diff options
author | Stefan Roese <sr@denx.de> | 2012-04-12 09:05:35 (GMT) |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-04-13 18:18:23 (GMT) |
commit | b3201b563d36eb799d3f9e14871d5dda2b11f3e8 (patch) | |
tree | ed564c4124d4be56e44a8e98b987c38d2fec3bea /drivers | |
parent | 6d59ba2f9676210b4631e9c447ab1c9faf0a9577 (diff) | |
download | linux-b3201b563d36eb799d3f9e14871d5dda2b11f3e8.tar.xz |
staging:iio:adc: Add SPEAr ADC driver
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. Resulting in a multi-arch binary.
This driver is currently tested only on SPEAr600. Future patches may add
support for other SoC variants (SPEAr3xx) and features like software
buffer or DMA.
Signed-off-by: Stefan Roese <sr@denx.de>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@st.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/staging/iio/adc/Kconfig | 7 | ||||
-rw-r--r-- | drivers/staging/iio/adc/Makefile | 1 | ||||
-rw-r--r-- | drivers/staging/iio/adc/spear_adc.c | 447 |
3 files changed, 455 insertions, 0 deletions
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..bea5778 --- /dev/null +++ b/drivers/staging/iio/adc/spear_adc.c @@ -0,0 +1,447 @@ +/* + * ST SPEAr ADC driver + * + * Copyright 2012 Stefan Roese <sr@denx.de> + * + * 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 <linux/of_address.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 + +#define CLK_MIN 2500000 +#define CLK_MAX 20000000 + +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 __iomem *adc_base_spear3xx; + struct adc_regs_spear6xx __iomem *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_mv; + 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_mv = (info->vref_external * 1000) >> DATA_BITS; + *val = scale_mv / 1000; + *val2 = (scale_mv % 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, \ + .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; + 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); + + 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 device *dev = &pdev->dev; + struct spear_adc_info *info; + struct iio_dev *iodev = NULL; + int ret = -ENODEV; + int irq; + + iodev = iio_allocate_device(sizeof(struct spear_adc_info)); + if (!iodev) { + dev_err(dev, "failed allocating iio device\n"); + ret = -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 = of_iomap(np, 0); + if (!info->adc_base_spear6xx) { + dev_err(dev, "failed mapping memory\n"); + ret = -ENOMEM; + goto errout2; + } + info->adc_base_spear3xx = + (struct adc_regs_spear3xx *)info->adc_base_spear6xx; + + info->clk = clk_get(dev, NULL); + if (IS_ERR(info->clk)) { + dev_err(dev, "failed getting clock\n"); + goto errout3; + } + + ret = clk_prepare(info->clk); + if (ret) { + dev_err(dev, "failed preparing clock\n"); + goto errout4; + } + + ret = clk_enable(info->clk); + if (ret) { + dev_err(dev, "failed enabling clock\n"); + goto errout5; + } + + irq = platform_get_irq(pdev, 0); + if ((irq < 0) || (irq >= NR_IRQS)) { + dev_err(dev, "failed getting interrupt resource\n"); + ret = -EINVAL; + goto errout6; + } + + ret = devm_request_irq(dev, irq, spear_adc_isr, 0, MOD_NAME, info); + if (ret < 0) { + dev_err(dev, "failed requesting interrupt\n"); + goto errout6; + } + + if (of_property_read_u32(np, "sampling-frequency", + &info->sampling_freq)) { + dev_err(dev, "sampling-frequency missing in DT\n"); + ret = -EINVAL; + goto errout6; + } + + /* + * 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 = 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); + + ret = iio_device_register(iodev); + if (ret) + goto errout6; + + dev_info(dev, "SPEAR ADC driver loaded, IRQ %d\n", irq); + + return 0; + +errout6: + clk_disable(info->clk); +errout5: + clk_unprepare(info->clk); +errout4: + clk_put(info->clk); +errout3: + iounmap(info->adc_base_spear6xx); +errout2: + iio_free_device(iodev); +errout1: + return ret; +} + +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); + + iio_device_unregister(iodev); + platform_set_drvdata(pdev, NULL); + clk_disable(info->clk); + clk_unprepare(info->clk); + 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@denx.de>"); +MODULE_DESCRIPTION("SPEAr ADC driver"); +MODULE_LICENSE("GPL"); |