diff mbox series

[v4,1/7] leds: add TI LMU backlight driver

Message ID 20181023170623.31820-1-dmurphy@ti.com
State New
Headers show
Series [v4,1/7] leds: add TI LMU backlight driver | expand

Commit Message

Dan Murphy Oct. 23, 2018, 5:06 p.m. UTC
From: Pavel Machek <pavel@ucw.cz>


This adds backlight support for the following TI LMU
chips: LM3532, LM3631, LM3632, LM3633, LM3695 and LM3697.

It controls LEDs on Droid 4
smartphone, including keyboard and screen backlights.

Signed-off-by: Milo Kim <milo.kim@ti.com>

[add LED subsystem support for keyboard backlight and rework DT
binding according to Rob Herrings feedback]
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

[remove backlight subsystem support for now]
Signed-off-by: Pavel Machek <pavel@ucw.cz>

---
 drivers/leds/Kconfig              |   8 ++
 drivers/leds/Makefile             |   1 +
 drivers/leds/ti-lmu-led-common.c  | 138 ++++++++++++++++++++++++++++++
 include/linux/ti-lmu-led-common.h |  59 +++++++++++++
 4 files changed, 206 insertions(+)
 create mode 100644 drivers/leds/ti-lmu-led-common.c
 create mode 100644 include/linux/ti-lmu-led-common.h

-- 
2.19.0

Comments

Rob Herring Oct. 24, 2018, 2:49 p.m. UTC | #1
On Tue, Oct 23, 2018 at 12:06:18PM -0500, Dan Murphy wrote:
> The LM3697 is a single function LED driver. The single function LED

> driver needs to reside in the LED directory as a dedicated LED driver

> and not as a MFD device.  The device does have common brightness and ramp

> features and those can be accomodated by a TI LMU framework.

> 

> The LM3697 dt binding needs to be moved from the ti-lmu.txt and a dedicated

> LED dt binding needs to be added.  The new LM3697 LED dt binding will then

> reside in the Documentation/devicetree/bindings/leds directory and follow the

> current LED and general bindings guidelines.

> 

> Signed-off-by: Dan Murphy <dmurphy@ti.com>

> ---

> 

> v4 - Squashed removal and addition of the dt bindings into a single patch - https://lore.kernel.org/patchwork/patch/998703/


Still not really the sequence I'd like to see and what I think would 
help the discussion move along.

Patch 1: move all the devices out of ti-lmu.txt into the grouping which 
makes sense. IOW, no functional changes. Probably only strict 
sub/supersets of each other should be shared.

Patch 2-N: Make binding changes. Then we discuss things like ramp time 
properties separately from binding structure.

> 

>  .../devicetree/bindings/leds/leds-lm3697.txt  | 98 +++++++++++++++++++

>  .../devicetree/bindings/mfd/ti-lmu.txt        | 26 +----

>  2 files changed, 99 insertions(+), 25 deletions(-)

>  create mode 100644 Documentation/devicetree/bindings/leds/leds-lm3697.txt
Rob Herring Oct. 24, 2018, 2:54 p.m. UTC | #2
On Wed, Oct 24, 2018 at 07:07:57AM -0500, Dan Murphy wrote:
> Pavel

> 

> On 10/24/2018 04:04 AM, Pavel Machek wrote:

> > Hi!

> > 

> >> The LM3697 is a single function LED driver. The single function LED

> >> driver needs to reside in the LED directory as a dedicated LED driver

> >> and not as a MFD device.  The device does have common brightness and ramp

> > 

> > So it is single function LED driver. That does not mean it can not

> > share bindings with the rest. Where the bindings live is not imporant.

> > 

> 

> It can share bindings that are correctly done, not ones that are incomplete and incorrect.

> 

> Where bindings live is important to new Linux kernel developers and product 

> developers looking for the proper documentation on the H/W bindings.

> 

> >> reside in the Documentation/devicetree/bindings/leds directory and follow the

> >> current LED and general bindings guidelines.

> > 

> > What you forgot to tell us in the changelog:

> 

> I can add this to the changelog.

> 

> > 

> >> +Optional child properties:

> >> +	- runtime-ramp-up-msec: Current ramping from one brightness level to

> >> +				the a higher brightness level.

> >> +				Range from 2048 us - 117.44 s

> > 

> > The other binding uses "ramp-up-msec". Tell us why you are changing this, or

> > better don't change things needlessly.

> > 

> > We don't want to be using "runtime-ramp-up-msec" for one device and

> > "ramp-up-msec" for the other.

> 

> This is another example of how the original bindings were incorrect and misleading.

> 

> The LM3697 have 2 ramp implementations that can be used.

> 

> Startup/Shutdown ramp and Runtime Ramp.  Same Ramp rates different registers and

> different end user experience.

> 

> So having a single node call ramp-up-msec is misleading and it does not

> indicate what the H/W will do.


The existing ones aren't documented (present in the example is not 
documented). This seems like something that should be common rather than 
TI specific. Though it also seems more like something the user would 
want to control (i.e. sysfs) rather than fixed in DT.

Rob
diff mbox series

Patch

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 44097a3e0fcc..dc717b30d9d3 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -756,6 +756,14 @@  config LEDS_NIC78BX
 	  To compile this driver as a module, choose M here: the module
 	  will be called leds-nic78bx.
 
+config LEDS_TI_LMU_COMMON
+	tristate "LED driver for TI LMU"
+	depends on REGMAP
+	help
+          Say Y to enable the LED driver for TI LMU devices.
+          This supports common features between the TI LM3532, LM3631, LM3632,
+	  LM3633, LM3695 and LM3697.
+
 comment "LED Triggers"
 source "drivers/leds/trigger/Kconfig"
 
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 420b5d2cfa62..e09bb27bc7ea 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -78,6 +78,7 @@  obj-$(CONFIG_LEDS_MT6323)		+= leds-mt6323.o
 obj-$(CONFIG_LEDS_LM3692X)		+= leds-lm3692x.o
 obj-$(CONFIG_LEDS_SC27XX_BLTC)		+= leds-sc27xx-bltc.o
 obj-$(CONFIG_LEDS_LM3601X)		+= leds-lm3601x.o
+obj-$(CONFIG_LEDS_TI_LMU_COMMON)	+= ti-lmu-led-common.o
 
 # LED SPI Drivers
 obj-$(CONFIG_LEDS_CR0014114)		+= leds-cr0014114.o
diff --git a/drivers/leds/ti-lmu-led-common.c b/drivers/leds/ti-lmu-led-common.c
new file mode 100644
index 000000000000..a4435bd1d248
--- /dev/null
+++ b/drivers/leds/ti-lmu-led-common.c
@@ -0,0 +1,138 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2015 Texas Instruments
+ * Copyright 2018 Sebastian Reichel
+ * Copyright 2018 Pavel Machek <pavel@ucw.cz>
+ *
+ * TI LMU Led driver, based on previous work from
+ * Milo Kim <milo.kim@ti.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/notifier.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+#include <linux/ti-lmu-led-common.h>
+
+const static int ramp_table[16] = { 2, 262, 524, 1049, 2090, 4194, 8389,
+				16780, 33550, 41940, 50330, 58720,
+				67110, 83880, 100660, 117440};
+
+static int ti_lmu_common_update_brightness_register(struct ti_lmu_bank *lmu_bank,
+						       int brightness)
+{
+	struct regmap *regmap = lmu_bank->regmap;
+	u8 reg, val;
+	int ret;
+
+	/*
+	 * Brightness register update
+	 *
+	 * 11 bit dimming: update LSB bits and write MSB byte.
+	 *		   MSB brightness should be shifted.
+	 *  8 bit dimming: write MSB byte.
+	 */
+	if (lmu_bank->max_brightness == MAX_BRIGHTNESS_11BIT) {
+		reg = lmu_bank->lsb_brightness_reg;
+		ret = regmap_update_bits(regmap, reg,
+					 LMU_11BIT_LSB_MASK,
+					 brightness);
+		if (ret)
+			return ret;
+
+		val = brightness >> LMU_11BIT_MSB_SHIFT;
+	} else {
+		val = brightness;
+	}
+
+	reg = lmu_bank->msb_brightness_reg;
+
+	return regmap_write(regmap, reg, val);
+}
+
+int ti_lmu_common_set_brightness(struct ti_lmu_bank *lmu_bank,
+				    int brightness)
+{
+	lmu_bank->current_brightness = brightness;
+
+	return ti_lmu_common_update_brightness_register(lmu_bank, brightness);
+}
+EXPORT_SYMBOL(ti_lmu_common_set_brightness);
+
+static int ti_lmu_common_convert_ramp_to_index(unsigned int msec)
+{
+	int size = ARRAY_SIZE(ramp_table);
+	int i;
+
+	if (msec <= ramp_table[0])
+		return 0;
+
+	if (msec > ramp_table[size - 1])
+		return size - 1;
+
+	for (i = 1; i < size; i++) {
+		if (msec == ramp_table[i])
+			return i;
+
+		/* Find an approximate index by looking up the table */
+		if (msec > ramp_table[i - 1] && msec < ramp_table[i]) {
+			if (msec - ramp_table[i - 1] < ramp_table[i] - msec)
+				return i - 1;
+			else
+				return i;
+		}
+	}
+
+	return -EINVAL;
+}
+
+int ti_lmu_common_set_ramp(struct ti_lmu_bank *lmu_bank)
+{
+	struct regmap *regmap = lmu_bank->regmap;
+	u8 ramp, ramp_up, ramp_down;
+
+	if (lmu_bank->ramp_up_msec == 0 && lmu_bank->ramp_down_msec == 0) {
+		ramp_up = 0;
+		ramp_down = 0;
+	} else {
+		ramp_up = ti_lmu_common_convert_ramp_to_index(lmu_bank->ramp_up_msec);
+		ramp_down = ti_lmu_common_convert_ramp_to_index(lmu_bank->ramp_down_msec);
+	}
+
+	if (ramp_up < 0 || ramp_down < 0)
+		return -EINVAL;
+
+	ramp = (ramp_up << 4) | ramp_down;
+
+	return regmap_write(regmap, lmu_bank->runtime_ramp_reg, ramp);
+
+}
+EXPORT_SYMBOL(ti_lmu_common_set_ramp);
+
+int ti_lmu_common_get_ramp_params(struct device *dev,
+				  struct fwnode_handle *child,
+				  struct ti_lmu_bank *lmu_data)
+{
+	int ret;
+
+	ret = fwnode_property_read_u32(child, "ramp-up-ms",
+				 &lmu_data->ramp_up_msec);
+	if (ret)
+		dev_warn(dev, "ramp-up-ms property missing\n");
+
+
+	ret = fwnode_property_read_u32(child, "ramp-down-ms",
+				 &lmu_data->ramp_down_msec);
+	if (ret)
+		dev_warn(dev, "ramp-down-ms property missing\n");
+
+	return 0;
+}
+EXPORT_SYMBOL(ti_lmu_common_get_ramp_params);
+
+MODULE_DESCRIPTION("TI LMU LED Driver");
+MODULE_AUTHOR("Sebastian Reichel");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:ti-lmu-led");
diff --git a/include/linux/ti-lmu-led-common.h b/include/linux/ti-lmu-led-common.h
new file mode 100644
index 000000000000..b0fe08f05be2
--- /dev/null
+++ b/include/linux/ti-lmu-led-common.h
@@ -0,0 +1,59 @@ 
+// SPDX-License-Identifier: GPL-2.0
+// TI LMU Common Core
+// Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
+
+#ifndef _TI_LMU_COMMON_H_
+#define _TI_LMU_COMMON_H_
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <uapi/linux/uleds.h>
+
+#define LMU_DUAL_CHANNEL_USED	(BIT(0) | BIT(1))
+#define LMU_11BIT_LSB_MASK	(BIT(0) | BIT(1) | BIT(2))
+#define LMU_11BIT_MSB_SHIFT	3
+
+#define MAX_BRIGHTNESS_8BIT	255
+#define MAX_BRIGHTNESS_11BIT	2047
+
+#define NUM_DUAL_CHANNEL	2
+
+struct ti_lmu_bank {
+	struct regmap *regmap;
+
+	int bank_id;
+	int fault_monitor_used;
+
+	u8 enable_reg;
+	unsigned long enable_usec;
+
+	int current_brightness;
+	u32 default_brightness;
+	int max_brightness;
+
+	u8 lsb_brightness_reg;
+	u8 msb_brightness_reg;
+
+	u8 runtime_ramp_reg;
+	u32 ramp_up_msec;
+	u32 ramp_down_msec;
+};
+
+
+int ti_lmu_common_set_brightness(struct ti_lmu_bank *lmu_bank,
+				    int brightness);
+
+int ti_lmu_common_set_ramp(struct ti_lmu_bank *lmu_bank);
+
+int ti_lmu_common_get_ramp_params(struct device *dev,
+				  struct fwnode_handle *child,
+				  struct ti_lmu_bank *lmu_data);
+
+#endif /* _TI_LMU_COMMON_H_ */