Re: [PATCH 2/2] hwmon: Aspeed AST2400/AST2500 ADC

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




Resending in plain text.

On Tue, Feb 28, 2017 at 7:45 PM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> On 02/28/2017 04:49 PM, Joel Stanley wrote:
>>
>> On Wed, Mar 1, 2017 at 6:44 AM, Rick Altherr <raltherr@xxxxxxxxxx> wrote:
>>>
>>> Aspeed AST2400/AST2500 BMC SoCs include a 16 channel, 10-bit ADC. This
>>> driver implements reading the ADC values, enabling channels via device
>>> tree, and optionally providing channel labels via device tree.  Low and
>>> high threshold interrupts are supported by the hardware but not
>>> implemented.
>>>
>>> Signed-off-by: Rick Altherr <raltherr@xxxxxxxxxx>
>>
>>
>> Looks good. Some minor comments below.
>>
>> Is there a reason you wrote a hwmon driver instead of an iio driver? I
>> wasn't sure what the recommended subsystem is.
>
>
> Excellent point. Question is really if there is a plan to add support for
> thresholds. If not, an iio driver might be more appropriate.
>
> Guenter
>

The hardware supports firing interrupts on high and low thresholds.
I'm not planning to use that feature yet so I didn't implement it.
Would you prefer that I leave it as is (maybe with a TODO), implement
the thresholding, or change to iio?

Rick

>>
>>> ---
>>>  drivers/hwmon/Kconfig      |  10 ++
>>>  drivers/hwmon/Makefile     |   1 +
>>>  drivers/hwmon/aspeed_adc.c | 383
>>> +++++++++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 394 insertions(+)
>>>  create mode 100644 drivers/hwmon/aspeed_adc.c
>>>
>>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
>>> index 0649d53f3d16..c99a67b4afe4 100644
>>> --- a/drivers/hwmon/Kconfig
>>> +++ b/drivers/hwmon/Kconfig
>>> @@ -261,6 +261,16 @@ config SENSORS_ASC7621
>>>           This driver can also be built as a module.  If so, the module
>>>           will be called asc7621.
>>>
>>> +config SENSORS_ASPEED_ADC
>>> +       tristate "Aspeed AST2400/AST2500 ADC"
>>> +       depends on ARCH_ASPEED
>>
>>
>> depends on ARCH_ASPEED || COMPILE_TEST.
>>
>>> +       help
>>> +         If you say yes here you get support for the Aspeed
>>> AST2400/AST2500
>>> +         ADC.
>>> +
>>> +         This driver can also be built as a module.  If so, the module
>>> +         will be called aspeed_adc.
>>> +
>>>  config SENSORS_K8TEMP
>>>         tristate "AMD Athlon64/FX or Opteron temperature sensor"
>>>         depends on X86 && PCI
>>> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
>>> index 5509edf6186a..eede049c9d0d 100644
>>> --- a/drivers/hwmon/Makefile
>>> +++ b/drivers/hwmon/Makefile
>>> @@ -46,6 +46,7 @@ obj-$(CONFIG_SENSORS_ADT7475) += adt7475.o
>>>  obj-$(CONFIG_SENSORS_APPLESMC) += applesmc.o
>>>  obj-$(CONFIG_SENSORS_ARM_SCPI) += scpi-hwmon.o
>>>  obj-$(CONFIG_SENSORS_ASC7621)  += asc7621.o
>>> +obj-$(CONFIG_SENSORS_ASPEED_ADC) += aspeed_adc.o
>>>  obj-$(CONFIG_SENSORS_ATXP1)    += atxp1.o
>>>  obj-$(CONFIG_SENSORS_CORETEMP) += coretemp.o
>>>  obj-$(CONFIG_SENSORS_DA9052_ADC)+= da9052-hwmon.o
>>> diff --git a/drivers/hwmon/aspeed_adc.c b/drivers/hwmon/aspeed_adc.c
>>> new file mode 100644
>>> index 000000000000..098e32315264
>>> --- /dev/null
>>> +++ b/drivers/hwmon/aspeed_adc.c
>>> @@ -0,0 +1,383 @@
>>> +/*
>>> + * Aspeed AST2400/2500 ADC
>>> + *
>>> + * Copyright (C) 2017 Google, Inc.
>>> + *
>>> + * This program is free software; you can redistribute it and/or modify
>>> it
>>> + * under the terms and conditions of the GNU General Public License,
>>> + * version 2, as published by the Free Software Foundation.
>>> + *
>>> + */
>>> +
>>> +#include <asm/io.h>
>>> +#include <linux/clk.h>
>>> +#include <linux/err.h>
>>> +#include <linux/errno.h>
>>> +#include <linux/hwmon.h>
>>> +#include <linux/hwmon-sysfs.h>
>>> +#include <linux/module.h>
>>> +#include <linux/mutex.h>
>>> +#include <linux/of_platform.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/types.h>
>>> +
>>> +#define ASPEED_ADC_NUM_CHANNELS        16
>>> +#define ASPEED_ADC_REF_VOLTAGE 2500 /* millivolts */
>>> +
>>> +#define ASPEED_ADC_REG_ADC00 0x00
>>> +#define ASPEED_ADC_REG_ADC04 0x04
>>> +#define ASPEED_ADC_REG_ADC08 0x08
>>> +#define ASPEED_ADC_REG_ADC0C 0x0C
>>> +#define ASPEED_ADC_REG_ADC10 0x10
>>> +#define ASPEED_ADC_REG_ADC14 0x14
>>> +#define ASPEED_ADC_REG_ADC18 0x18
>>> +#define ASPEED_ADC_REG_ADC1C 0x1C
>>> +#define ASPEED_ADC_REG_ADC20 0x20
>>> +#define ASPEED_ADC_REG_ADC24 0x24
>>> +#define ASPEED_ADC_REG_ADC28 0x28
>>> +#define ASPEED_ADC_REG_ADC2C 0x2C
>>
>>
>> I'm not sure that these defines add any value. I'd either give them
>> names such as "ASPEED_ADC_ENGINE_CTRL". or just use the register
>> offset directly.
>>
>>> +
>>> +#define ASPEED_ADC_OPERATION_MODE_POWER_DOWN   (0x0 << 1)
>>> +#define ASPEED_ADC_OPERATION_MODE_STANDBY      (0x1 << 1)
>>> +#define ASPEED_ADC_OPERATION_MODE_NORMAL       (0x7 << 1)
>>> +
>>> +#define ASPEED_ADC_ENGINE_ENABLE       BIT(0)
>>> +
>>> +struct aspeed_adc_data {
>>> +       struct device   *dev;
>>> +       void __iomem    *base;
>>> +       struct clk      *pclk;
>>> +       struct mutex    lock;
>>> +       unsigned long   update_interval_ms;
>>> +       u32             enabled_channel_mask;
>>> +       const char*     channel_labels[ASPEED_ADC_NUM_CHANNELS];
>>> +};
>>> +
>>> +static int aspeed_adc_set_adc_clock_frequency(
>>> +               struct aspeed_adc_data *data,
>>> +               unsigned long desired_update_interval_ms)
>>> +{
>>> +       long pclk_hz = clk_get_rate(data->pclk);
>>> +       long adc_combined_divisor;
>>> +       long adc_pre_divisor;
>>> +       long adc_divisor;
>>> +       long adc_clock_control_reg_val;
>>> +        long num_enabled_channels =
>>> hweight32(data->enabled_channel_mask);
>>
>>
>> Some whitespace damage here.
>>
>>> +
>>> +       if (desired_update_interval_ms < 1)
>>> +               return -EINVAL;
>>> +
>>> +       /* From the AST2400 datasheet:
>>
>>
>> Nit: kernel style is to leave a blank line on the first line of
>> multi-line comments:
>>
>>  /*
>>   * Foo
>>   * etc
>>
>>> +        *   adc_period_s = pclk_period_s * 2 * (pre_divisor+1) *
>>> (divisor+1)
>>> +        *
>>> +        *   and
>>> +        *
>>> +        *   sample_period_s = 12 * adc_period_s
>>> +        *
>>> +        * Substitute pclk_period_s = (1 / pclk_hz)
>>> +        *
>>> +        * Solve for (pre-divisor+1) * (divisor+1) as those are settings
>>> we need
>>> +        * to program:
>>> +        *   (pre-divisor+1) * (divisor+1) = (sample_period_s * pclk_hz)
>>> / 24
>>> +        */
>>> +
>>> +       /* Assume PCLK runs at a fairly high frequency so dividing it
>>> first
>>> +        * loses little accuracy.  Also note that the above formulas have
>>> +        * sample_period in seconds while our desired_update_interval is
>>> in
>>> +        * milliseconds, hence the divide by 1000.
>>> +        */
>>> +       adc_combined_divisor = desired_update_interval_ms *
>>> +                       (pclk_hz / 24 / 1000 / num_enabled_channels);
>>> +
>>> +       /* Prefer to use the ADC divisor over the ADC pre-divisor.  ADC
>>> divisor
>>> +        * is 10-bits wide so anything over 1024 must use the
>>> pre-divisor.
>>> +        */
>>> +       adc_pre_divisor = 1;
>>> +       while (adc_combined_divisor/adc_pre_divisor > (1<<10)) {
>>> +               adc_pre_divisor += 1;
>>> +       };
>>> +       adc_divisor = adc_combined_divisor / adc_pre_divisor;
>>> +
>>> +       /* Since ADC divisor and pre-divisor are used in division, the
>>> register
>>> +        * value is implicitly incremented by one before use.  This means
>>> we
>>> +        * need to subtract one from our calculated values above.
>>> +        */
>>> +       adc_pre_divisor -= 1;
>>> +       adc_divisor -= 1;
>>> +
>>> +       adc_clock_control_reg_val = (adc_pre_divisor << 17) |
>>> adc_divisor;
>>> +
>>> +       mutex_lock(&data->lock);
>>> +       data->update_interval_ms =
>>> +                       (adc_pre_divisor + 1) * (adc_divisor + 1)
>>> +                       / (pclk_hz / 24 / 1000);
>>> +       writel(adc_clock_control_reg_val, data->base +
>>> ASPEED_ADC_REG_ADC0C);
>>> +       mutex_unlock(&data->lock);
>>> +
>>> +       return 0;
>>> +}
>>> +
>>> +static int aspeed_adc_get_channel_reading(struct aspeed_adc_data *data,
>>> +                                               int channel, long *val)
>>> +{
>>> +       u32 data_reg;
>>> +       u32 data_reg_val;
>>> +       long adc_val;
>>> +
>>> +       /* Each 32-bit data register contains 2 10-bit ADC values. */
>>> +       data_reg = ASPEED_ADC_REG_ADC10 + (channel / 2) * 4;
>>> +       data_reg_val = readl(data->base + data_reg);
>>> +       if (channel % 2 == 0) {
>>> +               adc_val = data_reg_val & 0x3FF;
>>> +       } else {
>>> +               adc_val = (data_reg_val >> 16) & 0x3FF;
>>> +       }
>>
>>
>> I wonder if you could replace the above block with:
>>
>>             adc_val = readw(data->base + ASPEED_ADC_REG_ADC10 + channel);
>>
>>> +
>>> +       /* Scale 10-bit input reading to millivolts. */
>>> +       *val = adc_val * ASPEED_ADC_REF_VOLTAGE / 1024;
>>> +
>>> +       return 0;
>>> +}
>>> +
>>> +static umode_t aspeed_adc_hwmon_is_visible(const void *_data,
>>> +                                               enum hwmon_sensor_types
>>> type,
>>> +                                               u32 attr, int channel)
>>> +{
>>> +       const struct aspeed_adc_data* data = _data;
>>> +
>>> +       if (type == hwmon_chip && attr == hwmon_chip_update_interval) {
>>> +               return S_IRUGO | S_IWUSR;
>>> +       } else if (type == hwmon_in) {
>>> +               /* Only channels that are enabled should be visible. */
>>> +               if (channel >= 0 && channel <= ASPEED_ADC_NUM_CHANNELS &&
>>> +                   (data->enabled_channel_mask & BIT(channel))) {
>>> +
>>> +                       /* All enabled channels have an input but labels
>>> are
>>> +                        * optional in the device tree.
>>> +                        */
>>> +                       if (attr == hwmon_in_input) {
>>> +                               return S_IRUGO;
>>> +                       } else if (attr == hwmon_in_label &&
>>> +                                       data->channel_labels[channel] !=
>>> NULL) {
>>> +                               return S_IRUGO;
>>> +                       }
>>> +               }
>>> +       }
>>> +
>>> +       return 0;
>>> +}
>>> +
>>> +static int aspeed_adc_hwmon_read(struct device *dev, enum
>>> hwmon_sensor_types type,
>>> +                        u32 attr, int channel, long *val)
>>> +{
>>> +       struct aspeed_adc_data *data = dev_get_drvdata(dev);
>>> +
>>> +       if (type == hwmon_chip && attr == hwmon_chip_update_interval) {
>>> +               *val = data->update_interval_ms;
>>> +               return 0;
>>> +       } else if (type == hwmon_in && attr == hwmon_in_input) {
>>> +               return aspeed_adc_get_channel_reading(data, channel,
>>> val);
>>> +       }
>>> +
>>> +       return -EOPNOTSUPP;
>>> +}
>>> +
>>> +static int aspeed_adc_hwmon_read_string(struct device *dev,
>>> +                                       enum hwmon_sensor_types type,
>>> +                                       u32 attr, int channel, char
>>> **str)
>>> +{
>>> +       struct aspeed_adc_data *data = dev_get_drvdata(dev);
>>> +
>>> +       if (type == hwmon_in && attr == hwmon_in_label) {
>>> +               *str = (char*)data->channel_labels[channel];
>>> +               return 0;
>>> +       }
>>> +
>>> +       return -EOPNOTSUPP;
>>> +}
>>> +
>>> +static int aspeed_adc_hwmon_write(struct device *dev, enum
>>> hwmon_sensor_types type,
>>> +                         u32 attr, int channel, long val)
>>> +{
>>> +       struct aspeed_adc_data *data = dev_get_drvdata(dev);
>>> +
>>> +       if (type == hwmon_chip && attr == hwmon_chip_update_interval) {
>>> +               return aspeed_adc_set_adc_clock_frequency(data, val);
>>> +       }
>>> +
>>> +       return -EOPNOTSUPP;
>>> +}
>>> +
>>> +static const struct hwmon_ops aspeed_adc_hwmon_ops = {
>>> +       .is_visible = aspeed_adc_hwmon_is_visible,
>>> +       .read = aspeed_adc_hwmon_read,
>>> +       .read_string = aspeed_adc_hwmon_read_string,
>>> +       .write = aspeed_adc_hwmon_write,
>>> +};
>>> +
>>> +static const u32 aspeed_adc_hwmon_chip_config[] = {
>>> +       HWMON_C_UPDATE_INTERVAL,
>>> +       0
>>> +};
>>> +
>>> +static const struct hwmon_channel_info aspeed_adc_hwmon_chip_channel = {
>>> +       .type = hwmon_chip,
>>> +       .config = aspeed_adc_hwmon_chip_config,
>>> +};
>>> +
>>> +static const u32 aspeed_adc_hwmon_in_config[] = {
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       HWMON_I_INPUT | HWMON_I_LABEL,
>>> +       0
>>> +};
>>> +
>>> +static const struct hwmon_channel_info aspeed_adc_hwmon_in_channel = {
>>> +       .type = hwmon_in,
>>> +       .config = aspeed_adc_hwmon_in_config,
>>> +};
>>> +
>>> +static const struct hwmon_channel_info *aspeed_adc_hwmon_channel_info[]
>>> = {
>>> +       &aspeed_adc_hwmon_chip_channel,
>>> +       &aspeed_adc_hwmon_in_channel,
>>> +       NULL
>>> +};
>>> +
>>> +static const struct hwmon_chip_info aspeed_adc_hwmon_chip_info = {
>>> +       .ops = &aspeed_adc_hwmon_ops,
>>> +       .info = aspeed_adc_hwmon_channel_info,
>>> +};
>>> +
>>> +static int aspeed_adc_probe(struct platform_device *pdev)
>>> +{
>>> +       struct aspeed_adc_data *data;
>>> +       struct resource *res;
>>> +       int ret;
>>> +       struct device *hwmon_dev;
>>> +       u32 desired_update_interval_ms;
>>> +       u32 adc_engine_control_reg_val;
>>> +       struct device_node* node;
>>> +
>>> +       data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
>>> +       if (!data)
>>> +               return -ENOMEM;
>>> +
>>> +       data->pclk = devm_clk_get(&pdev->dev, NULL);
>>> +       if (IS_ERR(data->pclk)) {
>>> +               dev_err(&pdev->dev, "clk_get failed\n");
>>> +               return PTR_ERR(data->pclk);
>>> +       }
>>> +
>>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> +       data->base = devm_ioremap_resource(&pdev->dev, res);
>>> +       if (IS_ERR(data->base))
>>> +               return PTR_ERR(data->base);
>>> +
>>> +       ret = of_property_read_u32(pdev->dev.of_node,
>>> +                       "update-interval-ms",
>>> &desired_update_interval_ms);
>>> +       if (ret < 0 || desired_update_interval_ms == 0) {
>>> +               dev_err(&pdev->dev,
>>> +                               "Missing or zero update-interval-ms
>>> property, "
>>> +                               "defaulting to 100ms\n");
>>
>>
>> Put the string on one line so it can be easily searched for.
>>
>>> +               desired_update_interval_ms = 100;
>>> +       }
>>> +
>>> +       mutex_init(&data->lock);
>>> +
>>> +       ret = clk_prepare_enable(data->pclk);
>>> +       if (ret) {
>>> +               dev_err(&pdev->dev, "failed to enable clock\n");
>>> +               mutex_destroy(&data->lock);
>>> +                return ret;
>>
>>
>> Strange whitespace here.
>>
>>> +       }
>>> +
>>> +       /* Figure out which channels are marked available in the device
>>> tree. */
>>> +       data->enabled_channel_mask = 0;
>>> +       for_each_available_child_of_node(pdev->dev.of_node, node) {
>>> +               u32 pval;
>>> +               unsigned int channel;
>>> +
>>> +               if (of_property_read_u32(node, "reg", &pval)) {
>>> +                       dev_err(&pdev->dev, "invalid reg on %s\n",
>>> +                               node->full_name);
>>> +                       continue;
>>> +               }
>>> +
>>> +               channel = pval;
>>> +               if (channel >= ASPEED_ADC_NUM_CHANNELS) {
>>> +                       dev_err(&pdev->dev,
>>> +                               "invalid channel index %d on %s\n",
>>> +                               channel, node->full_name);
>>> +                       continue;
>>> +               }
>>> +
>>> +               data->enabled_channel_mask |= BIT(channel);
>>> +
>>> +               /* Cache a pointer to the label if one is specified.
>>> Ignore any
>>> +                * errors as the label property is optional.
>>> +                */
>>> +               of_property_read_string(node, "label",
>>> &data->channel_labels[channel]);
>>
>>
>> I was wondering how long we could keep that pointer around. I think we
>> are ok for the lifetime of the driver, as we hold a reference to the
>> node in dev.of_node.
>>
>>> +       }
>>> +
>>> +       platform_set_drvdata(pdev, data);
>>> +       aspeed_adc_set_adc_clock_frequency(data,
>>> desired_update_interval_ms);
>>
>>
>> This reads funny. aspeed_adc_set_clock_frequency instead?
>>
>>> +
>>> +       /* Start all the requested channels in normal mode. */
>>> +       adc_engine_control_reg_val = (data->enabled_channel_mask << 16) |
>>> +               ASPEED_ADC_OPERATION_MODE_NORMAL |
>>> ASPEED_ADC_ENGINE_ENABLE;
>>> +       writel(adc_engine_control_reg_val, data->base +
>>> ASPEED_ADC_REG_ADC00);
>>> +
>>> +       /* Register sysfs hooks */
>>> +       hwmon_dev = devm_hwmon_device_register_with_info(
>>> +                       &pdev->dev, "aspeed_adc", data,
>>> +                       &aspeed_adc_hwmon_chip_info, NULL);
>>> +       if (IS_ERR(hwmon_dev)) {
>>> +               clk_disable_unprepare(data->pclk);
>>> +               mutex_destroy(&data->lock);
>>> +               return PTR_ERR(hwmon_dev);
>>> +       }
>>> +
>>> +       return 0;
>>> +}
>>> +
>>> +static int aspeed_adc_remove(struct platform_device *pdev) {
>>> +       struct aspeed_adc_data *data = dev_get_drvdata(&pdev->dev);
>>> +       clk_disable_unprepare(data->pclk);
>>> +       mutex_destroy(&data->lock);
>>> +       return 0;
>>> +}
>>> +
>>> +const struct of_device_id aspeed_adc_matches[] = {
>>> +       { .compatible = "aspeed,ast2400-adc" },
>>> +       { .compatible = "aspeed,ast2500-adc" },
>>> +};
>>> +MODULE_DEVICE_TABLE(of, aspeed_adc_matches);
>>> +
>>> +static struct platform_driver aspeed_adc_driver = {
>>> +       .probe = aspeed_adc_probe,
>>> +       .remove = aspeed_adc_remove,
>>> +       .driver = {
>>> +               .name = KBUILD_MODNAME,
>>> +               .of_match_table = aspeed_adc_matches,
>>> +       }
>>> +};
>>> +
>>> +module_platform_driver(aspeed_adc_driver);
>>> +
>>> +MODULE_AUTHOR("Rick Altherr <raltherr@xxxxxxxxxx>");
>>> +MODULE_DESCRIPTION("Aspeed AST2400/2500 ADC Driver");
>>> +MODULE_LICENSE("GPL");
>>> --
>>> 2.11.0.483.g087da7b7c-goog
>>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in
>> the body of a message to majordomo@xxxxxxxxxxxxxxx
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]
  Powered by Linux