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authorSascha Hauer <s.hauer@pengutronix.de>2012-01-31 10:19:50 +0100
committerSascha Hauer <s.hauer@pengutronix.de>2012-02-17 10:18:27 +0100
commitf917e6f866e6b0304a9f4e64980c27fb85271a40 (patch)
treeaf91238075be4467346b9e6db8032beb23d095ba /drivers/pwm
parentc20952a62135d791a1a070aeedeee712a3bf017e (diff)
downloadbarebox-f917e6f866e6b0304a9f4e64980c27fb85271a40.tar.gz
barebox-f917e6f866e6b0304a9f4e64980c27fb85271a40.tar.xz
Add pwm core support
This patch adds framework support for PWM (pulse width modulation) devices. A new pwm can be registered from a hardware driver using pwmchip_add(). It can then be requested from a client driver using pwm_request(). A string is used as a unique identifier for the pwms. It should usually be initialized by the hardware drivers using dev_name(dev). The client API is the same as currently in the Linux Kernel. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'drivers/pwm')
-rw-r--r--drivers/pwm/Kconfig12
-rw-r--r--drivers/pwm/Makefile1
-rw-r--r--drivers/pwm/core.c163
3 files changed, 176 insertions, 0 deletions
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
new file mode 100644
index 0000000000..93c1052291
--- /dev/null
+++ b/drivers/pwm/Kconfig
@@ -0,0 +1,12 @@
+menuconfig PWM
+ bool "PWM Support"
+ help
+ This enables PWM support through the generic PWM framework.
+ You only need to enable this, if you also want to enable
+ one or more of the PWM drivers below.
+
+ If unsure, say N.
+
+if PWM
+
+endif
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
new file mode 100644
index 0000000000..3469c3d28b
--- /dev/null
+++ b/drivers/pwm/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_PWM) += core.o
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
new file mode 100644
index 0000000000..af30edfd32
--- /dev/null
+++ b/drivers/pwm/core.c
@@ -0,0 +1,163 @@
+/*
+ * Generic pwmlib implementation
+ *
+ * Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.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, 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; see the file COPYING. If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <common.h>
+#include <errno.h>
+#include <malloc.h>
+#include <pwm.h>
+#include <linux/list.h>
+
+struct pwm_device {
+ struct pwm_chip *chip;
+ unsigned long flags;
+#define FLAG_REQUESTED 0
+#define FLAG_ENABLED 1
+ struct list_head node;
+};
+
+static LIST_HEAD(pwm_list);
+
+static struct pwm_device *_find_pwm(const char *devname)
+{
+ struct pwm_device *pwm;
+
+ list_for_each_entry(pwm, &pwm_list, node) {
+ if (!strcmp(pwm->chip->devname, devname))
+ return pwm;
+ }
+
+ return NULL;
+}
+
+/**
+ * pwmchip_add() - register a new pwm
+ * @chip: the pwm
+ *
+ * register a new pwm. pwm->devname must be initialized, usually
+ * from dev_name(dev) from the hardware driver.
+ */
+int pwmchip_add(struct pwm_chip *chip)
+{
+ struct pwm_device *pwm;
+ int ret = 0;
+
+ if (_find_pwm(chip->devname))
+ return -EBUSY;
+
+ pwm = xzalloc(sizeof(*pwm));
+ pwm->chip = chip;
+
+ list_add_tail(&pwm->node, &pwm_list);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(pwmchip_add);
+
+/**
+ * pwmchip_remove() - remove a pwm
+ * @chip: the pwm
+ *
+ * remove a pwm. This function may return busy if the pwm is still requested.
+ */
+int pwmchip_remove(struct pwm_chip *chip)
+{
+ struct pwm_device *pwm;
+
+ pwm = _find_pwm(chip->devname);
+ if (!pwm)
+ return -ENOENT;
+
+ if (test_bit(FLAG_REQUESTED, &pwm->flags))
+ return -EBUSY;
+
+ list_del(&pwm->node);
+
+ kfree(pwm);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pwmchip_remove);
+
+/*
+ * pwm_request - request a PWM device
+ */
+struct pwm_device *pwm_request(const char *devname)
+{
+ struct pwm_device *pwm;
+ int ret;
+
+ pwm = _find_pwm(devname);
+ if (!pwm)
+ return NULL;
+
+ if (test_bit(FLAG_REQUESTED, &pwm->flags))
+ return NULL;
+
+ if (pwm->chip->ops->request) {
+ ret = pwm->chip->ops->request(pwm->chip);
+ if (ret)
+ return NULL;
+ }
+
+ set_bit(FLAG_REQUESTED, &pwm->flags);
+
+ return pwm;
+}
+EXPORT_SYMBOL_GPL(pwm_request);
+
+/*
+ * pwm_free - free a PWM device
+ */
+void pwm_free(struct pwm_device *pwm)
+{
+ if (!test_and_clear_bit(FLAG_REQUESTED, &pwm->flags))
+ return;
+}
+EXPORT_SYMBOL_GPL(pwm_free);
+
+/*
+ * pwm_config - change a PWM device configuration
+ */
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+ return pwm->chip->ops->config(pwm->chip, duty_ns, period_ns);
+}
+EXPORT_SYMBOL_GPL(pwm_config);
+
+/*
+ * pwm_enable - start a PWM output toggling
+ */
+int pwm_enable(struct pwm_device *pwm)
+{
+ if (!test_and_set_bit(FLAG_ENABLED, &pwm->flags))
+ return pwm->chip->ops->enable(pwm->chip);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pwm_enable);
+
+/*
+ * pwm_disable - stop a PWM output toggling
+ */
+void pwm_disable(struct pwm_device *pwm)
+{
+ if (test_and_clear_bit(FLAG_ENABLED, &pwm->flags))
+ pwm->chip->ops->disable(pwm->chip);
+}
+EXPORT_SYMBOL_GPL(pwm_disable);