Re: [PATCH 1/5] iio:adc:at91_adc8xx: introduce new atmel adc driver
From: Jonathan Cameron
Date: Tue Dec 22 2015 - 13:34:11 EST
On 21/12/15 09:24, Ludovic Desroches wrote:
> This driver supports the new version of the Atmel ADC device introduced
> with the SAMA5D2 SoC family.
>
> Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
A few more bits and bobs from me. Mostly looking good.
Jonathan
> ---
> .../devicetree/bindings/iio/adc/at91_adc8xx.txt | 27 ++
> drivers/iio/adc/Kconfig | 11 +
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/at91_adc8xx.c | 417 +++++++++++++++++++++
> 4 files changed, 456 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/iio/adc/at91_adc8xx.txt
> create mode 100644 drivers/iio/adc/at91_adc8xx.c
>
> diff --git a/Documentation/devicetree/bindings/iio/adc/at91_adc8xx.txt b/Documentation/devicetree/bindings/iio/adc/at91_adc8xx.txt
> new file mode 100644
> index 0000000..64ad6a5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/at91_adc8xx.txt
> @@ -0,0 +1,27 @@
> +* AT91 SAMA5D2 Analog to Digital Converter (ADC)
> +
> +Required properties:
> + - compatible: Should be "atmel,sama5d2-adc".
> + - reg: Should contain ADC registers location and length.
> + - interrupts: Should contain the IRQ line for the ADC.
> + - clocks: phandles to clocks.
> + - clock-names: tuple listing clock names.
> + Required elements: "adc_clk", "adc_op_clk". "adc_clk" is the peripheral
> + clock, "adc_clk" is the sampling clock.
> + - vref-supply: Supply used as reference for conversions.
> +
> +Optional properties:
> + - vddana-supply: Supply for the adc device.
> +
> +
> +Example:
> +
> +adc: adc@fc030000 {
> + compatible = "atmel,sama5d2-adc";
> + reg = <0xfc030000 0x100>;
> + interrupts = <40 IRQ_TYPE_LEVEL_HIGH 7>;
> + clocks = <&adc_clk>, <&adc_op_clk>;
> + clock-names = "adc_clk", "adc_op_clk";
> + vddana-supply = <&vdd_3v3_lp_reg>;
> + vref-supply = <&vdd_3v3_lp_reg>;
> +}
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 9162dfe..5819e41 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -131,6 +131,17 @@ config AT91_ADC
> To compile this driver as a module, choose M here: the module will be
> called at91_adc.
>
> +config AT91_ADC8xx
> + tristate "Atmel AT91 ADC 8xx"
> + depends on ARCH_AT91
> + depends on INPUT
> + help
> + Say yes here to build support for Atmel ADC 8xx which is available
> + from SAMA5D2 SoC family.
> +
> + To compile this driver as a module, choose M here: the module will be
> + called at91_adc8xx.
> +
> config AXP288_ADC
> tristate "X-Powers AXP288 ADC driver"
> depends on MFD_AXP20X
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 91a65bf..d684a52 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_AD7793) += ad7793.o
> obj-$(CONFIG_AD7887) += ad7887.o
> obj-$(CONFIG_AD799X) += ad799x.o
> obj-$(CONFIG_AT91_ADC) += at91_adc.o
> +obj-$(CONFIG_AT91_ADC8xx) += at91_adc8xx.o
> obj-$(CONFIG_AXP288_ADC) += axp288_adc.o
> obj-$(CONFIG_BERLIN2_ADC) += berlin2-adc.o
> obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o
> diff --git a/drivers/iio/adc/at91_adc8xx.c b/drivers/iio/adc/at91_adc8xx.c
> new file mode 100644
> index 0000000..8b4a6e7
> --- /dev/null
> +++ b/drivers/iio/adc/at91_adc8xx.c
> @@ -0,0 +1,417 @@
> +/*
> + * Atmel ADC driver for SAMA5D2 devices and later.
> + *
> + * Copyright (C) 2015 Atmel,
> + * 2015 Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * 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/clk.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/sched.h>
> +#include <linux/wait.h>
> +#include <linux/iio/iio.h>
> +#include <linux/regulator/consumer.h>
> +
> +#define ADC_CR 0x00 /* Control Register */
> +#define ADC_CR_SWRST BIT(0) /* Software Reset */
> +#define ADC_CR_START BIT(1) /* Start Conversion */
> +#define ADC_CR_TSCALIB BIT(2) /* Touchscreen Calibration */
> +#define ADC_CR_CMPRST BIT(4) /* Comparison Restart */
> +#define ADC_MR 0x04 /* Mode Register */
> +#define ADC_MR_TRGSEL(v) (v << 1) /* Trigger Selection */
> +#define ADC_MR_TRGSEL_TRIG0 0 /* ADTRG */
> +#define ADC_MR_TRGSEL_TRIG1 1 /* TIOA0 */
> +#define ADC_MR_TRGSEL_TRIG2 2 /* TIOA1 */
> +#define ADC_MR_TRGSEL_TRIG3 3 /* TIOA2 */
> +#define ADC_MR_TRGSEL_TRIG4 4 /* PWM event line 0 */
> +#define ADC_MR_TRGSEL_TRIG5 5 /* PWM event line 1 */
> +#define ADC_MR_TRGSEL_TRIG6 6 /* TIOA3 */
> +#define ADC_MR_TRGSEL_TRIG7 7 /* RTCOUT0 */
> +#define ADC_MR_SLEEP BIT(5) /* Sleep Mode */
> +#define ADC_MR_FWUP BIT(6) /* Fast Wake Up */
> +#define ADC_MR_PRESCAL(v) (v << 8) /* Prescaler Rate Selection */
> +#define ADC_MR_PRESCAL_MAX 0xffff
> +#define ADC_MR_STARTUP(v) (v << 16) /* Startup Time */
> +#define ADC_MR_STARTUP_SUT0 0 /* 0 period of ADCCLK */
> +#define ADC_MR_STARTUP_SUT8 1 /* 8 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT16 2 /* 16 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT24 3 /* 24 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT64 4 /* 64 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT80 5 /* 80 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT96 6 /* 96 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT112 7 /* 112 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT512 8 /* 512 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT576 9 /* 576 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT640 10 /* 640 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT704 11 /* 704 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT768 12 /* 768 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT832 13 /* 832 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT896 14 /* 896 periods of ADCCLK */
> +#define ADC_MR_STARTUP_SUT960 15 /* 960 periods of ADCCLK */
> +#define ADC_MR_ANACH BIT(23) /* Analog Change */
> +#define ADC_MR_TRACKTIM(v) (v << 24) /* Tracking Time */
> +#define ADC_MR_TRACKTIM_MAX 0xff
> +#define ADC_MR_TRANSFER(v) (v << 28) /* Transfer Time */
> +#define ADC_MR_TRANSFER_MAX 0x3
> +#define ADC_MR_USEQ BIT(31) /* Use Sequence Enable */
> +#define ADC_SEQR1 0x08 /* Channel Sequence Register 1 */
> +#define ADC_SEQR2 0x0c /* Channel Sequence Register 2 */
> +#define ADC_CHER 0x10 /* Channel Enable Register */
> +#define ADC_CHDR 0x14 /* Channel Disable Register */
> +#define ADC_CHSR 0x18 /* Channel Status Register */
> +#define ADC_LCDR 0x20 /* Last Converted Data Register */
> +#define ADC_IER 0x24 /* Interrupt Enable Register */
> +#define ADC_IDR 0x28 /* Interrupt Disable Register */
> +#define ADC_IMR 0x2c /* Interrupt Mask Register */
> +#define ADC_ISR 0x30 /* Interrupt Status Register */
> +#define ADC_LCTMR 0x34 /* Last Channel Trigger Mode Register */
> +#define ADC_LCCWR 0x38 /* Last Channel Compare Window Register */
> +#define ADC_OVER 0x3c /* Overrun Status Register */
> +#define ADC_EMR 0x40 /* Extended Mode Register */
> +#define ADC_CWR 0x44 /* Compare Window Register */
> +#define ADC_CGR 0x48 /* Channel Gain Register */
> +#define ADC_COR 0x4c /* Channel Offset Register */
> +#define ADC_CDR0 0x50 /* Channel Data Register 0 */
> +#define ADC_ACR 0x94 /* Analog Control Register */
> +#define ADC_TSMR 0xb0 /* Touchscreen Mode Register */
> +#define ADC_XPOSR 0xb4 /* Touchscreen X Position Register */
> +#define ADC_YPOSR 0xb8 /* Touchscreen Y Position Register */
> +#define ADC_PRESSR 0xbc /* Touchscreen Pressure Register */
> +#define ADC_TRGR 0xc0 /* Trigger Register */
> +#define ADC_COSR 0xd0 /* Correction Select Register */
> +#define ADC_CVR 0xd4 /* Correction Value Register */
> +#define ADC_CECR 0xd8 /* Channel Error Correction Register */
> +#define ADC_WPMR 0xe4 /* Write Protection Mode Register */
> +#define ADC_WPSR 0xe8 /* Write Protection Status Register */
> +#define ADC_VERSION 0xfc /* Version Register */
> +
> +#define AT91_ADC_CHAN(num, addr) \
> + { \
> + .type = IIO_VOLTAGE, \
> + .channel = num, \
> + .address = addr, \
> + .scan_type = { \
> + .sign = 'u', \
> + .realbits = 12, \
> + .storagebits = 14, \
> + }, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> + .datasheet_name = "CH"#num, \
> + .indexed = 1, \
> + }
> +
> +#define at91_adc_readl(st, reg) readl_relaxed(st->base + reg)
> +#define at91_adc_writel(st, reg, val) writel_relaxed(val, st->base + reg)
> +
> +struct at91_adc_soc_info {
> + unsigned startup_time;
> + unsigned min_f_adc;
> + unsigned max_f_adc;
> + const struct iio_chan_spec *channels;
> + int num_channels;
> +};
> +
> +struct at91_adc_state {
> + void __iomem *base;
> + struct clk *per_clk;
> + struct clk *adc_clk;
> + int irq;
> + struct regulator *reg;
> + struct regulator *vref;
> + u32 vref_uv;
> + struct at91_adc_soc_info *soc_info;
> + wait_queue_head_t wq_data_available;
> + bool done;
> + const struct iio_chan_spec *chan;
> + u32 last_value;
> + struct mutex lock;
> +};
> +
> +static struct at91_adc_soc_info at91_adc_sama5d2_soc_info = {
> + .startup_time = 4,
> + .min_f_adc = 200000,
> + .max_f_adc = 20000000,
These rather look like things that should be in the device tree if they
are going to change between SoC varients.
> +};
> +
> +static const struct iio_chan_spec at91_adc_channels[] = {
> + AT91_ADC_CHAN(0, 0x50),
> + AT91_ADC_CHAN(1, 0x54),
> + AT91_ADC_CHAN(2, 0x58),
> + AT91_ADC_CHAN(3, 0x5c),
> + AT91_ADC_CHAN(4, 0x60),
> + AT91_ADC_CHAN(5, 0x64),
> + AT91_ADC_CHAN(6, 0x68),
> + AT91_ADC_CHAN(7, 0x6c),
> + AT91_ADC_CHAN(8, 0x70),
> + AT91_ADC_CHAN(9, 0x74),
> + AT91_ADC_CHAN(10, 0x78),
> + AT91_ADC_CHAN(11, 0x7c),
> +};
> +
> +static irqreturn_t at91_adc_interrupt(int irq, void *private)
> +{
> + struct iio_dev *indio = private;
> + struct at91_adc_state *st = iio_priv(indio);
> + u32 status = at91_adc_readl(st, ADC_ISR);
> +
> + status &= at91_adc_readl(st, ADC_IMR);
> + if (status & 0xFFF) {
> + st->last_value = at91_adc_readl(st, st->chan->address);
If this is a polled read - is there any reason to read this value here
rather than outside the interrupt?
> + st->done = true;
> + wake_up_interruptible(&st->wq_data_available);
> + }
> +
> + return IRQ_HANDLED;
> +}
> +
> +static bool at91_adc_freq_supported(struct at91_adc_state *st, unsigned freq)
> +{
> + return ((freq >= st->soc_info->min_f_adc)
> + && (freq <= st->soc_info->max_f_adc));
> +}
> +
> +static unsigned at91_adc_startup_time(unsigned startup_time_min,
> + unsigned adc_clk_khz)
> +{
> + const unsigned startup_lookup[] = {
> + 0, 8, 16, 24,
> + 64, 80, 96, 112,
> + 512, 576, 640, 704,
> + 768, 832, 896, 960
> + };
> + unsigned ticks_min, i;
> +
> + /*
> + * Since the adc frequency is checked before, there is no reason
> + * to not meet the startup time constraint.
> + */
> +
> + ticks_min = startup_time_min * adc_clk_khz / 1000;
> + for (i = 0; i < ARRAY_SIZE(startup_lookup); i++)
> + if (startup_lookup[i] > ticks_min)
> + break;
> +
> + return i;
> +}
> +
> +static int at91_adc_init(struct at91_adc_state *st)
> +{
> + struct iio_dev *indio_dev = iio_priv_to_dev(st);
> + unsigned f_adc, f_per, prescal, startup;
> +
> + at91_adc_writel(st, ADC_CR, ADC_CR_SWRST);
> + at91_adc_writel(st, ADC_IDR, 0xffffffff);
> +
> + f_adc = clk_get_rate(st->adc_clk);
> + if (!at91_adc_freq_supported(st, f_adc)) {
> + dev_err(&indio_dev->dev, "unsupported adc clock frequency\n");
> + return -EINVAL;
> + }
> +
> + f_per = clk_get_rate(st->per_clk);
> + prescal = (f_per / (2 * f_adc)) - 1;
> +
> + startup = at91_adc_startup_time(st->soc_info->startup_time,
> + f_adc / 1000);
> +
> + at91_adc_writel(st, ADC_MR,
> + ADC_MR_TRANSFER(2)
> + | ADC_MR_STARTUP(startup)
> + | ADC_MR_PRESCAL(prescal));
> +
> + dev_dbg(&indio_dev->dev, "startup: %u, prescal: %u\n",
> + startup, prescal);
> +
> + return 0;
> +}
> +
> +static int at91_adc_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + struct at91_adc_state *st = iio_priv(indio_dev);
> + int ret;
> +
> + st->chan = chan;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + mutex_lock(&st->lock);
> +
> + at91_adc_writel(st, ADC_CHER, BIT(chan->channel));
> + at91_adc_writel(st, ADC_IER, BIT(chan->channel));
> + at91_adc_writel(st, ADC_CR, ADC_CR_START);
> +
> + ret = wait_event_interruptible_timeout(st->wq_data_available,
> + st->done,
> + msecs_to_jiffies(1000));
> + if (ret == 0)
> + ret = -ETIMEDOUT;
> +
> + if (ret <= 0) {
> + at91_adc_writel(st, ADC_CHDR, BIT(chan->channel));
> + at91_adc_writel(st, ADC_IDR, BIT(chan->channel));
> + mutex_unlock(&st->lock);
> + return ret;
> + }
> +
> + if (chan->scan_type.sign == 's')
> + *val = sign_extend32(st->last_value,
> + chan->scan_type.realbits - 1);
> + else
> + *val = st->last_value;
> + at91_adc_writel(st, ADC_CHDR, BIT(chan->channel));
> + at91_adc_writel(st, ADC_IDR, BIT(chan->channel));
> + st->done = false;
> +
> + mutex_unlock(&st->lock);
> + return IIO_VAL_INT;
> +
> + case IIO_CHAN_INFO_SCALE:
> + *val = st->vref_uv / 1000;
> + *val2 = chan->scan_type.realbits;
> + return IIO_VAL_FRACTIONAL_LOG2;
> +
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static const struct iio_info at91_adc_info = {
> + .read_raw = &at91_adc_read_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static int at91_adc_probe(struct platform_device *pdev)
> +{
> + struct iio_dev *indio_dev;
> + struct at91_adc_state *st;
> + struct resource *res;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(&pdev->dev,
> + sizeof(struct at91_adc_state));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + indio_dev->dev.parent = &pdev->dev;
> + indio_dev->name = dev_name(&pdev->dev);
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->info = &at91_adc_info;
> + indio_dev->channels = at91_adc_channels;
> + indio_dev->num_channels = ARRAY_SIZE(at91_adc_channels);
> +
> + st = iio_priv(indio_dev);
> + st->soc_info = (struct at91_adc_soc_info *)
> + of_device_get_match_data(&pdev->dev);
> + init_waitqueue_head(&st->wq_data_available);
> + mutex_init(&st->lock);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res)
> + return -EINVAL;
> +
> + st->base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(st->base))
> + return PTR_ERR(st->base);
> +
> + st->irq = platform_get_irq(pdev, 0);
> + if (st->irq < 0)
could be be 0 (effectively marked as not present) - probably want to check
for that and fault out if so.
> + return st->irq;
> +
> + st->per_clk = devm_clk_get(&pdev->dev, "adc_clk");
> + if (IS_ERR(st->per_clk))
> + return PTR_ERR(st->per_clk);
> +
> + st->adc_clk = devm_clk_get(&pdev->dev, "adc_op_clk");
> + if (IS_ERR(st->adc_clk))
> + return PTR_ERR(st->adc_clk);
> +
> + st->reg = devm_regulator_get(&pdev->dev, "vddana");
> + if (IS_ERR(st->reg))
> + return PTR_ERR(st->reg);
You get this regulator but never explicitly request that it is on...
I can understand that for a reference like below (though probably want
to turn that on as well really).
> +
> + st->vref = devm_regulator_get(&pdev->dev, "vref");
> + if (IS_ERR(st->vref))
> + return PTR_ERR(st->vref);
> +
> + ret = devm_request_irq(&pdev->dev, st->irq, at91_adc_interrupt, 0,
> + pdev->dev.driver->name, indio_dev);
> + if (ret)
> + return ret;
> +
> + st->vref_uv = regulator_get_voltage(st->vref);
> + if (st->vref_uv <= 0) {
> + ret = -EINVAL;
> + goto error;
> + }
> +
> + ret = at91_adc_init(st);
> + if (ret)
> + goto error;
> +
> + ret = clk_prepare_enable(st->adc_clk);
Handle these possible errors.
> + ret = clk_prepare_enable(st->per_clk);
> +
> + ret = iio_device_register(indio_dev);
> + if (ret < 0)
> + return ret;
> +
> + dev_info(&pdev->dev, "version: %x\n",
> + readl_relaxed(st->base + ADC_VERSION));
> +
> +error:
> + return ret;
> +}
> +
> +static int at91_adc_remove(struct platform_device *pdev)
> +{
> + struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> + struct at91_adc_state *st = iio_priv(indio_dev);
> +
> + iio_device_unregister(indio_dev);
> +
> + clk_disable_unprepare(st->per_clk);
> + clk_disable_unprepare(st->adc_clk);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id at91_adc_dt_match[] = {
> + {
> + .compatible = "atmel,sama5d2-adc",
> + .data = &at91_adc_sama5d2_soc_info
> + }, {
> + /* sentinel */
> + }
> +};
> +MODULE_DEVICE_TABLE(of, at91_adc_dt_match);
> +
> +static struct platform_driver at91_adc_driver = {
> + .probe = at91_adc_probe,
> + .remove = at91_adc_remove,
> + .driver = {
> + .name = "at91_adc8xx",
> + .of_match_table = at91_adc_dt_match,
> + },
> +};
> +module_platform_driver(at91_adc_driver)
> +
> +MODULE_AUTHOR("Ludovic Desroches <ludovic.desroches@xxxxxxxxx>");
> +MODULE_DESCRIPTION("Atmel AT91 ADC 8xx");
> +MODULE_LICENSE("GPL v2");
>
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