[PATCH] ARM: LPC32xx: ADC support
From: Jonathan Cameron <hidden>
Date: 2012-02-02 15:52:20
Also in:
linux-iio, lkml
My comments are down near the iio bits.
quoted hunk ↗ jump to hunk
This patch adds a 3-channel ADC driver for the LPC32xx ARM SoC Signed-off-by: Roland Stigge<redacted>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.
quoted hunk ↗ jump to hunk
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.odiff --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@antcom.de> + * + * 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[off-list ref]");
+MODULE_DESCRIPTION("LPC32XX ADC driver");
+MODULE_LICENSE("GPL");