My comments are down near the iio bits.
This patch adds a 3-channel ADC driver for the LPC32xx ARM SoC
Signed-off-by: Roland Stigge<stigge@xxxxxxxxx>
diff --git a/arch/arm/mach-lpc32xx/clock.c b/arch/arm/mach-lpc32xx/clock.c
index c269ef5..9cda6fa 100644
--- a/arch/arm/mach-lpc32xx/clock.c
+++ b/arch/arm/mach-lpc32xx/clock.c
@@ -760,6 +760,36 @@ static struct clk clk_tsc = {
.get_rate = local_return_parent_rate,
};
+static int adc_onoff_enable(struct clk *clk, int enable)
+{
+ u32 tmp;
+
+ /* Use PERIPH_CLOCK */
+ tmp = __raw_readl(LPC32XX_CLKPWR_ADC_CLK_CTRL_1);
+ tmp |= LPC32XX_CLKPWR_ADCCTRL1_PCLK_SEL;
+ /*
+ * Set clock divider so that we have equal to or less than
+ * 4.5MHz clock at ADC
+ */
+ tmp |= clk->get_rate(clk) / 4500000 + 1;
+ __raw_writel(tmp, LPC32XX_CLKPWR_ADC_CLK_CTRL_1);
+
+ if (enable == 0)
+ __raw_writel(0, clk->enable_reg);
+ else
+ __raw_writel(clk->enable_mask, clk->enable_reg);
+
+ return 0;
+}
+
+static struct clk clk_adc = {
+ .parent =&clk_pclk,
+ .enable = adc_onoff_enable,
+ .enable_reg = LPC32XX_CLKPWR_ADC_CLK_CTRL,
+ .enable_mask = LPC32XX_CLKPWR_ADC32CLKCTRL_CLK_EN,
+ .get_rate = local_return_parent_rate,
+};
+
static int mmc_onoff_enable(struct clk *clk, int enable)
{
u32 tmp;
@@ -1097,6 +1127,7 @@ static struct clk_lookup lookups[] = {
_REGISTER_CLOCK("dev:ssp1", NULL, clk_ssp1)
_REGISTER_CLOCK("lpc32xx_keys.0", NULL, clk_kscan)
_REGISTER_CLOCK("lpc32xx-nand.0", "nand_ck", clk_nand)
+ _REGISTER_CLOCK("lpc32xx-adc", NULL, clk_adc)
_REGISTER_CLOCK(NULL, "i2s0_ck", clk_i2s0)
_REGISTER_CLOCK(NULL, "i2s1_ck", clk_i2s1)
_REGISTER_CLOCK("ts-lpc32xx", NULL, clk_tsc)
diff --git a/arch/arm/mach-lpc32xx/common.c b/arch/arm/mach-lpc32xx/common.c
index f220eb0..2f869c0 100644
--- a/arch/arm/mach-lpc32xx/common.c
+++ b/arch/arm/mach-lpc32xx/common.c
@@ -137,6 +137,27 @@ struct platform_device lpc32xx_rtc_device = {
.resource = lpc32xx_rtc_resources,
};
+/*
+ * ADC support
+ */
+static struct resource adc_resources[] = {
+ {
+ .start = LPC32XX_ADC_BASE,
+ .end = LPC32XX_ADC_BASE + SZ_4K - 1,
+ .flags = IORESOURCE_MEM,
+ }, {
+ .start = IRQ_LPC32XX_TS_IRQ,
+ .end = IRQ_LPC32XX_TS_IRQ,
+ .flags = IORESOURCE_IRQ,
+ },
+};
+struct platform_device lpc32xx_adc_device = {
+ .name = "lpc32xx-adc",
+ .id = -1,
+ .num_resources = ARRAY_SIZE(adc_resources),
+ .resource = adc_resources,
+};
+
#if defined(CONFIG_USB_OHCI_HCD)
/* The dmamask must be set for OHCI to work */
static u64 ohci_dmamask = ~(u32) 0;
diff --git a/arch/arm/mach-lpc32xx/common.h b/arch/arm/mach-lpc32xx/common.h
index e42d702..5bf0050 100644
--- a/arch/arm/mach-lpc32xx/common.h
+++ b/arch/arm/mach-lpc32xx/common.h
@@ -30,6 +30,7 @@ extern struct platform_device lpc32xx_i2c0_device;
extern struct platform_device lpc32xx_i2c1_device;
extern struct platform_device lpc32xx_i2c2_device;
extern struct platform_device lpc32xx_tsc_device;
+extern struct platform_device lpc32xx_adc_device;
extern struct platform_device lpc32xx_rtc_device;
extern struct platform_device lpc32xx_ohci_device;
diff --git a/arch/arm/mach-lpc32xx/phy3250.c b/arch/arm/mach-lpc32xx/phy3250.c
index 69a5ceb..23b484c 100644
--- a/arch/arm/mach-lpc32xx/phy3250.c
+++ b/arch/arm/mach-lpc32xx/phy3250.c
@@ -317,6 +317,9 @@ static struct platform_device *phy3250_devs[] __initdata = {
#if defined(CONFIG_LPC_ENET)
&lpc32xx_net_device,
#endif
+#if defined(CONFIG_LPC32XX_ADC)
+ &lpc32xx_adc_device,
+#endif
};
static struct amba_device *amba_devs[] __initdata = {
diff --git a/drivers/staging/iio/adc/Kconfig b/drivers/staging/iio/adc/Kconfig
index d9decea..592eabd 100644
--- a/drivers/staging/iio/adc/Kconfig
+++ b/drivers/staging/iio/adc/Kconfig
@@ -193,4 +193,13 @@ config MAX1363_RING_BUFFER
Say yes here to include ring buffer support in the MAX1363
ADC driver.
+config LPC32XX_ADC
+ tristate "NXP LPC32XX ADC"
+ depends on ARCH_LPC32XX&& !TOUCHSCREEN_LPC32XX
+ help
+ Say yes here to build support for the integrated ADC inside the
+ LPC32XX SoC. Note that this feature uses the same hardware as the
+ touchscreen driver, so you can only select one of the two drivers
+ (lpc32xx_adc or lpc32xx_ts). Provides direct access via sysfs.
This should be a good base for messing around with the in kernel
interfaces then ;)
+
endmenu
A few structural changes needed, mainly to catch up with newer
interfaces than used here, but
fundamentally sound.
diff --git a/drivers/staging/iio/adc/Makefile b/drivers/staging/iio/adc/Makefile
index ceee7f3..f83ab95 100644
--- a/drivers/staging/iio/adc/Makefile
+++ b/drivers/staging/iio/adc/Makefile
@@ -37,3 +37,4 @@ obj-$(CONFIG_AD7192) += ad7192.o
obj-$(CONFIG_ADT7310) += adt7310.o
obj-$(CONFIG_ADT7410) += adt7410.o
obj-$(CONFIG_AD7280) += ad7280a.o
+obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
diff --git a/drivers/staging/iio/adc/lpc32xx_adc.c b/drivers/staging/iio/adc/lpc32xx_adc.c
new file mode 100644
index 0000000..6b27446
--- /dev/null
+++ b/drivers/staging/iio/adc/lpc32xx_adc.c
@@ -0,0 +1,286 @@
+/*
+ * lpc32xx_adc.c - Support for ADC in LPC32XX
+ *
+ * Copyright (C) 2011 Roland Stigge<stigge@xxxxxxxxx>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#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 "../iio.h"
+#include "../sysfs.h"
+
+/*
+ * LPC32XX registers definitions
+ */
+
+#define LPC32XX_ADC_SELECT(x) ((x) + 0x04)
+#define LPC32XX_ADC_CTRL(x) ((x) + 0x08)
+#define LPC32XX_ADC_VALUE(x) ((x) + 0x48)
+
+/* Bit definitions for LPC32XX_ADC_SELECT: */
+#define AD_REFm 0x00000200 /* constant, always write this value! */
+#define AD_REFp 0x00000080 /* constant, always write this value! */
+#define AD_IN 0x00000010 /* multiple of this is the */
+ /* channel number: 0, 1, 2 */
+#define AD_INTERNAL 0x00000004 /* constant, always write this value! */
+
+/* Bit definitions for LPC32XX_ADC_CTRL: */
+#define AD_STROBE 0x00000002
+#define AD_PDN_CTRL 0x00000004
+
+/* Bit definitions for LPC32XX_ADC_VALUE: */
+#define ADC_VALUE_MASK 0x000003FF
+
+#define MOD_NAME "lpc32xx-adc"
+
+/*
+ * chip specifc information
+ */
+
+struct lpc32xx_adc_info {
+ struct iio_dev *dev;
+ void __iomem *adc_base;
irq is only used where the platform device is readily available so you could
drop it from this structure.
There is provision in iio via the iio_device_allocate parameter and iio_priv
to embed this structure within an iio_dev structure. It makes for a
cleaner code
but will require a trivial bit of reorganizing in your probe and remove
+ int irq;
+ struct clk *clk;
+ struct completion completion;
+
+ u32 value;
+};
+
+/*
+ * sysfs nodes
+ */
+static ssize_t lpc32xx_adin_value(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct iio_dev *dev_info = dev_get_drvdata(dev);
+ struct lpc32xx_adc_info *info = iio_priv(dev_info);
+ struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
+ int result;
+
+ mutex_lock(&dev_info->mlock);
+ /* Measurement setup */
+ __raw_writel(AD_INTERNAL | (AD_IN * this_attr->address) |
+ AD_REFp | AD_REFm,
+ LPC32XX_ADC_SELECT(info->adc_base));
+ /* Trigger conversion */
+ __raw_writel(AD_PDN_CTRL | AD_STROBE,
+ LPC32XX_ADC_CTRL(info->adc_base));
+
+ wait_for_completion(&info->completion); /* set by ISR */
+
+ result = sprintf(buf, "%d\n", info->value);
+
+ mutex_unlock(&dev_info->mlock);
+
+ return result;
+}
+
+static IIO_DEVICE_ATTR(in0_raw, S_IRUGO, lpc32xx_adin_value, NULL, 0);
+static IIO_DEVICE_ATTR(in1_raw, S_IRUGO, lpc32xx_adin_value, NULL, 1);
+static IIO_DEVICE_ATTR(in2_raw, S_IRUGO, lpc32xx_adin_value, NULL, 2);
+
+static struct attribute *lpc32xx_adin_attributes[] = {
+ &iio_dev_attr_in0_raw.dev_attr.attr,
+ &iio_dev_attr_in1_raw.dev_attr.attr,
+ &iio_dev_attr_in2_raw.dev_attr.attr,
+ NULL,
Please use iio_chan_info structures and the read_raw callback
rather than doing these attributes like this. That will make for a much
easier
job if anyone ever wants to use the inkernel interfaces (highly likely
with a soc adc).
+};
+
+static const struct attribute_group lpc32xx_adin_attribute_group = {
+ .attrs = lpc32xx_adin_attributes,
+};
+
+static const struct iio_info lpc32xx_adc_iio_info = {
+ .attrs =&lpc32xx_adin_attribute_group,
+ .driver_module = THIS_MODULE,
+};
+
+static irqreturn_t lpc32xx_adc_isr(int irq, void *dev_id)
+{
+ struct lpc32xx_adc_info *info = (struct lpc32xx_adc_info *) dev_id;
+
+ /* Read value and clear irq */
+ info->value = __raw_readl(LPC32XX_ADC_VALUE(info->adc_base))&
+ ADC_VALUE_MASK;
+ complete(&info->completion);
+
+ return IRQ_HANDLED;
+}
+
+static int __devinit lpc32xx_adc_probe(struct platform_device *pdev)
+{
+ struct lpc32xx_adc_info *info = NULL;
+ struct resource *res;
+ int retval = -ENODEV;
+ struct iio_dev *iodev = NULL;
+
+ 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 lpc32xx_adc_info));
+ if (!iodev) {
+ dev_err(&pdev->dev, "failed allocating iio device\n");
+ retval = -ENOMEM;
+ goto errout1;
+ }
+
+ info = iio_priv(iodev);
+ info->dev = iodev;
+
+ info->adc_base = ioremap(res->start, res->end - res->start + 1);
+ if (!info->adc_base) {
+ dev_err(&pdev->dev, "failed mapping memory\n");
+ retval = -EBUSY;
+ goto errout3;
+ }
+
+ iodev->name = MOD_NAME;
+ iodev->dev.parent =&pdev->dev;
+ iodev->info =&lpc32xx_adc_iio_info;
+ iodev->modes = INDIO_DIRECT_MODE;
+
+ retval = iio_device_register(iodev);
+ if (retval)
+ goto errout4;
Generally we'd make the iio_device_register call only after everything
else is set up as it is
at this point that the userspace interface becomes active. Hence there
might be a racecondition
if someone reads just after here. I haven't checked thoroughly, but as
a general rule, keeping
any interfaces from becoming available until everything else is done
makes for easier to review
code if nothing else!
+
+ info->clk = clk_get(&pdev->dev, NULL);
+ if (IS_ERR(info->clk)) {
+ dev_err(&pdev->dev, "failed getting clock\n");
+ goto errout5;
+ }
+ clk_enable(info->clk);
+
+ info->irq = platform_get_irq(pdev, 0);
+ if ((info->irq< 0) || (info->irq>= NR_IRQS)) {
+ dev_err(&pdev->dev, "failed getting interrupt resource\n");
+ retval = -EINVAL;
+ goto errout6;
+ }
+
+ retval = request_irq(info->irq, lpc32xx_adc_isr, 0, MOD_NAME, info);
+ if (retval< 0) {
+ dev_err(&pdev->dev, "failed requesting interrupt\n");
+ goto errout6;
+ }
+
+ platform_set_drvdata(pdev, info);
+
+ device_init_wakeup(&pdev->dev, 1);
+ init_completion(&info->completion);
+
+ printk(KERN_INFO "LPC32XX ADC driver loaded, IRQ %d\n", info->irq);
+
+ return 0;
+
+errout6:
+ clk_disable(info->clk);
+ clk_put(info->clk);
+errout5:
+ iio_device_unregister(info->dev);
+errout4:
+ iounmap(info->adc_base);
+errout3:
+ iio_free_device(info->dev);
+errout1:
+ return retval;
+}
+
+static int __devexit lpc32xx_adc_remove(struct platform_device *pdev)
+{
+ struct lpc32xx_adc_info *info = platform_get_drvdata(pdev);
+
+ free_irq(info->irq, info->dev);
+ platform_set_drvdata(pdev, NULL);
+ clk_disable(info->clk);
+ clk_put(info->clk);
+ iio_device_unregister(info->dev);
+ iio_free_device(info->dev);
+ iounmap(info->adc_base);
+ kfree(info);
+
+ printk(KERN_INFO "LPC32XX ADC driver unloaded\n");
+
+ return 0;
+}
+
+#if defined(CONFIG_SUSPEND)
+static int lpc32xx_adc_suspend(struct device *dev)
+{
+ struct lpc32xx_adc_info *info = dev_get_drvdata(dev);
+
+ clk_disable(info->clk);
+ return 0;
+}
+
+static int lpc32xx_adc_resume(struct device *dev)
+{
+ struct lpc32xx_adc_info *info = dev_get_drvdata(dev);
+
+ clk_enable(info->clk);
+ return 0;
+}
+
+static const struct dev_pm_ops lpc32xx_adc_pm_ops = {
+ .suspend = lpc32xx_adc_suspend,
+ .resume = lpc32xx_adc_resume,
+};
+#define LPC32XX_ADC_PM_OPS (&lpc32xx_adc_pm_ops)
+#else
+#define LPC32XX_ADC_PM_OPS NULL
+#endif
+
+static struct platform_driver lpc32xx_adc_driver = {
+ .probe = lpc32xx_adc_probe,
+ .remove = __devexit_p(lpc32xx_adc_remove),
+ .driver = {
+ .name = MOD_NAME,
+ .owner = THIS_MODULE,
+ .pm = LPC32XX_ADC_PM_OPS,
+ },
+};
+
+static int __init lpc32xx_adc_init(void)
+{
+ return platform_driver_register(&lpc32xx_adc_driver);
+}
+
+static void __exit lpc32xx_adc_exit(void)
+{
+ platform_driver_unregister(&lpc32xx_adc_driver);
+}
+
+module_init(lpc32xx_adc_init);
+module_exit(lpc32xx_adc_exit);
+
+MODULE_AUTHOR("Roland Stigge<stigge@xxxxxxxxx>");
+MODULE_DESCRIPTION("LPC32XX ADC driver");
+MODULE_LICENSE("GPL");
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