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linux-next/drivers/iio/adc/ingenic-adc.c
Maarten ter Huurne 5a304e1a4e IIO: Ingenic JZ47xx: Set clock divider on probe 
The SADC component can run at up to 8 MHz on JZ4725B, but is fed
a 12 MHz input clock (EXT). Divide it by two to get 6 MHz, then
set up another divider to match, to produce a 10us clock.

If the clock dividers are left on their power-on defaults (a divider
of 1), the SADC mostly works, but will occasionally produce erroneous
readings. This led to button presses being detected out of nowhere on
the RS90 every few minutes. With this change, no ghost button presses
were logged in almost a day worth of testing.

The ADCLK register for configuring clock dividers doesn't exist on
JZ4740, so avoid writing it there.

A function has been introduced rather than a flag because there is a lot
of variation between the ADCLK registers on JZ47xx SoCs, both in
the internal layout of the register and in the frequency range
supported by the SADC. So this solution should make it easier
to add support for other JZ47xx SoCs later.

Fixes: 1a78daea10 ("iio: adc: probe should set clock divider")
Signed-off-by: Maarten ter Huurne <maarten@treewalker.org>
Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2019-07-14 16:02:08 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* ADC driver for the Ingenic JZ47xx SoCs
* Copyright (c) 2019 Artur Rojek <contact@artur-rojek.eu>
*
* based on drivers/mfd/jz4740-adc.c
*/
#include <dt-bindings/iio/adc/ingenic,adc.h>
#include <linux/clk.h>
#include <linux/iio/iio.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#define JZ_ADC_REG_ENABLE 0x00
#define JZ_ADC_REG_CFG 0x04
#define JZ_ADC_REG_CTRL 0x08
#define JZ_ADC_REG_STATUS 0x0c
#define JZ_ADC_REG_ADTCH 0x18
#define JZ_ADC_REG_ADBDAT 0x1c
#define JZ_ADC_REG_ADSDAT 0x20
#define JZ_ADC_REG_ADCLK 0x28
#define JZ_ADC_REG_CFG_BAT_MD BIT(4)
#define JZ_ADC_REG_ADCLK_CLKDIV_LSB 0
#define JZ_ADC_REG_ADCLK_CLKDIV10US_LSB 16
#define JZ_ADC_AUX_VREF 3300
#define JZ_ADC_AUX_VREF_BITS 12
#define JZ_ADC_BATTERY_LOW_VREF 2500
#define JZ_ADC_BATTERY_LOW_VREF_BITS 12
#define JZ4725B_ADC_BATTERY_HIGH_VREF 7500
#define JZ4725B_ADC_BATTERY_HIGH_VREF_BITS 10
#define JZ4740_ADC_BATTERY_HIGH_VREF (7500 * 0.986)
#define JZ4740_ADC_BATTERY_HIGH_VREF_BITS 12
struct ingenic_adc;
struct ingenic_adc_soc_data {
unsigned int battery_high_vref;
unsigned int battery_high_vref_bits;
const int *battery_raw_avail;
size_t battery_raw_avail_size;
const int *battery_scale_avail;
size_t battery_scale_avail_size;
int (*init_clk_div)(struct device *dev, struct ingenic_adc *adc);
};
struct ingenic_adc {
void __iomem *base;
struct clk *clk;
struct mutex lock;
const struct ingenic_adc_soc_data *soc_data;
bool low_vref_mode;
};
static void ingenic_adc_set_config(struct ingenic_adc *adc,
uint32_t mask,
uint32_t val)
{
uint32_t cfg;
clk_enable(adc->clk);
mutex_lock(&adc->lock);
cfg = readl(adc->base + JZ_ADC_REG_CFG) & ~mask;
cfg |= val;
writel(cfg, adc->base + JZ_ADC_REG_CFG);
mutex_unlock(&adc->lock);
clk_disable(adc->clk);
}
static void ingenic_adc_enable(struct ingenic_adc *adc,
int engine,
bool enabled)
{
u8 val;
mutex_lock(&adc->lock);
val = readb(adc->base + JZ_ADC_REG_ENABLE);
if (enabled)
val |= BIT(engine);
else
val &= ~BIT(engine);
writeb(val, adc->base + JZ_ADC_REG_ENABLE);
mutex_unlock(&adc->lock);
}
static int ingenic_adc_capture(struct ingenic_adc *adc,
int engine)
{
u8 val;
int ret;
ingenic_adc_enable(adc, engine, true);
ret = readb_poll_timeout(adc->base + JZ_ADC_REG_ENABLE, val,
!(val & BIT(engine)), 250, 1000);
if (ret)
ingenic_adc_enable(adc, engine, false);
return ret;
}
static int ingenic_adc_write_raw(struct iio_dev *iio_dev,
struct iio_chan_spec const *chan,
int val,
int val2,
long m)
{
struct ingenic_adc *adc = iio_priv(iio_dev);
switch (m) {
case IIO_CHAN_INFO_SCALE:
switch (chan->channel) {
case INGENIC_ADC_BATTERY:
if (val > JZ_ADC_BATTERY_LOW_VREF) {
ingenic_adc_set_config(adc,
JZ_ADC_REG_CFG_BAT_MD,
0);
adc->low_vref_mode = false;
} else {
ingenic_adc_set_config(adc,
JZ_ADC_REG_CFG_BAT_MD,
JZ_ADC_REG_CFG_BAT_MD);
adc->low_vref_mode = true;
}
return 0;
default:
return -EINVAL;
}
default:
return -EINVAL;
}
}
static const int jz4725b_adc_battery_raw_avail[] = {
0, 1, (1 << JZ_ADC_BATTERY_LOW_VREF_BITS) - 1,
};
static const int jz4725b_adc_battery_scale_avail[] = {
JZ4725B_ADC_BATTERY_HIGH_VREF, JZ4725B_ADC_BATTERY_HIGH_VREF_BITS,
JZ_ADC_BATTERY_LOW_VREF, JZ_ADC_BATTERY_LOW_VREF_BITS,
};
static const int jz4740_adc_battery_raw_avail[] = {
0, 1, (1 << JZ_ADC_BATTERY_LOW_VREF_BITS) - 1,
};
static const int jz4740_adc_battery_scale_avail[] = {
JZ4740_ADC_BATTERY_HIGH_VREF, JZ4740_ADC_BATTERY_HIGH_VREF_BITS,
JZ_ADC_BATTERY_LOW_VREF, JZ_ADC_BATTERY_LOW_VREF_BITS,
};
static int jz4725b_adc_init_clk_div(struct device *dev, struct ingenic_adc *adc)
{
struct clk *parent_clk;
unsigned long parent_rate, rate;
unsigned int div_main, div_10us;
parent_clk = clk_get_parent(adc->clk);
if (!parent_clk) {
dev_err(dev, "ADC clock has no parent\n");
return -ENODEV;
}
parent_rate = clk_get_rate(parent_clk);
/*
* The JZ4725B ADC works at 500 kHz to 8 MHz.
* We pick the highest rate possible.
* In practice we typically get 6 MHz, half of the 12 MHz EXT clock.
*/
div_main = DIV_ROUND_UP(parent_rate, 8000000);
div_main = clamp(div_main, 1u, 64u);
rate = parent_rate / div_main;
if (rate < 500000 || rate > 8000000) {
dev_err(dev, "No valid divider for ADC main clock\n");
return -EINVAL;
}
/* We also need a divider that produces a 10us clock. */
div_10us = DIV_ROUND_UP(rate, 100000);
writel(((div_10us - 1) << JZ_ADC_REG_ADCLK_CLKDIV10US_LSB) |
(div_main - 1) << JZ_ADC_REG_ADCLK_CLKDIV_LSB,
adc->base + JZ_ADC_REG_ADCLK);
return 0;
}
static const struct ingenic_adc_soc_data jz4725b_adc_soc_data = {
.battery_high_vref = JZ4725B_ADC_BATTERY_HIGH_VREF,
.battery_high_vref_bits = JZ4725B_ADC_BATTERY_HIGH_VREF_BITS,
.battery_raw_avail = jz4725b_adc_battery_raw_avail,
.battery_raw_avail_size = ARRAY_SIZE(jz4725b_adc_battery_raw_avail),
.battery_scale_avail = jz4725b_adc_battery_scale_avail,
.battery_scale_avail_size = ARRAY_SIZE(jz4725b_adc_battery_scale_avail),
.init_clk_div = jz4725b_adc_init_clk_div,
};
static const struct ingenic_adc_soc_data jz4740_adc_soc_data = {
.battery_high_vref = JZ4740_ADC_BATTERY_HIGH_VREF,
.battery_high_vref_bits = JZ4740_ADC_BATTERY_HIGH_VREF_BITS,
.battery_raw_avail = jz4740_adc_battery_raw_avail,
.battery_raw_avail_size = ARRAY_SIZE(jz4740_adc_battery_raw_avail),
.battery_scale_avail = jz4740_adc_battery_scale_avail,
.battery_scale_avail_size = ARRAY_SIZE(jz4740_adc_battery_scale_avail),
.init_clk_div = NULL, /* no ADCLK register on JZ4740 */
};
static int ingenic_adc_read_avail(struct iio_dev *iio_dev,
struct iio_chan_spec const *chan,
const int **vals,
int *type,
int *length,
long m)
{
struct ingenic_adc *adc = iio_priv(iio_dev);
switch (m) {
case IIO_CHAN_INFO_RAW:
*type = IIO_VAL_INT;
*length = adc->soc_data->battery_raw_avail_size;
*vals = adc->soc_data->battery_raw_avail;
return IIO_AVAIL_RANGE;
case IIO_CHAN_INFO_SCALE:
*type = IIO_VAL_FRACTIONAL_LOG2;
*length = adc->soc_data->battery_scale_avail_size;
*vals = adc->soc_data->battery_scale_avail;
return IIO_AVAIL_LIST;
default:
return -EINVAL;
};
}
static int ingenic_adc_read_raw(struct iio_dev *iio_dev,
struct iio_chan_spec const *chan,
int *val,
int *val2,
long m)
{
struct ingenic_adc *adc = iio_priv(iio_dev);
int ret;
switch (m) {
case IIO_CHAN_INFO_RAW:
clk_enable(adc->clk);
ret = ingenic_adc_capture(adc, chan->channel);
if (ret) {
clk_disable(adc->clk);
return ret;
}
switch (chan->channel) {
case INGENIC_ADC_AUX:
*val = readw(adc->base + JZ_ADC_REG_ADSDAT);
break;
case INGENIC_ADC_BATTERY:
*val = readw(adc->base + JZ_ADC_REG_ADBDAT);
break;
}
clk_disable(adc->clk);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
switch (chan->channel) {
case INGENIC_ADC_AUX:
*val = JZ_ADC_AUX_VREF;
*val2 = JZ_ADC_AUX_VREF_BITS;
break;
case INGENIC_ADC_BATTERY:
if (adc->low_vref_mode) {
*val = JZ_ADC_BATTERY_LOW_VREF;
*val2 = JZ_ADC_BATTERY_LOW_VREF_BITS;
} else {
*val = adc->soc_data->battery_high_vref;
*val2 = adc->soc_data->battery_high_vref_bits;
}
break;
}
return IIO_VAL_FRACTIONAL_LOG2;
default:
return -EINVAL;
}
}
static void ingenic_adc_clk_cleanup(void *data)
{
clk_unprepare(data);
}
static const struct iio_info ingenic_adc_info = {
.write_raw = ingenic_adc_write_raw,
.read_raw = ingenic_adc_read_raw,
.read_avail = ingenic_adc_read_avail,
};
static const struct iio_chan_spec ingenic_channels[] = {
{
.extend_name = "aux",
.type = IIO_VOLTAGE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE),
.indexed = 1,
.channel = INGENIC_ADC_AUX,
},
{
.extend_name = "battery",
.type = IIO_VOLTAGE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE),
.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE),
.indexed = 1,
.channel = INGENIC_ADC_BATTERY,
},
};
static int ingenic_adc_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct iio_dev *iio_dev;
struct ingenic_adc *adc;
struct resource *mem_base;
const struct ingenic_adc_soc_data *soc_data;
int ret;
soc_data = device_get_match_data(dev);
if (!soc_data)
return -EINVAL;
iio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
if (!iio_dev)
return -ENOMEM;
adc = iio_priv(iio_dev);
mutex_init(&adc->lock);
adc->soc_data = soc_data;
mem_base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
adc->base = devm_ioremap_resource(dev, mem_base);
if (IS_ERR(adc->base))
return PTR_ERR(adc->base);
adc->clk = devm_clk_get(dev, "adc");
if (IS_ERR(adc->clk)) {
dev_err(dev, "Unable to get clock\n");
return PTR_ERR(adc->clk);
}
ret = clk_prepare_enable(adc->clk);
if (ret) {
dev_err(dev, "Failed to enable clock\n");
return ret;
}
/* Set clock dividers. */
if (soc_data->init_clk_div) {
ret = soc_data->init_clk_div(dev, adc);
if (ret) {
clk_disable_unprepare(adc->clk);
return ret;
}
}
/* Put hardware in a known passive state. */
writeb(0x00, adc->base + JZ_ADC_REG_ENABLE);
writeb(0xff, adc->base + JZ_ADC_REG_CTRL);
clk_disable(adc->clk);
ret = devm_add_action_or_reset(dev, ingenic_adc_clk_cleanup, adc->clk);
if (ret) {
dev_err(dev, "Unable to add action\n");
return ret;
}
iio_dev->dev.parent = dev;
iio_dev->name = "jz-adc";
iio_dev->modes = INDIO_DIRECT_MODE;
iio_dev->channels = ingenic_channels;
iio_dev->num_channels = ARRAY_SIZE(ingenic_channels);
iio_dev->info = &ingenic_adc_info;
ret = devm_iio_device_register(dev, iio_dev);
if (ret)
dev_err(dev, "Unable to register IIO device\n");
return ret;
}
#ifdef CONFIG_OF
static const struct of_device_id ingenic_adc_of_match[] = {
{ .compatible = "ingenic,jz4725b-adc", .data = &jz4725b_adc_soc_data, },
{ .compatible = "ingenic,jz4740-adc", .data = &jz4740_adc_soc_data, },
{ },
};
MODULE_DEVICE_TABLE(of, ingenic_adc_of_match);
#endif
static struct platform_driver ingenic_adc_driver = {
.driver = {
.name = "ingenic-adc",
.of_match_table = of_match_ptr(ingenic_adc_of_match),
},
.probe = ingenic_adc_probe,
};
module_platform_driver(ingenic_adc_driver);
MODULE_LICENSE("GPL v2");
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