> Aspeed AST2400/AST2500 BMC SoCs include a 16 channel, 10-bit ADC. Low
> and high threshold interrupts are supported by the hardware but are not
> currently implemented.
comments below
link to a datasheet would be nice
> Signed-off-by: Rick Altherr <ralth...@google.com>
> ---
>
> 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 | 10 ++
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/aspeed_adc.c | 271
> +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 282 insertions(+)
> create mode 100644 drivers/iio/adc/aspeed_adc.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 2268a6fb9865..9672d799a3fb 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -130,6 +130,16 @@ config AD799X
> To compile this driver as a module, choose M here: the module will be
> called ad799x.
>
> +config ASPEED_ADC
> + tristate "Aspeed AST2400/AST2500 ADC"
> + depends on ARCH_ASPEED || COMPILE_TEST
> + help
> + If you say yes here you get support for the Aspeed AST2400/AST2500
> + ADC.
> +
> + 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..9220909aefd4
> --- /dev/null
> +++ b/drivers/iio/adc/aspeed_adc.c
> @@ -0,0 +1,271 @@
> +/*
> + * 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_ADC_NUM_CHANNELS 16
_NUM_CHANNELS is not used, remove
> +#define ASPEED_ADC_REF_VOLTAGE 2500 /* millivolts */
should be used below
> +#define ASPEED_ADC_RESOLUTION_BITS 10
should be used below
> +#define ASPEED_ADC_MIN_SAMP_RATE 10000
> +#define ASPEED_ADC_MAX_SAMP_RATE 500000
> +#define ASPEED_ADC_CLOCKS_PER_SAMPLE 12
> +
> +#define ASPEED_ADC_REG_ENGINE_CONTROL 0x00
> +#define ASPEED_ADC_REG_INTERRUPT_CONTROL 0x04
> +#define ASPEED_ADC_REG_VGA_DETECT_CONTROL 0x08
> +#define ASPEED_ADC_REG_CLOCK_CONTROL 0x0C
> +#define ASPEED_ADC_REG_MAX 0xC0
> +
> +#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;
> +
> + spinlock_t clk_lock;
> + struct clk_hw *clk_prescaler;
> + struct clk_hw *clk_scaler;
> +};
> +
> +#define ASPEED_ADC_CHAN(_idx, _addr) { \
> + .type = IIO_VOLTAGE, \
> + .indexed = 1, \
> + .channel = (_idx), \
> + .address = (_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_ADC_CHAN(0, 0x10),
> + ASPEED_ADC_CHAN(1, 0x12),
> + ASPEED_ADC_CHAN(2, 0x14),
> + ASPEED_ADC_CHAN(3, 0x16),
> + ASPEED_ADC_CHAN(4, 0x18),
> + ASPEED_ADC_CHAN(5, 0x1A),
> + ASPEED_ADC_CHAN(6, 0x1C),
> + ASPEED_ADC_CHAN(7, 0x1E),
> + ASPEED_ADC_CHAN(8, 0x20),
> + ASPEED_ADC_CHAN(9, 0x22),
> + ASPEED_ADC_CHAN(10, 0x24),
> + ASPEED_ADC_CHAN(11, 0x26),
> + ASPEED_ADC_CHAN(12, 0x28),
> + ASPEED_ADC_CHAN(13, 0x2A),
> + ASPEED_ADC_CHAN(14, 0x2C),
> + ASPEED_ADC_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);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + *val = readw(data->base + chan->address);
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_SCALE:
> + *val = 2500; // mV
REF_VOLTAGE?
> + *val2 = 10;
> + return IIO_VAL_FRACTIONAL_LOG2;
> +
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + *val = clk_get_rate(data->clk_scaler->clk) /
> + ASPEED_ADC_CLOCKS_PER_SAMPLE;
> + return IIO_VAL_INT;
> +
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +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);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + if (val < ASPEED_ADC_MIN_SAMP_RATE ||
> + val > ASPEED_ADC_MAX_SAMP_RATE)
> + return -EINVAL;
> +
> + clk_set_rate(data->clk_scaler->clk,
> + val * ASPEED_ADC_CLOCKS_PER_SAMPLE);
> + return 0;
> +
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +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_ADC_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,
without & (matter of taste)
> + .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;
> + 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) {
> + dev_err(&pdev->dev, "Failed allocating iio device\n");
> + return -ENOMEM;
> + }
> +
> + data = iio_priv(indio_dev);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + data->base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(data->base)) {
> + dev_err(&pdev->dev, "Failed allocating device resources\n");
> + ret = PTR_ERR(data->base);
> + goto resource_error;
just return here?
> + }
> +
> + /* 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_ADC_REG_CLOCK_CONTROL,
> + 17, 15, 0, &data->clk_lock);
> + if (IS_ERR(data->clk_prescaler)) {
> + dev_err(&pdev->dev, "Failed allocating prescaler clock\n");
> + ret = PTR_ERR(data->clk_prescaler);
> + goto prescaler_error;
just return here?
> + }
> +
> + /*
> + * 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_ADC_REG_CLOCK_CONTROL,
> + 0, 10, 0, &data->clk_lock);
> + if (IS_ERR(data->clk_scaler)) {
> + dev_err(&pdev->dev, "Failed allocating scaler clock\n");
> + 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_ADC_OPERATION_MODE_NORMAL | ASPEED_ADC_ENGINE_ENABLE;
> + writel(adc_engine_control_reg_val,
> + data->base + ASPEED_ADC_REG_ENGINE_CONTROL);
> +
> + indio_dev->name = dev_name(&pdev->dev);
> + 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) {
> + dev_err(&pdev->dev, "Could't register the device.\n");
Couldn't
> + goto iio_register_error;
> + }
> +
> + return 0;
> +
> +iio_register_error:
> + writel(0x0, data->base + ASPEED_ADC_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);
> +
> +prescaler_error:
> +resource_error:
> + 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(0x0, data->base + ASPEED_ADC_REG_ENGINE_CONTROL);
I guess this power off the device?
the MODE #defines are now used (powerdown, normal, etc.)
> + clk_disable_unprepare(data->clk_scaler->clk);
> + clk_hw_unregister_divider(data->clk_scaler);
> + clk_hw_unregister_divider(data->clk_prescaler);
> +
> + 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 <ralth...@google.com>");
> +MODULE_DESCRIPTION("Aspeed AST2400/2500 ADC Driver");
> +MODULE_LICENSE("GPL");
>
--
Peter Meerwald-Stadler
Mobile: +43 664 24 44 418
