[PATCH v2 2/2] iio: adc: sun4i_lradc: new driver
Jonathan Cameron
jic23 at kernel.org
Mon Jul 18 06:38:25 PDT 2016
On 12/07/16 20:04, Alexandre Belloni wrote:
> Add an IIO driver for the Allwinner Low Resolution ADC. This ADC is usually
> used for physical buttons connected using a resistor ladder.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni at free-electrons.com>
A few small bits and pieces from me...
Jonathan
> ---
> Changes in v2:
> - prefixed defines with SUN4I_LRADC_
> - removed sun4i_lradc_write_raw_get_fmt
> - set indio_dev->dev.of_node
> - pushed devm_iio_device_register() at the end of the probe function
> - added a remove function to call regulator_disable()
>
> drivers/iio/adc/Kconfig | 10 ++
> drivers/iio/adc/Makefile | 3 +-
> drivers/iio/adc/sun4i_lradc.c | 323 ++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 335 insertions(+), 1 deletion(-)
> create mode 100644 drivers/iio/adc/sun4i_lradc.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 25378c5882e2..87aaac6a5f44 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -384,6 +384,16 @@ config ROCKCHIP_SARADC
> To compile this driver as a module, choose M here: the
> module will be called rockchip_saradc.
>
> +config SUN4I_LRADC
> + tristate "Allwinner sun4i LRADC driver"
> + depends on ARCH_SUNXI || COMPILE_TEST
> + select IIO_TRIGGER
> + help
> + Say yes here to build support for the LRADC found on Allwinner SoCs.
> +
> + To compile this driver as a module, choose M here: the module will be
> + called sun4i_lradc.
> +
> config TI_ADC081C
> tristate "Texas Instruments ADC081C/ADC101C/ADC121C family"
> depends on I2C
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 38638d46f972..a3b165af6bde 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -1,4 +1,4 @@
> -#
> +
??
> # Makefile for IIO ADC drivers
> #
>
> @@ -37,6 +37,7 @@ obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
> obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
> obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
> obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
> +obj-$(CONFIG_SUN4I_LRADC) += sun4i_lradc.o
> obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
> obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
> diff --git a/drivers/iio/adc/sun4i_lradc.c b/drivers/iio/adc/sun4i_lradc.c
> new file mode 100644
> index 000000000000..cd42e1a994b9
> --- /dev/null
> +++ b/drivers/iio/adc/sun4i_lradc.c
> @@ -0,0 +1,323 @@
> +/*
> + * Driver for the LRADC present on the Allwinner sun4i
> + *
> + * Copyright 2016 Free Electrons
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/sched.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/regulator/consumer.h>
> +
> +#define SUN4I_LRADC_CTRL 0x00
> +#define SUN4I_LRADC_INTC 0x04
> +#define SUN4I_LRADC_INTS 0x08
> +#define SUN4I_LRADC_DATA0 0x0c
> +#define SUN4I_LRADC_DATA1 0x10
> +
> +/* LRADC_CTRL bits */
> +#define SUN4I_LRADC_FIRST_CONVERT_DLY(x) ((x) << 24) /* 8 bits */
> +#define SUN4I_LRADC_CHAN_SELECT(x) ((x) << 22) /* 2 bits */
> +#define SUN4I_LRADC_CONTINUE_TIME_SEL(x) ((x) << 16) /* 4 bits */
> +#define SUN4I_LRADC_KEY_MODE_SEL(x) ((x) << 12) /* 2 bits */
> +#define SUN4I_LRADC_LEVELA_B_CNT(x) ((x) << 8) /* 4 bits */
> +#define SUN4I_LRADC_HOLD_EN BIT(6)
> +#define SUN4I_LRADC_LEVELB_VOL(x) ((x) << 4) /* 2 bits */
> +#define SUN4I_LRADC_SAMPLE_RATE(x) ((x) << 2) /* 2 bits */
> +#define SUN4I_LRADC_EN BIT(0)
> +
> +/* LRADC_INTC and LRADC_INTS bits */
> +#define SUN4I_LRADC_CHAN1_KEYUP_IRQ BIT(12)
> +#define SUN4I_LRADC_CHAN1_ALRDY_HOLD_IRQ BIT(11)
> +#define SUN4I_LRADC_CHAN1_HOLD_IRQ BIT(10)
> +#define SUN4I_LRADC_CHAN1_KEYDOWN_IRQ BIT(9)
> +#define SUN4I_LRADC_CHAN1_DATA_IRQ BIT(8)
> +#define SUN4I_LRADC_CHAN0_KEYUP_IRQ BIT(4)
> +#define SUN4I_LRADC_CHAN0_ALRDY_HOLD_IRQ BIT(3)
> +#define SUN4I_LRADC_CHAN0_HOLD_IRQ BIT(2)
> +#define SUN4I_LRADC_CHAN0_KEYDOWN_IRQ BIT(1)
> +#define SUN4I_LRADC_CHAN0_DATA_IRQ BIT(0)
> +
> +#define NUM_SUN4I_LRADC_CHANS 2
> +
> +struct sun4i_lradc_state {
> + void __iomem *base;
> + struct regulator *vref_supply;
> + u32 vref_mv;
> + struct completion data_ok[NUM_SUN4I_LRADC_CHANS];
> + spinlock_t lock;
> +};
> +
> +#define SUN4I_LRADC_CHANNEL(chan) { \
> + .type = IIO_VOLTAGE, \
> + .indexed = 1, \
> + .channel = (chan), \
> + .scan_index = (chan), \
> + .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 sun4i_lradc_chan_array[] = {
> + SUN4I_LRADC_CHANNEL(0),
> + SUN4I_LRADC_CHANNEL(1),
> +};
> +
> +static const struct {
> + int val;
> + int val2;
> +} sun4i_lradc_sample_freq_avail[] = {
> + {250, 0},
> + {125, 0},
> + {62, 500000},
> + {32, 250000},
> +};
> +
> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("32.25 62.5 125 250");
> +
> +static struct attribute *sun4i_lradc_attributes[] = {
> + &iio_const_attr_sampling_frequency_available.dev_attr.attr,
> + NULL
> +};
> +
> +static const struct attribute_group sun4i_lradc_attribute_group = {
> + .attrs = sun4i_lradc_attributes,
> +};
> +
> +static irqreturn_t sun4i_lradc_irq(int irq, void *dev_id)
> +{
> + struct iio_dev *indio_dev = dev_id;
> + struct sun4i_lradc_state *st = iio_priv(indio_dev);
> + u32 ints, intc;
> +
> + spin_lock(&st->lock);
> +
> + ints = readl(st->base + SUN4I_LRADC_INTS);
> + intc = readl(st->base + SUN4I_LRADC_INTC);
> +
> + if (ints & SUN4I_LRADC_CHAN0_DATA_IRQ)
> + complete_all(&st->data_ok[0]);
> +
> + if (ints & SUN4I_LRADC_CHAN1_DATA_IRQ)
> + complete_all(&st->data_ok[1]);
> +
> + intc &= ~ints;
> + writel(intc, st->base + SUN4I_LRADC_INTC);
> + writel(ints, st->base + SUN4I_LRADC_INTS);
> +
> + spin_unlock(&st->lock);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int sun4i_lradc_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct sun4i_lradc_state *st = iio_priv(indio_dev);
> + int ret, tmp, idx;
> + unsigned long flags;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + reinit_completion(&st->data_ok[chan->channel]);
> + spin_lock_irqsave(&st->lock, flags);
> + tmp = readl(st->base + SUN4I_LRADC_INTC);
> +
> + if (chan->channel)
> + tmp |= SUN4I_LRADC_CHAN1_DATA_IRQ;
> + else
> + tmp |= SUN4I_LRADC_CHAN0_DATA_IRQ;
> +
> + writel(tmp, st->base + SUN4I_LRADC_INTC);
> + spin_unlock_irqrestore(&st->lock, flags);
> +
> + ret = wait_for_completion_interruptible_timeout(
> + &st->data_ok[chan->channel],
> + msecs_to_jiffies(1000));
> + if (ret == 0)
> + return -ETIMEDOUT;
> +
> + if (chan->channel)
> + *val = readl(st->base + SUN4I_LRADC_DATA1);
> + else
> + *val = readl(st->base + SUN4I_LRADC_DATA0);
> +
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_SCALE:
> + *val = st->vref_mv;
> + *val2 = 6;
> +
> + return IIO_VAL_FRACTIONAL_LOG2;
> +
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + tmp = readl(st->base + SUN4I_LRADC_CTRL);
> + idx = (tmp >> 2) & 0x3;
> + *val = sun4i_lradc_sample_freq_avail[idx].val;
> + *val2 = sun4i_lradc_sample_freq_avail[idx].val2;
> + return IIO_VAL_INT_PLUS_MICRO;
> +
> + default:
> + break;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int sun4i_lradc_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct sun4i_lradc_state *st = iio_priv(indio_dev);
> + u32 ctrl;
> + int i;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + for (i = 0; i < ARRAY_SIZE(sun4i_lradc_sample_freq_avail); i++)
> + if (sun4i_lradc_sample_freq_avail[i].val == val &&
> + sun4i_lradc_sample_freq_avail[i].val2 == val2)
> + break;
> + if (i == ARRAY_SIZE(sun4i_lradc_sample_freq_avail))
> + return -EINVAL;
> +
> + ctrl = readl(st->base + SUN4I_LRADC_CTRL);
> + ctrl &= ~SUN4I_LRADC_SAMPLE_RATE(0x3);
> + writel(ctrl | SUN4I_LRADC_SAMPLE_RATE(i),
> + st->base + SUN4I_LRADC_CTRL);
> +
> + return 0;
> +
> + default:
> + break;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static const struct iio_info sun4i_lradc_info = {
> + .driver_module = THIS_MODULE,
> + .read_raw = sun4i_lradc_read_raw,
> + .write_raw = sun4i_lradc_write_raw,
> + .attrs = &sun4i_lradc_attribute_group,
> +};
> +
> +static int sun4i_lradc_probe(struct platform_device *pdev)
> +{
> + struct iio_dev *indio_dev;
> + struct device *dev = &pdev->dev;
> + struct sun4i_lradc_state *st;
> + int err;
> +
> + indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + st = iio_priv(indio_dev);
> +
> + platform_set_drvdata(pdev, indio_dev);
> +
> + indio_dev->dev.parent = dev;
> + indio_dev->dev.of_node = dev->of_node;
> + indio_dev->name = dev_name(dev);
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->info = &sun4i_lradc_info;
> +
> + st->vref_supply = devm_regulator_get(dev, "vref");
> + if (IS_ERR(st->vref_supply))
> + return PTR_ERR(st->vref_supply);
> +
> + st->base = devm_ioremap_resource(dev,
> + platform_get_resource(pdev, IORESOURCE_MEM, 0));
> + if (IS_ERR(st->base))
> + return PTR_ERR(st->base);
> +
> + /* Disable then clear all interrupts */
> + writel(0, st->base + SUN4I_LRADC_INTC);
> + writel(0xffffffff, st->base + SUN4I_LRADC_INTS);
> +
> + err = devm_request_irq(dev, platform_get_irq(pdev, 0),
> + sun4i_lradc_irq, 0,
> + "sun4i-a10-lradc", indio_dev);
> + if (err)
> + return err;
> +
> + /* Setup the ADC channels available on the board */
> + indio_dev->num_channels = ARRAY_SIZE(sun4i_lradc_chan_array);
> + indio_dev->channels = sun4i_lradc_chan_array;
> +
> + err = regulator_enable(st->vref_supply);
> + if (err)
> + return err;
> +
> + /* lradc Vref internally is divided by 2/3 */
> + st->vref_mv = regulator_get_voltage(st->vref_supply) * 2 / 3000;
> +
> + init_completion(&st->data_ok[0]);
> + init_completion(&st->data_ok[1]);
> + spin_lock_init(&st->lock);
> +
> + /* Continuous mode on both channels */
> + writel(SUN4I_LRADC_CHAN_SELECT(0x3) | SUN4I_LRADC_KEY_MODE_SEL(0x2) |
> + SUN4I_LRADC_SAMPLE_RATE(0x00) | SUN4I_LRADC_EN,
> + st->base + SUN4I_LRADC_CTRL);
> +
> + err = devm_iio_device_register(dev, indio_dev);
> + if (err < 0) {
> + dev_err(dev, "Couldn't register the device.\n");
> + return err;
> + }
> +
> + return 0;
> +}
> +
> +static int sun4i_lradc_remove(struct platform_device *pdev)
> +{
> + struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> + struct sun4i_lradc_state *st = iio_priv(indio_dev);
> +
Race condition here. The interfaces this driver provides (both in
kernel and sysfs etc) are visible until iio_device_unregister occurs.
As you are using the devm_iio_device_register call it'll happen after
you've turned the power off. Probably not the best plan ;)
Yeah, it's a small race, but lets get it right. Just don't use
the devm_ version and do an explicit unregister before calling
the next line.
> + regulator_disable(st->vref_supply);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id sun4i_lradc_of_match[] = {
> + { .compatible = "allwinner,sun4i-a10-lradc", },
> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, sun4i_lradc_of_match);
> +
> +static struct platform_driver sun4i_lradc_driver = {
> + .probe = sun4i_lradc_probe,
> + .remove = sun4i_lradc_remove,
> + .driver = {
> + .name = "sun4i-a10-lradc",
> + .of_match_table = of_match_ptr(sun4i_lradc_of_match),
> + },
> +};
> +
> +module_platform_driver(sun4i_lradc_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Allwinner sun4i low resolution ADC driver");
> +MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni at free-electrons.com>");
>
More information about the linux-arm-kernel
mailing list