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Subject: Re: [PATCH v5 2/4] thermal: k3: Add support for bandgap sensors
To:     Amit Kucheria <amit.kucheria@verdurent.com>
CC:     Zhang Rui <rui.zhang@intel.com>, Rob Herring <robh+dt@kernel.org>,
        Daniel Lezcano <daniel.lezcano@linaro.org>, <t-kristo@ti.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        lakml <linux-arm-kernel@lists.infradead.org>,
        Linux PM list <linux-pm@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>
References: <20200331075356.19171-1-j-keerthy@ti.com>
 <20200331075356.19171-3-j-keerthy@ti.com>
 <CAHLCerNvRvp7QAeODb34EV89a0g77ZDLuDioBct7kuBjPgrjwQ@mail.gmail.com>
From:   "J, KEERTHY" <j-keerthy@ti.com>
Message-ID: <55b6dc5b-9c3c-792b-4785-42c9279b2127@ti.com>
Date:   Tue, 7 Apr 2020 06:52:19 +0530
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On 4/7/2020 12:25 AM, Amit Kucheria wrote:
> On Tue, Mar 31, 2020 at 1:24 PM Keerthy <j-keerthy@ti.com> wrote:
>>
>> The bandgap provides current and voltage reference for its internal
>> circuits and other analog IP blocks. The analog-to-digital
>> converter (ADC) produces an output value that is proportional
>> to the silicon temperature.
>>
>> Currently reading temperatures only is supported.
>> There are no active/passive cooling agent supported.
>>
>> Signed-off-by: Keerthy <j-keerthy@ti.com>
>> ---
>>
>> Changes in v5:
>>
>>    * Removed thermal work function which was unused.
>>    * Removed unused preve_tenmp and a couple more struct variables.
>>    * Removed couple of redundant header function include.
>>
>>   drivers/thermal/Kconfig      |  10 ++
>>   drivers/thermal/Makefile     |   1 +
>>   drivers/thermal/k3_bandgap.c | 268 +++++++++++++++++++++++++++++++++++
>>   3 files changed, 279 insertions(+)
>>   create mode 100644 drivers/thermal/k3_bandgap.c
>>
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index 5a05db5438d6..1df434527f8d 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -251,6 +251,16 @@ config IMX_THERMAL
>>            cpufreq is used as the cooling device to throttle CPUs when the
>>            passive trip is crossed.
>>
>> +config K3_THERMAL
>> +       tristate "Texas Instruments K3 thermal support"
>> +       depends on ARCH_K3 || COMPILE_TEST
>> +       help
>> +         If you say yes here you get thermal support for the Texas Instruments
>> +         K3 SoC family. The current chip supported is:
>> +          - AM654
>> +
>> +         This includes temperature reading functionality.
>> +
>>   config MAX77620_THERMAL
>>          tristate "Temperature sensor driver for Maxim MAX77620 PMIC"
>>          depends on MFD_MAX77620
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index 9fb88e26fb10..5ad6535139ae 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -28,6 +28,7 @@ thermal_sys-$(CONFIG_CLOCK_THERMAL)   += clock_cooling.o
>>   # devfreq cooling
>>   thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
>>
>> +obj-$(CONFIG_K3_THERMAL)       += k3_bandgap.o
>>   # platform thermal drivers
>>   obj-y                          += broadcom/
>>   obj-$(CONFIG_THERMAL_MMIO)             += thermal_mmio.o
>> diff --git a/drivers/thermal/k3_bandgap.c b/drivers/thermal/k3_bandgap.c
>> new file mode 100644
>> index 000000000000..1d976af4461a
>> --- /dev/null
>> +++ b/drivers/thermal/k3_bandgap.c
>> @@ -0,0 +1,268 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * TI Bandgap temperature sensor driver for K3 SoC Family
>> + *
>> + * Copyright (C) 2020 Texas Instruments Incorporated - http://www.ti.com/
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/init.h>
>> +#include <linux/kernel.h>
>> +#include <linux/pm_runtime.h>
>> +#include <linux/err.h>
>> +#include <linux/types.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/io.h>
>> +#include <linux/thermal.h>
>> +#include <linux/of.h>
>> +
> 
> Sort these includes alphabetically

Okay

> 
> 
>> +#define K3_VTM_DEVINFO_PWR0_OFFSET             0x4
>> +#define K3_VTM_DEVINFO_PWR0_CVD_CT_MASK        0xf
> 
> Not used, remove.

Okay

> 
>> +#define K3_VTM_DEVINFO_PWR0_TEMPSENS_CT_MASK   0xf0
>> +#define K3_VTM_TMPSENS0_CTRL_OFFSET    0x80
>> +#define K3_VTM_REGS_PER_TS                     0x10
>> +#define K3_VTM_TS_STAT_DTEMP_MASK      0x3ff
>> +#define K3_VTM_MAX_NUM_TS              8
> 
> Not used, remove

okay

> 
>> +#define K3_VTM_TMPSENS_CTRL_CBIASSEL   BIT(0)
>> +#define K3_VTM_TMPSENS_CTRL_SOC                BIT(5)
>> +#define K3_VTM_TMPSENS_CTRL_CLRZ               BIT(6)
>> +#define K3_VTM_TMPSENS_CTRL_CLKON_REQ  BIT(7)
>> +
>> +#define K3_VTM_ADC_BEGIN_VAL           540
>> +#define K3_VTM_ADC_END_VAL             944
>> +
>> +static const int k3_adc_to_temp[] = {
>> +       -40000, -40000, -40000, -40000, -39800, -39400, -39000, -38600, -38200,
>> +       -37800, -37400, -37000, -36600, -36200, -35800, -35300, -34700, -34200,
>> +       -33800, -33400, -33000, -32600, -32200, -31800, -31400, -31000, -30600,
>> +       -30200, -29800, -29400, -29000, -28600, -28200, -27700, -27100, -26600,
>> +       -26200, -25800, -25400, -25000, -24600, -24200, -23800, -23400, -23000,
>> +       -22600, -22200, -21800, -21400, -21000, -20500, -19900, -19400, -19000,
>> +       -18600, -18200, -17800, -17400, -17000, -16600, -16200, -15800, -15400,
>> +       -15000, -14600, -14200, -13800, -13400, -13000, -12500, -11900, -11400,
>> +       -11000, -10600, -10200, -9800, -9400, -9000, -8600, -8200, -7800, -7400,
>> +       -7000, -6600, -6200, -5800, -5400, -5000, -4500, -3900, -3400, -3000,
>> +       -2600, -2200, -1800, -1400, -1000, -600, -200, 200, 600, 1000, 1400,
>> +       1800, 2200, 2600, 3000, 3400, 3900, 4500, 5000, 5400, 5800, 6200, 6600,
>> +       7000, 7400, 7800, 8200, 8600, 9000, 9400, 9800, 10200, 10600, 11000,
>> +       11400, 11800, 12200, 12700, 13300, 13800, 14200, 14600, 15000, 15400,
>> +       15800, 16200, 16600, 17000, 17400, 17800, 18200, 18600, 19000, 19400,
>> +       19800, 20200, 20600, 21000, 21400, 21900, 22500, 23000, 23400, 23800,
>> +       24200, 24600, 25000, 25400, 25800, 26200, 26600, 27000, 27400, 27800,
>> +       28200, 28600, 29000, 29400, 29800, 30200, 30600, 31000, 31400, 31900,
>> +       32500, 33000, 33400, 33800, 34200, 34600, 35000, 35400, 35800, 36200,
>> +       36600, 37000, 37400, 37800, 38200, 38600, 39000, 39400, 39800, 40200,
>> +       40600, 41000, 41400, 41800, 42200, 42600, 43100, 43700, 44200, 44600,
>> +       45000, 45400, 45800, 46200, 46600, 47000, 47400, 47800, 48200, 48600,
>> +       49000, 49400, 49800, 50200, 50600, 51000, 51400, 51800, 52200, 52600,
>> +       53000, 53400, 53800, 54200, 54600, 55000, 55400, 55900, 56500, 57000,
>> +       57400, 57800, 58200, 58600, 59000, 59400, 59800, 60200, 60600, 61000,
>> +       61400, 61800, 62200, 62600, 63000, 63400, 63800, 64200, 64600, 65000,
>> +       65400, 65800, 66200, 66600, 67000, 67400, 67800, 68200, 68600, 69000,
>> +       69400, 69800, 70200, 70600, 71000, 71500, 72100, 72600, 73000, 73400,
>> +       73800, 74200, 74600, 75000, 75400, 75800, 76200, 76600, 77000, 77400,
>> +       77800, 78200, 78600, 79000, 79400, 79800, 80200, 80600, 81000, 81400,
>> +       81800, 82200, 82600, 83000, 83400, 83800, 84200, 84600, 85000, 85400,
>> +       85800, 86200, 86600, 87000, 87400, 87800, 88200, 88600, 89000, 89400,
>> +       89800, 90200, 90600, 91000, 91400, 91800, 92200, 92600, 93000, 93400,
>> +       93800, 94200, 94600, 95000, 95400, 95800, 96200, 96600, 97000, 97500,
>> +       98100, 98600, 99000, 99400, 99800, 100200, 100600, 101000, 101400,
>> +       101800, 102200, 102600, 103000, 103400, 103800, 104200, 104600, 105000,
>> +       105400, 105800, 106200, 106600, 107000, 107400, 107800, 108200, 108600,
>> +       109000, 109400, 109800, 110200, 110600, 111000, 111400, 111800, 112200,
>> +       112600, 113000, 113400, 113800, 114200, 114600, 115000, 115400, 115800,
>> +       116200, 116600, 117000, 117400, 117800, 118200, 118600, 119000, 119400,
>> +       119800, 120200, 120600, 121000, 121400, 121800, 122200, 122600, 123000,
>> +       123400, 123800, 124200, 124600, 124900, 125000,
>> +};
>> +
>> +struct k3_bandgap {
>> +       void __iomem *base;
>> +       const struct k3_bandgap_data *conf;
>> +};
>> +
>> +/* common data structures */
>> +struct k3_thermal_data {
>> +       struct thermal_zone_device *ti_thermal;
> 
> Nit: perhap use tzd/tzdev instead of ti_thermal which doesn't really say much?

okay

> 
>> +       struct k3_bandgap *bgp;
>> +       int sensor_id;
>> +       u32 ctrl_offset;
>> +       u32 stat_offset;
>> +};
>> +
>> +static unsigned int vtm_get_best_value(unsigned int s0, unsigned int s1,
>> +                                      unsigned int s2)
>> +{
>> +       int d01 = abs(s0 - s1);
>> +       int d02 = abs(s0 - s2);
>> +       int d12 = abs(s1 - s2);
>> +
>> +       if (d01 <= d02 && d01 <= d12)
>> +               return (s0 + s1) / 2;
>> +
>> +       if (d02 <= d01 && d02 <= d12)
>> +               return (s0 + s2) / 2;
>> +
>> +       return (s1 + s2) / 2;
>> +}
>> +
>> +static int k3_bgp_read_temp(struct k3_thermal_data *devdata,
>> +                           int *temp)
>> +{
>> +       struct k3_bandgap *bgp;
>> +       unsigned int dtemp, s0, s1, s2;
>> +
>> +       bgp = devdata->bgp;
>> +
>> +       /*
>> +        * Errata is applicable for am654 pg 1.0 silicon. There
>> +        * is a variation of the order for 8-10 degree centigrade.
>> +        * Work around that by getting the average of two closest
>> +        * readings out of three readings everytime we want to
>> +        * report temperatures.
>> +        *
>> +        * Errata workaround.
> 
> So there is no fix in later versions of silicon? If so, shouldn't this
> errata only apply to a subset of chips after checking some IP version?

The previous version of the driver had a check. Since no version of the 
silcion with that errata fixed it out i was adviced to on keeping this 
default.
Once that is supported will bring in the check.

> 
> 
>> +        */
>> +       s0 = readl(bgp->base + devdata->stat_offset) &
>> +               K3_VTM_TS_STAT_DTEMP_MASK;
>> +       s1 = readl(bgp->base + devdata->stat_offset) &
>> +               K3_VTM_TS_STAT_DTEMP_MASK;
>> +       s2 = readl(bgp->base + devdata->stat_offset) &
>> +               K3_VTM_TS_STAT_DTEMP_MASK;
>> +       dtemp = vtm_get_best_value(s0, s1, s2);
>> +
>> +       if (dtemp < K3_VTM_ADC_BEGIN_VAL || dtemp > K3_VTM_ADC_END_VAL)
>> +               return -EINVAL;
>> +
>> +       *temp = k3_adc_to_temp[dtemp - K3_VTM_ADC_BEGIN_VAL];
>> +
>> +       return 0;
>> +}
>> +
>> +static int k3_thermal_get_temp(void *devdata, int *temp)
>> +{
>> +       struct k3_thermal_data *data = devdata;
>> +       int ret = 0;
>> +
>> +       ret = k3_bgp_read_temp(data, temp);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return ret;
>> +}
>> +
>> +static const struct thermal_zone_of_device_ops k3_of_thermal_ops = {
>> +       .get_temp = k3_thermal_get_temp,
>> +};
>> +
>> +static const struct of_device_id of_k3_bandgap_match[];
>> +
>> +static int k3_bandgap_probe(struct platform_device *pdev)
>> +{
>> +       int ret = 0, cnt, val, id, reg_cnt = 0;
>> +       struct resource *res;
>> +       struct device *dev = &pdev->dev;
>> +       struct k3_bandgap *bgp;
>> +       struct k3_thermal_data *data;
>> +
>> +       if (ARRAY_SIZE(k3_adc_to_temp) != (K3_VTM_ADC_END_VAL + 1 -
>> +                                               K3_VTM_ADC_BEGIN_VAL))
>> +               return -EINVAL;
>> +
>> +       bgp = devm_kzalloc(&pdev->dev, sizeof(*bgp), GFP_KERNEL);
>> +       if (!bgp)
>> +               return -ENOMEM;
>> +
>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       bgp->base = devm_ioremap_resource(dev, res);
>> +       if (IS_ERR(bgp->base))
>> +               return PTR_ERR(bgp->base);
>> +
>> +       pm_runtime_enable(dev);
>> +       ret = pm_runtime_get_sync(dev);
>> +       if (ret < 0) {
>> +               pm_runtime_put_noidle(dev);
>> +               pm_runtime_disable(dev);
>> +               return ret;
>> +       }
>> +
>> +       /* Get the sensor count in the VTM */
>> +       val = readl(bgp->base + K3_VTM_DEVINFO_PWR0_OFFSET);
>> +       cnt = val & K3_VTM_DEVINFO_PWR0_TEMPSENS_CT_MASK;
>> +       cnt >>= __ffs(K3_VTM_DEVINFO_PWR0_TEMPSENS_CT_MASK);
>> +
>> +       data = devm_kcalloc(dev, cnt, sizeof(*data), GFP_KERNEL);
>> +       if (!data) {
>> +               ret = -ENOMEM;
>> +               goto err_alloc;
>> +       }
>> +
>> +       /* Register the thermal sensors */
>> +       for (id = 0; id < cnt; id++) {
>> +               data[id].sensor_id = id;
>> +               data[id].bgp = bgp;
>> +               data[id].ctrl_offset = K3_VTM_TMPSENS0_CTRL_OFFSET +
>> +                                       id * K3_VTM_REGS_PER_TS;
>> +               data[id].stat_offset = data[id].ctrl_offset + 0x8;
>> +
>> +               val = readl(data[id].bgp->base + data[id].ctrl_offset);
>> +               val |= (K3_VTM_TMPSENS_CTRL_SOC |
>> +                       K3_VTM_TMPSENS_CTRL_CLRZ |
>> +                       K3_VTM_TMPSENS_CTRL_CLKON_REQ);
>> +               val &= ~K3_VTM_TMPSENS_CTRL_CBIASSEL;
>> +               writel(val, data[id].bgp->base + data[id].ctrl_offset);
>> +
>> +               data[id].ti_thermal =
>> +               devm_thermal_zone_of_sensor_register(dev, id,
>> +                                                    &data[id],
>> +                                                    &k3_of_thermal_ops);
>> +               if (IS_ERR(data[id].ti_thermal)) {
>> +                       dev_err(dev, "thermal zone device is NULL\n");
>> +                       ret = PTR_ERR(data[id].ti_thermal);
>> +                       goto err_alloc;
>> +               }
>> +
>> +               reg_cnt++;
>> +       }
>> +
>> +       platform_set_drvdata(pdev, bgp);
>> +
>> +       return 0;
>> +
>> +err_alloc:
>> +       pm_runtime_put_sync(&pdev->dev);
>> +       pm_runtime_disable(&pdev->dev);
> 
> Just use dev?

Okay

Thanks for the review.

Regards,
Keerthy
> 
> 
>> +
>> +       return ret;
>> +}
>> +
>> +static int k3_bandgap_remove(struct platform_device *pdev)
>> +{
>> +       pm_runtime_put_sync(&pdev->dev);
>> +       pm_runtime_disable(&pdev->dev);
>> +
>> +       return 0;
>> +}
>> +
>> +static const struct of_device_id of_k3_bandgap_match[] = {
>> +       {
>> +               .compatible = "ti,am654-vtm",
>> +       },
>> +       { /* sentinel */ },
>> +};
>> +MODULE_DEVICE_TABLE(of, of_k3_bandgap_match);
>> +
>> +static struct platform_driver k3_bandgap_sensor_driver = {
>> +       .probe = k3_bandgap_probe,
>> +       .remove = k3_bandgap_remove,
>> +       .driver = {
>> +               .name = "k3-soc-thermal",
>> +               .of_match_table = of_k3_bandgap_match,
>> +       },
>> +};
>> +
>> +module_platform_driver(k3_bandgap_sensor_driver);
>> +
>> +MODULE_DESCRIPTION("K3 bandgap temperature sensor driver");
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_AUTHOR("J Keerthy <j-keerthy@ti.com>");
>> --
>> 2.17.1
>>