Re: [PATCH v4 2/2] iio: Aspeed ADC

[Joel Stanley]

On Fri, Mar 24, 2017 at 5:11 AM, Rick Altherr <raltherr@xxxxxxxxxx> wrote:
> Aspeed BMC SoCs include a 16 channel, 10-bit ADC. Low and high threshold
> interrupts are supported by the hardware but are not currently implemented.
>
> Signed-off-by: Rick Altherr <raltherr@xxxxxxxxxx>

I gave it another test with the hwmon bridge on my ast2500-evb:

root@evb-ast2500:~# sensors
iio_hwmon-isa-0000
Adapter: ISA adapter
in1:          +1.30 V

root@evb-ast2500:~# sensors
iio_hwmon-isa-0000
Adapter: ISA adapter
in1:          +1.80 V

Does what it says on the box! The changes you made look good too. If
you do respin, please mention that it was tested on an ast2500evb and
whatever hardware you tested it on.

Reviewed-by: Joel Stanley <joel@xxxxxxxxx>

Cheers,

Joel

> ---
>
> Changes in v4:
> - Avoid copying per-model data to per-instance data
>
> Changes in v3:
> - Drop model numbers from description as same IP is used in every generation
> - Remove unused macros
> - Shorten macro prefix to just ASPEED_
> - Remove extraneous whitespace
> - Rename 2nd argument of ASPEED_CHAN() to clarify purpose
> - Use existing macros in place of magic constants
> - Remove unnecessary logging in failure conditions during probe
> - Disable ADC hardware during remove()
> - Add a NULL terminator to of_match_table
> - Add per-model data to accomodate slight variations (vref, min/max sample rate)
> - Added missing Kconfig depends on COMMON_CLK
>
> Changes in v2:
> - Rewritten as an IIO device
> - Renamed register macros to describe the register's purpose
> - Replaced awkward reading of 16-bit data registers with readw()
> - Added Kconfig dependency on COMPILE_TEST
>
>  drivers/iio/adc/Kconfig      |  11 ++
>  drivers/iio/adc/Makefile     |   1 +
>  drivers/iio/adc/aspeed_adc.c | 284 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 296 insertions(+)
>  create mode 100644 drivers/iio/adc/aspeed_adc.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 2268a6fb9865..236d05f99e80 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -130,6 +130,17 @@ config AD799X
>           To compile this driver as a module, choose M here: the module will be
>           called ad799x.
>
> +config ASPEED_ADC
> +       tristate "Aspeed ADC"
> +       depends on ARCH_ASPEED || COMPILE_TEST
> +       depends on COMMON_CLK
> +       help
> +         If you say yes here you get support for the ADC included in Aspeed
> +         BMC SoCs.
> +
> +         To compile this driver as a module, choose M here: the module will be
> +         called aspeed_adc.
> +
>  config AT91_ADC
>         tristate "Atmel AT91 ADC"
>         depends on ARCH_AT91
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 73dbe399f894..306f10ffca74 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_AD7791) += ad7791.o
>  obj-$(CONFIG_AD7793) += ad7793.o
>  obj-$(CONFIG_AD7887) += ad7887.o
>  obj-$(CONFIG_AD799X) += ad799x.o
> +obj-$(CONFIG_ASPEED_ADC) += aspeed_adc.o
>  obj-$(CONFIG_AT91_ADC) += at91_adc.o
>  obj-$(CONFIG_AT91_SAMA5D2_ADC) += at91-sama5d2_adc.o
>  obj-$(CONFIG_AXP288_ADC) += axp288_adc.o
> diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c
> new file mode 100644
> index 000000000000..e051fdf8ecbd
> --- /dev/null
> +++ b/drivers/iio/adc/aspeed_adc.c
> @@ -0,0 +1,284 @@
> +/*
> + * 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/clk-provider.h>
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +#include <linux/types.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/driver.h>
> +
> +#define ASPEED_RESOLUTION_BITS         10
> +#define ASPEED_CLOCKS_PER_SAMPLE       12
> +
> +#define ASPEED_REG_ENGINE_CONTROL      0x00
> +#define ASPEED_REG_INTERRUPT_CONTROL   0x04
> +#define ASPEED_REG_VGA_DETECT_CONTROL  0x08
> +#define ASPEED_REG_CLOCK_CONTROL       0x0C
> +#define ASPEED_REG_MAX                 0xC0
> +
> +#define ASPEED_OPERATION_MODE_POWER_DOWN       (0x0 << 1)
> +#define ASPEED_OPERATION_MODE_STANDBY          (0x1 << 1)
> +#define ASPEED_OPERATION_MODE_NORMAL           (0x7 << 1)
> +
> +#define ASPEED_ENGINE_ENABLE           BIT(0)
> +
> +struct aspeed_adc_model_data {
> +       const char *model_name;
> +       unsigned int min_sampling_rate; // Hz
> +       unsigned int max_sampling_rate; // Hz
> +       unsigned int vref_voltage;      // mV
> +};
> +
> +struct aspeed_adc_data {
> +       struct device   *dev;
> +       void __iomem    *base;
> +       spinlock_t      clk_lock;
> +       struct clk_hw   *clk_prescaler;
> +       struct clk_hw   *clk_scaler;
> +};
> +
> +#define ASPEED_CHAN(_idx, _data_reg_addr) {                    \
> +       .type = IIO_VOLTAGE,                                    \
> +       .indexed = 1,                                           \
> +       .channel = (_idx),                                      \
> +       .address = (_data_reg_addr),                            \
> +       .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
> +       .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |  \
> +                               BIT(IIO_CHAN_INFO_SAMP_FREQ),   \
> +}
> +
> +static const struct iio_chan_spec aspeed_adc_iio_channels[] = {
> +       ASPEED_CHAN(0, 0x10),
> +       ASPEED_CHAN(1, 0x12),
> +       ASPEED_CHAN(2, 0x14),
> +       ASPEED_CHAN(3, 0x16),
> +       ASPEED_CHAN(4, 0x18),
> +       ASPEED_CHAN(5, 0x1A),
> +       ASPEED_CHAN(6, 0x1C),
> +       ASPEED_CHAN(7, 0x1E),
> +       ASPEED_CHAN(8, 0x20),
> +       ASPEED_CHAN(9, 0x22),
> +       ASPEED_CHAN(10, 0x24),
> +       ASPEED_CHAN(11, 0x26),
> +       ASPEED_CHAN(12, 0x28),
> +       ASPEED_CHAN(13, 0x2A),
> +       ASPEED_CHAN(14, 0x2C),
> +       ASPEED_CHAN(15, 0x2E),
> +};
> +
> +static int aspeed_adc_read_raw(struct iio_dev *indio_dev,
> +                              struct iio_chan_spec const *chan,
> +                              int *val, int *val2, long mask)
> +{
> +       struct aspeed_adc_data *data = iio_priv(indio_dev);
> +       const struct aspeed_adc_model_data *model_data =
> +                       of_device_get_match_data(data->dev);
> +
> +       switch (mask) {
> +       case IIO_CHAN_INFO_RAW:
> +               *val = readw(data->base + chan->address);
> +               return IIO_VAL_INT;
> +
> +       case IIO_CHAN_INFO_SCALE:
> +               *val = model_data->vref_voltage;
> +               *val2 = ASPEED_RESOLUTION_BITS;
> +               return IIO_VAL_FRACTIONAL_LOG2;
> +
> +       case IIO_CHAN_INFO_SAMP_FREQ:
> +               *val = clk_get_rate(data->clk_scaler->clk) /
> +                               ASPEED_CLOCKS_PER_SAMPLE;
> +               return IIO_VAL_INT;
> +
> +       default:
> +               return -EPERM;
> +       }
> +}
> +
> +static int aspeed_adc_write_raw(struct iio_dev *indio_dev,
> +                               struct iio_chan_spec const *chan,
> +                               int val, int val2, long mask)
> +{
> +       struct aspeed_adc_data *data = iio_priv(indio_dev);
> +       const struct aspeed_adc_model_data *model_data =
> +                       of_device_get_match_data(data->dev);
> +
> +       switch (mask) {
> +       case IIO_CHAN_INFO_SAMP_FREQ:
> +               if (val < model_data->min_sampling_rate ||
> +                       val > model_data->max_sampling_rate)
> +                       return -EINVAL;
> +
> +               clk_set_rate(data->clk_scaler->clk,
> +                               val * ASPEED_CLOCKS_PER_SAMPLE);
> +               return 0;
> +
> +       default:
> +               return -EPERM;
> +       }
> +}
> +
> +static int aspeed_adc_reg_access(struct iio_dev *indio_dev,
> +                                unsigned int reg, unsigned int writeval,
> +                                unsigned int *readval)
> +{
> +       struct aspeed_adc_data *data = iio_priv(indio_dev);
> +
> +       if (!readval || reg % 4 || reg > ASPEED_REG_MAX)
> +               return -EINVAL;
> +
> +       *readval = readl(data->base + reg);
> +       return 0;
> +}
> +
> +static const struct iio_info aspeed_adc_iio_info = {
> +       .driver_module = THIS_MODULE,
> +       .read_raw = aspeed_adc_read_raw,
> +       .write_raw = aspeed_adc_write_raw,
> +       .debugfs_reg_access = aspeed_adc_reg_access,
> +};
> +
> +static int aspeed_adc_probe(struct platform_device *pdev)
> +{
> +       struct iio_dev *indio_dev;
> +       struct aspeed_adc_data *data;
> +       const struct aspeed_adc_model_data *model_data;
> +       struct resource *res;
> +       const char *clk_parent_name;
> +       int ret;
> +       u32 adc_engine_control_reg_val;
> +
> +       indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data));
> +       if (!indio_dev)
> +               return -ENOMEM;
> +
> +       data = iio_priv(indio_dev);
> +       data->dev = &pdev->dev;
> +
> +       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);
> +
> +       /* Register ADC clock prescaler with source specified by device tree. */
> +       spin_lock_init(&data->clk_lock);
> +       clk_parent_name = of_clk_get_parent_name(pdev->dev.of_node, 0);
> +
> +       data->clk_prescaler = clk_hw_register_divider(
> +                               &pdev->dev, "prescaler", clk_parent_name, 0,
> +                               data->base + ASPEED_REG_CLOCK_CONTROL,
> +                               17, 15, 0, &data->clk_lock);
> +       if (IS_ERR(data->clk_prescaler))
> +               return PTR_ERR(data->clk_prescaler);
> +
> +       /*
> +        * Register ADC clock scaler downstream from the prescaler. Allow rate
> +        * setting to adjust the prescaler as well.
> +        */
> +       data->clk_scaler = clk_hw_register_divider(
> +                               &pdev->dev, "scaler", "prescaler",
> +                               CLK_SET_RATE_PARENT,
> +                               data->base + ASPEED_REG_CLOCK_CONTROL,
> +                               0, 10, 0, &data->clk_lock);
> +       if (IS_ERR(data->clk_scaler)) {
> +               ret = PTR_ERR(data->clk_scaler);
> +               goto scaler_error;
> +       }
> +
> +       /* Start all channels in normal mode. */
> +       clk_prepare_enable(data->clk_scaler->clk);
> +       adc_engine_control_reg_val = GENMASK(31, 16) |
> +               ASPEED_OPERATION_MODE_NORMAL | ASPEED_ENGINE_ENABLE;
> +       writel(adc_engine_control_reg_val,
> +               data->base + ASPEED_REG_ENGINE_CONTROL);
> +
> +       model_data = of_device_get_match_data(&pdev->dev);
> +       indio_dev->name = model_data->model_name;
> +       indio_dev->dev.parent = &pdev->dev;
> +       indio_dev->info = &aspeed_adc_iio_info;
> +       indio_dev->modes = INDIO_DIRECT_MODE;
> +       indio_dev->channels = aspeed_adc_iio_channels;
> +       indio_dev->num_channels = ARRAY_SIZE(aspeed_adc_iio_channels);
> +
> +       ret = iio_device_register(indio_dev);
> +       if (ret)
> +               goto iio_register_error;
> +
> +       return 0;
> +
> +iio_register_error:
> +       writel(ASPEED_OPERATION_MODE_POWER_DOWN,
> +               data->base + ASPEED_REG_ENGINE_CONTROL);
> +       clk_disable_unprepare(data->clk_scaler->clk);
> +       clk_hw_unregister_divider(data->clk_scaler);
> +
> +scaler_error:
> +       clk_hw_unregister_divider(data->clk_prescaler);
> +       return ret;
> +}
> +
> +static int aspeed_adc_remove(struct platform_device *pdev)
> +{
> +       struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +       struct aspeed_adc_data *data = iio_priv(indio_dev);
> +
> +       iio_device_unregister(indio_dev);
> +       writel(ASPEED_OPERATION_MODE_POWER_DOWN,
> +               data->base + ASPEED_REG_ENGINE_CONTROL);
> +       clk_disable_unprepare(data->clk_scaler->clk);
> +       clk_hw_unregister_divider(data->clk_scaler);
> +       clk_hw_unregister_divider(data->clk_prescaler);
> +
> +       return 0;
> +}
> +
> +static const struct aspeed_adc_model_data ast2400_model_data = {
> +       .model_name = "ast2400-adc",
> +       .vref_voltage = 2500, // mV
> +       .min_sampling_rate = 10000,
> +       .max_sampling_rate = 500000,
> +};
> +
> +static const struct aspeed_adc_model_data ast2500_model_data = {
> +       .model_name = "ast2500-adc",
> +       .vref_voltage = 1800, // mV
> +       .min_sampling_rate = 1,
> +       .max_sampling_rate = 1000000,
> +};
> +
> +static const struct of_device_id aspeed_adc_matches[] = {
> +       { .compatible = "aspeed,ast2400-adc", .data = &ast2400_model_data },
> +       { .compatible = "aspeed,ast2500-adc", .data = &ast2500_model_data },
> +       {},
> +};
> +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");
> --
> 2.12.1.500.gab5fba24ee-goog
>