD_BITS 10
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#define BCM2835_TS_TSENSCTL_THOLD_MASK \
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GENMASK(BCM2835_TS_TSENSCTL_THOLD_BITS + \
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BCM2835_TS_TSENSCTL_THOLD_SHIFT - 1, \
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BCM2835_TS_TSENSCTL_THOLD_SHIFT)
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/*
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* time how long the block to be asserted in reset
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* which based on a clock counter (TSENS clock assumed)
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*/
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#define BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT 18
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#define BCM2835_TS_TSENSCTL_RSTDELAY_BITS 8
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#define BCM2835_TS_TSENSCTL_REGULEN BIT(26)
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#define BCM2835_TS_TSENSSTAT_DATA_BITS 10
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#define BCM2835_TS_TSENSSTAT_DATA_SHIFT 0
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#define BCM2835_TS_TSENSSTAT_DATA_MASK \
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GENMASK(BCM2835_TS_TSENSSTAT_DATA_BITS + \
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BCM2835_TS_TSENSSTAT_DATA_SHIFT - 1, \
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BCM2835_TS_TSENSSTAT_DATA_SHIFT)
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#define BCM2835_TS_TSENSSTAT_VALID BIT(10)
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#define BCM2835_TS_TSENSSTAT_INTERRUPT BIT(11)
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struct bcm2835_thermal_data {
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struct thermal_zone_device *tz;
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void __iomem *regs;
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struct clk *clk;
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struct dentry *debugfsdir;
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};
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static int bcm2835_thermal_adc2temp(u32 adc, int offset, int slope)
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{
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return offset + slope * adc;
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}
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static int bcm2835_thermal_temp2adc(int temp, int offset, int slope)
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{
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temp -= offset;
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temp /= slope;
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if (temp < 0)
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temp = 0;
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if (temp >= BIT(BCM2835_TS_TSENSSTAT_DATA_BITS))
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temp = BIT(BCM2835_TS_TSENSSTAT_DATA_BITS) - 1;
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return temp;
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}
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static int bcm2835_thermal_get_temp(void *d, int *temp)
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{
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struct bcm2835_thermal_data *data = d;
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u32 val = readl(data->regs + BCM2835_TS_TSENSSTAT);
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if (!(val & BCM2835_TS_TSENSSTAT_VALID))
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return -EIO;
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val &= BCM2835_TS_TSENSSTAT_DATA_MASK;
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*temp = bcm2835_thermal_adc2temp(
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val,
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thermal_zone_get_offset(data->tz),
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thermal_zone_get_slope(data->tz));
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return 0;
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}
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static const struct debugfs_reg32 bcm2835_thermal_regs[] = {
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{
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.name = "ctl",
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.offset = 0
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},
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{
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.name = "stat",
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.offset = 4
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}
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};
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static void bcm2835_thermal_debugfs(struct platform_device *pdev)
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{
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struct thermal_zone_device *tz = platform_get_drvdata(pdev);
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struct bcm2835_thermal_data *data = tz->devdata;
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struct debugfs_regset32 *regset;
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data->debugfsdir = debugfs_create_dir("bcm2835_thermal", NULL);
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if (!data->debugfsdir)
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return;
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regset = devm_kzalloc(&pdev->dev, sizeof(*regset), GFP_KERNEL);
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if (!regset)
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return;
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regset->regs = bcm2835_thermal_regs;
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regset->nregs = ARRAY_SIZE(bcm2835_thermal_regs);
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regset->base = data->regs;
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debugfs_create_regset32("regset", 0444, data->debugfsdir, regset);
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}
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static const struct thermal_zone_of_device_ops bcm2835_thermal_ops = {
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.get_temp = bcm2835_thermal_get_temp,
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};
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/*
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* Note: as per Raspberry Foundation FAQ
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* (https://www.raspberrypi.org/help/faqs/#performanceOperatingTemperature)
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* the recommended temperature range for the SoC -40C to +85C
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* so the trip limit is set to 80C.
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* this applies to all the BCM283X SoC
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*/
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static const struct of_device_id bcm2835_thermal_of_match_table[] = {
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{
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.compatible = "brcm,bcm2835-thermal",
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},
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{
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.compatible = "brcm,bcm2836-thermal",
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},
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{
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.compatible = "brcm,bcm2837-thermal",
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},
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{},
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};
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MODULE_DEVICE_TABLE(of, bcm2835_thermal_of_match_table);
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static int bcm2835_thermal_probe(struct platform_device *pdev)
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{
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const struct of_device_id *match;
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struct thermal_zone_device *tz;
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struct bcm2835_thermal_data *data;
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struct resource *res;
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int err = 0;
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u32 val;
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unsigned long rate;
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data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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match = of_match_device(bcm2835_thermal_of_match_table,
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&pdev->dev);
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if (!match)
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return -EINVAL;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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data->regs = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(data->regs)) {
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err = PTR_ERR(data->regs);
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dev_err(&pdev->dev, "Could not get registers: %d\n", err);
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return err;
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}
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data->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(data->clk)) {
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err = PTR_ERR(data->clk);
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if (err != -EPROBE_DEFER)
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dev_err(&pdev->dev, "Could not get clk: %d\n", err);
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return err;
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}
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err = clk_prepare_enable(data->clk);
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if (err)
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return err;
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rate = clk_get_rate(data->clk);
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if ((rate < 1920000) || (rate > 5000000))
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dev_warn(&pdev->dev,
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"Clock %pCn running at %pCr Hz is outside of the recommended range: 1.92 to 5MHz\n",
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data->clk, data->clk);
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/* register of thermal sensor and get info from DT */
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tz = thermal_zone_of_sensor_register(&pdev->dev, 0, data,
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&bcm2835_thermal_ops);
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if (IS_ERR(tz)) {
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err = PTR_ERR(tz);
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dev_err(&pdev->dev,
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"Failed to register the thermal device: %d\n",
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err);
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goto err_clk;
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}
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/*
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* right now the FW does set up the HW-block, so we are not
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* touching the configuration registers.
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* But if the HW is not enabled, then set it up
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* using "sane" values used by the firmware right now.
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*/
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val = readl(data->regs + BCM2835_TS_TSENSCTL);
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if (!(val & BCM2835_TS_TSENSCTL_RSTB)) {
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int trip_temp, offset, slope;
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slope = thermal_zone_get_slope(tz);
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offset = thermal_zone_get_offset(tz);
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/*
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* For now we deal only with critical, otherwise
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* would need to iterate
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*/
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err = tz->ops->get_trip_temp(tz, 0, &trip_temp);
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if (err < 0) {
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dev_err(&pdev->dev,
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"Not able to read trip_temp: %d\n",
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err);
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goto err_tz;
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}
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/* set bandgap reference voltage and enable voltage regulator */
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val = (BCM2835_TS_TSENSCTL_CTRL_DEFAULT <<
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BCM2835_TS_TSENSCTL_CTRL_SHIFT) |
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BCM2835_TS_TSENSCTL_REGULEN;
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/* use the recommended reset duration */
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val |= (0xFE << BCM2835_TS_TSENSCTL_RSTDELAY_SHIFT);
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/* trip_adc value from info */
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val |= bcm2835_thermal_temp2adc(trip_temp,
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offset,
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slope)
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<< BCM2835_TS_TSENSCTL_THOLD_SHIFT;
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/* write the value back to the register as 2 steps */
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writel(val, data->regs + BCM2835_TS_TSENSCTL);
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val |= BCM2835_TS_TSENSCTL_RSTB;
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writel(val, data->regs + BCM2835_TS_TSENSCTL);
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}
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data->tz = tz;
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platform_set_drvdata(pdev, tz);
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bcm2835_thermal_debugfs(pdev);
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return 0;
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err_tz:
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thermal_zone_of_sensor_unregister(&pdev->dev, tz);
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err_clk:
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clk_disable_unprepare(data->clk);
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return err;
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}
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static int bcm2835_thermal_remove(struct platform_device *pdev)
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{
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struct thermal_zone_device *tz = platform_get_drvdata(pdev);
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struct bcm2835_thermal_data *data = tz->devdata;
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debugfs_remove_recursive(data->debugfsdir);
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thermal_zone_of_sensor_unregister(&pdev->dev, tz);
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clk_disable_unprepare(data->clk);
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return 0;
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}
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static struct platform_driver bcm2835_thermal_driver = {
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.probe = bcm2835_thermal_probe,
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.remove = bcm2835_thermal_remove,
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.driver = {
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.name = "bcm2835_thermal",
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.of_match_table = bcm2835_thermal_of_match_table,
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},
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};
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module_platform_driver(bcm2835_thermal_driver);
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MODULE_AUTHOR("Martin Sperl");
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MODULE_DESCRIPTION("Thermal driver for bcm2835 chip");
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MODULE_LICENSE("GPL");
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