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linux-next/drivers/iio/adc/aspeed_adc.c
Mykola Kostenok 737cc2a593 iio: aspeed-adc: wait for initial sequence.
This patch enables adc engine at initialization time and waits
for the initial sequence completion before enabling adc channels.

Without this code adc channels are not functional and shows
zeros for all connected channels.

Tested on mellanox msn platform.

v1 -> v2:
Pointed by Rick Altherr:
 - Wait init sequence code enabled by bool
from OF match table.

Signed-off-by: Mykola Kostenok <c_mykolak@mellanox.com>
Reviewed-by: Rick Altherr <raltherr@google.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2017-07-23 12:02:40 +01:00

322 lines
8.6 KiB
C

/*
* 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>
#include <linux/iopoll.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)
#define ASPEED_ADC_CTRL_INIT_RDY BIT(8)
#define ASPEED_ADC_INIT_POLLING_TIME 500
#define ASPEED_ADC_INIT_TIMEOUT 500000
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
bool wait_init_sequence;
};
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;
}
model_data = of_device_get_match_data(&pdev->dev);
if (model_data->wait_init_sequence) {
/* Enable engine in normal mode. */
writel(ASPEED_OPERATION_MODE_NORMAL | ASPEED_ENGINE_ENABLE,
data->base + ASPEED_REG_ENGINE_CONTROL);
/* Wait for initial sequence complete. */
ret = readl_poll_timeout(data->base + ASPEED_REG_ENGINE_CONTROL,
adc_engine_control_reg_val,
adc_engine_control_reg_val &
ASPEED_ADC_CTRL_INIT_RDY,
ASPEED_ADC_INIT_POLLING_TIME,
ASPEED_ADC_INIT_TIMEOUT);
if (ret)
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,
.wait_init_sequence = true,
};
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");