[PATCH v4 2/2] iio: Aspeed ADC
Rick Altherr
raltherr at google.com
Tue Mar 28 10:05:59 AEDT 2017
On Sat, Mar 25, 2017 at 10:32 AM, Jonathan Cameron <jic23 at kernel.org> wrote:
> On 23/03/17 18:41, Rick Altherr 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 at google.com>
> Nice little driver.
>
> I'd like input from clk maintainers on the clk stuff though before applying.
> Michael, Stephen MAINTAINERS suggests this is you two. Any comments?
>
> Thanks,
>
> Jonathan
>
>> ---
>>
>> 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;
> Unusual, but I supose a valid choice.
I must have changed this one by accident. It was EINVAL previously
and that is at least literally true.
>> + }
>> +}
>> +
>> +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;
Similar to above, EINVAL makes more sense as the default case. EPERM
came from thinking about attempts to write INFO_SCALE or INFO_RAW.
Technically EINVAL is accurate but it's more a policy decision that
I'm not allowing writes to those.
>> + }
>> +}
>> +
>> +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 at google.com>");
>> +MODULE_DESCRIPTION("Aspeed AST2400/2500 ADC Driver");
>> +MODULE_LICENSE("GPL");
>>
>
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