Re: [PATCH v14 2/2] leds: Add driver for Qualcomm LPG

[Marijn Suijten]

Apologies for replying twice to the same patch with disjoint review.

On 2022-03-03 13:43:00, Bjorn Andersson wrote:
> The Light Pulse Generator (LPG) is a PWM-block found in a wide range of
> PMICs from Qualcomm. These PMICs typically comes with 1-8 LPG instances,
> with their output being routed to various other components, such as
> current sinks or GPIOs.
>
> Each LPG instance can operate on fixed parameters or based on a shared
> lookup-table, altering the duty cycle over time. This provides the means
> for hardware assisted transitions of LED brightness.
>
> A typical use case for the fixed parameter mode is to drive a PWM
> backlight control signal, the driver therefor allows each LPG instance
> to be exposed to the kernel either through the LED framework or the PWM
> framework.
>
> A typical use case for the LED configuration is to drive RGB LEDs in
> smartphones etc, for which the driver supports multiple channels to be
> ganged up to a MULTICOLOR LED. In this configuration the pattern
> generators will be synchronized, to allow for multi-color patterns.
>
> The idea of modelling this as a LED driver ontop of a PWM driver was
> considered, but setting the properties related to patterns does not fit
> in the PWM API. Similarly the idea of just duplicating the lower bits in
> a PWM and LED driver separately was considered, but this would not allow
> the PWM channels and LEDs to be configured on a per-board basis. The
> driver implements the more complex LED interface, and provides a PWM
> interface on the side of that, in the same driver.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>

Having seen most of the patch revisions over time, I'm now happy to add
yet another:

Reviewed-by: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>

and, if relevant on top of a review:

Tested-by: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>
[On the Sony Xperia Nile Discovery, SDM630]

Some nits follow.

> ---
>
> Changes since v13:
> - Fixed mixed space/tab indentation in documentation
> - Added 0 as to lpg_clk_rates[] to match the hardware state, to avoid + 1 in
>   lpg_apply_freq() and - 1 in lpg_pwm_get_state()
> - Don't divide with 0 if current clock is 0 in lpg_pwm_get_state(), just return
>   period = duty = 0 in this case
> - Renamed "clk" in struct lpg_channel to clk_sel
> - Renamed "pre_div" in struct lpg_channel to pre_div_sel
>
> Changes since v12:
> - Initialize ret in lpg_pwm_apply()
>
> Changes since v11:
> - Extended commit message to cover decision to put pwm_chip in the LED driver
> - Added Documentation, in particular for the hw_pattern format
> - Added a lock to synchronize requests from LED and PWM frameworks
> - Turned out that the 9bit selector differs per channel in some PMICs, so
>   replaced bitmask in lpg_data with lookup based on QPNP SUBTYPE
> - Fixed kerneldoc for the struct device pointer in struct lpg
> - Rewrote conditional in lut_free() to make it easier to read
> - Corrected and deduplicated max_period expression in lpg_calc_freq()
> - Extended nom/dom to numerator/denominator in lpg_calc_freq()
> - Replaced 1 << 9 with LPG_RESOLUTION in one more place in lpg_calc_freq()
> - Use FIELD_PREP() in lpg_apply_freq() as masks was introduced for reading the
>   same in get_state()
> - Cleaned up the pattern format, to allow specifying both low and high pause
>   with and without pingpong mode.
> - Only update frequency and pwm_value if PWM channel is enabled in lpg_pwm_apply
> - Make lpg_pwm_get_state() read the hardware state, in order to pick up e.g.
>   bootloader backlight configuration
> - Use devm_bitmap_zalloc() to allocate the lut_bitmap
> - Use dev_err_probe() in lpg_probe()
> - Extended Kconfig help text to mention module name and satisfy checkpatch
>
>  Documentation/leds/leds-qcom-lpg.rst |   76 ++
>  drivers/leds/Kconfig                 |    3 +
>  drivers/leds/Makefile                |    3 +
>  drivers/leds/rgb/Kconfig             |   18 +
>  drivers/leds/rgb/Makefile            |    3 +
>  drivers/leds/rgb/leds-qcom-lpg.c     | 1405 ++++++++++++++++++++++++++
>  6 files changed, 1508 insertions(+)
>  create mode 100644 Documentation/leds/leds-qcom-lpg.rst
>  create mode 100644 drivers/leds/rgb/Kconfig
>  create mode 100644 drivers/leds/rgb/Makefile
>  create mode 100644 drivers/leds/rgb/leds-qcom-lpg.c
>
> diff --git a/Documentation/leds/leds-qcom-lpg.rst b/Documentation/leds/leds-qcom-lpg.rst
> new file mode 100644
> index 000000000000..f12416f02dd8
> --- /dev/null
> +++ b/Documentation/leds/leds-qcom-lpg.rst
> @@ -0,0 +1,76 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +==============================
> +Kernel driver for Qualcomm LPG
> +==============================
> +
> +Description
> +-----------
> +
> +The Qualcomm LPG can be found in a variety of Qualcomm PMICs and consists of a
> +number of PWM channels, a programmable pattern lookup table and a RGB LED
> +current sink.
> +
> +To facilitate the various use cases, the LPG channels can be exposed as
> +individual LEDs, grouped together as RGB LEDs or otherwise be accessed as PWM
> +channels. The output of each PWM channel is routed to other hardware
> +blocks, such as the RGB current sink, GPIO pins etc.
> +
> +The each PWM channel can operate with a period between 27us and 384 seconds and
> +has a 9 bit resolution of the duty cycle.
> +
> +In order to provide support for status notifications with the CPU subsystem in
> +deeper idle states the LPG provides pattern support. This consists of a shared
> +lookup table of brightness values and per channel properties to select the
> +range within the table to use, the rate and if the pattern should repeat.
> +
> +The pattern for a channel can be programmed using the "pattern" trigger, using
> +the hw_pattern attribute.
> +
> +/sys/class/leds/<led>/hw_pattern
> +--------------------------------
> +
> +Specify a hardware pattern for a Qualcomm LPG LED.
> +
> +The pattern is a series of brightness and hold-time pairs, with the hold-time
> +expressed in milliseconds. The hold time is a property of the pattern and must
> +therefor be identical for each element in the pattern (except for the pauses
> +described below).
> +
> +Simple pattern::
> +
> +    "255 500 0 500"
> +
> +        ^
> +        |
> +    255 +----+    +----+
> +        |    |    |    |      ...
> +      0 |    +----+    +----
> +        +---------------------->
> +        0    5   10   15     time (100ms)
> +
> +The LPG supports specifying a longer hold-time for the first and last element
> +in the pattern, the so called "low pause" and "high pause".
> +
> +Low-pause pattern::
> +
> +    "255 1000 0 500 255 500 0 500"

Note that this actually holds for 1500ms HIGH on the start and 1000ms
LOW on the end.  That should be easily fixable, and is explained in more
detail below in my review on the appropriate lines of code.

Because of the same issue, the simple "255 500 0 500" pattern above
actually takes 1000ms at the start and stop (every) step.

> +        ^
> +        |
> +    255 +--------+    +----+    +----+    +--------+
> +        |        |    |    |    |    |    |        |      ...
> +      0 |        +----+    +----+    +----+        +----

                                   ^^^^^^^^^

The underlined part of the pattern does not seem to be contained in the
pattern string.  It's high once for 1000ms, then high another time for
500ms (and 500ms in between every step), then repeats.  It does not
become high for 500ms twice nor is it a palindrome that plays in
reverse.

> +        +----------------------------->
> +        0    5   10   15  20   25   time (100ms)
> +
> +Similarily, the last entry can be stretched by using a higher hold-time on the

Similarly*.

How about showcasing this by copying the (fixed) pattern above and
changing the stop duration?  Or is that too verbose?

> +last entry.
> +
> +In order to save space in the shared lookup table the LPG supports "ping-pong"
> +mode, in which case each run through the pattern is performed by first running
> +the pattern forward, then backwards. This mode is automatically used by the
> +driver when the given pattern is a palindrome. In this case the "high pause"
> +denotes the wait time before the pattern is run in reverse and as such the
> +specified hold-time of the middle item in the pattern is allowed to have a
> +different hold-time.

This could perhaps also use a copy-pastable example, for testing :).
Something that "gradually" breathes in and out and holds at the end.

Other than that I have to say this documentation is really, _really_
well written.  It's packed full of information yet very concise to read.

> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 6090e647daee..a49979f41eee 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -869,6 +869,9 @@ source "drivers/leds/blink/Kconfig"
>  comment "Flash and Torch LED drivers"
>  source "drivers/leds/flash/Kconfig"
>
> +comment "RGB LED drivers"
> +source "drivers/leds/rgb/Kconfig"
> +
>  comment "LED Triggers"
>  source "drivers/leds/trigger/Kconfig"
>
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index e58ecb36360f..4fd2f92cd198 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -99,6 +99,9 @@ obj-$(CONFIG_LEDS_USER)			+= uleds.o
>  # Flash and Torch LED Drivers
>  obj-$(CONFIG_LEDS_CLASS_FLASH)		+= flash/
>
> +# RGB LED Drivers
> +obj-$(CONFIG_LEDS_CLASS_MULTICOLOR)	+= rgb/
> +
>  # LED Triggers
>  obj-$(CONFIG_LEDS_TRIGGERS)		+= trigger/
>
> diff --git a/drivers/leds/rgb/Kconfig b/drivers/leds/rgb/Kconfig
> new file mode 100644
> index 000000000000..5dd27ad80856
> --- /dev/null
> +++ b/drivers/leds/rgb/Kconfig
> @@ -0,0 +1,18 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +if LEDS_CLASS_MULTICOLOR
> +
> +config LEDS_QCOM_LPG
> +	tristate "LED support for Qualcomm LPG"
> +	depends on OF
> +	depends on SPMI
> +	help
> +	  This option enables support for the Light Pulse Generator found in a
> +	  wide variety of Qualcomm PMICs. The LPG consists of a number of PWM
> +	  channels and typically a shared pattern lookup table and a current
> +	  sink, intended to drive RGB LEDs. Each channel can either be used as
> +	  a LED, grouped to represent a RGB LED or exposed as PWM channels.
> +
> +	  If compiled as a module, the module will be named leds-qcom-lpg.
> +
> +endif # LEDS_CLASS_MULTICOLOR
> diff --git a/drivers/leds/rgb/Makefile b/drivers/leds/rgb/Makefile
> new file mode 100644
> index 000000000000..83114f44c4ea
> --- /dev/null
> +++ b/drivers/leds/rgb/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +obj-$(CONFIG_LEDS_QCOM_LPG)	+= leds-qcom-lpg.o
> diff --git a/drivers/leds/rgb/leds-qcom-lpg.c b/drivers/leds/rgb/leds-qcom-lpg.c
> new file mode 100644
> index 000000000000..17576f77c423
> --- /dev/null
> +++ b/drivers/leds/rgb/leds-qcom-lpg.c
> @@ -0,0 +1,1405 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2017-2022 Linaro Ltd
> + * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
> + */
> +#include <linux/bits.h>
> +#include <linux/bitfield.h>
> +#include <linux/led-class-multicolor.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +
> +#define LPG_SUBTYPE_REG		0x05
> +#define  LPG_SUBTYPE_LPG	0x2
> +#define  LPG_SUBTYPE_PWM	0xb
> +#define  LPG_SUBTYPE_LPG_LITE	0x11
> +#define LPG_PATTERN_CONFIG_REG	0x40
> +#define LPG_SIZE_CLK_REG	0x41
> +#define  PWM_CLK_SELECT_MASK	GENMASK(1, 0)
> +#define LPG_PREDIV_CLK_REG	0x42
> +#define  PWM_FREQ_PRE_DIV_MASK	GENMASK(6, 5)
> +#define  PWM_FREQ_EXP_MASK	GENMASK(2, 0)
> +#define PWM_TYPE_CONFIG_REG	0x43
> +#define PWM_VALUE_REG		0x44
> +#define PWM_ENABLE_CONTROL_REG	0x46
> +#define PWM_SYNC_REG		0x47
> +#define LPG_RAMP_DURATION_REG	0x50
> +#define LPG_HI_PAUSE_REG	0x52
> +#define LPG_LO_PAUSE_REG	0x54
> +#define LPG_HI_IDX_REG		0x56
> +#define LPG_LO_IDX_REG		0x57
> +#define PWM_SEC_ACCESS_REG	0xd0
> +#define PWM_DTEST_REG(x)	(0xe2 + (x) - 1)
> +
> +#define TRI_LED_SRC_SEL		0x45
> +#define TRI_LED_EN_CTL		0x46
> +#define TRI_LED_ATC_CTL		0x47
> +
> +#define LPG_LUT_REG(x)		(0x40 + (x) * 2)
> +#define RAMP_CONTROL_REG	0xc8
> +
> +#define LPG_RESOLUTION		512
> +#define LPG_MAX_M		7
> +
> +struct lpg_channel;
> +struct lpg_data;
> +
> +/**
> + * struct lpg - LPG device context
> + * @dev:	pointer to LPG device
> + * @map:	regmap for register access
> + * @lock:	used to synchronize LED and pwm callback requests
> + * @pwm:	PWM-chip object, if operating in PWM mode
> + * @data:	reference to version specific data
> + * @lut_base:	base address of the LUT block (optional)
> + * @lut_size:	number of entries in the LUT block
> + * @lut_bitmap:	allocation bitmap for LUT entries
> + * @triled_base: base address of the TRILED block (optional)
> + * @triled_src:	power-source for the TRILED
> + * @triled_has_atc_ctl:	true if there is TRI_LED_ATC_CTL register
> + * @triled_has_src_sel:	true if there is TRI_LED_SRC_SEL register
> + * @channels:	list of PWM channels
> + * @num_channels: number of @channels

Nit: It seems the members here and in struct lpg_channel are all
misaligned: most should have two tab characters, and no spaces like
@triled_base and @num_channels.

> + */
> +struct lpg {
> +	struct device *dev;
> +	struct regmap *map;
> +
> +	struct mutex lock;
> +
> +	struct pwm_chip pwm;
> +
> +	const struct lpg_data *data;
> +
> +	u32 lut_base;
> +	u32 lut_size;
> +	unsigned long *lut_bitmap;
> +
> +	u32 triled_base;
> +	u32 triled_src;
> +	bool triled_has_atc_ctl;
> +	bool triled_has_src_sel;
> +
> +	struct lpg_channel *channels;
> +	unsigned int num_channels;
> +};
> +
> +/**
> + * struct lpg_channel - per channel data
> + * @lpg:	reference to parent lpg
> + * @base:	base address of the PWM channel
> + * @triled_mask: mask in TRILED to enable this channel
> + * @lut_mask:	mask in LUT to start pattern generator for this channel
> + * @subtype:	PMIC hardware block subtype
> + * @in_use:	channel is exposed to LED framework
> + * @color:	color of the LED attached to this channel
> + * @dtest_line:	DTEST line for output, or 0 if disabled
> + * @dtest_value: DTEST line configuration
> + * @pwm_value:	duty (in microseconds) of the generated pulses, overridden by LUT
> + * @enabled:	output enabled?
> + * @period:	period (in nanoseconds) of the generated pulses
> + * @clk_sel:	reference clock frequency selector
> + * @pre_div_sel: divider selector of the reference clock
> + * @pre_div_exp: exponential divider of the reference clock
> + * @ramp_enabled: duty cycle is driven by iterating over lookup table
> + * @ramp_ping_pong: reverse through pattern, rather than wrapping to start
> + * @ramp_oneshot: perform only a single pass over the pattern
> + * @ramp_reverse: iterate over pattern backwards
> + * @ramp_tick_ms: length (in milliseconds) of one step in the pattern
> + * @ramp_lo_pause_ms: pause (in milliseconds) before iterating over pattern
> + * @ramp_hi_pause_ms: pause (in milliseconds) after iterating over pattern
> + * @pattern_lo_idx: start index of associated pattern
> + * @pattern_hi_idx: last index of associated pattern

So, same here.  Should it be a single space, or enough tab characters to
align them all?

> + */
> +struct lpg_channel {
> +	struct lpg *lpg;
> +
> +	u32 base;
> +	unsigned int triled_mask;
> +	unsigned int lut_mask;
> +	unsigned int subtype;
> +
> +	bool in_use;
> +
> +	int color;
> +
> +	u32 dtest_line;
> +	u32 dtest_value;
> +
> +	u16 pwm_value;
> +	bool enabled;
> +
> +	u64 period;
> +	unsigned int clk_sel;
> +	unsigned int pre_div_sel;
> +	unsigned int pre_div_exp;
> +
> +	bool ramp_enabled;
> +	bool ramp_ping_pong;
> +	bool ramp_oneshot;
> +	bool ramp_reverse;
> +	unsigned short ramp_tick_ms;
> +	unsigned long ramp_lo_pause_ms;
> +	unsigned long ramp_hi_pause_ms;
> +
> +	unsigned int pattern_lo_idx;
> +	unsigned int pattern_hi_idx;
> +};
> +
> +/**
> + * struct lpg_led - logical LED object
> + * @lpg:		lpg context reference
> + * @cdev:		LED class device
> + * @mcdev:		Multicolor LED class device
> + * @num_channels:	number of @channels
> + * @channels:		list of channels associated with the LED
> + */
> +struct lpg_led {
> +	struct lpg *lpg;
> +
> +	struct led_classdev cdev;
> +	struct led_classdev_mc mcdev;
> +
> +	unsigned int num_channels;
> +	struct lpg_channel *channels[];
> +};
> +
> +/**
> + * struct lpg_channel_data - per channel initialization data
> + * @base:		base address for PWM channel registers
> + * @triled_mask:	bitmask for controlling this channel in TRILED
> + */
> +struct lpg_channel_data {
> +	unsigned int base;
> +	u8 triled_mask;
> +};
> +
> +/**
> + * struct lpg_data - initialization data
> + * @lut_base:		base address of LUT block
> + * @lut_size:		number of entries in LUT
> + * @triled_base:	base address of TRILED
> + * @triled_has_atc_ctl:	true if there is TRI_LED_ATC_CTL register
> + * @triled_has_src_sel:	true if there is TRI_LED_SRC_SEL register
> + * @num_channels:	number of channels in LPG
> + * @channels:		list of channel initialization data
> + */
> +struct lpg_data {
> +	unsigned int lut_base;
> +	unsigned int lut_size;
> +	unsigned int triled_base;
> +	bool triled_has_atc_ctl;
> +	bool triled_has_src_sel;
> +	int num_channels;
> +	const struct lpg_channel_data *channels;
> +};
> +
> +static int triled_set(struct lpg *lpg, unsigned int mask, unsigned int enable)
> +{
> +	/* Skip if we don't have a triled block */
> +	if (!lpg->triled_base)
> +		return 0;
> +
> +	return regmap_update_bits(lpg->map, lpg->triled_base + TRI_LED_EN_CTL,
> +				  mask, enable);
> +}
> +
> +static int lpg_lut_store(struct lpg *lpg, struct led_pattern *pattern,
> +			 size_t len, unsigned int *lo_idx, unsigned int *hi_idx)
> +{
> +	unsigned int idx;
> +	u16 val;
> +	int i;
> +
> +	idx = bitmap_find_next_zero_area(lpg->lut_bitmap, lpg->lut_size,
> +					 0, len, 0);
> +	if (idx >= lpg->lut_size)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < len; i++) {
> +		val = pattern[i].brightness;
> +
> +		regmap_bulk_write(lpg->map, lpg->lut_base + LPG_LUT_REG(idx + i),
> +				  &val, sizeof(val));
> +	}
> +
> +	bitmap_set(lpg->lut_bitmap, idx, len);
> +
> +	*lo_idx = idx;
> +	*hi_idx = idx + len - 1;
> +
> +	return 0;
> +}
> +
> +static void lpg_lut_free(struct lpg *lpg, unsigned int lo_idx, unsigned int hi_idx)
> +{
> +	int len;
> +
> +	len = hi_idx - lo_idx + 1;
> +	if (len == 1)
> +		return;
> +
> +	bitmap_clear(lpg->lut_bitmap, lo_idx, len);
> +}
> +
> +static int lpg_lut_sync(struct lpg *lpg, unsigned int mask)
> +{
> +	return regmap_write(lpg->map, lpg->lut_base + RAMP_CONTROL_REG, mask);
> +}
> +
> +static const unsigned int lpg_clk_rates[] = {0, 1024, 32768, 19200000};
> +static const unsigned int lpg_pre_divs[] = {1, 3, 5, 6};
> +
> +static int lpg_calc_freq(struct lpg_channel *chan, uint64_t period)
> +{
> +	unsigned int clk_sel, best_clk = 0;
> +	unsigned int div, best_div = 0;
> +	unsigned int m, best_m = 0;
> +	unsigned int error;
> +	unsigned int best_err = UINT_MAX;
> +	u64 best_period = 0;
> +	u64 max_period;
> +
> +	/*
> +	 * The PWM period is determined by:
> +	 *
> +	 *          resolution * pre_div * 2^M
> +	 * period = --------------------------
> +	 *                   refclk
> +	 *
> +	 * With resolution fixed at 2^9 bits, pre_div = {1, 3, 5, 6} and
> +	 * M = [0..7].
> +	 *
> +	 * This allows for periods between 27uS and 384s, as the PWM framework
> +	 * wants a period of equal or lower length than requested, reject
> +	 * anything below 27uS.
> +	 */
> +	if (period <= (u64)NSEC_PER_SEC * LPG_RESOLUTION / 19200000)
> +		return -EINVAL;
> +
> +	/* Limit period to largest possible value, to avoid overflows */
> +	max_period = (u64)NSEC_PER_SEC * LPG_RESOLUTION * 6 * (1 << LPG_MAX_M) / 1024;
> +	if (period > max_period)
> +		period = max_period;
> +
> +	/*
> +	 * Search for the pre_div, refclk and M by solving the rewritten formula
> +	 * for each refclk and pre_div value:
> +	 *
> +	 *                     period * refclk
> +	 * M = log2 -------------------------------------
> +	 *           NSEC_PER_SEC * pre_div * resolution
> +	 */
> +	for (clk_sel = 1; clk_sel < ARRAY_SIZE(lpg_clk_rates); clk_sel++) {
> +		u64 numerator = period * lpg_clk_rates[clk_sel];
> +
> +		for (div = 0; div < ARRAY_SIZE(lpg_pre_divs); div++) {
> +			u64 denominator = (u64)NSEC_PER_SEC * lpg_pre_divs[div] * LPG_RESOLUTION;
> +			u64 actual;
> +			u64 ratio;
> +
> +			if (numerator < denominator)
> +				continue;
> +
> +			ratio = div64_u64(numerator, denominator);
> +			m = ilog2(ratio);
> +			if (m > LPG_MAX_M)
> +				m = LPG_MAX_M;
> +
> +			actual = DIV_ROUND_UP_ULL(denominator * (1 << m), lpg_clk_rates[clk_sel]);
> +
> +			error = period - actual;
> +			if (error < best_err) {
> +				best_err = error;
> +
> +				best_div = div;
> +				best_m = m;
> +				best_clk = clk_sel;
> +				best_period = actual;
> +			}
> +		}
> +	}
> +
> +	chan->clk_sel = best_clk;
> +	chan->pre_div_sel = best_div;
> +	chan->pre_div_exp = best_m;
> +	chan->period = best_period;
> +
> +	return 0;
> +}
> +
> +static void lpg_calc_duty(struct lpg_channel *chan, uint64_t duty)
> +{
> +	unsigned int max = LPG_RESOLUTION - 1;
> +	unsigned int val;
> +
> +	val = div64_u64(duty * lpg_clk_rates[chan->clk_sel],
> +			(u64)NSEC_PER_SEC * lpg_pre_divs[chan->pre_div_sel] * (1 << chan->pre_div_exp));
> +
> +	chan->pwm_value = min(val, max);
> +}
> +
> +static void lpg_apply_freq(struct lpg_channel *chan)
> +{
> +	unsigned long val;
> +	struct lpg *lpg = chan->lpg;
> +
> +	if (!chan->enabled)
> +		return;
> +
> +	val = chan->clk_sel;
> +
> +	/* Specify 9bit resolution, based on the subtype of the channel */
> +	switch (chan->subtype) {
> +	case LPG_SUBTYPE_LPG:
> +		val |= GENMASK(5, 4);
> +		break;
> +	case LPG_SUBTYPE_PWM:
> +		val |= BIT(2);
> +		break;
> +	case LPG_SUBTYPE_LPG_LITE:
> +	default:
> +		val |= BIT(4);
> +		break;
> +	}
> +
> +	regmap_write(lpg->map, chan->base + LPG_SIZE_CLK_REG, val);
> +
> +	val = FIELD_PREP(PWM_FREQ_PRE_DIV_MASK, chan->pre_div_sel) |
> +	      FIELD_PREP(PWM_FREQ_EXP_MASK, chan->pre_div_exp);
> +	regmap_write(lpg->map, chan->base + LPG_PREDIV_CLK_REG, val);
> +}
> +
> +#define LPG_ENABLE_GLITCH_REMOVAL	BIT(5)
> +
> +static void lpg_enable_glitch(struct lpg_channel *chan)
> +{
> +	struct lpg *lpg = chan->lpg;
> +
> +	regmap_update_bits(lpg->map, chan->base + PWM_TYPE_CONFIG_REG,
> +			   LPG_ENABLE_GLITCH_REMOVAL, 0);
> +}
> +
> +static void lpg_disable_glitch(struct lpg_channel *chan)
> +{
> +	struct lpg *lpg = chan->lpg;
> +
> +	regmap_update_bits(lpg->map, chan->base + PWM_TYPE_CONFIG_REG,
> +			   LPG_ENABLE_GLITCH_REMOVAL,
> +			   LPG_ENABLE_GLITCH_REMOVAL);
> +}
> +
> +static void lpg_apply_pwm_value(struct lpg_channel *chan)
> +{
> +	struct lpg *lpg = chan->lpg;
> +	u16 val = chan->pwm_value;
> +
> +	if (!chan->enabled)
> +		return;
> +
> +	regmap_bulk_write(lpg->map, chan->base + PWM_VALUE_REG, &val, sizeof(val));
> +}
> +
> +#define LPG_PATTERN_CONFIG_LO_TO_HI	BIT(4)
> +#define LPG_PATTERN_CONFIG_REPEAT	BIT(3)
> +#define LPG_PATTERN_CONFIG_TOGGLE	BIT(2)
> +#define LPG_PATTERN_CONFIG_PAUSE_HI	BIT(1)
> +#define LPG_PATTERN_CONFIG_PAUSE_LO	BIT(0)
> +
> +static void lpg_apply_lut_control(struct lpg_channel *chan)
> +{
> +	struct lpg *lpg = chan->lpg;
> +	unsigned int hi_pause;
> +	unsigned int lo_pause;
> +	unsigned int conf = 0;
> +	unsigned int lo_idx = chan->pattern_lo_idx;
> +	unsigned int hi_idx = chan->pattern_hi_idx;
> +	u16 step = chan->ramp_tick_ms;
> +
> +	if (!chan->ramp_enabled || chan->pattern_lo_idx == chan->pattern_hi_idx)
> +		return;
> +
> +	hi_pause = DIV_ROUND_UP(chan->ramp_hi_pause_ms, step);
> +	lo_pause = DIV_ROUND_UP(chan->ramp_lo_pause_ms, step);
> +
> +	if (!chan->ramp_reverse)
> +		conf |= LPG_PATTERN_CONFIG_LO_TO_HI;
> +	if (!chan->ramp_oneshot)
> +		conf |= LPG_PATTERN_CONFIG_REPEAT;
> +	if (chan->ramp_ping_pong)
> +		conf |= LPG_PATTERN_CONFIG_TOGGLE;
> +	if (chan->ramp_hi_pause_ms)
> +		conf |= LPG_PATTERN_CONFIG_PAUSE_HI;
> +	if (chan->ramp_lo_pause_ms)
> +		conf |= LPG_PATTERN_CONFIG_PAUSE_LO;
> +
> +	regmap_write(lpg->map, chan->base + LPG_PATTERN_CONFIG_REG, conf);
> +	regmap_write(lpg->map, chan->base + LPG_HI_IDX_REG, hi_idx);
> +	regmap_write(lpg->map, chan->base + LPG_LO_IDX_REG, lo_idx);
> +
> +	regmap_bulk_write(lpg->map, chan->base + LPG_RAMP_DURATION_REG, &step, sizeof(step));
> +	regmap_write(lpg->map, chan->base + LPG_HI_PAUSE_REG, hi_pause);
> +	regmap_write(lpg->map, chan->base + LPG_LO_PAUSE_REG, lo_pause);
> +}
> +
> +#define LPG_ENABLE_CONTROL_OUTPUT		BIT(7)
> +#define LPG_ENABLE_CONTROL_BUFFER_TRISTATE	BIT(5)
> +#define LPG_ENABLE_CONTROL_SRC_PWM		BIT(2)
> +#define LPG_ENABLE_CONTROL_RAMP_GEN		BIT(1)
> +
> +static void lpg_apply_control(struct lpg_channel *chan)
> +{
> +	unsigned int ctrl;
> +	struct lpg *lpg = chan->lpg;
> +
> +	ctrl = LPG_ENABLE_CONTROL_BUFFER_TRISTATE;
> +
> +	if (chan->enabled)
> +		ctrl |= LPG_ENABLE_CONTROL_OUTPUT;
> +
> +	if (chan->pattern_lo_idx != chan->pattern_hi_idx)
> +		ctrl |= LPG_ENABLE_CONTROL_RAMP_GEN;
> +	else
> +		ctrl |= LPG_ENABLE_CONTROL_SRC_PWM;
> +
> +	regmap_write(lpg->map, chan->base + PWM_ENABLE_CONTROL_REG, ctrl);
> +
> +	/*
> +	 * Due to LPG hardware bug, in the PWM mode, having enabled PWM,
> +	 * We have to write PWM values one more time.

Nit: If we're going for v15 anyway, could you reword this comment to be
a bit easier to read?

> +	 */
> +	if (chan->enabled)
> +		lpg_apply_pwm_value(chan);
> +}
> +
> +#define LPG_SYNC_PWM	BIT(0)
> +
> +static void lpg_apply_sync(struct lpg_channel *chan)
> +{
> +	struct lpg *lpg = chan->lpg;
> +
> +	regmap_write(lpg->map, chan->base + PWM_SYNC_REG, LPG_SYNC_PWM);
> +}
> +
> +static int lpg_parse_dtest(struct lpg *lpg)
> +{
> +	struct lpg_channel *chan;
> +	struct device_node *np = lpg->dev->of_node;
> +	int count;
> +	int ret;
> +	int i;
> +
> +	count = of_property_count_u32_elems(np, "qcom,dtest");
> +	if (count == -EINVAL) {
> +		return 0;
> +	} else if (count < 0) {
> +		ret = count;
> +		goto err_malformed;
> +	} else if (count != lpg->data->num_channels * 2) {
> +		dev_err(lpg->dev, "qcom,dtest needs to be %d items\n",
> +			lpg->data->num_channels * 2);
> +		return -EINVAL;
> +	}
> +
> +	for (i = 0; i < lpg->data->num_channels; i++) {
> +		chan = &lpg->channels[i];
> +
> +		ret = of_property_read_u32_index(np, "qcom,dtest", i * 2,
> +						 &chan->dtest_line);
> +		if (ret)
> +			goto err_malformed;
> +
> +		ret = of_property_read_u32_index(np, "qcom,dtest", i * 2 + 1,
> +						 &chan->dtest_value);
> +		if (ret)
> +			goto err_malformed;
> +	}
> +
> +	return 0;
> +
> +err_malformed:
> +	dev_err(lpg->dev, "malformed qcom,dtest\n");
> +	return ret;
> +}
> +
> +static void lpg_apply_dtest(struct lpg_channel *chan)
> +{
> +	struct lpg *lpg = chan->lpg;
> +
> +	if (!chan->dtest_line)
> +		return;
> +
> +	regmap_write(lpg->map, chan->base + PWM_SEC_ACCESS_REG, 0xa5);
> +	regmap_write(lpg->map, chan->base + PWM_DTEST_REG(chan->dtest_line),
> +		     chan->dtest_value);
> +}
> +
> +static void lpg_apply(struct lpg_channel *chan)
> +{
> +	lpg_disable_glitch(chan);
> +	lpg_apply_freq(chan);
> +	lpg_apply_pwm_value(chan);
> +	lpg_apply_control(chan);
> +	lpg_apply_sync(chan);
> +	lpg_apply_lut_control(chan);
> +	lpg_enable_glitch(chan);
> +}
> +
> +static void lpg_brightness_set(struct lpg_led *led, struct led_classdev *cdev,
> +			       struct mc_subled *subleds)
> +{
> +	enum led_brightness brightness;
> +	struct lpg_channel *chan;
> +	unsigned int triled_enabled = 0;
> +	unsigned int triled_mask = 0;
> +	unsigned int lut_mask = 0;
> +	unsigned int duty;
> +	struct lpg *lpg = led->lpg;
> +	int i;
> +
> +	for (i = 0; i < led->num_channels; i++) {
> +		chan = led->channels[i];
> +		brightness = subleds[i].brightness;
> +
> +		if (brightness == LED_OFF) {
> +			chan->enabled = false;
> +			chan->ramp_enabled = false;
> +		} else if (chan->pattern_lo_idx != chan->pattern_hi_idx) {
> +			lpg_calc_freq(chan, NSEC_PER_MSEC);
> +
> +			chan->enabled = true;
> +			chan->ramp_enabled = true;
> +
> +			lut_mask |= chan->lut_mask;
> +			triled_enabled |= chan->triled_mask;
> +		} else {
> +			lpg_calc_freq(chan, NSEC_PER_MSEC);
> +
> +			duty = div_u64(brightness * chan->period, cdev->max_brightness);
> +			lpg_calc_duty(chan, duty);
> +			chan->enabled = true;
> +			chan->ramp_enabled = false;
> +
> +			triled_enabled |= chan->triled_mask;
> +		}
> +
> +		triled_mask |= chan->triled_mask;
> +
> +		lpg_apply(chan);
> +	}
> +
> +	/* Toggle triled lines */
> +	if (triled_mask)
> +		triled_set(lpg, triled_mask, triled_enabled);
> +
> +	/* Trigger start of ramp generator(s) */
> +	if (lut_mask)
> +		lpg_lut_sync(lpg, lut_mask);
> +}
> +
> +static void lpg_brightness_single_set(struct led_classdev *cdev,
> +				      enum led_brightness value)
> +{
> +	struct lpg_led *led = container_of(cdev, struct lpg_led, cdev);
> +	struct mc_subled info;
> +
> +	mutex_lock(&led->lpg->lock);
> +
> +	info.brightness = value;
> +	lpg_brightness_set(led, cdev, &info);
> +
> +	mutex_unlock(&led->lpg->lock);
> +}
> +
> +static void lpg_brightness_mc_set(struct led_classdev *cdev,
> +				  enum led_brightness value)
> +{
> +	struct led_classdev_mc *mc = lcdev_to_mccdev(cdev);
> +	struct lpg_led *led = container_of(mc, struct lpg_led, mcdev);
> +
> +	mutex_lock(&led->lpg->lock);
> +
> +	led_mc_calc_color_components(mc, value);
> +	lpg_brightness_set(led, cdev, mc->subled_info);
> +
> +	mutex_unlock(&led->lpg->lock);
> +}
> +
> +static int lpg_blink_set(struct lpg_led *led,
> +			 unsigned long *delay_on, unsigned long *delay_off)
> +{
> +	struct lpg_channel *chan;
> +	unsigned int period;
> +	unsigned int triled_mask = 0;
> +	struct lpg *lpg = led->lpg;
> +	u64 duty;
> +	int i;
> +
> +	if (!*delay_on && !*delay_off) {
> +		*delay_on = 500;
> +		*delay_off = 500;
> +	}
> +
> +	duty = *delay_on * NSEC_PER_MSEC;
> +	period = (*delay_on + *delay_off) * NSEC_PER_MSEC;
> +
> +	for (i = 0; i < led->num_channels; i++) {
> +		chan = led->channels[i];
> +
> +		lpg_calc_freq(chan, period);
> +		lpg_calc_duty(chan, duty);
> +
> +		chan->enabled = true;
> +		chan->ramp_enabled = false;
> +
> +		triled_mask |= chan->triled_mask;
> +
> +		lpg_apply(chan);
> +	}
> +
> +	/* Enable triled lines */
> +	triled_set(lpg, triled_mask, triled_mask);
> +
> +	chan = led->channels[0];
> +	duty = div_u64(chan->pwm_value * chan->period, LPG_RESOLUTION);
> +	*delay_on = div_u64(duty, NSEC_PER_MSEC);
> +	*delay_off = div_u64(chan->period - duty, NSEC_PER_MSEC);
> +
> +	return 0;
> +}
> +
> +static int lpg_blink_single_set(struct led_classdev *cdev,
> +				unsigned long *delay_on, unsigned long *delay_off)
> +{
> +	struct lpg_led *led = container_of(cdev, struct lpg_led, cdev);
> +	int ret;
> +
> +	mutex_lock(&led->lpg->lock);
> +
> +	ret = lpg_blink_set(led, delay_on, delay_off);
> +
> +	mutex_unlock(&led->lpg->lock);
> +
> +	return ret;
> +}
> +
> +static int lpg_blink_mc_set(struct led_classdev *cdev,
> +			    unsigned long *delay_on, unsigned long *delay_off)
> +{
> +	struct led_classdev_mc *mc = lcdev_to_mccdev(cdev);
> +	struct lpg_led *led = container_of(mc, struct lpg_led, mcdev);
> +	int ret;
> +
> +	mutex_lock(&led->lpg->lock);
> +
> +	ret = lpg_blink_set(led, delay_on, delay_off);
> +
> +	mutex_unlock(&led->lpg->lock);
> +
> +	return ret;
> +}
> +
> +static int lpg_pattern_set(struct lpg_led *led, struct led_pattern *pattern,
> +			   u32 len, int repeat)
> +{
> +	struct lpg_channel *chan;
> +	struct lpg *lpg = led->lpg;
> +	unsigned int brightness_a;
> +	unsigned int brightness_b;
> +	unsigned int actual_len;
> +	unsigned int hi_pause;
> +	unsigned int lo_pause;
> +	unsigned int delta_t;
> +	unsigned int lo_idx;
> +	unsigned int hi_idx;
> +	unsigned int i;
> +	bool ping_pong = true;
> +	int ret;
> +
> +	/* Hardware only support oneshot or indefinite loops */
> +	if (repeat != -1 && repeat != 1)
> +		return -EINVAL;
> +
> +	/*
> +	 * Specifying a pattern of length 1 causes the hardware to iterate
> +	 * through the entire LUT, so prohibit this.
> +	 */
> +	if (len < 2)
> +		return -EINVAL;
> +
> +	/*
> +	 * The LPG plays patterns with at a fixed pace, a "low pause" can be

With or at?

> +	 * used to stretch the first delay of the pattern and a "high pause"
> +	 * the last one.
> +	 *
> +	 * In order to save space the pattern can be played in "ping pong"
> +	 * mode, in which the pattern is first played forward, then "high
> +	 * pause" is applied, then the pattern is played backwards and finally
> +	 * the "low pause" is applied.
> +	 *
> +	 * The middle elements of the pattern are used to determine delta_t and
> +	 * the "low pause" and "high pause" multipliers are derrived from this.

derived*

> +	 *
> +	 * The first element in the pattern is used to determine "low pause".
> +	 *
> +	 * If the specified pattern is a palindrome the ping pong mode is
> +	 * enabled. In this scenario the delta_t of the middle entry (i.e. the
> +	 * last in the programmed pattern) determines the "high pause".

... otherwise the last entry is used [to determine "high pause"].?

> +	 */
> +
> +	/* Detect palindromes and use "ping pong" to reduce LUT usage */
> +	for (i = 0; i < len / 2; i++) {
> +		brightness_a = pattern[i].brightness;
> +		brightness_b = pattern[len - i - 1].brightness;
> +
> +		if (brightness_a != brightness_b) {
> +			ping_pong = false;
> +			break;
> +		}
> +	}
> +
> +	/* The pattern length to be written to the LUT */
> +	if (ping_pong)
> +		actual_len = (len + 1) / 2;
> +	else
> +		actual_len = len;
> +
> +	/*
> +	 * Validate that all delta_t in the pattern are the same, with the
> +	 * exception of the middle element in case of ping_pong.
> +	 */
> +	delta_t = pattern[1].delta_t;
> +	for (i = 2; i < len; i++) {

I'm having some trouble getting this bit of code to accept patterns of
length 2 (or palindromes of length 3 with actual_len = 2):
pattern[1].delta_t here represents the "middle" delta_t yet is also used
as hi_pause in these cases and is hence allowed to deviate from the
usual validation.

In case of palindromes pattern[2] is expected to take just as long as
pattern[1] yet actually represents the same value as pattern[0], but
this is probably a niche-enough use-case to not worry about.

Otherwise the limit of BIT(9) makes it impossible to have simple len-2
patterns like "255 1000 0 1000" even though these are trivially possible
with pauses.  In reality one can compute delta_t = min(BIT(9) - 1,
min(pattern[i].delta_t)) here and use lo/hi_pause to compensate the
rest.

> +		if (pattern[i].delta_t != delta_t) {
> +			/*
> +			 * Allow last entry in the full or shortened pattern to
> +			 * specify hi pause. Reject other variations.
> +			 */
> +			if (i != actual_len - 1)
> +				return -EINVAL;
> +		}
> +	}
> +
> +	/* LPG_RAMP_DURATION_REG is a 9bit */
> +	if (delta_t >= BIT(9))
> +		return -EINVAL;
> +
> +	/* Find "low pause" and "high pause" in the pattern */
> +	lo_pause = pattern[0].delta_t;
> +	hi_pause = pattern[actual_len - 1].delta_t;

As mentioned above in the RST documentation (and IIRC we discussed this
in a previous review and/or IRC), I think delta_t from the rest of this
pattern should be _subtracted_ from these values (and error if wrapping
around).  After all the pattern will execute as normal without pausing,
and these pausing times seem to be _additive_ on top of the pattern.

This can be clearly seen when running the pattern from the examples:

    "255 1000 0 500 255 500 0 500"

Timing this shows that LED is high for 1500ms (500ms pattern + 1000ms
lo_pause).  Similarly for the final low case, the LED stays low for
1000ms (500ms pattern + 500ms hi_pause).

Obviously the documentation has to be updated to explain that these
pauses (rather, the durations for the first and last entry) must be
identical to or higher than the delta_t for the rest of the pattern, not
lower.

> +
> +	mutex_lock(&lpg->lock);
> +	ret = lpg_lut_store(lpg, pattern, actual_len, &lo_idx, &hi_idx);
> +	if (ret < 0)
> +		goto out_unlock;
> +
> +	for (i = 0; i < led->num_channels; i++) {
> +		chan = led->channels[i];
> +
> +		chan->ramp_tick_ms = delta_t;
> +		chan->ramp_ping_pong = ping_pong;
> +		chan->ramp_oneshot = repeat != -1;
> +
> +		chan->ramp_lo_pause_ms = lo_pause;
> +		chan->ramp_hi_pause_ms = hi_pause;
> +
> +		chan->pattern_lo_idx = lo_idx;
> +		chan->pattern_hi_idx = hi_idx;
> +	}
> +
> +out_unlock:
> +	mutex_unlock(&lpg->lock);
> +
> +	return ret;
> +}
> +
> +static int lpg_pattern_single_set(struct led_classdev *cdev,
> +				  struct led_pattern *pattern, u32 len,
> +				  int repeat)
> +{
> +	struct lpg_led *led = container_of(cdev, struct lpg_led, cdev);
> +	int ret;
> +
> +	ret = lpg_pattern_set(led, pattern, len, repeat);
> +	if (ret < 0)
> +		return ret;
> +
> +	lpg_brightness_single_set(cdev, LED_FULL);
> +
> +	return 0;
> +}
> +
> +static int lpg_pattern_mc_set(struct led_classdev *cdev,
> +			      struct led_pattern *pattern, u32 len,
> +			      int repeat)
> +{
> +	struct led_classdev_mc *mc = lcdev_to_mccdev(cdev);
> +	struct lpg_led *led = container_of(mc, struct lpg_led, mcdev);
> +	int ret;
> +
> +	ret = lpg_pattern_set(led, pattern, len, repeat);
> +	if (ret < 0)
> +		return ret;
> +
> +	led_mc_calc_color_components(mc, LED_FULL);
> +	lpg_brightness_set(led, cdev, mc->subled_info);
> +
> +	return 0;
> +}
> +
> +static int lpg_pattern_clear(struct lpg_led *led)
> +{
> +	struct lpg_channel *chan;
> +	struct lpg *lpg = led->lpg;
> +	int i;
> +
> +	mutex_lock(&lpg->lock);
> +
> +	chan = led->channels[0];
> +	lpg_lut_free(lpg, chan->pattern_lo_idx, chan->pattern_hi_idx);
> +
> +	for (i = 0; i < led->num_channels; i++) {
> +		chan = led->channels[i];
> +		chan->pattern_lo_idx = 0;
> +		chan->pattern_hi_idx = 0;
> +	}
> +
> +	mutex_unlock(&lpg->lock);
> +
> +	return 0;
> +}
> +
> +static int lpg_pattern_single_clear(struct led_classdev *cdev)
> +{
> +	struct lpg_led *led = container_of(cdev, struct lpg_led, cdev);
> +
> +	return lpg_pattern_clear(led);
> +}
> +
> +static int lpg_pattern_mc_clear(struct led_classdev *cdev)
> +{
> +	struct led_classdev_mc *mc = lcdev_to_mccdev(cdev);
> +	struct lpg_led *led = container_of(mc, struct lpg_led, mcdev);
> +
> +	return lpg_pattern_clear(led);
> +}
> +
> +static int lpg_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct lpg *lpg = container_of(chip, struct lpg, pwm);
> +	struct lpg_channel *chan = &lpg->channels[pwm->hwpwm];
> +
> +	return chan->in_use ? -EBUSY : 0;
> +}
> +
> +/*
> + * Limitations:
> + * - Updating both duty and period is not done atomically, so the output signal
> + *   will momentarily be a mix of the settings.
> + * - Changed parameters takes effect immediately.

take*?

> + * - A disabled channel outputs a logical 0.
> + */
> +static int lpg_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> +			 const struct pwm_state *state)
> +{
> +	struct lpg *lpg = container_of(chip, struct lpg, pwm);
> +	struct lpg_channel *chan = &lpg->channels[pwm->hwpwm];
> +	int ret = 0;
> +
> +	if (state->polarity != PWM_POLARITY_NORMAL)
> +		return -EINVAL;
> +
> +	mutex_lock(&lpg->lock);
> +
> +	if (state->enabled) {
> +		ret = lpg_calc_freq(chan, state->period);
> +		if (ret < 0)
> +			goto out_unlock;
> +
> +		lpg_calc_duty(chan, state->duty_cycle);
> +	}
> +	chan->enabled = state->enabled;
> +
> +	lpg_apply(chan);
> +
> +	triled_set(lpg, chan->triled_mask, chan->enabled ? chan->triled_mask : 0);
> +
> +out_unlock:
> +	mutex_unlock(&lpg->lock);
> +
> +	return ret;
> +}
> +
> +static void lpg_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
> +			      struct pwm_state *state)
> +{
> +	struct lpg *lpg = container_of(chip, struct lpg, pwm);
> +	struct lpg_channel *chan = &lpg->channels[pwm->hwpwm];
> +	unsigned int pre_div;
> +	unsigned int refclk;
> +	unsigned int val;
> +	unsigned int m;
> +	u16 pwm_value;
> +	int ret;
> +
> +	ret = regmap_read(lpg->map, chan->base + LPG_SIZE_CLK_REG, &val);
> +	if (ret)
> +		return;
> +
> +	refclk = lpg_clk_rates[val & PWM_CLK_SELECT_MASK];
> +	if (refclk) {
> +		ret = regmap_read(lpg->map, chan->base + LPG_PREDIV_CLK_REG, &val);
> +		if (ret)
> +			return;
> +
> +		pre_div = lpg_pre_divs[FIELD_GET(PWM_FREQ_PRE_DIV_MASK, val)];
> +		m = FIELD_GET(PWM_FREQ_EXP_MASK, val);
> +
> +		ret = regmap_bulk_read(lpg->map, chan->base + PWM_VALUE_REG, &pwm_value, sizeof(pwm_value));
> +		if (ret)
> +			return;
> +
> +		state->period = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC * LPG_RESOLUTION * pre_div * (1 << m), refclk);
> +		state->duty_cycle = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC * pwm_value * pre_div * (1 << m), refclk);
> +	} else {
> +		state->period = 0;
> +		state->duty_cycle = 0;
> +	}
> +
> +	ret = regmap_read(lpg->map, chan->base + PWM_ENABLE_CONTROL_REG, &val);
> +	if (ret)
> +		return;
> +
> +	state->enabled = FIELD_GET(LPG_ENABLE_CONTROL_OUTPUT, val);
> +	state->polarity = PWM_POLARITY_NORMAL;
> +
> +	if (state->duty_cycle > state->period)
> +		state->duty_cycle = state->period;
> +}
> +
> +static const struct pwm_ops lpg_pwm_ops = {
> +	.request = lpg_pwm_request,
> +	.apply = lpg_pwm_apply,
> +	.get_state = lpg_pwm_get_state,
> +	.owner = THIS_MODULE,
> +};
> +
> +static int lpg_add_pwm(struct lpg *lpg)
> +{
> +	int ret;
> +
> +	lpg->pwm.base = -1;
> +	lpg->pwm.dev = lpg->dev;
> +	lpg->pwm.npwm = lpg->num_channels;
> +	lpg->pwm.ops = &lpg_pwm_ops;
> +
> +	ret = pwmchip_add(&lpg->pwm);
> +	if (ret)
> +		dev_err(lpg->dev, "failed to add PWM chip: ret %d\n", ret);
> +
> +	return ret;
> +}
> +
> +static int lpg_parse_channel(struct lpg *lpg, struct device_node *np,
> +			     struct lpg_channel **channel)
> +{
> +	struct lpg_channel *chan;
> +	u32 color = LED_COLOR_ID_GREEN;
> +	u32 reg;
> +	int ret;
> +
> +	ret = of_property_read_u32(np, "reg", &reg);
> +	if (ret || !reg || reg > lpg->num_channels) {
> +		dev_err(lpg->dev, "invalid \"reg\" of %pOFn\n", np);
> +		return -EINVAL;
> +	}
> +
> +	chan = &lpg->channels[reg - 1];
> +	chan->in_use = true;
> +
> +	ret = of_property_read_u32(np, "color", &color);
> +	if (ret < 0 && ret != -EINVAL) {
> +		dev_err(lpg->dev, "failed to parse \"color\" of %pOF\n", np);
> +		return ret;
> +	}
> +
> +	chan->color = color;
> +
> +	*channel = chan;
> +
> +	return 0;
> +}
> +
> +static int lpg_add_led(struct lpg *lpg, struct device_node *np)
> +{
> +	struct led_init_data init_data = {};
> +	struct led_classdev *cdev;
> +	struct device_node *child;
> +	struct mc_subled *info;
> +	struct lpg_led *led;
> +	const char *state;
> +	int num_channels;
> +	u32 color = 0;
> +	int ret;
> +	int i;
> +
> +	ret = of_property_read_u32(np, "color", &color);
> +	if (ret < 0 && ret != -EINVAL) {
> +		dev_err(lpg->dev, "failed to parse \"color\" of %pOF\n", np);
> +		return ret;
> +	}
> +
> +	if (color == LED_COLOR_ID_RGB)
> +		num_channels = of_get_available_child_count(np);
> +	else
> +		num_channels = 1;
> +
> +	led = devm_kzalloc(lpg->dev, struct_size(led, channels, num_channels), GFP_KERNEL);
> +	if (!led)
> +		return -ENOMEM;
> +
> +	led->lpg = lpg;
> +	led->num_channels = num_channels;
> +
> +	if (color == LED_COLOR_ID_RGB) {
> +		info = devm_kcalloc(lpg->dev, num_channels, sizeof(*info), GFP_KERNEL);
> +		if (!info)
> +			return -ENOMEM;
> +		i = 0;
> +		for_each_available_child_of_node(np, child) {
> +			ret = lpg_parse_channel(lpg, child, &led->channels[i]);
> +			if (ret < 0)
> +				return ret;
> +
> +			info[i].color_index = led->channels[i]->color;
> +			info[i].intensity = 0;

This struct also has a "channel" field that doesn't seem to be used
anywhere.  Should we still initialize it to something sensible, or is it
better reported upstream for removal?

- Marijn

> +			i++;
> +		}
> +
> +		led->mcdev.subled_info = info;
> +		led->mcdev.num_colors = num_channels;
> +
> +		cdev = &led->mcdev.led_cdev;
> +		cdev->brightness_set = lpg_brightness_mc_set;
> +		cdev->blink_set = lpg_blink_mc_set;
> +
> +		/* Register pattern accessors only if we have a LUT block */
> +		if (lpg->lut_base) {
> +			cdev->pattern_set = lpg_pattern_mc_set;
> +			cdev->pattern_clear = lpg_pattern_mc_clear;
> +		}
> +	} else {
> +		ret = lpg_parse_channel(lpg, np, &led->channels[0]);
> +		if (ret < 0)
> +			return ret;
> +
> +		cdev = &led->cdev;
> +		cdev->brightness_set = lpg_brightness_single_set;
> +		cdev->blink_set = lpg_blink_single_set;
> +
> +		/* Register pattern accessors only if we have a LUT block */
> +		if (lpg->lut_base) {
> +			cdev->pattern_set = lpg_pattern_single_set;
> +			cdev->pattern_clear = lpg_pattern_single_clear;
> +		}
> +	}
> +
> +	cdev->default_trigger = of_get_property(np, "linux,default-trigger", NULL);
> +	cdev->max_brightness = LPG_RESOLUTION - 1;
> +
> +	if (!of_property_read_string(np, "default-state", &state) &&
> +	    !strcmp(state, "on"))
> +		cdev->brightness = cdev->max_brightness;
> +	else
> +		cdev->brightness = LED_OFF;
> +
> +	cdev->brightness_set(cdev, cdev->brightness);
> +
> +	init_data.fwnode = of_fwnode_handle(np);
> +
> +	if (color == LED_COLOR_ID_RGB)
> +		ret = devm_led_classdev_multicolor_register_ext(lpg->dev, &led->mcdev, &init_data);
> +	else
> +		ret = devm_led_classdev_register_ext(lpg->dev, &led->cdev, &init_data);
> +	if (ret)
> +		dev_err(lpg->dev, "unable to register %s\n", cdev->name);
> +
> +	return ret;
> +}
> +
> +static int lpg_init_channels(struct lpg *lpg)
> +{
> +	const struct lpg_data *data = lpg->data;
> +	struct lpg_channel *chan;
> +	int i;
> +
> +	lpg->num_channels = data->num_channels;
> +	lpg->channels = devm_kcalloc(lpg->dev, data->num_channels,
> +				     sizeof(struct lpg_channel), GFP_KERNEL);
> +	if (!lpg->channels)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < data->num_channels; i++) {
> +		chan = &lpg->channels[i];
> +
> +		chan->lpg = lpg;
> +		chan->base = data->channels[i].base;
> +		chan->triled_mask = data->channels[i].triled_mask;
> +		chan->lut_mask = BIT(i);
> +
> +		regmap_read(lpg->map, chan->base + LPG_SUBTYPE_REG, &chan->subtype);
> +	}
> +
> +	return 0;
> +}
> +
> +static int lpg_init_triled(struct lpg *lpg)
> +{
> +	struct device_node *np = lpg->dev->of_node;
> +	int ret;
> +
> +	/* Skip initialization if we don't have a triled block */
> +	if (!lpg->data->triled_base)
> +		return 0;
> +
> +	lpg->triled_base = lpg->data->triled_base;
> +	lpg->triled_has_atc_ctl = lpg->data->triled_has_atc_ctl;
> +	lpg->triled_has_src_sel = lpg->data->triled_has_src_sel;
> +
> +	if (lpg->triled_has_src_sel) {
> +		ret = of_property_read_u32(np, "qcom,power-source", &lpg->triled_src);
> +		if (ret || lpg->triled_src == 2 || lpg->triled_src > 3) {
> +			dev_err(lpg->dev, "invalid power source\n");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	/* Disable automatic trickle charge LED */
> +	if (lpg->triled_has_atc_ctl)
> +		regmap_write(lpg->map, lpg->triled_base + TRI_LED_ATC_CTL, 0);
> +
> +	/* Configure power source */
> +	if (lpg->triled_has_src_sel)
> +		regmap_write(lpg->map, lpg->triled_base + TRI_LED_SRC_SEL, lpg->triled_src);
> +
> +	/* Default all outputs to off */
> +	regmap_write(lpg->map, lpg->triled_base + TRI_LED_EN_CTL, 0);
> +
> +	return 0;
> +}
> +
> +static int lpg_init_lut(struct lpg *lpg)
> +{
> +	const struct lpg_data *data = lpg->data;
> +
> +	if (!data->lut_base)
> +		return 0;
> +
> +	lpg->lut_base = data->lut_base;
> +	lpg->lut_size = data->lut_size;
> +
> +	lpg->lut_bitmap = devm_bitmap_zalloc(lpg->dev, lpg->lut_size, GFP_KERNEL);
> +	if (!lpg->lut_bitmap)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static int lpg_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np;
> +	struct lpg *lpg;
> +	int ret;
> +	int i;
> +
> +	lpg = devm_kzalloc(&pdev->dev, sizeof(*lpg), GFP_KERNEL);
> +	if (!lpg)
> +		return -ENOMEM;
> +
> +	lpg->data = of_device_get_match_data(&pdev->dev);
> +	if (!lpg->data)
> +		return -EINVAL;
> +
> +	platform_set_drvdata(pdev, lpg);
> +
> +	lpg->dev = &pdev->dev;
> +	mutex_init(&lpg->lock);
> +
> +	lpg->map = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!lpg->map)
> +		return dev_err_probe(&pdev->dev, -ENXIO, "parent regmap unavailable\n");
> +
> +	ret = lpg_init_channels(lpg);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = lpg_parse_dtest(lpg);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = lpg_init_triled(lpg);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = lpg_init_lut(lpg);
> +	if (ret < 0)
> +		return ret;
> +
> +	for_each_available_child_of_node(pdev->dev.of_node, np) {
> +		ret = lpg_add_led(lpg, np);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; i < lpg->num_channels; i++)
> +		lpg_apply_dtest(&lpg->channels[i]);
> +
> +	return lpg_add_pwm(lpg);
> +}
> +
> +static int lpg_remove(struct platform_device *pdev)
> +{
> +	struct lpg *lpg = platform_get_drvdata(pdev);
> +
> +	pwmchip_remove(&lpg->pwm);
> +
> +	return 0;
> +}
> +
> +static const struct lpg_data pm8916_pwm_data = {
> +	.num_channels = 1,
> +	.channels = (const struct lpg_channel_data[]) {
> +		{ .base = 0xbc00 },
> +	},
> +};
> +
> +static const struct lpg_data pm8941_lpg_data = {
> +	.lut_base = 0xb000,
> +	.lut_size = 64,
> +
> +	.triled_base = 0xd000,
> +	.triled_has_atc_ctl = true,
> +	.triled_has_src_sel = true,
> +
> +	.num_channels = 8,
> +	.channels = (const struct lpg_channel_data[]) {
> +		{ .base = 0xb100 },
> +		{ .base = 0xb200 },
> +		{ .base = 0xb300 },
> +		{ .base = 0xb400 },
> +		{ .base = 0xb500, .triled_mask = BIT(5) },
> +		{ .base = 0xb600, .triled_mask = BIT(6) },
> +		{ .base = 0xb700, .triled_mask = BIT(7) },
> +		{ .base = 0xb800 },
> +	},
> +};
> +
> +static const struct lpg_data pm8994_lpg_data = {
> +	.lut_base = 0xb000,
> +	.lut_size = 64,
> +
> +	.num_channels = 6,
> +	.channels = (const struct lpg_channel_data[]) {
> +		{ .base = 0xb100 },
> +		{ .base = 0xb200 },
> +		{ .base = 0xb300 },
> +		{ .base = 0xb400 },
> +		{ .base = 0xb500 },
> +		{ .base = 0xb600 },
> +	},
> +};
> +
> +static const struct lpg_data pmi8994_lpg_data = {
> +	.lut_base = 0xb000,
> +	.lut_size = 24,
> +
> +	.triled_base = 0xd000,
> +	.triled_has_atc_ctl = true,
> +	.triled_has_src_sel = true,
> +
> +	.num_channels = 4,
> +	.channels = (const struct lpg_channel_data[]) {
> +		{ .base = 0xb100, .triled_mask = BIT(5) },
> +		{ .base = 0xb200, .triled_mask = BIT(6) },
> +		{ .base = 0xb300, .triled_mask = BIT(7) },
> +		{ .base = 0xb400 },
> +	},
> +};
> +
> +static const struct lpg_data pmi8998_lpg_data = {
> +	.lut_base = 0xb000,
> +	.lut_size = 49,
> +
> +	.triled_base = 0xd000,
> +
> +	.num_channels = 6,
> +	.channels = (const struct lpg_channel_data[]) {
> +		{ .base = 0xb100 },
> +		{ .base = 0xb200 },
> +		{ .base = 0xb300, .triled_mask = BIT(5) },
> +		{ .base = 0xb400, .triled_mask = BIT(6) },
> +		{ .base = 0xb500, .triled_mask = BIT(7) },
> +		{ .base = 0xb600 },
> +	},
> +};
> +
> +static const struct lpg_data pm8150b_lpg_data = {
> +	.lut_base = 0xb000,
> +	.lut_size = 24,
> +
> +	.triled_base = 0xd000,
> +
> +	.num_channels = 2,
> +	.channels = (const struct lpg_channel_data[]) {
> +		{ .base = 0xb100, .triled_mask = BIT(7) },
> +		{ .base = 0xb200, .triled_mask = BIT(6) },
> +	},
> +};
> +
> +static const struct lpg_data pm8150l_lpg_data = {
> +	.lut_base = 0xb000,
> +	.lut_size = 48,
> +
> +	.triled_base = 0xd000,
> +
> +	.num_channels = 5,
> +	.channels = (const struct lpg_channel_data[]) {
> +		{ .base = 0xb100, .triled_mask = BIT(7) },
> +		{ .base = 0xb200, .triled_mask = BIT(6) },
> +		{ .base = 0xb300, .triled_mask = BIT(5) },
> +		{ .base = 0xbc00 },
> +		{ .base = 0xbd00 },
> +
> +	},
> +};
> +
> +static const struct of_device_id lpg_of_table[] = {
> +	{ .compatible = "qcom,pm8150b-lpg", .data = &pm8150b_lpg_data },
> +	{ .compatible = "qcom,pm8150l-lpg", .data = &pm8150l_lpg_data },
> +	{ .compatible = "qcom,pm8916-pwm", .data = &pm8916_pwm_data },
> +	{ .compatible = "qcom,pm8941-lpg", .data = &pm8941_lpg_data },
> +	{ .compatible = "qcom,pm8994-lpg", .data = &pm8994_lpg_data },
> +	{ .compatible = "qcom,pmi8994-lpg", .data = &pmi8994_lpg_data },
> +	{ .compatible = "qcom,pmi8998-lpg", .data = &pmi8998_lpg_data },
> +	{ .compatible = "qcom,pmc8180c-lpg", .data = &pm8150l_lpg_data },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, lpg_of_table);
> +
> +static struct platform_driver lpg_driver = {
> +	.probe = lpg_probe,
> +	.remove = lpg_remove,
> +	.driver = {
> +		.name = "qcom-spmi-lpg",
> +		.of_match_table = lpg_of_table,
> +	},
> +};
> +module_platform_driver(lpg_driver);
> +
> +MODULE_DESCRIPTION("Qualcomm LPG LED driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.33.1
>