iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

iio: Aspeed ADC

Browse Source 
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@google.com>
Tested-by: Xo Wang <xow@google.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Rick Altherr 2017-03-28 14:52:59 -07:00 committed by Jonathan Cameron
parent fb87ecf19e
commit 573803234e
3 changed files with 307 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/iio/adc/Kconfig
View File

@ -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

1
drivers/iio/adc/Makefile
View File

@ -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

295
drivers/iio/adc/aspeed_adc.c Normal file
View File

@ -0,0 +1,295 @@
/*
* 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 <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/io.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 -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);
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;
case IIO_CHAN_INFO_SCALE:
case IIO_CHAN_INFO_RAW:
/*
* Technically, these could be written but the only reasons
* for doing so seem better handled in userspace. EPERM is
* returned to signal this is a policy choice rather than a
* hardware limitation.
*/
return -EPERM;
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_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@google.com>");
MODULE_DESCRIPTION("Aspeed AST2400/2500 ADC Driver");
MODULE_LICENSE("GPL");