On 2/12/2012 8:09 PM, Roland Stigge wrote:
This patch adds a 3-channel ADC driver for the LPC32xx ARM SoC
Nice clean short driver. A pleasure to review. Few trivial bits inline.
Only changes I'd definitely like are
1) using the recently introduced macro to avoid the boiler plate for the
registering of a platform driver.
2) drop the .scan_type setting, it's pointless here and slightly confusing.
Otherwise I'm just being fussy about over enthusiastic comments :)
Signed-off-by: Roland Stigge<stigge@xxxxxxxxx>
Index: linux-arm-soc/arch/arm/mach-lpc32xx/clock.c
===================================================================
--- linux-arm-soc.orig/arch/arm/mach-lpc32xx/clock.c 2012-02-12 20:04:49.000000000 +0100
+++ linux-arm-soc/arch/arm/mach-lpc32xx/clock.c 2012-02-12 20:17:13.000000000 +0100
@@ -721,6 +721,41 @@
.get_rate = local_return_parent_rate,
};
+static int adc_onoff_enable(struct clk *clk, int enable)
+{
+ u32 tmp;
+ u32 divider;
+
+ /* 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
+ */
+ divider = clk->get_rate(clk) / 4500000 + 1;
+ tmp |= divider;
+ __raw_writel(tmp, LPC32XX_CLKPWR_ADC_CLK_CTRL_1);
+
+ /* synchronize rate of this clock w/ actual HW setting */
+ clk->rate = clk->get_rate(clk->parent) / divider;
+
+ 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;
@@ -1055,6 +1090,7 @@
_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)
Index: linux-arm-soc/arch/arm/mach-lpc32xx/common.c
===================================================================
--- linux-arm-soc.orig/arch/arm/mach-lpc32xx/common.c 2012-02-12 20:04:49.000000000 +0100
+++ linux-arm-soc/arch/arm/mach-lpc32xx/common.c 2012-02-12 20:17:13.000000000 +0100
@@ -138,6 +138,28 @@
};
/*
+ * 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,
+};
+
+/*
* Returns the unique ID for the device
*/
void lpc32xx_get_uid(u32 devid[4])
Index: linux-arm-soc/arch/arm/mach-lpc32xx/common.h
===================================================================
--- linux-arm-soc.orig/arch/arm/mach-lpc32xx/common.h 2012-02-12 20:04:49.000000000 +0100
+++ linux-arm-soc/arch/arm/mach-lpc32xx/common.h 2012-02-12 20:17:13.000000000 +0100
@@ -29,6 +29,7 @@
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;
/*
Index: linux-arm-soc/arch/arm/mach-lpc32xx/phy3250.c
===================================================================
--- linux-arm-soc.orig/arch/arm/mach-lpc32xx/phy3250.c 2012-02-12 20:04:49.000000000 +0100
+++ linux-arm-soc/arch/arm/mach-lpc32xx/phy3250.c 2012-02-12 20:17:13.000000000 +0100
@@ -252,6 +252,9 @@
&lpc32xx_i2c2_device,
&lpc32xx_watchdog_device,
&lpc32xx_gpio_led_device,
+#if defined(CONFIG_LPC32XX_ADC)
+ &lpc32xx_adc_device,
+#endif
};
static struct amba_device *amba_devs[] __initdata = {
Index: linux-arm-soc/drivers/staging/iio/adc/Kconfig
===================================================================
--- linux-arm-soc.orig/drivers/staging/iio/adc/Kconfig 2012-02-12 20:04:00.000000000 +0100
+++ linux-arm-soc/drivers/staging/iio/adc/Kconfig 2012-02-12 20:17:13.000000000 +0100
@@ -193,4 +193,13 @@
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.
+
endmenu
Index: linux-arm-soc/drivers/staging/iio/adc/Makefile
===================================================================
--- linux-arm-soc.orig/drivers/staging/iio/adc/Makefile 2012-02-12 20:04:00.000000000 +0100
+++ linux-arm-soc/drivers/staging/iio/adc/Makefile 2012-02-12 20:17:13.000000000 +0100
@@ -37,3 +37,4 @@
obj-$(CONFIG_ADT7310) += adt7310.o
obj-$(CONFIG_ADT7410) += adt7410.o
obj-$(CONFIG_AD7280) += ad7280a.o
+obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
Index: linux-arm-soc/drivers/staging/iio/adc/lpc32xx_adc.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-arm-soc/drivers/staging/iio/adc/lpc32xx_adc.c 2012-02-12 20:17:13.000000000 +0100
@@ -0,0 +1,259 @@
+/*
+ * lpc32xx_adc.c - Support for ADC in LPC32XX
+ *
+ * 3-channel, 10-bit ADC
+ *
+ * Copyright (C) 2011, 2012 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
+ */
Utter nitpicks, but I'd drop some of the comments. Many are rather
obvious and hence
don't need to be here! (I like short drivers ;)
+
+struct lpc32xx_adc_info {
+ void __iomem *adc_base;
+ struct clk *clk;
+ struct completion completion;
+
+ u32 value;
+};
+
+/*
+ * read callback
+ */
Comment is rather obvious. So I'd not bother with it. These sort of
'obvious'
comments just tend to end up out of date due to later patches. By all
means document anything non obvious, but don't bother with the other
ones.
+static int lpc32xx_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long mask)
+{
+ struct lpc32xx_adc_info *info = iio_priv(indio_dev);
+
+ if (mask == 0) {
+ mutex_lock(&indio_dev->mlock);
+ clk_enable(info->clk);
+ /* Measurement setup */
+ __raw_writel(AD_INTERNAL | (chan->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 */
+ clk_disable(info->clk);
+ *val = info->value;
+ mutex_unlock(&indio_dev->mlock);
+
+ return IIO_VAL_INT;
+ }
+
+ return -EINVAL;
+}
+
+static const struct iio_info lpc32xx_adc_iio_info = {
+ .read_raw =&lpc32xx_read_raw,
+ .driver_module = THIS_MODULE,
+};
+
+#define LPC32XX_ADC_CHANNEL(_index) { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = _index, \
+ .address = AD_IN * _index, \
+ .scan_type = IIO_ST('u', 10, 10, 0), \
a) you don't need to set scan_type unless you are doing buffers.
b) Typically one actually sets the third parameter to nearest aligned size
(here 16 bits). The point is for efficient access to the data in the buffer
if there is one.
So just drop setting scan_type at all.
+ .scan_index = _index, \
+}
+
+static struct iio_chan_spec lpc32xx_adc_iio_channels[] = {
+ LPC32XX_ADC_CHANNEL(0),
+ LPC32XX_ADC_CHANNEL(1),
+ LPC32XX_ADC_CHANNEL(2),
+};
+
+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;
+ 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 lpc32xx_adc_info));
+ if (!iodev) {
+ dev_err(&pdev->dev, "failed allocating iio device\n");
+ retval = -ENOMEM;
+ goto errout1;
+ }
+
+ info = iio_priv(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 errout2;
+ }
+
+ info->clk = clk_get(&pdev->dev, NULL);
+ if (IS_ERR(info->clk)) {
+ dev_err(&pdev->dev, "failed getting clock\n");
+ goto errout3;
+ }
+
+ 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, lpc32xx_adc_isr, 0, MOD_NAME, info);
+ if (retval< 0) {
+ dev_err(&pdev->dev, "failed requesting interrupt\n");
+ goto errout4;
+ }
+
+ platform_set_drvdata(pdev, iodev);
+
+ init_completion(&info->completion);
+
+ iodev->name = MOD_NAME;
+ iodev->dev.parent =&pdev->dev;
+ iodev->info =&lpc32xx_adc_iio_info;
+ iodev->modes = INDIO_DIRECT_MODE;
+ iodev->channels = lpc32xx_adc_iio_channels;
+ iodev->num_channels = ARRAY_SIZE(lpc32xx_adc_iio_channels);
+
+ retval = iio_device_register(iodev);
+ if (retval)
+ goto errout5;
+
+ dev_info(&pdev->dev, "LPC32XX ADC driver loaded, IRQ %d\n", irq);
+
+ return 0;
+
+errout5:
+ free_irq(irq, iodev);
+errout4:
+ clk_put(info->clk);
+errout3:
+ iounmap(info->adc_base);
+errout2:
+ iio_free_device(iodev);
+errout1:
+ return retval;
+}
+
+static int __devexit lpc32xx_adc_remove(struct platform_device *pdev)
+{
+ struct iio_dev *iodev = platform_get_drvdata(pdev);
+ struct lpc32xx_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);
+ iio_free_device(iodev);
+
+ dev_info(&pdev->dev, "LPC32XX ADC driver unloaded\n");
Personally I'd drop this sort of comment. Useful during development but
not really
anymore.
+
+ return 0;
+}
+
+static struct platform_driver lpc32xx_adc_driver = {
+ .probe = lpc32xx_adc_probe,
+ .remove = __devexit_p(lpc32xx_adc_remove),
+ .driver = {
+ .name = MOD_NAME,
+ .owner = THIS_MODULE,
+ },
+};
+
+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);
Nice macro introduced recently to cut out this boiler plate.
module_platform_driver (in platform_device.h)
+
+MODULE_AUTHOR("Roland Stigge<stigge@xxxxxxxxx>");
+MODULE_DESCRIPTION("LPC32XX ADC driver");
+MODULE_LICENSE("GPL");
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