Add PWM framework and device tree support

This patch series adds very rudimentary device-tree support for PWM devices. With all of these patches applied (plus one board-specific patch that is not included), I'm able to control the backlight on the device I'm working on using the sysfs interface provided by the pwm-bl driver and the backlight class.

This series is based on Sascha Hauer's series of patches[0] to add a generic PWM framework. The first patch in this series is taken from Sascha's branch, while the second patch enables each PWM chip to provide multiple PWM devices (the Blackfin and PXA drivers have been ported to the framework for reference). Currently a global namespace is still provided to keep backwards-compatibility with the legacy PWM API. In order to achieve this, the number of global PWM devices is limited to 1024. However, patch 2 introduces per-chip indexing of PWM devices in the core and patch 4 adds an API to request a PWM device using a lookup table registered by board setup code. They are supposed to eventually replace pwm_request() and allow to get rid of the global namespace. The device tree support code does not use the global namespace.

Patch 3 adds a debugfs interface.

Patch 5 adds some code to lookup a PWM chip given its device-tree handle. This code will be used later on by the pwm-bl driver to find the PWM device that it should be using. If the no corresponding PWM chip is available yet, the code returns EPROBE_DEFER to have users automatically probed again later when the PWM provider may have become available. Device tree binding documentation is also provided.

Patch 6 was taken from the Chromium tree and is required to provide proper clocking of the Tegra2 PWFM controller. All Chromium-specific tags have been removed from the commit message. Some cleanup of the clock registration for Tegra is done in patch 7 because a subsequent patch will instantiate one PWFM controller device instead of four.

Patch 8 adds a generic PWM framework driver for the Tegra2 PWFM controller. The code is taken from the Chromium tree with some adjustments to integrate it with the PWM framework. Device tree based probing of the driver is implemented in patch 9.

Patches 10 and 11 are ports of the Blackfin PWM and the PXA PWM drivers to the PWM framework. These are only compile-tested as I do not have any hardware to test them on.

Patches 12, 13 and 14 move the i.MX, Samsung and VT8500 drivers over to the framework. These are originally by Sascha Hauer and were updated to take advantage of the multiple PWM devices per chip feature. Patch 15 adds support for Freescale MXS by Shawn Guo.

Patch 16 implements DT-based probing in the pwm-backlight driver. Note that this code only handles the "pwms" property (by looking up the PWM device via the new PWM DT binding). Switching power to the backlight via GPIOs is not supported yet. The DT binding also deviates from the platform data in that it requires a list of brightness levels to be specified instead of assuming a linearily spaced range from 0 to a given maximum brightness.

Finally, patch 17 makes me the new maintainer of the PWM subsystem.

The whole series is based on the linux-next tree from 20120405. I think I've addressed all of the concerns raised in the first five versions. I have also pushed this version of the series to the PWM subsystem repository[1].

Thierry

[0]: http://git.pengutronix.de/?p=imx/linux-2.6.git;a=shortlog;h=refs/heads/pwmlib
[1]: http://gitorious.org/linux-pwm/linux-pwm/trees/pwm-v6

Sascha Hauer (4):
pwm: Add PWM framework support
ARM i.MX: Move i.MX pwm driver to pwm framework ARM Samsung: Move s3c pwm driver to pwm framework ARM vt8500: Move vt8500 pwm driver to pwm framework

Shawn Guo (1):
pwm: add pwm-mxs support

Simon Que (1):
ARM: tegra: Fix PWM clock programming

Thierry Reding (11):
pwm: Allow chips to support multiple PWMs
pwm: Add debugfs interface
pwm: Add table-based lookup for static mappings
pwm: Add device tree support
ARM: tegra: Provide clock for only one PWM controller
pwm: Add NVIDIA Tegra SoC support
pwm: tegra: Add device tree support
pwm: Move Blackfin PWM driver to PWM framework
pwm: Move PXA PWM driver to PWM framework
pwm-backlight: Add rudimentary device tree support
pwm: Take over maintainership of the PWM subsystem

 Documentation/devicetree/bindings/pwm/mxs-pwm.txt  |   17 +
 .../devicetree/bindings/pwm/nvidia,tegra20-pwm.txt |   18 +
 Documentation/devicetree/bindings/pwm/pwm.txt      |   57 ++
 .../bindings/video/backlight/pwm-backlight         |   28 +
 Documentation/pwm.txt                              |   76 +++
 MAINTAINERS                                        |   12 +
 arch/arm/boot/dts/tegra20.dtsi                     |    6 +
 arch/arm/boot/dts/tegra30.dtsi                     |    6 +
 arch/arm/mach-tegra/board-dt-tegra20.c             |    1 +
 arch/arm/mach-tegra/board-dt-tegra30.c             |    3 +
 arch/arm/mach-tegra/tegra2_clocks.c                |   36 +-
 arch/arm/mach-tegra/tegra30_clocks.c               |    6 +-
 arch/arm/mach-vt8500/Makefile                      |    2 -
 arch/arm/plat-mxc/Kconfig                          |    6 -
 arch/arm/plat-mxc/Makefile                         |    1 -
 arch/arm/plat-pxa/Makefile                         |    1 -
 arch/arm/plat-samsung/Makefile                     |    4 -
 arch/blackfin/Kconfig                              |   10 -
 arch/blackfin/kernel/Makefile                      |    1 -
 drivers/Kconfig                                    |    2 +
 drivers/Makefile                                   |    1 +
 drivers/pwm/Kconfig                                |   76 +++
 drivers/pwm/Makefile                               |    8 +
 drivers/pwm/core.c                                 |  712 ++++++++++++++++++++
 .../kernel/pwm.c => drivers/pwm/pwm-bfin.c         |  138 +++-
 arch/arm/plat-mxc/pwm.c => drivers/pwm/pwm-imx.c   |  182 ++---
 drivers/pwm/pwm-mxs.c                              |  207 ++++++
 arch/arm/plat-pxa/pwm.c => drivers/pwm/pwm-pxa.c   |  172 ++---
 .../pwm.c => drivers/pwm/pwm-samsung.c             |  228 +++----
 drivers/pwm/pwm-tegra.c                            |  265 ++++++++
 .../mach-vt8500/pwm.c => drivers/pwm/pwm-vt8500.c  |  169 ++---
 drivers/video/backlight/Kconfig                    |    2 +-
 drivers/video/backlight/pwm_bl.c                   |  149 +++-
 include/linux/pwm.h                                |  117 ++++
 include/linux/pwm_backlight.h                      |    1 +
 35 files changed, 2145 insertions(+), 575 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/pwm/mxs-pwm.txt
 create mode 100644 Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt
 create mode 100644 Documentation/devicetree/bindings/pwm/pwm.txt
 create mode 100644 Documentation/devicetree/bindings/video/backlight/pwm-backlight
 create mode 100644 Documentation/pwm.txt
 create mode 100644 drivers/pwm/Kconfig
 create mode 100644 drivers/pwm/Makefile
 create mode 100644 drivers/pwm/core.c
 rename arch/blackfin/kernel/pwm.c => drivers/pwm/pwm-bfin.c (26%)
 rename arch/arm/plat-mxc/pwm.c => drivers/pwm/pwm-imx.c (58%)
 create mode 100644 drivers/pwm/pwm-mxs.c
 rename arch/arm/plat-pxa/pwm.c => drivers/pwm/pwm-pxa.c (57%)
 rename arch/arm/plat-samsung/pwm.c => drivers/pwm/pwm-samsung.c (58%)
 create mode 100644 drivers/pwm/pwm-tegra.c
 rename arch/arm/mach-vt8500/pwm.c => drivers/pwm/pwm-vt8500.c (52%)

1.7.9.6

From: Sascha Hauer <[email protected]>

This patch adds framework support for PWM (pulse width modulation) devices.

The is a barebone PWM API already in the kernel under include/linux/pwm.h, but it does not allow for multiple drivers as each of them implements the pwm_*() functions.

There are other PWM framework patches around from Bill Gatliff. Unlike his framework this one does not change the existing API for PWMs so that this framework can act as a drop in replacement for the existing API.

Why another framework?

Several people argue that there should not be another framework for PWMs but they should be integrated into one of the existing frameworks like led or hwmon. Unlike these frameworks the PWM framework is agnostic to the purpose of the PWM. In fact, a PWM can drive a LED, but this makes the LED framework a user of a PWM, like already done in leds-pwm.c. The gpio framework also is not suitable for PWMs. Every gpio could be turned into a PWM using timer based toggling, but on the other hand not every PWM hardware device can be turned into a gpio due to the lack of hardware capabilities.

This patch does not try to improve the PWM API yet, this could be done in subsequent patches.

---
Changes in v6:
- some editorial cleanups

Changes in v5:
- minor cleanups and typo fixes
- add some kerneldoc comments

 Documentation/pwm.txt |   54 ++++++++++++
 MAINTAINERS           |    6 ++
 drivers/Kconfig       |    2 +
 drivers/Makefile      |    1 +
 drivers/pwm/Kconfig   |   12 +++
 drivers/pwm/Makefile  |    1 +
 drivers/pwm/core.c    |  227 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pwm.h   |   38 +++++++++
 8 files changed, 341 insertions(+)
 create mode 100644 Documentation/pwm.txt
 create mode 100644 drivers/pwm/Kconfig
 create mode 100644 drivers/pwm/Makefile
 create mode 100644 drivers/pwm/core.c

new file mode 100644
index 0000000..03e39d1
@@ -0,0 +1,54 @@
+Pulse Width Modulation (PWM) interface
+
+This provides an overview about the Linux PWM interface
+
+PWMs are commonly used for controlling LEDs, fans or vibrators in
+cell phones. PWMs with a fixed purpose have no need implementing
+the Linux PWM API (although they could). However, PWMs are often
+found as discrete devices on SoCs which have no fixed purpose. It's
+up to the board designer to connect them to LEDs or fans. To provide
+this kind of flexibility the generic PWM API exists.
+
+Identifying PWMs
+----------------
+
+Users of the legacy PWM API use unique IDs to refer to PWM devices. One
+goal of the new PWM framework is to get rid of this global namespace.
+
+Using PWMs
+----------
+
+A PWM can be requested using pwm_request() and freed after usage with
+pwm_free(). After being requested a PWM has to be configured using
+
+int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns);
+
+To start/stop toggling the PWM output use pwm_enable()/pwm_disable().
+
+Implementing a PWM driver
+-------------------------
+
+Currently there are two ways to implement pwm drivers. Traditionally
+there only has been the barebone API meaning that each driver has
+to implement the pwm_*() functions itself. This means that it's impossible
+to have multiple PWM drivers in the system. For this reason it's mandatory
+for new drivers to use the generic PWM framework.
+A new PWM device can be added using pwmchip_add() and removed again with
+pwmchip_remove(). pwmchip_add() takes a filled in struct pwm_chip as
+argument which provides the ops and the pwm id to the framework.
+
+Locking
+-------
+
+The PWM core list manipulations are protected by a mutex, so pwm_request()
+and pwm_free() may not be called from an atomic context. Currently the
+PWM core does not enforce any locking to pwm_enable(), pwm_disable() and
+pwm_config(), so the calling context is currently driver specific. This
+is an issue derived from the former barebone API and should be fixed soon.
+
+Helpers
+-------
+
+Currently a PWM can only be configured with period_ns and duty_ns. For several
+use cases freq_hz and duty_percent might be better. Instead of calculating
+this in your driver please consider adding appropriate helpers to the framework.

index 6454433..275db57 100644
@@ -5420,6 +5420,12 @@ S:	Maintained
 F:	Documentation/video4linux/README.pvrusb2
 F:	drivers/media/video/pvrusb2/
 
+PWM core
+M:	Sascha Hauer <[email protected]>
+L:	linux-kernel at vger.kernel.org
+S:	Maintained
+F:	drivers/pwm/
+
 PXA2xx/PXA3xx SUPPORT
 M:	Eric Miao <[email protected]>
 M:	Russell King <[email protected]>

index b3ae9e5..ec094b5 100644
@@ -142,4 +142,6 @@ source "drivers/devfreq/Kconfig"
 
 source "drivers/modem_shm/Kconfig"
 
+source "drivers/pwm/Kconfig"
+
 endmenu

index 4855a1a..52fe956 100644
@@ -8,6 +8,7 @@
 # GPIO must come after pinctrl as gpios may need to mux pins etc
 obj-y				+= pinctrl/
 obj-y				+= gpio/
+obj-y				+= pwm/
 obj-$(CONFIG_PCI)		+= pci/
 obj-$(CONFIG_PARISC)		+= parisc/
 obj-$(CONFIG_RAPIDIO)		+= rapidio/

new file mode 100644
index 0000000..93c1052
@@ -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

new file mode 100644
index 0000000..3469c3d
@@ -0,0 +1 @@
+obj-$(CONFIG_PWM)		+= core.o

index 7c77575..1f308a1 100644
@@ -28,4 +28,42 @@ int pwm_enable(struct pwm_device *pwm);
  */
 void pwm_disable(struct pwm_device *pwm);
 
+#ifdef CONFIG_PWM
+struct pwm_chip;
+
+/**
+ * struct pwm_ops - PWM controller operations
+ * @request: optional hook for requesting a PWM
+ * @free: optional hook for freeing a PWM
+ * @config: configure duty cycles and period length for this PWM
+ * @enable: enable PWM output toggling
+ * @disable: disable PWM output toggling
+ * @owner: helps prevent removal of modules exporting active PWMs
+ */
+struct pwm_ops {
+	int			(*request)(struct pwm_chip *chip);
+	void			(*free)(struct pwm_chip *chip);
+	int			(*config)(struct pwm_chip *chip, int duty_ns,
+						int period_ns);
+	int			(*enable)(struct pwm_chip *chip);
+	void			(*disable)(struct pwm_chip *chip);
+	struct module		*owner;
+};
+
+/**
+ * struct pwm_chip - abstract a PWM
+ * @pwm_id: global PWM device index
+ * @label: PWM device label
+ * @ops: controller operations
+ */
+struct pwm_chip {
+	int			pwm_id;
+	const char		*label;
+	struct pwm_ops		*ops;
+};
+
+int pwmchip_add(struct pwm_chip *chip);
+int pwmchip_remove(struct pwm_chip *chip);
+#endif
+
 #endif /* __LINUX_PWM_H */

1.7.9.6

Many PWM controllers provide access to more than a single PWM output and may even share some resource among them. Allowing a PWM chip to provide multiple PWM devices enables better sharing of those resources. As a side-effect this change allows easy integration with the device tree where a given PWM can be looked up based on the PWM chip's phandle and a corresponding index.

This commit modifies the PWM core to support multiple PWMs per struct pwm_chip. It achieves this in a similar way to how gpiolib works, by allowing PWM ranges to be requested dynamically (pwm_chip.base == -1) or starting at a given offset (pwm_chip.base >= 0). A chip specifies how many PWMs it controls using the npwm member. Each of the functions in the pwm_ops structure gets an additional argument that specified the PWM number (it can be converted to a per-chip index by subtracting the chip's base).

The total maximum number of PWM devices is currently fixed to 1024 while the data is actually stored in a radix tree, thus saving resources if not all of them are used.

---
Changes in v5:
- add sanity checks to pwmchip_add()
- make pwm_chip.pwm_ops constant
- remove unused pwm_request_from_device() function
- check for valid chip in pwm_request_from_chip()
- add sanity checks to pwm_config(), pwm_enable() and pwm_disable()
- update Documentation/pwm.txt
- use deferred driver probing if pwm_request() cannot find a PWM

Changes in v4:
- remove OF-specific code to preserve bisectability
- add pwm_request_from_device() and pwm_request_from_chip() functions
- refactor PWM requesting code
- store period in struct pwm_device and get rid of the unused struct pwm_spec

Changes in v3:
- get rid of pwm_desc structure and keep only struct pwm_device
- keep a list of pwm_chip structures for fast and easy lookup
- pass struct pwm_device directly to pwm_ops
- add debugfs file

Changes in v2:
- add 'struct device *dev' field to pwm_chip, drop label field
- use radix tree for PWM descriptors
- add pwm_set_chip_data() and pwm_get_chip_data() functions to allow storing and retrieving chip-specific per-PWM data

 Documentation/pwm.txt |    9 +-
 drivers/pwm/core.c    |  263 ++++++++++++++++++++++++++++++++++---------------
 include/linux/pwm.h   |   71 ++++++++++---
 3 files changed, 250 insertions(+), 93 deletions(-)

index 03e39d1..48f598a 100644
@@ -33,9 +33,12 @@ there only has been the barebone API meaning that each driver has
 to implement the pwm_*() functions itself. This means that it's impossible
 to have multiple PWM drivers in the system. For this reason it's mandatory
 for new drivers to use the generic PWM framework.
-A new PWM device can be added using pwmchip_add() and removed again with
-pwmchip_remove(). pwmchip_add() takes a filled in struct pwm_chip as
-argument which provides the ops and the pwm id to the framework.
+
+A new PWM controller/chip can be added using pwmchip_add() and removed
+again with pwmchip_remove(). pwmchip_add() takes a filled in struct
+pwm_chip as argument which provides a description of the PWM chip, the
+number of PWM devices provider by the chip and the chip-specific
+implementation of the supported PWM operations to the framework.
 
 Locking
 -------

1.7.9.6

This commit adds a debugfs interface that can be used to list the current internal state of the PWM devices registered with the PWM framework.

---
Changes in v5:
- new patch splitting off debugfs interface implementation
- use seq_file's iterator interface for debugfs support
- add missing forward declaration of struct seq_file

 drivers/pwm/core.c  |   90 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pwm.h |    6 ++++
 2 files changed, 96 insertions(+)

index 8688754..7e13da1 100644
@@ -27,6 +27,8 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/device.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
 
 #define MAX_PWMS 1024
 

@@ -334,3 +336,91 @@ void pwm_disable(struct pwm_device *pwm)
 		pwm->chip->ops->disable(pwm->chip, pwm);
 }
 EXPORT_SYMBOL_GPL(pwm_disable);
+
+#ifdef CONFIG_DEBUG_FS
+static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
+{
+	unsigned int i;
+
+	for (i = 0; i < chip->npwm; i++) {
+		struct pwm_device *pwm = &chip->pwms[i];
+
+		seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
+
+		if (test_bit(PWMF_REQUESTED, &pwm->flags))
+			seq_printf(s, " requested");
+
+		if (test_bit(PWMF_ENABLED, &pwm->flags))
+			seq_printf(s, " enabled");
+
+		seq_printf(s, "\n");
+	}
+}
+
+static void *pwm_seq_start(struct seq_file *s, loff_t *pos)
+{
+	mutex_lock(&pwm_lock);
+	s->private = "";
+
+	return seq_list_start(&pwm_chips, *pos);
+}
+
+static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	s->private = "\n";
+
+	return seq_list_next(v, &pwm_chips, pos);
+}
+
+static void pwm_seq_stop(struct seq_file *s, void *v)
+{
+	mutex_unlock(&pwm_lock);
+}
+
+static int pwm_seq_show(struct seq_file *s, void *v)
+{
+	struct pwm_chip *chip = list_entry(v, struct pwm_chip, list);
+
+	seq_printf(s, "%s%s/%s, %d PWM device%s\n", (char *)s->private,
+		   chip->dev->bus ? chip->dev->bus->name : "no-bus",
+		   dev_name(chip->dev), chip->npwm,
+		   (chip->npwm != 1) ? "s" : "");
+
+	if (chip->ops->dbg_show)
+		chip->ops->dbg_show(chip, s);
+	else
+		pwm_dbg_show(chip, s);
+
+	return 0;
+}
+
+static const struct seq_operations pwm_seq_ops = {
+	.start = pwm_seq_start,
+	.next = pwm_seq_next,
+	.stop = pwm_seq_stop,
+	.show = pwm_seq_show,
+};
+
+static int pwm_seq_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &pwm_seq_ops);
+}
+
+static const struct file_operations pwm_debugfs_ops = {
+	.owner = THIS_MODULE,
+	.open = pwm_seq_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = seq_release,
+};
+
+static int __init pwm_debugfs_init(void)
+{
+	debugfs_create_file("pwm", S_IFREG | S_IRUGO, NULL, NULL,
+			    &pwm_debugfs_ops);
+
+	return 0;
+}
+
+subsys_initcall(pwm_debugfs_init);
+#endif /* CONFIG_DEBUG_FS */

index 5710391..047cd53 100644
@@ -2,6 +2,7 @@
 #define __LINUX_PWM_H
 
 struct pwm_device;
+struct seq_file;
 
 /*
  * pwm_request - request a PWM device

@@ -65,6 +66,7 @@ static inline unsigned int pwm_get_period(struct pwm_device *pwm)
  * @config: configure duty cycles and period length for this PWM
  * @enable: enable PWM output toggling
  * @disable: disable PWM output toggling
+ * @dbg_show: optional routine to show contents in debugfs
  * @owner: helps prevent removal of modules exporting active PWMs
  */
 struct pwm_ops {

@@ -79,6 +81,10 @@ struct pwm_ops {
 					  struct pwm_device *pwm);
 	void			(*disable)(struct pwm_chip *chip,
 					   struct pwm_device *pwm);
+#ifdef CONFIG_DEBUG_FS
+	void			(*dbg_show)(struct pwm_chip *chip,
+					    struct seq_file *s);
+#endif
 	struct module		*owner;
 };
 

1.7.9.6

I have done review only once :)

Regards,
Shawn

Heh, good catch! =)

Thanks,
Thierry
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But it was a really thorough and detailed review!

In order to get rid of the global namespace for PWM devices, this commit provides an alternative method, similar to that of the regulator or clock frameworks, for registering a static mapping for PWM devices. This works by providing a table with a provider/consumer map in the board setup code.

With the new pwm_get() and pwm_put() functions available, usage of pwm_request() and pwm_free() becomes deprecated.

---
Changes in v6:
- synchronize documentation with pwm_get() signature
- allow registering multiple PWM devices per user

Changes in v5:
- new patch with table-based lookup for statically registered devices
- update Documentation/pwm.txt

 Documentation/pwm.txt |   27 ++++++--
 drivers/pwm/core.c    |  169 ++++++++++++++++++++++++++++++++++++++++++++-----
 include/linux/pwm.h   |   22 +++++++
 3 files changed, 199 insertions(+), 19 deletions(-)

index 48f598a..bb3d2f9 100644
@@ -12,14 +12,33 @@ this kind of flexibility the generic PWM API exists.
 Identifying PWMs
 ----------------
 
-Users of the legacy PWM API use unique IDs to refer to PWM devices. One
-goal of the new PWM framework is to get rid of this global namespace.
+Users of the legacy PWM API use unique IDs to refer to PWM devices.
+
+Instead of referring to a PWM device via its unique ID, board setup code
+should instead register a static mapping that can be used to match PWM
+consumers to providers, as given in the following example:
+
+	static struct pwm_lookup board_pwm_lookup[] = {
+		PWM_LOOKUP("tegra-pwm", 0, "pwm-backlight"),
+	};
+
+	static void __init board_init(void)
+	{
+		...
+		pwm_add_table(board_pwm_lookup, ARRAY_SIZE(board_pwm_lookup));
+		...
+	}
 
 Using PWMs
 ----------
 
-A PWM can be requested using pwm_request() and freed after usage with
-pwm_free(). After being requested a PWM has to be configured using
+Legacy users can request a PWM device using pwm_request() and free it
+after usage with pwm_free().
+
+New users should use the pwm_get() function and pass to it the consumer
+device or a consumer name. pwm_put() is used to free the PWM device.
+
+After being requested a PWM has to be configured using:
 
 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns);
 

index 047cd53..2947a4f 100644
@@ -115,6 +115,28 @@ int pwmchip_remove(struct pwm_chip *chip);
 struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
 					 unsigned int index,
 					 const char *label);
+
+struct pwm_device *pwm_get(struct device *dev, const char *consumer);
+void pwm_put(struct pwm_device *pwm);
+
+struct pwm_lookup {
+	struct list_head list;
+	const char *provider;
+	unsigned int index;
+	const char *dev_id;
+	const char *con_id;
+};
+
+#define PWM_LOOKUP(_provider, _index, _dev_id, _con_id)	\
+	{						\
+		.provider = _provider,			\
+		.index = _index,			\
+		.dev_id = _dev_id,			\
+		.con_id = _con_id,			\
+	}
+
+void pwm_add_table(struct pwm_lookup *table, size_t num);
+
 #endif
 
 #endif /* __LINUX_PWM_H */

1.7.9.6

...

[...]

Right, I missed that.

Thanks,
Thierry
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This patch adds helpers to support device tree bindings for the generic PWM API. Device tree binding documentation for PWM controllers is also provided.

---
Changes in v6:
- don't override error code in of_pwm_simple_xlate()
- no longer export of_pwm_request(), only pwm_get() should be used
- do a reverse lookup of the index into the "pwms" property by matching the con_id parameter to the "pwm-names" property

Changes in v5:
- use IS_ENABLED(CONFIG_OF) along with the compiler's DCE instead of empty implementations of of_pwmchip_add() and of_pwmchip_remove() in the !OF case
- remove OF_PWM Kconfig symbol and make OF support code conditional on the OF symbol only
- use "pwms" and "pwm-names" fixed property names
- remove redundant check in of_pwm_simple_xlate()
- use pwm_request_from_chip() instead of pwm_request_from_device()
- integrate OF support with pwm_get() from new patch 4

Changes in v4:
- add OF-specific code removed from patch 2
- make of_node_to_pwmchip() and of_pwm_simple_xlate() static
- rename of_get_named_pwm() to of_pwm_request(), return a struct pwm_device, get rid of the now unused spec parameter and use the device_node.name field as the PWM's name
- return a requested struct pwm_device from pwm_chip.of_xlate and drop the now unused spec parameter
- move OF support code into drivers/pwm/core.c
- used deferred probing if a PWM chip is not available yet

Changes in v2:
- add device tree binding documentation
- add of_xlate to parse controller-specific PWM-specifier

 Documentation/devicetree/bindings/pwm/pwm.txt |   57 ++++++++++
 drivers/pwm/core.c                            |  151 ++++++++++++++++++++++++-
 include/linux/pwm.h                           |    6 +
 3 files changed, 212 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/pwm/pwm.txt

new file mode 100644
index 0000000..73ec962
@@ -0,0 +1,57 @@
+Specifying PWM information for devices
+======================================
+
+1) PWM user nodes
+-----------------
+
+PWM users should specify a list of PWM devices that they want to use
+with a property containing a 'pwm-list':
+
+	pwm-list ::= <single-pwm> [pwm-list]
+	single-pwm ::= <pwm-phandle> <pwm-specifier>
+	pwm-phandle : phandle to PWM controller node
+	pwm-specifier : array of #pwm-cells specifying the given PWM
+			(controller specific)
+
+PWM properties should be named "pwms". The exact meaning of each pwms
+property must be documented in the device tree binding for each device.
+An optional property "pwm-names" may contain a list of strings to label
+each of the PWM devices listed in the "pwms" property. If no "pwm-names"
+property is given, the name of the user node will be used as fallback.
+
+Drivers for devices that use more than a single PWM device can use the
+"pwm-names" property to map the name of the PWM device requested by the
+pwm_get() call to an index into the list given by the "pwms" property.
+
+The following example could be used to describe a PWM-based backlight
+device:
+
+	pwm: pwm {
+		#pwm-cells = <2>;
+	};
+
+	[...]
+
+	bl: backlight {
+		pwms = <&pwm 0 5000000>;
+		pwm-names = "backlight";
+	};
+
+pwm-specifier typically encodes the chip-relative PWM number and the PWM
+period in nanoseconds. Note that in the example above, specifying the
+"pwm-names" is redundant because the name "backlight" would be used as
+fallback anyway.
+
+2) PWM controller nodes
+-----------------------
+
+PWM controller nodes must specify the number of cells used for the
+specifier using the '#pwm-cells' property.
+
+An example PWM controller might look like this:
+
+	pwm: pwm at 7000a000 {
+		compatible = "nvidia,tegra20-pwm";
+		reg = <0x7000a000 0x100>;
+		#pwm-cells = <2>;
+	};

index 2947a4f..21d076c 100644
@@ -1,6 +1,8 @@
 #ifndef __LINUX_PWM_H
 #define __LINUX_PWM_H
 
+#include <linux/of.h>
+
 struct pwm_device;
 struct seq_file;
 

@@ -105,6 +107,10 @@ struct pwm_chip {
 	unsigned int		npwm;
 
 	struct pwm_device	*pwms;
+
+	struct pwm_device *	(*of_xlate)(struct pwm_chip *pc,
+					    const struct of_phandle_args *args);
+	unsigned int		of_pwm_n_cells;
 };
 
 int pwm_set_chip_data(struct pwm_device *pwm, void *data);

1.7.9.6

Ok, I read this here ...

...

You are absolutely right. I always thought that gcc would complain if you tried to export a static function. Funny also that my compile tests haven't caught this in the !OF configuration. Anyway, since of_pwm_request() is no longer exported, I've replaced this by an IS_ENABLED(CONFIG_OF) construct similar to the calls to of_pwmchip_add() and of_pwmchip_remove().

Thanks,
Thierry
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From: Simon Que <[email protected]>

PWM clock source registers in Tegra 2 have different clock source selection bit fields than other registers. PWM clock source bits in CLK_SOURCE_PWM_0 register are located at bit field bit[30:28] while others are at bit field bit[31:30] in their respective clock source register.

This patch updates the clock programming to correctly reflect that, by adding a flag to indicate the alternate bit field format and checking for it when selecting a clock source (parent clock).

---
Changes in v4:
- reuse PWM flag from Tegra 30 clock programming
- mask out bit 31 explicitly

 arch/arm/mach-tegra/tegra2_clocks.c |   32 ++++++++++++++++++++++++++++----
 1 file changed, 28 insertions(+), 4 deletions(-)

index 592a4ee..64735bd 100644
@@ -69,6 +69,8 @@
 
 #define PERIPH_CLK_SOURCE_MASK		(3<<30)
 #define PERIPH_CLK_SOURCE_SHIFT		30
+#define PERIPH_CLK_SOURCE_PWM_MASK	(7<<28)
+#define PERIPH_CLK_SOURCE_PWM_SHIFT	28
 #define PERIPH_CLK_SOURCE_ENABLE	(1<<28)
 #define PERIPH_CLK_SOURCE_DIVU71_MASK	0xFF
 #define PERIPH_CLK_SOURCE_DIVU16_MASK	0xFFFF

@@ -908,9 +910,20 @@ static void tegra2_periph_clk_init(struct clk *c)
 	u32 val = clk_readl(c->reg);
 	const struct clk_mux_sel *mux = NULL;
 	const struct clk_mux_sel *sel;
+	u32 shift;
+	u32 mask;
+
+	if (c->flags & MUX_PWM) {
+		shift = PERIPH_CLK_SOURCE_PWM_SHIFT;
+		mask = PERIPH_CLK_SOURCE_PWM_MASK;
+	} else {
+		shift = PERIPH_CLK_SOURCE_SHIFT;
+		mask = PERIPH_CLK_SOURCE_MASK;
+	}
+
 	if (c->flags & MUX) {
 		for (sel = c->inputs; sel->input != NULL; sel++) {
-			if (val >> PERIPH_CLK_SOURCE_SHIFT == sel->value)
+			if ((val & mask) >> shift == sel->value)
 				mux = sel;
 		}
 		BUG_ON(!mux);

@@ -1023,12 +1036,23 @@ static int tegra2_periph_clk_set_parent(struct clk *c, struct clk *p)
 {
 	u32 val;
 	const struct clk_mux_sel *sel;
+	u32 mask, shift;
+
 	pr_debug("%s: %s %s\n", __func__, c->name, p->name);
+
+	if (c->flags & MUX_PWM) {
+		shift = PERIPH_CLK_SOURCE_PWM_SHIFT;
+		mask = PERIPH_CLK_SOURCE_PWM_MASK;
+	} else {
+		shift = PERIPH_CLK_SOURCE_SHIFT;
+		mask = PERIPH_CLK_SOURCE_MASK;
+	}
+
 	for (sel = c->inputs; sel->input != NULL; sel++) {
 		if (sel->input == p) {
 			val = clk_readl(c->reg);
-			val &= ~PERIPH_CLK_SOURCE_MASK;
-			val |= (sel->value) << PERIPH_CLK_SOURCE_SHIFT;
+			val &= ~mask;
+			val |= (sel->value) << shift;
 
 			if (c->refcnt)
 				clk_enable(p);

@@ -2146,7 +2170,7 @@ static struct clk tegra_list_clks[] = {
 	PERIPH_CLK("i2s2",	"tegra-i2s.1",		NULL,	18,	0x104,	26000000,  mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("spdif_out",	"spdif_out",		NULL,	10,	0x108,	100000000, mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("spdif_in",	"spdif_in",		NULL,	10,	0x10c,	100000000, mux_pllp_pllc_pllm,		MUX | DIV_U71),
-	PERIPH_CLK("pwm",	"pwm",			NULL,	17,	0x110,	432000000, mux_pllp_pllc_audio_clkm_clk32,	MUX | DIV_U71),
+	PERIPH_CLK("pwm",	"pwm",			NULL,	17,	0x110,	432000000, mux_pllp_pllc_audio_clkm_clk32,	MUX | DIV_U71 | MUX_PWM),
 	PERIPH_CLK("spi",	"spi",			NULL,	43,	0x114,	40000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("xio",	"xio",			NULL,	45,	0x120,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("twc",	"twc",			NULL,	16,	0x12c,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),

1.7.9.6

A subsequent patch will add a generic PWM API driver for the Tegra PWFM controller, supporting all four PWM devices with a single PWM chip. The device will be named tegra-pwm and only one clock needs to be provided.

---
Changes in v5:
- rename the device name to "tegra-pwm" in the clock lookup table
- get rid of all CLK_DUPLICATE entries which are no longer needed

 arch/arm/mach-tegra/tegra2_clocks.c  |    6 +-----
 arch/arm/mach-tegra/tegra30_clocks.c |    6 +-----
 2 files changed, 2 insertions(+), 10 deletions(-)

index 64735bd..c95a878 100644
@@ -2170,7 +2170,7 @@ static struct clk tegra_list_clks[] = {
 	PERIPH_CLK("i2s2",	"tegra-i2s.1",		NULL,	18,	0x104,	26000000,  mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("spdif_out",	"spdif_out",		NULL,	10,	0x108,	100000000, mux_pllaout0_audio2x_pllp_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("spdif_in",	"spdif_in",		NULL,	10,	0x10c,	100000000, mux_pllp_pllc_pllm,		MUX | DIV_U71),
-	PERIPH_CLK("pwm",	"pwm",			NULL,	17,	0x110,	432000000, mux_pllp_pllc_audio_clkm_clk32,	MUX | DIV_U71 | MUX_PWM),
+	PERIPH_CLK("pwm",	"tegra-pwm",		NULL,	17,	0x110,	432000000, mux_pllp_pllc_audio_clkm_clk32,	MUX | DIV_U71 | MUX_PWM),
 	PERIPH_CLK("spi",	"spi",			NULL,	43,	0x114,	40000000,  mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("xio",	"xio",			NULL,	45,	0x120,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("twc",	"twc",			NULL,	16,	0x12c,	150000000, mux_pllp_pllc_pllm_clkm,	MUX | DIV_U71),

@@ -2269,10 +2269,6 @@ static struct clk_duplicate tegra_clk_duplicates[] = {
 	CLK_DUPLICATE("usbd", "tegra-otg", NULL),
 	CLK_DUPLICATE("hdmi", "tegradc.0", "hdmi"),
 	CLK_DUPLICATE("hdmi", "tegradc.1", "hdmi"),
-	CLK_DUPLICATE("pwm", "tegra_pwm.0", NULL),
-	CLK_DUPLICATE("pwm", "tegra_pwm.1", NULL),
-	CLK_DUPLICATE("pwm", "tegra_pwm.2", NULL),
-	CLK_DUPLICATE("pwm", "tegra_pwm.3", NULL),
 	CLK_DUPLICATE("host1x", "tegra_grhost", "host1x"),
 	CLK_DUPLICATE("2d", "tegra_grhost", "gr2d"),
 	CLK_DUPLICATE("3d", "tegra_grhost", "gr3d"),

index 6d08b53..18afd0c 100644
@@ -2886,7 +2886,7 @@ struct clk tegra_list_clks[] = {
 	PERIPH_CLK("i2s4",	"tegra30-i2s.4",	NULL,	102,	0x3c0,	26000000,  mux_pllaout0_audio4_2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("spdif_out",	"tegra30-spdif",	"spdif_out",	10,	0x108,	100000000, mux_pllaout0_audio_2x_pllp_clkm,	MUX | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("spdif_in",	"tegra30-spdif",	"spdif_in",	10,	0x10c,	100000000, mux_pllp_pllc_pllm,		MUX | DIV_U71 | PERIPH_ON_APB),
-	PERIPH_CLK("pwm",	"pwm",			NULL,	17,	0x110,	432000000, mux_pllp_pllc_clk32_clkm,	MUX | MUX_PWM | DIV_U71 | PERIPH_ON_APB),
+	PERIPH_CLK("pwm",	"tegra-pwm",		NULL,	17,	0x110,	432000000, mux_pllp_pllc_clk32_clkm,	MUX | MUX_PWM | DIV_U71 | PERIPH_ON_APB),
 	PERIPH_CLK("d_audio",	"tegra30-ahub",		"d_audio", 106,	0x3d0,	48000000,  mux_plla_pllc_pllp_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("dam0",	"tegra30-dam.0",	NULL,   108,	0x3d8,	48000000,  mux_plla_pllc_pllp_clkm,	MUX | DIV_U71),
 	PERIPH_CLK("dam1",	"tegra30-dam.1",	NULL,   109,	0x3dc,	48000000,  mux_plla_pllc_pllp_clkm,	MUX | DIV_U71),

@@ -2990,10 +2990,6 @@ struct clk_duplicate tegra_clk_duplicates[] = {
 	CLK_DUPLICATE("hdmi", "tegradc.1", "hdmi"),
 	CLK_DUPLICATE("dsib", "tegradc.0", "dsib"),
 	CLK_DUPLICATE("dsia", "tegradc.1", "dsia"),
-	CLK_DUPLICATE("pwm", "tegra_pwm.0", NULL),
-	CLK_DUPLICATE("pwm", "tegra_pwm.1", NULL),
-	CLK_DUPLICATE("pwm", "tegra_pwm.2", NULL),
-	CLK_DUPLICATE("pwm", "tegra_pwm.3", NULL),
 	CLK_DUPLICATE("bsev", "tegra-avp", "bsev"),
 	CLK_DUPLICATE("bsev", "nvavp", "bsev"),
 	CLK_DUPLICATE("vde", "tegra-aes", "vde"),

1.7.9.6

This commit adds a generic PWM framework driver for the PWFM controller found on NVIDIA Tegra SoCs. The driver is based on code from the Chromium kernel tree and was originally written by Gary King (NVIDIA) and later modified by Simon Que (Chromium).

---
Changes in v6:
- return EADDRNOTAVAIL if devm_request_and_ioremap() fails
- make tegra_pwm_ops constant

Changes in v5:
- use devm_request_and_ioremap()
- use clk_prepare_enable() and clk_disable_unprepare()
- call pwmchip_remove() after disabling PWM devices
- remove tegra_pwm_chip.enable[] field and use the PWM flags instead
- use pwm_readl()/pwm_writel() for register accesses and split out clock management to where it's needed
- add MODULE_ALIAS to enable automatic module loading

Changes in v4:
- merge patch from ChromiumOS kernel to fix a rounding issue
- move DT code to patch 7

Changes in v3:
- use pwm_device.hwpwm instead of recomputing it
- update pwm_ops for changes in patch 2

Changes in v2:
- set pwm_chip.dev field
- rename clk_enb to enable
- introduce NUM_PWM macro instead of hard-coding the number of PWM devices
- update comment in tegra_pwm_config
- fix coding-style for multi-line comments
- use module_platform_driver
- change license to GPL

 drivers/pwm/Kconfig     |   10 ++
 drivers/pwm/Makefile    |    1 +
 drivers/pwm/pwm-tegra.c |  254 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 265 insertions(+)
 create mode 100644 drivers/pwm/pwm-tegra.c

index 93c1052..bda6f23 100644
@@ -9,4 +9,14 @@ menuconfig PWM
 
 if PWM
 
+config PWM_TEGRA
+	tristate "NVIDIA Tegra PWM support"
+	depends on ARCH_TEGRA
+	help
+	  Generic PWM framework driver for the PWFM controller found on NVIDIA
+	  Tegra SoCs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-tegra.
+
 endif

index 3469c3d..12300f5 100644
@@ -1 +1,2 @@
 obj-$(CONFIG_PWM)		+= core.o
+obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o

1.7.9.6

Add auxdata to instantiate the PWFM controller from a device tree, include the corresponding nodes in the dtsi files for Tegra 20 and Tegra 30 and add binding documentation.

---
Changes in v5:
- rename tegra-pwm.txt to nvidia,tegra20-pwm.txt

Changes in v4:
- add DT binding documentation
- allow nvidia,tegra20-pwm as fallback for nvidia,tegra30-pwm
- export OF device table (for module auto-loading)

Changes in v3:
- add missing include for mach/iomap.h

 .../devicetree/bindings/pwm/nvidia,tegra20-pwm.txt |   18 ++++++++++++++++++
 arch/arm/boot/dts/tegra20.dtsi                     |    6 ++++++
 arch/arm/boot/dts/tegra30.dtsi                     |    6 ++++++
 arch/arm/mach-tegra/board-dt-tegra20.c             |    1 +
 arch/arm/mach-tegra/board-dt-tegra30.c             |    3 +++
 drivers/pwm/pwm-tegra.c                            |   11 +++++++++++
 6 files changed, 45 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/nvidia,tegra20-pwm.txt

new file mode 100644
index 0000000..bbbeedb
@@ -0,0 +1,18 @@
+Tegra SoC PWFM controller
+
+Required properties:
+- compatible: should be one of:
+  - "nvidia,tegra20-pwm"
+  - "nvidia,tegra30-pwm"
+- reg: physical base address and length of the controller's registers
+- #pwm-cells: On Tegra the number of cells used to specify a PWM is 2. The
+  first cell specifies the per-chip index of the PWM to use and the second
+  cell is the duty cycle in nanoseconds.
+
+Example:
+
+	pwm: pwm at 7000a000 {
+		compatible = "nvidia,tegra20-pwm";
+		reg = <0x7000a000 0x100>;
+		#pwm-cells = <2>;
+	};

index 108e894..55b28fd 100644
@@ -154,6 +154,12 @@
 		interrupts = < 0 91 0x04 >;
 	};
 
+	pwm: pwm at 7000a000 {
+		compatible = "nvidia,tegra20-pwm";
+		reg = <0x7000a000 0x100>;
+		#pwm-cells = <2>;
+	};
+
 	emc at 7000f400 {
 		#address-cells = <1>;
 		#size-cells = <0>;

index 62a7b39..3fa5211 100644
@@ -154,6 +154,12 @@
 		interrupts = < 0 91 0x04 >;
 	};
 
+	pwm: pwm at 7000a000 {
+		compatible = "nvidia,tegra30-pwm", "nvidia,tegra20-pwm";
+		reg = <0x7000a000 0x100>;
+		#pwm-cells = <2>;
+	};
+
 	sdhci at 78000000 {
 		compatible = "nvidia,tegra30-sdhci", "nvidia,tegra20-sdhci";
 		reg = <0x78000000 0x200>;

index 0952494..87bdce5 100644
@@ -73,6 +73,7 @@ struct of_dev_auxdata tegra20_auxdata_lookup[] __initdata = {
 		       &tegra_ehci2_pdata),
 	OF_DEV_AUXDATA("nvidia,tegra20-ehci", TEGRA_USB3_BASE, "tegra-ehci.2",
 		       &tegra_ehci3_pdata),
+	OF_DEV_AUXDATA("nvidia,tegra20-pwm", TEGRA_PWFM_BASE, "tegra-pwm", NULL),
 	{}
 };
 

index 5f7c03e..5e1180f 100644
@@ -33,6 +33,8 @@
 #include <asm/mach/arch.h>
 #include <asm/hardware/gic.h>
 
+#include <mach/iomap.h>
+
 #include "board.h"
 #include "clock.h"
 

@@ -51,6 +53,7 @@ struct of_dev_auxdata tegra30_auxdata_lookup[] __initdata = {
 	OF_DEV_AUXDATA("nvidia,tegra20-i2c", 0x7000C500, "tegra-i2c.2", NULL),
 	OF_DEV_AUXDATA("nvidia,tegra20-i2c", 0x7000C700, "tegra-i2c.3", NULL),
 	OF_DEV_AUXDATA("nvidia,tegra20-i2c", 0x7000D000, "tegra-i2c.4", NULL),
+	OF_DEV_AUXDATA("nvidia,tegra30-pwm", TEGRA_PWFM_BASE, "tegra-pwm", NULL),
 	{}
 };
 

index 0950142..472b74e 100644
@@ -239,9 +239,20 @@ static int __devexit tegra_pwm_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_OF
+static struct of_device_id tegra_pwm_of_match[] = {
+	{ .compatible = "nvidia,tegra20-pwm" },
+	{ .compatible = "nvidia,tegra30-pwm" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
+#endif
+
 static struct platform_driver tegra_pwm_driver = {
 	.driver = {
 		.name = "tegra-pwm",
+		.of_match_table = of_match_ptr(tegra_pwm_of_match),
 	},
 	.probe = tegra_pwm_probe,
 	.remove = __devexit_p(tegra_pwm_remove),

1.7.9.6

This commit moves the Blackfin PWM driver to the drivers/pwm sub- directory and converts it to register with the new PWM framework.

---
 arch/blackfin/Kconfig                              |   10 --
 arch/blackfin/kernel/Makefile                      |    1 -
 drivers/pwm/Kconfig                                |    9 ++
 drivers/pwm/Makefile                               |    1 +
 .../kernel/pwm.c => drivers/pwm/pwm-bfin.c         |  138 ++++++++++++++------
 5 files changed, 111 insertions(+), 48 deletions(-)
 rename arch/blackfin/kernel/pwm.c => drivers/pwm/pwm-bfin.c (26%)

index 373a690..128357e 100644
@@ -950,16 +950,6 @@ config BFIN_GPTIMERS
 	  To compile this driver as a module, choose M here: the module
 	  will be called gptimers.
 
-config HAVE_PWM
-	tristate "Enable PWM API support"
-	depends on BFIN_GPTIMERS
-	help
-	  Enable support for the Pulse Width Modulation framework (as
-	  found in linux/pwm.h).
-
-	  To compile this driver as a module, choose M here: the module
-	  will be called pwm.
-
 choice
 	prompt "Uncached DMA region"
 	default DMA_UNCACHED_1M

index 9a0d6d7..00fef32 100644
@@ -21,7 +21,6 @@ obj-$(CONFIG_FUNCTION_TRACER)        += ftrace-entry.o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER)  += ftrace.o
 CFLAGS_REMOVE_ftrace.o = -pg
 
-obj-$(CONFIG_HAVE_PWM)               += pwm.o
 obj-$(CONFIG_IPIPE)                  += ipipe.o
 obj-$(CONFIG_BFIN_GPTIMERS)          += gptimers.o
 obj-$(CONFIG_CPLB_INFO)              += cplbinfo.o

index bda6f23..eb54042 100644
@@ -9,6 +9,15 @@ menuconfig PWM
 
 if PWM
 
+config PWM_BFIN
+	tristate "Blackfin PWM support"
+	depends on BFIN_GPTIMERS
+	help
+	  Generic PWM framework driver for Blackfin.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-bfin.
+
 config PWM_TEGRA
 	tristate "NVIDIA Tegra PWM support"
 	depends on ARCH_TEGRA

index 12300f5..251b8d2 100644
@@ -1,2 +1,3 @@
 obj-$(CONFIG_PWM)		+= core.o
+obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o

1.7.9.6

This commit moves the PXA PWM driver to the drivers/pwm subdirectory and converts it to use the new PWM framework.

---
Changes in v5:
- replace __raw_readl()/__raw_writel() by readl()/writel()
- use clk_prepare_enable() and clk_disable_unprepare()

Changes in v3:
- update PWM ops for changes in patch 2

 arch/arm/plat-pxa/Makefile                       |    1 -
 drivers/pwm/Kconfig                              |    9 ++
 drivers/pwm/Makefile                             |    1 +
 arch/arm/plat-pxa/pwm.c => drivers/pwm/pwm-pxa.c |  172 ++++++++--------------
 4 files changed, 68 insertions(+), 115 deletions(-)
 rename arch/arm/plat-pxa/pwm.c => drivers/pwm/pwm-pxa.c (57%)

index f302d04..af8e484 100644
@@ -8,5 +8,4 @@ obj-$(CONFIG_PXA3xx)		+= mfp.o
 obj-$(CONFIG_PXA95x)		+= mfp.o
 obj-$(CONFIG_ARCH_MMP)		+= mfp.o
 
-obj-$(CONFIG_HAVE_PWM)		+= pwm.o
 obj-$(CONFIG_PXA_SSP)		+= ssp.o

index eb54042..0ef4f30 100644
@@ -18,6 +18,15 @@ config PWM_BFIN
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-bfin.
 
+config PWM_PXA
+	tristate "PXA PWM support"
+	depends on ARCH_PXA
+	help
+	  Generic PWM framework driver for PXA.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-pxa.
+
 config PWM_TEGRA
 	tristate "NVIDIA Tegra PWM support"
 	depends on ARCH_TEGRA

index 251b8d2..e859c51 100644
@@ -1,3 +1,4 @@
 obj-$(CONFIG_PWM)		+= core.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
+obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o

1.7.9.6

From: Sascha Hauer <[email protected]>

Move the driver to drivers/pwm/ and convert it to use the framework.

---
Changes in v5:
- adopt patch by Sascha Hauer to move i.MX driver to PWM framework
- rename to imx_pwm internally

 arch/arm/plat-mxc/Kconfig                        |    6 -
 arch/arm/plat-mxc/Makefile                       |    1 -
 drivers/pwm/Kconfig                              |    9 ++
 drivers/pwm/Makefile                             |    1 +
 arch/arm/plat-mxc/pwm.c => drivers/pwm/pwm-imx.c |  182 +++++++++-------------
 5 files changed, 81 insertions(+), 118 deletions(-)
 rename arch/arm/plat-mxc/pwm.c => drivers/pwm/pwm-imx.c (58%)

index c722f9c..baf9064 100644
@@ -47,12 +47,6 @@ config MXC_TZIC
 config MXC_AVIC
 	bool
 
-config MXC_PWM
-	tristate "Enable PWM driver"
-	select HAVE_PWM
-	help
-	  Enable support for the i.MX PWM controller(s).
-
 config MXC_DEBUG_BOARD
 	bool "Enable MXC debug board(for 3-stack)"
 	help

index e81290c..46ba8de 100644
@@ -11,7 +11,6 @@ obj-$(CONFIG_MXC_AVIC) += avic.o
 obj-$(CONFIG_IMX_HAVE_IOMUX_V1) += iomux-v1.o
 obj-$(CONFIG_ARCH_MXC_IOMUX_V3) += iomux-v3.o
 obj-$(CONFIG_IRAM_ALLOC) += iram_alloc.o
-obj-$(CONFIG_MXC_PWM)  += pwm.o
 obj-$(CONFIG_MXC_ULPI) += ulpi.o
 obj-$(CONFIG_MXC_USE_EPIT) += epit.o
 obj-$(CONFIG_MXC_DEBUG_BOARD) += 3ds_debugboard.o

index 0ef4f30..a9a9715 100644
@@ -18,6 +18,15 @@ config PWM_BFIN
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-bfin.
 
+config PWM_IMX
+	tristate "i.MX pwm support"
+	depends on ARCH_MXC
+	help
+	  Generic PWM framework driver for i.MX.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-imx.
+
 config PWM_PXA
 	tristate "PXA PWM support"
 	depends on ARCH_PXA

index e859c51..3dd1b83 100644
@@ -1,4 +1,5 @@
 obj-$(CONFIG_PWM)		+= core.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
+obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o

1.7.9.6

From: Sascha Hauer <[email protected]>

Move the driver to drivers/pwm/ and convert it to use the framework.

---
Changes in v5:
- adopt patch by Sascha Hauer to move s3c driver to PWM framework
- This driver could use some cleanups and rework to actually take advantage of the multiple PWM devices per PWM chip feature. Currently, information about the controlling timers is passed via platform resources but is not used. Perhaps the corresponding information can be passed in a better way via platform data?

 arch/arm/plat-samsung/Makefile                     |    4 -
 drivers/pwm/Kconfig                                |    9 +
 drivers/pwm/Makefile                               |    1 +
 .../pwm.c => drivers/pwm/pwm-samsung.c             |  228 ++++++++------------
 4 files changed, 97 insertions(+), 145 deletions(-)
 rename arch/arm/plat-samsung/pwm.c => drivers/pwm/pwm-samsung.c (58%)

index 6012366..f09a7cf 100644
@@ -50,7 +50,3 @@ obj-$(CONFIG_SAMSUNG_WAKEMASK)	+= wakeup-mask.o
 # PD support
 
 obj-$(CONFIG_SAMSUNG_PD)	+= pd.o
-
-# PWM support
-
-obj-$(CONFIG_HAVE_PWM)		+= pwm.o

index a9a9715..0d9aa92 100644
@@ -36,6 +36,15 @@ config PWM_PXA
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-pxa.
 
+config PWM_SAMSUNG
+	tristate "Samsung pwm support"
+	depends on PLAT_SAMSUNG
+	help
+	  Generic PWM framework driver for Samsung.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-samsung.
+
 config PWM_TEGRA
 	tristate "NVIDIA Tegra PWM support"
 	depends on ARCH_TEGRA

index 3dd1b83..a1d87b1 100644
@@ -2,4 +2,5 @@ obj-$(CONFIG_PWM)		+= core.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
+obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o

1.7.9.6

From: Sascha Hauer <[email protected]>

Move the driver to drivers/pwm/ and convert it to use the framework.

---
Changes in v5:
- adopt patch by Sascha Hauer to move vt8500 driver to PWM framework

 arch/arm/mach-vt8500/Makefile                      |    2 -
 drivers/pwm/Kconfig                                |    9 ++
 drivers/pwm/Makefile                               |    1 +
 .../mach-vt8500/pwm.c => drivers/pwm/pwm-vt8500.c  |  169 +++++++-------------
 4 files changed, 66 insertions(+), 115 deletions(-)
 rename arch/arm/mach-vt8500/pwm.c => drivers/pwm/pwm-vt8500.c (52%)

index 81aedb7..8df9e4a 100644
@@ -5,5 +5,3 @@ obj-$(CONFIG_VTWM_VERSION_WM8505) += devices-wm8505.o
 
 obj-$(CONFIG_MACH_BV07) += bv07.o
 obj-$(CONFIG_MACH_WM8505_7IN_NETBOOK) += wm8505_7in.o
-
-obj-$(CONFIG_HAVE_PWM) += pwm.o

index 0d9aa92..a93feff 100644
@@ -55,4 +55,13 @@ config PWM_TEGRA
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-tegra.
 
+config PWM_VT8500
+	tristate "vt8500 pwm support"
+	depends on ARCH_VT8500
+	help
+	  Generic PWM framework driver for vt8500.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-vt8500.
+
 endif

index a1d87b1..b7c0fcf 100644
@@ -4,3 +4,4 @@ obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
 obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o
+obj-$(CONFIG_PWM_VT8500)	+= pwm-vt8500.o

1.7.9.6

From: Shawn Guo <[email protected]>

Add generic PWM framework driver (DT only) for Freescale MXS.

---
Changes in v6:
- adopt patch by Shawn Guo

 Documentation/devicetree/bindings/pwm/mxs-pwm.txt |   17 ++
 drivers/pwm/Kconfig                               |    9 +
 drivers/pwm/Makefile                              |    1 +
 drivers/pwm/pwm-mxs.c                             |  207 +++++++++++++++++++++
 4 files changed, 234 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/mxs-pwm.txt
 create mode 100644 drivers/pwm/pwm-mxs.c

new file mode 100644
index 0000000..48ead0d
@@ -0,0 +1,17 @@
+Freescale MXS PWM controller
+
+Required properties:
+- compatible: should be "fsl,mxs-pwm"
+- reg: physical base address and length of the controller's registers
+- #pwm-cells: should be 2.  The first cell specifies the per-chip index
+  of the PWM to use and the second cell is the duty cycle in nanoseconds.
+- fsl,pwm-number: the number of PWM devices
+
+Example:
+
+pwm: pwm at 80064000 {
+	compatible = "fsl,imx28-pwm", "fsl,mxs-pwm";
+	reg = <0x80064000 2000>;
+	#pwm-cells = <2>;
+	fsl,pwm-number = <8>;
+};

index a93feff..39bdebc 100644
@@ -27,6 +27,15 @@ config PWM_IMX
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-imx.
 
+config PWM_MXS
+	tristate "Freescale MXS PWM support"
+	depends on ARCH_MXS && OF
+	help
+	  Generic PWM framework driver for Freescale MXS.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-mxs.
+
 config PWM_PXA
 	tristate "PXA PWM support"
 	depends on ARCH_PXA

index b7c0fcf..cec2500 100644
@@ -1,6 +1,7 @@
 obj-$(CONFIG_PWM)		+= core.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
+obj-$(CONFIG_PWM_MXS)		+= pwm-mxs.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
 obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o

1.7.9.6

This commit adds very basic support for device tree probing. Currently, only a PWM and a list of distinct brightness levels can be specified. Enabling or disabling backlight power via GPIOs is not yet supported.

---
Changes in v6:
- don't pass consumer name to pwm_get() because we don't need multiple PWM devices
- drop num-brightness-levels property because it can be derived from the brightness-levels property itself

Changes in v5:
- use "pwms" fixed property name
- document brightness-levels and default-brightness-level properties
- check default-brightness-level against brightness-levels
- use new PWM API (pwm_get() and pwm_put()), legacy API (pwm_request()) as fallback

Changes in v4:
- store a PWM requested with of_pwm_request() in the platform data

Changes in v3:
- use a list of distinct brightness levels instead of a linear range as discussed with Stephen Warren and Mitch Bradley

Changes in v2:
- avoid oops by keeping a reference to the platform-specific exit() callback

TODO:
- add fixed-regulator support for backlight enable/disable

 .../bindings/video/backlight/pwm-backlight         |   28 ++++
 drivers/video/backlight/Kconfig                    |    2 +-
 drivers/video/backlight/pwm_bl.c                   |  149 +++++++++++++++++---
 include/linux/pwm_backlight.h                      |    1 +
 4 files changed, 159 insertions(+), 21 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/video/backlight/pwm-backlight

new file mode 100644
index 0000000..1e4fc72
@@ -0,0 +1,28 @@
+pwm-backlight bindings
+
+Required properties:
+  - compatible: "pwm-backlight"
+  - pwms: OF device-tree PWM specification (see PWM binding[0])
+  - brightness-levels: Array of distinct brightness levels. Typically these
+      are in the range from 0 to 255, but any range starting at 0 will do.
+      The actual brightness level (PWM duty cycle) will be interpolated
+      from these values. 0 means a 0% duty cycle (darkest/off), while the
+      last value in the array represents a 100% duty cycle (brightest).
+  - default-brightness-level: the default brightness level (index into the
+      array defined by the "brightness-levels" property)
+
+Optional properties:
+  - pwm-names: a list of names for the PWM devices specified in the
+               "pwms" property (see PWM binding[0])
+
+[0]: Documentation/devicetree/bindings/pwm/pwm.txt
+
+Example:
+
+	backlight {
+		compatible = "pwm-backlight";
+		pwms = <&pwm 0 5000000>;
+
+		brightness-levels = <0 4 8 16 32 64 128 255>;
+		default-brightness-level = <6>;
+	};

index 7ed9991..cd77e79 100644
@@ -233,7 +233,7 @@ config BACKLIGHT_CARILLO_RANCH
 
 config BACKLIGHT_PWM
 	tristate "Generic PWM based Backlight Driver"
-	depends on HAVE_PWM
+	depends on PWM
 	help
 	  If you have a LCD backlight adjustable by PWM, say Y to enable
 	  this driver.

index 63d2df4..56f4a86 100644
@@ -12,6 +12,7 @@ struct platform_pwm_backlight_data {
 	unsigned int dft_brightness;
 	unsigned int lth_brightness;
 	unsigned int pwm_period_ns;
+	unsigned int *levels;
 	int (*init)(struct device *dev);
 	int (*notify)(struct device *dev, int brightness);
 	void (*notify_after)(struct device *dev, int brightness);

1.7.9.6

[Tested on mach-mxs]

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I'm taking over the maintainership of the PWM subsystem. This commit also adds the URLs to the gitorious project and repository as well as any missing files related to the PWM subsystem.

---
Note: I guess this patch in particular could use some Acked-by, maybe from Arnd and Sascha so that people will know this happens with their blessing.

 MAINTAINERS |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

index 275db57..55a11ab 100644
@@ -5420,10 +5420,16 @@ S:	Maintained
 F:	Documentation/video4linux/README.pvrusb2
 F:	drivers/media/video/pvrusb2/
 
-PWM core
-M:	Sascha Hauer <[email protected]>
+PWM SUBSYSTEM
+M:	Thierry Reding <[email protected]>
 L:	linux-kernel at vger.kernel.org
 S:	Maintained
+W:	http://gitorious.org/linux-pwm
+T:	git git://gitorious.org/linux-pwm/linux-pwm.git
+F:	Documentation/pwm.txt
+F:	Documentation/devicetree/bindings/pwm/
+F:	include/linux/pwm.h
+F:	include/linux/of_pwm.h
 F:	drivers/pwm/
 
 PXA2xx/PXA3xx SUPPORT

1.7.9.6

As far as I can tell the series is in pretty good shape. I've integrated Shawn's latest comments and I think we could get this into 3.5. Does it make sense to take the PWM tree through Linux next before having it pulled into mainline during the next merge window?

Thierry
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Yes, that's the way to go. Just ask Stephen Rothwell to include it right away if you are sufficiently happy with the contents and believe that they don't break stuff.

Arnd

I just saw that there's been some discussion to remove IS_ENABLED() and replace it by something else. So maybe I should wait another day or two until those changes settle in next.

Thierry
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Seems like this issue is resolved, but something else came up. In the !OF builds, of_pwm_request() no longer builds because of_property_match_string() and of_parse_phandle_with_args() have no dummies for !OF. I've posted patches for these on Friday and they need to go in before the PWM subsystem. I could also revert the IS_ENABLED() parts and go back to a #ifdef CONFIG_OF but I'd rather not.

Thierry
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Agreed, using IS_ENABLED from C code is much nicer than #ifdef because we can be sure that all code actually builds.

Arnd

Hi Thierry,

Le Tue, 10 Apr 2012 17:06:23 +0200,
Thierry Reding <[email protected]> a ?crit :

for pwm-core & pwm-imx (with the 3 patches I sent a few minutes ago) :

Thanks !

Eric

..snip..
..snip..

I am planning to add PWM support in Linux for TI AM335x SOC. I am taking your new PWM framework as reference.

I see a lot of ack's for the patches. I see that you are maintaining these patches in a separate repo. However, I couldn't find any of these
patches in the mainline kernel (including recent 3.5-rc2).
Do you have any plans for pushing this again to mainline kernel.

Regards,
Gururaja

Yes, as a matter of fact I'm in the process of getting the series ready for inclusion into linux-next. I expect them to go into 3.6.

Thierry
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..snip..
..snip..

Thanks. Eagerly looking forward to it.

Thanks & Regards,
Gururaja