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Subject[PATCH 05/10] iio: trigger: at91-rtc-trigger: introduce at91 rtc adc trigger driver
Date
From: Eugen Hristev <eugen.hristev@microchip.com>

The AT91 RTC ADC trigger driver registers a trigger into the iio subsystem,
which can be associated with at91_sama5d2-adc compatible drivers.
The SAMA5D2 SoC contains a hardware link between the RTC block and the ADC
block that will allow the RTC to trigger the ADC to perform conversions.
The at91-rtc-trigger will allow the customisation of the trigger frequency
from sysfs:
trigger_frequency_hz_available will display possible frequencies in Hz
trigger_frequency_hz will allow configuring this frequency.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
drivers/iio/trigger/Kconfig | 10 ++
drivers/iio/trigger/Makefile | 1 +
drivers/iio/trigger/at91-rtc-trigger.c | 213 +++++++++++++++++++++++++++++++++
3 files changed, 224 insertions(+)
create mode 100644 drivers/iio/trigger/at91-rtc-trigger.c

diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
index 8cef2f7..dc7e6f4 100644
--- a/drivers/iio/trigger/Kconfig
+++ b/drivers/iio/trigger/Kconfig
@@ -68,4 +68,14 @@ config IIO_SYSFS_TRIGGER
To compile this driver as a module, choose M here: the
module will be called iio-trig-sysfs.

+config IIO_AT91_RTC_TRIGGER
+ tristate "AT91 RTC trigger"
+ help
+ Provides support for using AT91 RTC IP block to generate trigger
+ events for ADC devices.
+ If unsure, say N (but it's safe to say "Y").
+
+ To compile this driver as a module, choose M here: the
+ module will be called at91-rtc-trigger.
+
endmenu
diff --git a/drivers/iio/trigger/Makefile b/drivers/iio/trigger/Makefile
index f3d11ac..6512436 100644
--- a/drivers/iio/trigger/Makefile
+++ b/drivers/iio/trigger/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_IIO_STM32_LPTIMER_TRIGGER) += stm32-lptimer-trigger.o
obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
obj-$(CONFIG_IIO_SYSFS_TRIGGER) += iio-trig-sysfs.o
obj-$(CONFIG_IIO_TIGHTLOOP_TRIGGER) += iio-trig-loop.o
+obj-$(CONFIG_IIO_AT91_RTC_TRIGGER) += at91-rtc-trigger.o
diff --git a/drivers/iio/trigger/at91-rtc-trigger.c b/drivers/iio/trigger/at91-rtc-trigger.c
new file mode 100644
index 0000000..8cdcfeb
--- /dev/null
+++ b/drivers/iio/trigger/at91-rtc-trigger.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2019 Microchip Technology, Inc. and its subsidiaries
+ *
+ * Author: Eugen Hristev <eugen.hristev@microchip.com>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/irq_work.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+
+#define at91_adc_readl(t, reg) readl_relaxed((t)->base + (reg))
+#define at91_adc_writel(t, reg, val) writel_relaxed(val, (t)->base + (reg))
+
+#define AT91_RTC_MR 0x4
+#define AT91_RTC_OUT0_MASK GENMASK(18, 16)
+#define AT91_RTC_OUT0_NO_WAVE (0x0 << 16)
+#define AT91_RTC_OUT0_1HZ (0x1 << 16)
+#define AT91_RTC_OUT0_32HZ (0x2 << 16)
+#define AT91_RTC_OUT0_64HZ (0x3 << 16)
+#define AT91_RTC_OUT0_512HZ (0x4 << 16)
+
+/* attribute pack list */
+#define AT91_RTC_1HZ 1
+#define AT91_RTC_32HZ 32
+#define AT91_RTC_64HZ 64
+#define AT91_RTC_512HZ 512
+
+struct at91_rtc_adc_trig {
+ struct iio_trigger *trig;
+ void __iomem *base;
+ unsigned int hz_config;
+};
+
+static int at91_hz_config_sysfs_to_reg(unsigned int hz_config)
+{
+ switch (hz_config) {
+ case AT91_RTC_1HZ:
+ return AT91_RTC_OUT0_1HZ;
+ case AT91_RTC_32HZ:
+ return AT91_RTC_OUT0_32HZ;
+ case AT91_RTC_64HZ:
+ return AT91_RTC_OUT0_64HZ;
+ case AT91_RTC_512HZ:
+ return AT91_RTC_OUT0_512HZ;
+ }
+ return AT91_RTC_OUT0_1HZ;
+}
+
+static int at91_configure_trigger(struct iio_trigger *trig, bool state)
+{
+ struct at91_rtc_adc_trig *t = iio_trigger_get_drvdata(trig);
+ u32 mr = at91_adc_readl(t, AT91_RTC_MR);
+
+ mr &= ~AT91_RTC_OUT0_MASK;
+
+ if (state)
+ mr |= at91_hz_config_sysfs_to_reg(t->hz_config);
+
+ at91_adc_writel(t, AT91_RTC_MR, mr);
+
+ return 0;
+}
+
+static const struct iio_trigger_ops at91_rtc_adc_trigger_ops = {
+ .set_trigger_state = &at91_configure_trigger,
+};
+
+static ssize_t at91_rtc_trigger_frequency_get(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct iio_trigger *trig = to_iio_trigger(dev);
+ struct at91_rtc_adc_trig *t = iio_trigger_get_drvdata(trig);
+
+ return scnprintf(buf, PAGE_SIZE, "%u\n", t->hz_config);
+}
+
+static ssize_t at91_rtc_trigger_frequency_set(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct iio_trigger *trig = to_iio_trigger(dev);
+ struct at91_rtc_adc_trig *t = iio_trigger_get_drvdata(trig);
+ int ret;
+ unsigned int val;
+
+ ret = kstrtou32(buf, 10, &val);
+
+ if (ret)
+ return ret;
+
+ if (val != AT91_RTC_1HZ && val != AT91_RTC_32HZ &&
+ val != AT91_RTC_64HZ && val != AT91_RTC_512HZ)
+ return -EINVAL;
+
+ t->hz_config = val;
+
+ return count;
+}
+
+static IIO_DEVICE_ATTR(trigger_frequency_hz, 0644,
+ at91_rtc_trigger_frequency_get,
+ at91_rtc_trigger_frequency_set, 0);
+
+static IIO_CONST_ATTR(trigger_frequency_hz_available,
+ __stringify(AT91_RTC_1HZ) " "
+ __stringify(AT91_RTC_32HZ) " "
+ __stringify(AT91_RTC_64HZ) " "
+ __stringify(AT91_RTC_512HZ));
+
+static struct attribute *at91_rtc_adc_trigger_attributes[] = {
+ &iio_const_attr_trigger_frequency_hz_available.dev_attr.attr,
+ &iio_dev_attr_trigger_frequency_hz.dev_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group at91_rtc_adc_trigger_attribute_group = {
+ .attrs = at91_rtc_adc_trigger_attributes,
+};
+
+static const struct attribute_group *at91_rtc_adc_trigger_attr_groups[] = {
+ &at91_rtc_adc_trigger_attribute_group,
+ NULL
+};
+
+static void at91_rtc_adc_trigger_remove(void *priv)
+{
+ struct at91_rtc_adc_trig *t = priv;
+
+ iio_trigger_unregister(t->trig);
+ iio_trigger_free(t->trig);
+}
+
+static int at91_rtc_adc_trigger_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct resource *res;
+ struct at91_rtc_adc_trig *t;
+ int ret = 0;
+
+ t = devm_kzalloc(dev, sizeof(*t), GFP_KERNEL);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -EINVAL;
+
+ t->base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(t->base))
+ return PTR_ERR(t->base);
+
+ t->trig = iio_trigger_alloc("%x.at91_rtc_adc", res->start);
+ if (!t->trig) {
+ ret = -ENOMEM;
+ return ret;
+ }
+
+ t->hz_config = AT91_RTC_1HZ;
+
+ t->trig->ops = &at91_rtc_adc_trigger_ops;
+ t->trig->dev.parent = dev;
+ t->trig->dev.groups = at91_rtc_adc_trigger_attr_groups;
+
+ iio_trigger_set_drvdata(t->trig, t);
+
+ ret = iio_trigger_register(t->trig);
+ if (ret) {
+ dev_err(dev, "failed to register trigger.\n");
+ goto at91_rtc_adc_trigger_probe_fail_register;
+ }
+
+ ret = devm_add_action_or_reset(dev, at91_rtc_adc_trigger_remove, t);
+ if (ret) {
+ dev_err(dev, "failed to add disable action.\n");
+ goto at91_rtc_adc_trigger_probe_fail_add_action;
+ }
+
+ return 0;
+
+at91_rtc_adc_trigger_probe_fail_add_action:
+ iio_trigger_unregister(t->trig);
+at91_rtc_adc_trigger_probe_fail_register:
+ iio_trigger_free(t->trig);
+ return ret;
+}
+
+static const struct of_device_id at91_rtc_adc_trigger_of_match[] = {
+ {
+ .compatible = "microchip,rtc-adc-trigger",
+ },
+ { /* end node */ },
+};
+MODULE_DEVICE_TABLE(of, at91_rtc_adc_trigger_of_match);
+
+static struct platform_driver at91_rtc_adc_trigger_driver = {
+ .probe = at91_rtc_adc_trigger_probe,
+ .driver = {
+ .name = "at91-rtc-adc-trigger",
+ .of_match_table = at91_rtc_adc_trigger_of_match,
+ },
+};
+module_platform_driver(at91_rtc_adc_trigger_driver);
+
+MODULE_AUTHOR("Eugen Hristev <eugen.hristev@microchip.com>");
+MODULE_DESCRIPTION("AT91 RTC ADC trigger driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:iio-at91-rtc-trigger");
--
2.7.4
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