The existing pwm based led and backlight driver makes use of the
pwm(include/linux/pwm.h). So all the board specific pwm drivers will
be exposing the same set of function name as in include/linux/pwm.h.
Consder a platform with multi Soc or having more than one pwm module, in
such a case, there exists more than one pwm driver for a platform. Each
of these pwm drivers export the same set of function and hence leads to
re-declaration build error.
In order to overcome this issue all the pwm drivers must register to
some core pwm driver with function pointers for pwm operations (i.e
pwm_config, pwm_enable, pwm_disable).
The clients of pwm device will have to call pwm_request, wherein
they will get the pointer to struct pwm_ops. This structure include
function pointers for pwm_config, pwm_enable and pwm_disable.
Signed-off-by: Arun Murthy <arun.murthy@xxxxxxxxxxxxxx>
Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx>
---
drivers/Kconfig | 2 +
drivers/Makefile | 1 +
drivers/pwm/Kconfig | 18 +++++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-core.c | 171 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/pwm.h | 12 +++-
6 files changed, 204 insertions(+), 1 deletions(-)
create mode 100644 drivers/pwm/Kconfig
create mode 100644 drivers/pwm/Makefile
create mode 100644 drivers/pwm/pwm-core.c
diff --git a/drivers/Kconfig b/drivers/Kconfig
index a2b902f..e042f27 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -111,4 +111,6 @@ source "drivers/xen/Kconfig"
source "drivers/staging/Kconfig"
source "drivers/platform/Kconfig"
+
+source "drivers/pwm/Kconfig"
endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index 443c4eb..1aec04e 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -116,3 +116,4 @@ obj-$(CONFIG_STAGING) += staging/
obj-y += platform/
obj-y += ieee802154/
obj-y += vbus/
+obj-$(CONFIG_PWM_DEVICES) += pwm/
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
new file mode 100644
index 0000000..03a9813
--- /dev/null
+++ b/drivers/pwm/Kconfig
@@ -0,0 +1,18 @@
+#
+# PWM devices
+#
+
+menuconfig PWM_DEVICES
+ bool "PWM devices"
+ default y
+ ---help---
+ Say Y to enable pwm core driver and see options for various pwm
+ drivers. This option enables pwm drivers to register with the
+ pwm core driver and thereby provide a single interface to the
+ clients using PWM.
+
+ If you say N, all options in this submenu will be skipped and disabled.
+
+if PWM_DEVICES
+
+endif # PWM_DEVICES
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
new file mode 100644
index 0000000..552f969
--- /dev/null
+++ b/drivers/pwm/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_PWM_DEVICES) += pwm-core.o
diff --git a/drivers/pwm/pwm-core.c b/drivers/pwm/pwm-core.c
new file mode 100644
index 0000000..c323969
--- /dev/null
+++ b/drivers/pwm/pwm-core.c
@@ -0,0 +1,171 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Arun R Murthy <arun.murthy@xxxxxxxxxxxxxx>
+ */
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/rwsem.h>
+#include <linux/err.h>
+#include <linux/pwm.h>
+
+struct pwm_device {
+ struct pwm_ops *pops;
+ struct device *dev;
+ int pwm_id;
+ const char *name;
+};
+
+static struct class *pwm_class;
+
+/*
+ * TODO: This function is referenced in pwm based led and backlight driver.
+ * This function is no more required with the implementation of pwm core
+ * driver. This is retained as deprecated to make sure that the mips
+ * jz4740 pwm driver works fine as that is not aligned with this pwm core
+ * driver. On aligning the same this has to be removed.
+ */
+void __deprecated pwm_free(struct pwm_device *pwm)
+{
+}
+
+/**
+ * pwm_config() - configure the pwm device
+ * @pwm: pointer to the struct pwm_device
+ * @period_ns: period in nano seconds
+ *
+ * This function verifies for the presence of the pops structure and if so
+ * calls the pwm device specific config fucntion.
+ */
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
+{
+ if (!pwm->pops)
+ return -EFAULT;
+ return pwm->pops->pwm_config(pwm, duty_ns, period_ns);
+}
+EXPORT_SYMBOL(pwm_config);
+
+/**
+ * pwm_enable() - enable pwm device
+ * @pwm: pointer to the struct pwm_device
+ *
+ * This function verifies for the presence of the pops structure and if so
+ * calls the pwm device specific enable function.
+ */
+int pwm_enable(struct pwm_device *pwm)
+{
+ if (!pwm->pops)
+ return -EFAULT;
+ return pwm->pops->pwm_enable(pwm);
+}
+EXPORT_SYMBOL(pwm_enable);
+
+/**
+ * pwm_disable() - disable pwm device
+ * @pwm: pointer to the struct pwm_device
+ *
+ * This function verifies for the presence of the pops structure and if so
+ * calls the pwm device specific disable function.
+ */
+void pwm_disable(struct pwm_device *pwm)
+{
+ if (!pwm->pops)
+ return -EFAULT;
+ pwm->pops->pwm_disable(pwm);
+}
+EXPORT_SYMBOL(pwm_disable);
+
+static int pwm_match_device_by_pwm_id(struct device *dev, void *data)
+{
+ int *pwm_id = data;
+ struct pwm_device *pwm = dev_get_drvdata(dev);
+ const char *name = pwm->name;
+
+ return (strcmp(name, pwm->name) == 0 && pwm->pwm_id == *pwm_id);
+}
+
+static int pwm_match_device_by_name(struct device *dev, void *data)
+{
+ const char *name = data;
+ struct pwm_device *pwm = dev_get_drvdata(dev);
+
+ return strcmp(pwm->name, name) == 0;
+}
+
+/**
+ * pwm_request() - request for a pwm device
+ * @pwm_id: pwm device id
+ * @name: pwm device name
+ *
+ * This function searches for the pwm device with the specified name in the
+ * list of pre registered pwm devices and return the pointer to the struct
+ * pwm_device. Clients using pwm device will first have to call this function
+ * to get the pointer to the pwm_device. This pointer to struct pwm_device
+ * will be further be used in all operation(pwm_enable/disable/config).
+ */
+struct pwm_device *pwm_request(int pwm_id, const char *name)
+{
+ struct device *dev = class_find_device(pwm_class, NULL, name,
+ pwm_match_device_by_name);
+ dev = class_find_device(pwm_class, dev, pwm_id,
+ pwm_match_device_by_pwm_id);
+
+ return dev ? dev_get_drvdata(dev) : NULL;
+}
+EXPORT_SYMBOL(pwm_request);
+
+/**
+ * pwm_device_register() - registers pwm driver with the pwm core driver
+ * @parent: pointer to the parent's device struct
+ * @pwm: pointer to the struct pwm_device
+ *
+ * This function registers the pwm device with the pwm core driver, thereby
+ * proposing a single interface exposure to the clients using the pwm device.
+ */
+int pwm_device_register(struct device *parent, struct pwm_device *pwm)
+{
+ pwm->dev = device_create(pwm_class, parent, 0, pwm, "%s", pwm->name);
+ if (IS_ERR(pwm->dev))
+ return PTR_ERR(pwm->dev);
+
+ return 0;
+}
+EXPORT_SYMBOL(pwm_device_register);
+
+/**
+ * pwm_device_unregister() - unregisters the pre registered pwm device
+ * @pwm: pointer to the struct pwm_device
+ *
+ * This function unregisters the pwm device from the pwm core driver. Clients
+ * can no more use this pwm device.
+ */
+int pwm_device_unregister(struct pwm_device *pwm)
+{
+ device_unregister(pwm->dev);
+ return 0;
+}
+EXPORT_SYMBOL(pwm_device_unregister);
+
+static int __init pwm_init(void)
+{
+ pwm_class = class_create(THIS_MODULE, "pwm_core");
+ if (IS_ERR(pwm_class))
+ return PTR_ERR(pwm_class);
+
+ return 0;
+}
+subsys_initcall(pwm_init);
+
+static void __exit pwm_exit(void)
+{
+ class_destroy(pwm_class);
+}
+
+module_exit(pwm_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Arun R Murthy");
+MODULE_ALIAS("core:pwm");
+MODULE_DESCRIPTION("Core pwm driver");
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index 7c77575..c41e0da 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -3,6 +3,13 @@
struct pwm_device;
+struct pwm_ops {
+ int (*pwm_config)(struct pwm_device *pwm, int duty_ns, int period_ns);
+ int (*pwm_enable)(struct pwm_device *pwm);
+ int (*pwm_disable)(struct pwm_device *pwm);
+ char *name;
+};
+
/*
* pwm_request - request a PWM device
*/
@@ -11,7 +18,7 @@ struct pwm_device *pwm_request(int pwm_id, const char *label);
/*
* pwm_free - free a PWM device
*/
-void pwm_free(struct pwm_device *pwm);
+void __deprecated pwm_free(struct pwm_device *pwm);
/*
* pwm_config - change a PWM device configuration
@@ -28,4 +35,7 @@ int pwm_enable(struct pwm_device *pwm);
*/
void pwm_disable(struct pwm_device *pwm);
+int pwm_device_register(struct device *parent, struct pwm_device *pwm);
+int pwm_device_unregister(struct pwm_device *pwm);
+
#endif /* __LINUX_PWM_H */
--
1.7.2.dirty
