On 4/11/2012 2:19 PM, Stefan Roese wrote:
This patch implements the basic single data conversion support for
the SPEAr600 SoC ADC. The register layout of SPEAr600 differs a bit
from other SPEAr SoC variants (e.g. SPEAr3xx). These differences are
handled via DT compatible testing. Resuling in a multi-arch binary.
Resulting
This driver is currently tested only on SPEAr600. Futur patches may add
support for other SoC variants (SPEAr3xx) and features like software
buffer or DMA.
Future
Ironically that's about it wrt to comments. Couple of totally trivial
bits inline.
Basically I'm happy, so if/when someone acks the device tree side of
things, please
clean up the trivial bits and send on to GregKH.
Nice short, clean driver. The small line count lured me into reviewing
it ahead of
some others in my review pile!
Signed-off-by: Stefan Roese<sr@xxxxxxx>
Acked-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Cc: Jonathan Cameron<jic23@xxxxxxxxx>
Cc: Viresh Kumar<viresh.kumar@xxxxxx>
---
.../bindings/staging/iio/adc/spear-adc.txt | 26 ++
drivers/staging/iio/adc/Kconfig | 7 +
drivers/staging/iio/adc/Makefile | 1 +
drivers/staging/iio/adc/spear_adc.c | 439 ++++++++++++++++++++
4 files changed, 473 insertions(+)
create mode 100644 Documentation/devicetree/bindings/staging/iio/adc/spear-adc.txt
create mode 100644 drivers/staging/iio/adc/spear_adc.c
diff --git a/Documentation/devicetree/bindings/staging/iio/adc/spear-adc.txt b/Documentation/devicetree/bindings/staging/iio/adc/spear-adc.txt
new file mode 100644
index 0000000..02ea23a
--- /dev/null
+++ b/Documentation/devicetree/bindings/staging/iio/adc/spear-adc.txt
@@ -0,0 +1,26 @@
+* ST SPEAr ADC device driver
+
+Required properties:
+- compatible: Should be "st,spear600-adc"
+- reg: Address and length of the register set for the device
+- interrupt-parent: Should be the phandle for the interrupt controller
+ that services interrupts for this device
+- interrupts: Should contain the ADC interrupt
+- sampling-frequency: Default sampling frequency
+
+Optional properties:
+- vref-external: External voltage reference in milli-volts. If omitted
+ the internal voltage reference will be used.
+- average-samples: Number of samples to generate an average value. If
+ omitted, single data conversion will be used.
+
+Examples:
+
+ adc: adc@d8200000 {
+ compatible = "st,spear600-adc";
+ reg =<0xd8200000 0x1000>;
+ interrupt-parent =<&vic1>;
+ interrupts =<6>;
+ sampling-frequency =<5000000>;
+ vref-external =<2500>; /* 2.5V VRef */
+ };
I'd like someone with dt experience to give an ack on this. I really
have no idea!
diff --git a/drivers/staging/iio/adc/Kconfig b/drivers/staging/iio/adc/Kconfig
index 592eabd..ec006e7 100644
--- a/drivers/staging/iio/adc/Kconfig
+++ b/drivers/staging/iio/adc/Kconfig
@@ -202,4 +202,11 @@ config LPC32XX_ADC
touchscreen driver, so you can only select one of the two drivers
(lpc32xx_adc or lpc32xx_ts). Provides direct access via sysfs.
+config SPEAR_ADC
+ tristate "ST SPEAr ADC"
+ depends on PLAT_SPEAR
+ help
+ Say yes here to build support for the integrated ADC inside the
+ ST SPEAr SoC. Provides direct access via sysfs.
+
endmenu
diff --git a/drivers/staging/iio/adc/Makefile b/drivers/staging/iio/adc/Makefile
index f83ab95..14e98b6 100644
--- a/drivers/staging/iio/adc/Makefile
+++ b/drivers/staging/iio/adc/Makefile
@@ -38,3 +38,4 @@ obj-$(CONFIG_ADT7310) += adt7310.o
obj-$(CONFIG_ADT7410) += adt7410.o
obj-$(CONFIG_AD7280) += ad7280a.o
obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
+obj-$(CONFIG_SPEAR_ADC) += spear_adc.o
diff --git a/drivers/staging/iio/adc/spear_adc.c b/drivers/staging/iio/adc/spear_adc.c
new file mode 100644
index 0000000..ce518bc
--- /dev/null
+++ b/drivers/staging/iio/adc/spear_adc.c
@@ -0,0 +1,439 @@
+/*
+ * ST SPEAr ADC driver
+ *
+ * Copyright 2012 Stefan Roese<sr@xxxxxxx>
+ *
+ * Licensed under the GPL-2.
+ */
+
+#include<linux/module.h>
+#include<linux/platform_device.h>
+#include<linux/interrupt.h>
+#include<linux/device.h>
+#include<linux/kernel.h>
+#include<linux/slab.h>
+#include<linux/io.h>
+#include<linux/clk.h>
+#include<linux/err.h>
+#include<linux/completion.h>
+#include<linux/of.h>
+
+#include "../iio.h"
+#include "../sysfs.h"
+
+/*
+ * SPEAR registers definitions
+ */
+
+#define SCAN_RATE_LO(x) ((x)& 0xFFFF)
+#define SCAN_RATE_HI(x) (((x)>> 0x10)& 0xFFFF)
+#define CLK_LOW(x) (((x)& 0xf)<< 0)
+#define CLK_HIGH(x) (((x)& 0xf)<< 4)
+
+/* Bit definitions for SPEAR_ADC_STATUS */
+#define START_CONVERSION (1<< 0)
+#define CHANNEL_NUM(x) ((x)<< 1)
+#define ADC_ENABLE (1<< 4)
+#define AVG_SAMPLE(x) ((x)<< 5)
+#define VREF_INTERNAL (1<< 9)
+
+#define DATA_MASK 0x03ff
+#define DATA_BITS 10
+
+#define MOD_NAME "spear-adc"
+
+#define ADC_CHANNEL_NUM 8
+
+struct adc_regs_spear3xx {
+ u32 status;
+ u32 average;
+ u32 scan_rate;
+ u32 clk; /* Not avail for 1340& 1310 */
+ u32 ch_ctrl[ADC_CHANNEL_NUM];
+ u32 ch_data[ADC_CHANNEL_NUM];
+};
+
+struct chan_data {
+ u32 lsb;
+ u32 msb;
+};
+
+struct adc_regs_spear6xx {
+ u32 status;
+ u32 pad[2];
+ u32 clk;
+ u32 ch_ctrl[ADC_CHANNEL_NUM];
+ struct chan_data ch_data[ADC_CHANNEL_NUM];
+ u32 scan_rate_lo;
+ u32 scan_rate_hi;
+ struct chan_data average;
+};
+
+struct spear_adc_info {
+ struct device_node *np;
+ struct adc_regs_spear3xx *adc_base_spear3xx;
+ struct adc_regs_spear6xx *adc_base_spear6xx;
+ struct clk *clk;
+ struct completion completion;
+ u32 current_clk;
+ u32 sampling_freq;
+ u32 avg_samples;
+ u32 vref_external;
+ u32 value;
+};
+
+/*
+ * Functions to access some SPEAr ADC register. Abstracted into
+ * static inline functions, because of different register offsets
+ * on different SoC variants (SPEAr300 vs SPEAr600 etc).
+ */
+static void spear_adc_set_status(struct spear_adc_info *info, u32 val)
+{
+ __raw_writel(val,&info->adc_base_spear6xx->status);
+}
+
+static void spear_adc_set_clk(struct spear_adc_info *info, u32 val)
+{
+ u32 clk_high, clk_low, count;
+ u32 apb_clk = clk_get_rate(info->clk);
+
+ count = (apb_clk + val - 1) / val;
+ clk_low = count / 2;
+ clk_high = count - clk_low;
+ info->current_clk = apb_clk / count;
+
+ __raw_writel(CLK_LOW(clk_low) | CLK_HIGH(clk_high),
+ &info->adc_base_spear6xx->clk);
+}
+
+static void spear_adc_set_ctrl(struct spear_adc_info *info, int n,
+ u32 val)
+{
+ __raw_writel(val,&info->adc_base_spear6xx->ch_ctrl[n]);
+}
+
+static u32 spear_adc_get_average(struct spear_adc_info *info)
+{
+ if (of_device_is_compatible(info->np, "st,spear600-adc")) {
+ return __raw_readl(&info->adc_base_spear6xx->average.msb)&
+ DATA_MASK;
+ } else {
+ return __raw_readl(&info->adc_base_spear3xx->average)&
+ DATA_MASK;
+ }
+}
+
+static void spear_adc_set_scanrate(struct spear_adc_info *info, u32 rate)
+{
+ if (of_device_is_compatible(info->np, "st,spear600-adc")) {
+ __raw_writel(SCAN_RATE_LO(rate),
+ &info->adc_base_spear6xx->scan_rate_lo);
+ __raw_writel(SCAN_RATE_HI(rate),
+ &info->adc_base_spear6xx->scan_rate_hi);
+ } else {
+ __raw_writel(rate,&info->adc_base_spear3xx->scan_rate);
+ }
+}
+
+static int spear_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long mask)
+{
+ struct spear_adc_info *info = iio_priv(indio_dev);
+ u32 scale_uv;
+ u32 status;
+
+ switch (mask) {
+ case 0:
+ mutex_lock(&indio_dev->mlock);
+
+ status = CHANNEL_NUM(chan->channel) |
+ AVG_SAMPLE(info->avg_samples) |
+ START_CONVERSION | ADC_ENABLE;
+ if (info->vref_external == 0)
+ status |= VREF_INTERNAL;
+
+ spear_adc_set_status(info, status);
+ wait_for_completion(&info->completion); /* set by ISR */
+ *val = info->value;
+
+ mutex_unlock(&indio_dev->mlock);
+
+ return IIO_VAL_INT;
+
+ case IIO_CHAN_INFO_SCALE:
+ scale_uv = (info->vref_external * 1000)>> DATA_BITS;
Given the div 1000's I'm guessing scale_mv would be more appropriate as
a variable name?
+ *val = scale_uv / 1000;
+ *val2 = (scale_uv % 1000) * 1000;
+ return IIO_VAL_INT_PLUS_MICRO;
+ }
+
+ return -EINVAL;
+}
+
+#define SPEAR_ADC_CHAN(idx) { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .info_mask = IIO_CHAN_INFO_SCALE_SHARED_BIT, \
Given this'll probably hit the tree before the series to make the value
reading optional, I'll
add the relevant bits to the info mask in a new version of that series.
+ .channel = idx, \
+ .scan_type = { \
+ .sign = 'u', \
+ .storagebits = 16, \
+ }, \
+}
+
+static struct iio_chan_spec spear_adc_iio_channels[] = {
+ SPEAR_ADC_CHAN(0),
+ SPEAR_ADC_CHAN(1),
+ SPEAR_ADC_CHAN(2),
+ SPEAR_ADC_CHAN(3),
+ SPEAR_ADC_CHAN(4),
+ SPEAR_ADC_CHAN(5),
+ SPEAR_ADC_CHAN(6),
+ SPEAR_ADC_CHAN(7),
+};
+
+static irqreturn_t spear_adc_isr(int irq, void *dev_id)
+{
+ struct spear_adc_info *info = (struct spear_adc_info *)dev_id;
+
+ /* Read value to clear IRQ */
+ info->value = spear_adc_get_average(info);
+ complete(&info->completion);
+
+ return IRQ_HANDLED;
+}
+
+static int spear_adc_configure(struct spear_adc_info *info)
+{
+ int i;
+
+ /* Reset ADC core */
+ spear_adc_set_status(info, 0);
+ __raw_writel(0,&info->adc_base_spear6xx->clk);
+ for (i = 0; i< 8; i++)
+ spear_adc_set_ctrl(info, i, 0);
+ spear_adc_set_scanrate(info, 0);
+
+ spear_adc_set_clk(info, info->sampling_freq);
+
+ return 0;
+}
+
+static ssize_t spear_adc_read_frequency(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct iio_dev *indio_dev = dev_get_drvdata(dev);
+ struct spear_adc_info *info = iio_priv(indio_dev);
+
+ return sprintf(buf, "%d\n", info->current_clk);
+}
+
+static ssize_t spear_adc_write_frequency(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf,
+ size_t len)
+{
+ struct iio_dev *indio_dev = dev_get_drvdata(dev);
+ struct spear_adc_info *info = iio_priv(indio_dev);
+ u32 clk_high, clk_low, count, clk_min, clk_max;
+ u32 apb_clk = clk_get_rate(info->clk);
+ unsigned long lval;
+ int ret;
+
+ ret = kstrtoul(buf, 10,&lval);
+ if (ret)
+ return ret;
+
+ mutex_lock(&indio_dev->mlock);
+
+ clk_min = 2500000;
+ clk_max = 20000000;
These look like constants. I'd define them as such if they are. Maybe even
some #defines rather than locally.
+ if ((lval< clk_min) || (lval> clk_max)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ count = (apb_clk + lval - 1) / lval;
+ clk_low = count / 2;
+ clk_high = count - clk_low;
+ info->current_clk = apb_clk / count;
+ spear_adc_set_clk(info, lval);
+
+out:
+ mutex_unlock(&indio_dev->mlock);
+
+ return ret ? ret : len;
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
+ spear_adc_read_frequency,
+ spear_adc_write_frequency);
+
+static struct attribute *spear_attributes[] = {
+ &iio_dev_attr_sampling_frequency.dev_attr.attr,
+ NULL
+};
+
+static const struct attribute_group spear_attribute_group = {
+ .attrs = spear_attributes,
+};
+
+static const struct iio_info spear_adc_iio_info = {
+ .read_raw =&spear_read_raw,
+ .attrs =&spear_attribute_group,
+ .driver_module = THIS_MODULE,
+};
+
+static int __devinit spear_adc_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct spear_adc_info *info;
+ struct resource *res;
+ int retval = -ENODEV;
+ struct iio_dev *iodev = NULL;
+ int irq;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "failed to get platform I/O memory\n");
+ retval = -EBUSY;
+ goto errout1;
+ }
+
+ iodev = iio_allocate_device(sizeof(struct spear_adc_info));
+ if (!iodev) {
+ dev_err(&pdev->dev, "failed allocating iio device\n");
+ retval = -ENOMEM;
+ goto errout1;
+ }
+
+ info = iio_priv(iodev);
+ info->np = np;
+
+ /*
+ * SPEAr600 has a different register layout than other SPEAr SoC's
+ * (e.g. SPEAr3xx). Let's provide two register base addresses
+ * to support multi-arch kernels.
+ */
+ info->adc_base_spear6xx = ioremap(res->start, resource_size(res));
+ if (!info->adc_base_spear6xx) {
+ dev_err(&pdev->dev, "failed mapping memory\n");
+ retval = -EBUSY;
+ goto errout2;
+ }
+ info->adc_base_spear3xx =
+ (struct adc_regs_spear3xx *)info->adc_base_spear6xx;
+
+ info->clk = clk_get(&pdev->dev, NULL);
+ if (IS_ERR(info->clk)) {
+ dev_err(&pdev->dev, "failed getting clock\n");
+ goto errout3;
+ }
+ clk_enable(info->clk);
+
+ irq = platform_get_irq(pdev, 0);
+ if ((irq< 0) || (irq>= NR_IRQS)) {
+ dev_err(&pdev->dev, "failed getting interrupt resource\n");
+ retval = -EINVAL;
+ goto errout4;
+ }
+
+ retval = request_irq(irq, spear_adc_isr, 0, MOD_NAME, info);
Preference for threaded irqs... Though as it's trivial, guess not worth
bothering...
+ if (retval< 0) {
+ dev_err(&pdev->dev, "failed requesting interrupt\n");
+ goto errout4;
+ }
+
+ if (of_property_read_u32(np, "sampling-frequency",
+ &info->sampling_freq)) {
+ dev_err(&pdev->dev, "sampling-frequency missing in DT\n");
+ retval = -EINVAL;
+ goto errout5;
+ }
+
+ /*
+ * Optional avg_samples defaults to 0, resulting in single data
+ * conversion
+ */
+ of_property_read_u32(np, "average-samples",&info->avg_samples);
+
+ /*
+ * Optional vref_external defaults to 0, resulting in internal vref
+ * selection
+ */
+ of_property_read_u32(np, "vref-external",&info->vref_external);
+
+ spear_adc_configure(info);
+
+ platform_set_drvdata(pdev, iodev);
+
+ init_completion(&info->completion);
+
+ iodev->name = MOD_NAME;
+ iodev->dev.parent =&pdev->dev;
+ iodev->info =&spear_adc_iio_info;
+ iodev->modes = INDIO_DIRECT_MODE;
+ iodev->channels = spear_adc_iio_channels;
+ iodev->num_channels = ARRAY_SIZE(spear_adc_iio_channels);
+
+ retval = iio_device_register(iodev);
+ if (retval)
+ goto errout5;
+
+ dev_info(&pdev->dev, "SPEAR ADC driver loaded, IRQ %d\n", irq);
+
+ return 0;
+
+errout5:
+ free_irq(irq, iodev);
+errout4:
+ clk_put(info->clk);
+errout3:
+ iounmap(info->adc_base_spear6xx);
+errout2:
+ iio_free_device(iodev);
+errout1:
+ return retval;
+}
+
+static int __devexit spear_adc_remove(struct platform_device *pdev)
+{
+ struct iio_dev *iodev = platform_get_drvdata(pdev);
+ struct spear_adc_info *info = iio_priv(iodev);
+ int irq = platform_get_irq(pdev, 0);
+
+ iio_device_unregister(iodev);
+ free_irq(irq, iodev);
+ platform_set_drvdata(pdev, NULL);
+ clk_put(info->clk);
+ iounmap(info->adc_base_spear6xx);
+ iio_free_device(iodev);
+
+ return 0;
+}
+
+static const struct of_device_id spear_adc_dt_ids[] = {
+ { .compatible = "st,spear600-adc", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, spear_adc_dt_ids);
+
+static struct platform_driver spear_adc_driver = {
+ .probe = spear_adc_probe,
+ .remove = __devexit_p(spear_adc_remove),
+ .driver = {
+ .name = MOD_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(spear_adc_dt_ids),
+ },
+};
+
+module_platform_driver(spear_adc_driver);
+
+MODULE_AUTHOR("Stefan Roese<sr@xxxxxxx>");
+MODULE_DESCRIPTION("SPEAr ADC driver");
+MODULE_LICENSE("GPL");
--
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