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Date: Fri, 04 Mar 2016 17:01:52 +0100
From: Jacek Anaszewski <j.anaszewski@...sung.com>
To: "David Rivshin (Allworx)" <drivshin.allworx@...il.com>
Cc: linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
Richard Purdie <rpurdie@...ys.net>,
Rob Herring <robh+dt@...nel.org>,
Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>,
Stefan Wahren <stefan.wahren@...e.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] leds: Add driver for the ISSI IS31FL32xx family of LED
controllers
On 03/04/2016 04:05 PM, David Rivshin (Allworx) wrote:
> On Fri, 04 Mar 2016 08:54:02 +0100
> Jacek Anaszewski <j.anaszewski@...sung.com> wrote:
>
>> On 03/04/2016 01:45 AM, David Rivshin (Allworx) wrote:
>>> On Thu, 03 Mar 2016 15:51:32 +0100
>>> Jacek Anaszewski <j.anaszewski@...sung.com> wrote:
>>>
>>>> Hi David,
>>>>
>>>> Thanks for the update. Two remarks in the code.
>>>>
>>>> On 03/03/2016 04:01 AM, David Rivshin (Allworx) wrote:
>>>>> From: David Rivshin <drivshin@...worx.com>
>>>>>
>>>>> The IS31FL32xx family of LED controllers are I2C devices with multiple
>>>>> constant-current channels, each with independent 256-level PWM control.
>>>>>
>>>>> Datasheets: http://www.issi.com/US/product-analog-fxled-driver.shtml
>>>>>
>>>>> This has been tested on the IS31FL3236 and IS31FL3216, on an ARM
>>>>> (TI am335x) platform.
>>>>>
>>>>> The programming paradigm of these devices is similar in the following
>>>>> ways:
>>>>> - All registers are 8 bit
>>>>> - All LED control registers are write-only
>>>>> - Each LED channel has a PWM register (0-255)
>>>>> - PWM register writes are shadowed until an Update register is poked
>>>>> - All have a concept of Software Shutdown, which disables output
>>>>>
>>>>> However, there are some differences in devices:
>>>>> - 3236/3235 have a separate Control register for each LED,
>>>>> (3218/3216 pack the enable bits into fewer registers)
>>>>> - 3236/3235 have a per-channel current divisor setting
>>>>> - 3236/3235 have a Global Control register that can turn off all LEDs
>>>>> - 3216 is unique in a number of ways
>>>>> - OUT9-OUT16 can be configured as GPIOs instead of LED controls
>>>>> - LEDs can be programmed with an 8-frame animation, with
>>>>> programmable delay between frames
>>>>> - LEDs can be modulated by an input audio signal
>>>>> - Max output current can be adjusted from 1/4 to 2x globally
>>>>> - Has a Configuration register instead of a Shutdown register
>>>>>
>>>>> This driver currently only supports the base PWM control function
>>>>> of these devices. The following features of these devices are not
>>>>> implemented, although it should be possible to add them in the future:
>>>>> - All devices are capable of going into a lower-power "software
>>>>> shutdown" mode.
>>>>> - The is31fl3236 and is31fl3235 can reduce the max output current
>>>>> per-channel with a divisor of 1, 2, 3, or 4.
>>>>> - The is31fl3216 can use some LED channels as GPIOs instead.
>>>>> - The is31fl3216 can animate LEDs in hardware.
>>>>> - The is31fl3216 can modulate LEDs according to an audio input.
>>>>> - The is31fl3216 can reduce/increase max output current globally.
>>>>>
>>>>> Signed-off-by: David Rivshin <drivshin@...worx.com>
>>>>> ---
>>>>>
>>>>> You may see two instances of this warning:
>>>>> "passing argument 1 of 'of_property_read_string' discards 'const'
>>>>> qualifier from pointer target type"
>>>>> That is a result of of_property_read_string() taking a non-const
>>>>> struct device_node pointer parameter. I have separately submitted a
>>>>> patch to fix that [1], and a few related functions which had the same
>>>>> issue. I'm hoping that will get into linux-next before this does, so
>>>>> that the warnings never show up there.
>>>>
>>>> Please adjust the patch so that it compiles without warnings on
>>>> current linux-next. Your patch for DT API hasn't been reviewed yet
>>>> AFICS, and I can imagine that there will be some resistance against.
>>>
>>> Since the DT API patch was just accepted by Rob [1], would it be OK
>>> to wait for the results of Stefan's testing (and any other reviews)
>>> before making a decision on this? From Stefan's note, it won't be
>>> until this weekend that he will have a chance to test, and I'm
>>> guessing the DT API patch will make its way through Rob's tree to
>>> linux-next by then.
>>
>> OK.
>>
>>> FYI, the warning workaround would be to make the second parameter to
>>> is31fl32xx_parse_child_dt() non-const.
>>>
>>> [1] https://lkml.org/lkml/2016/3/3/924
>>>
>>>>> Changes from RFC:
>>>>> - Removed max-brightness DT property.
>>>>> - Refer to these devices as "LED controllers" in Kconfig.
>>>>> - Removed redundant last sentence from Kconfig entry
>>>>> - Removed unnecessary debug code.
>>>>> - Do not set led_classdev.brightness to 0 explicitly, as it is
>>>>> already initialized to 0 by devm_kzalloc().
>>>>> - Used of_property_read_string() instead of of_get_property().
>>>>> - Fail immediately on DT parsing error in a child node, rather than
>>>>> continuing on with the non-faulty ones.
>>>>> - Added additional comments for some things that might be non-obvious.
>>>>> - Added constants for the location of the SSD bit in the SHUTDOWN
>>>>> register, and the 3216's CONFIG register.
>>>>> - Added special sw_shutdown_func for the 3216 device, as that bit
>>>>> is in a different register, at a different position, and has reverse
>>>>> polarity compared to all the other devices.
>>>>> - Refactored is31fl32xx_init_regs() to separate out some logic into
>>>>> is31fl32xx_reset_regs() and is31fl32xx_software_shutdown().
>>>>>
>>>>> [1] https://lkml.org/lkml/2016/3/2/746
>>>>>
>>>>> drivers/leds/Kconfig | 8 +
>>>>> drivers/leds/Makefile | 1 +
>>>>> drivers/leds/leds-is31fl32xx.c | 505 +++++++++++++++++++++++++++++++++++++++++
>>>>> 3 files changed, 514 insertions(+)
>>>>> create mode 100644 drivers/leds/leds-is31fl32xx.c
>>>>>
>>>>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>>>>> index 1034696..9c63ba4 100644
>>>>> --- a/drivers/leds/Kconfig
>>>>> +++ b/drivers/leds/Kconfig
>>>>> @@ -580,6 +580,14 @@ config LEDS_SN3218
>>>>> This driver can also be built as a module. If so the module
>>>>> will be called leds-sn3218.
>>>>>
>>>>> +config LEDS_IS31FL32XX
>>>>> + tristate "LED support for ISSI IS31FL32XX I2C LED controller family"
>>>>> + depends on LEDS_CLASS && I2C && OF
>>>>> + help
>>>>> + Say Y here to include support for ISSI IS31FL32XX LED controllers.
>>>>> + They are I2C devices with multiple constant-current channels, each
>>>>> + with independent 256-level PWM control.
>>>>> +
>>>>> comment "LED driver for blink(1) USB RGB LED is under Special HID drivers (HID_THINGM)"
>>>>>
>>>>> config LEDS_BLINKM
>>>>> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
>>>>> index 89c9b6f..3fdf313 100644
>>>>> --- a/drivers/leds/Makefile
>>>>> +++ b/drivers/leds/Makefile
>>>>> @@ -67,6 +67,7 @@ obj-$(CONFIG_LEDS_KTD2692) += leds-ktd2692.o
>>>>> obj-$(CONFIG_LEDS_POWERNV) += leds-powernv.o
>>>>> obj-$(CONFIG_LEDS_SEAD3) += leds-sead3.o
>>>>> obj-$(CONFIG_LEDS_SN3218) += leds-sn3218.o
>>>>> +obj-$(CONFIG_LEDS_IS31FL32XX) += leds-is31fl32xx.o
>>>>>
>>>>> # LED SPI Drivers
>>>>> obj-$(CONFIG_LEDS_DAC124S085) += leds-dac124s085.o
>>>>> diff --git a/drivers/leds/leds-is31fl32xx.c b/drivers/leds/leds-is31fl32xx.c
>>>>> new file mode 100644
>>>>> index 0000000..49818f0
>>>>> --- /dev/null
>>>>> +++ b/drivers/leds/leds-is31fl32xx.c
>>>>> @@ -0,0 +1,505 @@
>>>>> +/*
>>>>> + * linux/drivers/leds-is31fl32xx.c
>>>>> + *
>>>>> + * Driver for ISSI IS31FL32xx family of I2C LED controllers
>>>>> + *
>>>>> + * Copyright 2015 Allworx Corp.
>>>>> + *
>>>>> + *
>>>>> + * This program is free software; you can redistribute it and/or modify
>>>>> + * it under the terms of the GNU General Public License version 2 as
>>>>> + * published by the Free Software Foundation.
>>>>> + *
>>>>> + * Datasheets: http://www.issi.com/US/product-analog-fxled-driver.shtml
>>>>> + */
>>>>> +
>>>>> +#include <linux/err.h>
>>>>> +#include <linux/i2c.h>
>>>>> +#include <linux/kernel.h>
>>>>> +#include <linux/leds.h>
>>>>> +#include <linux/module.h>
>>>>> +#include <linux/of_platform.h>
>>>>> +
>>>>> +/* Used to indicate a device has no such register */
>>>>> +#define IS31FL32XX_REG_NONE 0xFF
>>>>> +
>>>>> +/* Software Shutdown bit in Shutdown Register */
>>>>> +#define IS31FL32XX_SHUTDOWN_SSD_ENABLE 0
>>>>> +#define IS31FL32XX_SHUTDOWN_SSD_DISABLE BIT(0)
>>>>> +
>>>>> +/* IS31FL3216 has a number of unique registers */
>>>>> +#define IS31FL3216_CONFIG_REG 0x00
>>>>> +#define IS31FL3216_LIGHTING_EFFECT_REG 0x03
>>>>> +#define IS31FL3216_CHANNEL_CONFIG_REG 0x04
>>>>> +
>>>>> +/* Software Shutdown bit in 3216 Config Register */
>>>>> +#define IS31FL3216_CONFIG_SSD_ENABLE BIT(7)
>>>>> +#define IS31FL3216_CONFIG_SSD_DISABLE 0
>>>>> +
>>>>> +struct is31fl32xx_priv;
>>>>> +struct is31fl32xx_led_data {
>>>>> + struct led_classdev cdev;
>>>>> + u8 channel; /* 1-based, max priv->cdef->channels */
>>>>> + struct is31fl32xx_priv *priv;
>>>>> +};
>>>>> +
>>>>> +struct is31fl32xx_priv {
>>>>> + const struct is31fl32xx_chipdef *cdef;
>>>>> + struct i2c_client *client;
>>>>> + unsigned int num_leds;
>>>>> + struct is31fl32xx_led_data leds[0];
>>>>> +};
>>>>> +
>>>>> +/**
>>>>> + * struct is31fl32xx_chipdef - chip-specific attributes
>>>>> + * @channels : Number of LED channels
>>>>> + * @shutdown_reg : address of Shutdown register (optional)
>>>>> + * @pwm_update_reg : address of PWM Update register
>>>>> + * @global_control_reg : address of Global Control register (optional)
>>>>> + * @reset_reg : address of Reset register (optional)
>>>>> + * @pwm_register_base : address of first PWM register
>>>>> + * @pwm_registers_reversed: : true if PWM registers count down instead of up
>>>>> + * @led_control_register_base : address of first LED control register (optional)
>>>>> + * @enable_bits_per_led_control_register: number of LEDs enable bits in each
>>>>> + * @reset_func: : pointer to reset function
>>>>> + *
>>>>> + * For all optional register addresses, the sentinel value %IS31FL32XX_REG_NONE
>>>>> + * indicates that this chip has no such register.
>>>>> + *
>>>>> + * If non-NULL, @reset_func will be called during probing to set all
>>>>> + * necessary registers to a known initialization state. This is needed
>>>>> + * for chips that do not have a @reset_reg.
>>>>> + *
>>>>> + * @enable_bits_per_led_control_register must be >=1 if
>>>>> + * @led_control_register_base != %IS31FL32XX_REG_NONE.
>>>>> + */
>>>>> +struct is31fl32xx_chipdef {
>>>>> + u8 channels;
>>>>> + u8 shutdown_reg;
>>>>> + u8 pwm_update_reg;
>>>>> + u8 global_control_reg;
>>>>> + u8 reset_reg;
>>>>> + u8 pwm_register_base;
>>>>> + bool pwm_registers_reversed;
>>>>> + u8 led_control_register_base;
>>>>> + u8 enable_bits_per_led_control_register;
>>>>> + int (*reset_func)(struct is31fl32xx_priv *priv);
>>>>> + int (*sw_shutdown_func)(struct is31fl32xx_priv *priv, bool enable);
>>>>> +};
>>>>> +
>>>>> +static const struct is31fl32xx_chipdef is31fl3236_cdef = {
>>>>> + .channels = 36,
>>>>> + .shutdown_reg = 0x00,
>>>>> + .pwm_update_reg = 0x25,
>>>>> + .global_control_reg = 0x4a,
>>>>> + .reset_reg = 0x4f,
>>>>> + .pwm_register_base = 0x01,
>>>>> + .led_control_register_base = 0x26,
>>>>> + .enable_bits_per_led_control_register = 1,
>>>>> +};
>>>>> +
>>>>> +static const struct is31fl32xx_chipdef is31fl3235_cdef = {
>>>>> + .channels = 28,
>>>>> + .shutdown_reg = 0x00,
>>>>> + .pwm_update_reg = 0x25,
>>>>> + .global_control_reg = 0x4a,
>>>>> + .reset_reg = 0x4f,
>>>>> + .pwm_register_base = 0x05,
>>>>> + .led_control_register_base = 0x2a,
>>>>> + .enable_bits_per_led_control_register = 1,
>>>>> +};
>>>>> +
>>>>> +static const struct is31fl32xx_chipdef is31fl3218_cdef = {
>>>>> + .channels = 18,
>>>>> + .shutdown_reg = 0x00,
>>>>> + .pwm_update_reg = 0x16,
>>>>> + .global_control_reg = IS31FL32XX_REG_NONE,
>>>>> + .reset_reg = 0x17,
>>>>> + .pwm_register_base = 0x01,
>>>>> + .led_control_register_base = 0x13,
>>>>> + .enable_bits_per_led_control_register = 6,
>>>>> +};
>>>>> +
>>>>> +static int is31fl3216_reset(struct is31fl32xx_priv *priv);
>>>>> +static int is31fl3216_software_shutdown(struct is31fl32xx_priv *priv,
>>>>> + bool enable);
>>>>> +static const struct is31fl32xx_chipdef is31fl3216_cdef = {
>>>>> + .channels = 16,
>>>>> + .shutdown_reg = IS31FL32XX_REG_NONE,
>>>>> + .pwm_update_reg = 0xB0,
>>>>> + .global_control_reg = IS31FL32XX_REG_NONE,
>>>>> + .reset_reg = IS31FL32XX_REG_NONE,
>>>>> + .pwm_register_base = 0x10,
>>>>> + .pwm_registers_reversed = true,
>>>>> + .led_control_register_base = 0x01,
>>>>> + .enable_bits_per_led_control_register = 8,
>>>>> + .reset_func = is31fl3216_reset,
>>>>> + .sw_shutdown_func = is31fl3216_software_shutdown,
>>>>> +};
>>>>> +
>>>>> +static int is31fl32xx_write(struct is31fl32xx_priv *priv, u8 reg, u8 val)
>>>>> +{
>>>>> + int ret;
>>>>> +
>>>>> + dev_dbg(&priv->client->dev, "writing register 0x%02X=0x%02X", reg, val);
>>>>> +
>>>>> + ret = i2c_smbus_write_byte_data(priv->client, reg, val);
>>>>> + if (ret) {
>>>>> + dev_err(&priv->client->dev,
>>>>> + "register write to 0x%02X failed (error %d)",
>>>>> + reg, ret);
>>>>> + }
>>>>> + return ret;
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * Custom reset function for IS31FL3216 because it does not have a RESET
>>>>> + * register the way that the other IS31FL32xx chips do. We don't bother
>>>>> + * writing the GPIO and animation registers, because the registers we
>>>>> + * do write ensure those will have no effect.
>>>>> + */
>>>>> +static int is31fl3216_reset(struct is31fl32xx_priv *priv)
>>>>> +{
>>>>> + unsigned int i;
>>>>> + int ret;
>>>>> +
>>>>> + ret = is31fl32xx_write(priv, IS31FL3216_CONFIG_REG,
>>>>> + IS31FL3216_CONFIG_SSD_ENABLE);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> + for (i = 0; i < priv->cdef->channels; i++) {
>>>>> + ret = is31fl32xx_write(priv, priv->cdef->pwm_register_base+i,
>>>>> + 0x00);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> + }
>>>>> + ret = is31fl32xx_write(priv, priv->cdef->pwm_update_reg, 0);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> + ret = is31fl32xx_write(priv, IS31FL3216_LIGHTING_EFFECT_REG, 0x00);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> + ret = is31fl32xx_write(priv, IS31FL3216_CHANNEL_CONFIG_REG, 0x00);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * Custom Software-Shutdown function for IS31FL3216 because it does not have
>>>>> + * a SHUTDOWN register the way that the other IS31FL32xx chips do.
>>>>> + * We don't bother doing a read/modify/write on the CONFIG register because
>>>>> + * we only ever use a value of '0' for the other fields in that register.
>>>>> + */
>>>>> +static int is31fl3216_software_shutdown(struct is31fl32xx_priv *priv,
>>>>> + bool enable)
>>>>> +{
>>>>> + u8 value = enable ? IS31FL3216_CONFIG_SSD_ENABLE :
>>>>> + IS31FL3216_CONFIG_SSD_DISABLE;
>>>>> +
>>>>> + return is31fl32xx_write(priv, IS31FL3216_CONFIG_REG, value);
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * NOTE: A mutex is not needed in this function because:
>>>>> + * - All referenced data is read-only after probe()
>>>>> + * - The I2C core has a mutex on to protect the bus
>>>>> + * - There are no read/modify/write operations
>>>>> + * - Intervening operations between the write of the PWM register
>>>>> + * and the Update register are harmless.
>>>>> + *
>>>>> + * Example:
>>>>> + * PWM_REG_1 write 16
>>>>> + * UPDATE_REG write 0
>>>>> + * PWM_REG_2 write 128
>>>>> + * UPDATE_REG write 0
>>>>> + * vs:
>>>>> + * PWM_REG_1 write 16
>>>>> + * PWM_REG_2 write 128
>>>>> + * UPDATE_REG write 0
>>>>> + * UPDATE_REG write 0
>>>>> + * are equivalent. Poking the Update register merely applies all PWM
>>>>> + * register writes up to that point.
>>>>> + */
>>>>> +static int is31fl32xx_brightness_set(struct led_classdev *led_cdev,
>>>>> + enum led_brightness brightness)
>>>>> +{
>>>>> + const struct is31fl32xx_led_data *led_data =
>>>>> + container_of(led_cdev, struct is31fl32xx_led_data, cdev);
>>>>> + const struct is31fl32xx_chipdef *cdef = led_data->priv->cdef;
>>>>> + u8 pwm_register_offset;
>>>>> + int ret;
>>>>> +
>>>>> + dev_dbg(led_cdev->dev, "%s: %d\n", __func__, brightness);
>>>>> +
>>>>> + /* NOTE: led_data->channel is 1-based */
>>>>> + if (cdef->pwm_registers_reversed)
>>>>> + pwm_register_offset = cdef->channels - led_data->channel;
>>>>> + else
>>>>> + pwm_register_offset = led_data->channel - 1;
>>>>> +
>>>>> + ret = is31fl32xx_write(led_data->priv,
>>>>> + cdef->pwm_register_base + pwm_register_offset,
>>>>> + brightness);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> +
>>>>> + return is31fl32xx_write(led_data->priv, cdef->pwm_update_reg, 0);
>>>>> +}
>>>>> +
>>>>> +static int is31fl32xx_reset_regs(struct is31fl32xx_priv *priv)
>>>>> +{
>>>>> + const struct is31fl32xx_chipdef *cdef = priv->cdef;
>>>>> + int ret;
>>>>> +
>>>>> + if (cdef->reset_reg != IS31FL32XX_REG_NONE) {
>>>>> + ret = is31fl32xx_write(priv, cdef->reset_reg, 0);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> + }
>>>>> +
>>>>> + if (cdef->reset_func)
>>>>> + return cdef->reset_func(priv);
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static int is31fl32xx_software_shutdown(struct is31fl32xx_priv *priv,
>>>>> + bool enable)
>>>>> +{
>>>>> + const struct is31fl32xx_chipdef *cdef = priv->cdef;
>>>>> + int ret;
>>>>> +
>>>>> + if (cdef->shutdown_reg != IS31FL32XX_REG_NONE) {
>>>>> + u8 value = enable ? IS31FL32XX_SHUTDOWN_SSD_ENABLE :
>>>>> + IS31FL32XX_SHUTDOWN_SSD_DISABLE;
>>>>> + ret = is31fl32xx_write(priv, cdef->shutdown_reg, value);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> + }
>>>>> +
>>>>> + if (cdef->sw_shutdown_func)
>>>>> + return cdef->sw_shutdown_func(priv, enable);
>>>>
>>>> You seem to call sw_shutdown_func only here, so why should we have
>>>> enable parameter in this op?
>>>
>>> I'm not sure if I understand the question, but I will try to answer.
>>>
>>> 'enable' is passed through is31fl32xx_software_shutdown to
>>> cdef->sw_shutdown_func, so it can be either true or false at that
>>> point. The purpose of sw_shutdown_func is to add any special behavior
>>> when enabling/disabling software-shutdown mode, which is needed for
>>> the 3216 because its SSD bit is in a different position and with
>>> opposite polarity.
>>>
>>> Is it that 'enable' in that line of code makes it look like it's being
>>> called with an hardcoded value rather than a variable? If so, perhaps a
>>> different parameter name would make it more obvious? Or a kerneldoc
>>> comment for the function to describe the parameter?
>>>
>>> Or have I totally missed the point of the question?
>>
>> Actually I should have placed this question next to
>> the call to s31fl32xx_software_shutdown() in is31fl32xx_init_regs(),
>> which is passed "false" in the second argument, and there is no
>> other call to s31fl32xx_software_shutdown() in the driver.
>>
>> Having the argument makes people wondering that there is some
>> use case in the driver, where "true" is passed, but it seems not
>> to be the case.
>
> Thanks for the clarification.
>
> Yes, there is currently no explicit call to enable software-shutdown
> mode. Since the reset state of these devices is to have software-shutdown
> enabled, the only explicit operation on it that's currently needed is
> to disable it.
>
> Reasons I can think to have the 'enable' parameter anyways include:
> - It seems logical to me that an API to manipulate the software-shutdown
> state should allow both enabling and disabling.
> - Having a parameter for that seemed the most obvious way to go, and it
> was trivial to implement.
> - Alternatively having separate "enable" and "disable" functions would
> duplicate most of the logic, vs the parameter being just a single
> conditional. And that would also imply two function pointers in the
> chipdefs, which I'd prefer to minimize.
> - If anyone wanted to implement suspend/resume in the future, they would
> most likely do it by enabling/disabling software-shutdown. Supporting
> both enable/disable from the start should make that trivial to do.
Suspend/resume callbacks are already implemented in led-class.c and
related ops indirectly call brightness_set. If you want to support
suspend/resume you have to set LED_CORE_SUSPENDRESUME flag.
Setting brightness to 0 is equivalent to turning the LED controller
in a shutdown mode, provided that all sub-LEDs are off.
> - I thought the code read better with a bool parameter, vs a longer
> function name.
>
> So nothing really critical, but mostly just my aesthetic and preference.
>
> Also, I expect that is31fl32xx_software_shutdown() would be inlined, so
> the conditional check in there is optimized out anyways, and there is no
> performance penalty. Looking at the disassembly in my ARMv7a build, both
> of those have indeed happened there.
Not only the size of a binary and the performance, but also code
readability matters. The function is called only with false argument,
so I expect that some people may submit patches optimizing this.
Let's avoid the confusion.
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static int is31fl32xx_init_regs(struct is31fl32xx_priv *priv)
>>>>> +{
>>>>> + const struct is31fl32xx_chipdef *cdef = priv->cdef;
>>>>> + int ret;
>>>>> +
>>>>> + ret = is31fl32xx_reset_regs(priv);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> +
>>>>> + /*
>>>>> + * Set enable bit for all channels.
>>>>> + * We will control state with PWM registers alone.
>>>>> + */
>>>>> + if (cdef->led_control_register_base != IS31FL32XX_REG_NONE) {
>>>>> + u8 value =
>>>>> + GENMASK(cdef->enable_bits_per_led_control_register-1, 0);
>>>>> + u8 num_regs = cdef->channels /
>>>>> + cdef->enable_bits_per_led_control_register;
>>>>> + int i;
>>>>> +
>>>>> + for (i = 0; i < num_regs; i++) {
>>>>> + ret = is31fl32xx_write(priv,
>>>>> + cdef->led_control_register_base+i,
>>>>> + value);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> + }
>>>>> + }
>>>>> +
>>>>> + ret = is31fl32xx_software_shutdown(priv, false);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> +
>>>>> + if (cdef->global_control_reg != IS31FL32XX_REG_NONE) {
>>>>> + ret = is31fl32xx_write(priv, cdef->global_control_reg, 0x00);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> + }
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static inline size_t sizeof_is31fl32xx_priv(int num_leds)
>>>>> +{
>>>>> + return sizeof(struct is31fl32xx_priv) +
>>>>> + (sizeof(struct is31fl32xx_led_data) * num_leds);
>>>>> +}
>>>>> +
>>>>> +static int is31fl32xx_parse_child_dt(const struct device *dev,
>>>>> + const struct device_node *child,
>>>>> + struct is31fl32xx_led_data *led_data)
>>>>> +{
>>>>> + struct led_classdev *cdev = &led_data->cdev;
>>>>> + int ret = 0;
>>>>> + u32 reg;
>>>>> +
>>>>> + if (of_property_read_string(child, "label", &cdev->name))
>>>>> + cdev->name = child->name;
>>>>> +
>>>>> + ret = of_property_read_u32(child, "reg", ®);
>>>>> + if (ret || reg < 1 || reg > led_data->priv->cdef->channels) {
>>>>> + dev_err(dev,
>>>>> + "Child node %s does not have a valid reg property\n",
>>>>> + child->full_name);
>>>>> + return -EINVAL;
>>>>> + }
>>>>> + led_data->channel = reg;
>>>>> +
>>>>> + of_property_read_string(child, "linux,default-trigger",
>>>>> + &cdev->default_trigger);
>>>>> +
>>>>> + cdev->brightness_set_blocking = is31fl32xx_brightness_set;
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static struct is31fl32xx_led_data *is31fl32xx_find_led_data(
>>>>> + struct is31fl32xx_priv *priv,
>>>>> + u8 channel)
>>>>> +{
>>>>> + size_t i;
>>>>> +
>>>>> + for (i = 0; i < priv->num_leds; i++) {
>>>>> + if (priv->leds[i].channel == channel)
>>>>> + return &priv->leds[i];
>>>>> + }
>>>>> +
>>>>> + return NULL;
>>>>> +}
>>>>> +
>>>>> +static int is31fl32xx_parse_dt(struct device *dev,
>>>>> + struct is31fl32xx_priv *priv)
>>>>> +{
>>>>> + struct device_node *child;
>>>>> + int ret = 0;
>>>>> +
>>>>> + for_each_child_of_node(dev->of_node, child) {
>>>>> + struct is31fl32xx_led_data *led_data =
>>>>> + &priv->leds[priv->num_leds];
>>>>> + const struct is31fl32xx_led_data *other_led_data;
>>>>> +
>>>>> + led_data->priv = priv;
>>>>> +
>>>>> + ret = is31fl32xx_parse_child_dt(dev, child, led_data);
>>>>> + if (ret)
>>>>> + goto err;
>>>>> +
>>>>> + /* Detect if channel is already in use by another child */
>>>>> + other_led_data = is31fl32xx_find_led_data(priv,
>>>>> + led_data->channel);
>>>>> + if (other_led_data) {
>>>>> + dev_err(dev,
>>>>> + "%s and %s both attempting to use channel %d\n",
>>>>> + led_data->cdev.name,
>>>>> + other_led_data->cdev.name,
>>>>> + led_data->channel);
>>>>> + goto err;
>>>>> + }
>>>>> +
>>>>> + ret = devm_led_classdev_register(dev, &led_data->cdev);
>>>>> + if (ret) {
>>>>> + dev_err(dev, "failed to register PWM led for %s: %d\n",
>>>>> + led_data->cdev.name, ret);
>>>>> + goto err;
>>>>> + }
>>>>> +
>>>>> + priv->num_leds++;
>>>>> + }
>>>>> +
>>>>> + return 0;
>>>>> +
>>>>> +err:
>>>>> + of_node_put(child);
>>>>> + return ret;
>>>>> +}
>>>>> +
>>>>> +static const struct of_device_id of_is31fl31xx_match[] = {
>>>>> + { .compatible = "issi,is31fl3236", .data = &is31fl3236_cdef, },
>>>>> + { .compatible = "issi,is31fl3235", .data = &is31fl3235_cdef, },
>>>>> + { .compatible = "issi,is31fl3218", .data = &is31fl3218_cdef, },
>>>>> + { .compatible = "issi,is31fl3216", .data = &is31fl3216_cdef, },
>>>>> + {},
>>>>> +};
>>>>> +
>>>>> +MODULE_DEVICE_TABLE(of, of_is31fl31xx_match);
>>>>> +
>>>>> +static int is31fl32xx_probe(struct i2c_client *client,
>>>>> + const struct i2c_device_id *id)
>>>>> +{
>>>>> + const struct is31fl32xx_chipdef *cdef;
>>>>> + const struct of_device_id *of_dev_id;
>>>>> + struct device *dev = &client->dev;
>>>>> + struct is31fl32xx_priv *priv;
>>>>> + int count;
>>>>> + int ret = 0;
>>>>> +
>>>>> + of_dev_id = of_match_device(of_is31fl31xx_match, dev);
>>>>> + if (!of_dev_id)
>>>>> + return -EINVAL;
>>>>> +
>>>>> + cdef = of_dev_id->data;
>>>>> +
>>>>> + count = of_get_child_count(dev->of_node);
>>>>> + if (!count)
>>>>> + return -EINVAL;
>>>>> +
>>>>> + priv = devm_kzalloc(dev, sizeof_is31fl32xx_priv(count),
>>>>> + GFP_KERNEL);
>>>>> + if (!priv)
>>>>> + return -ENOMEM;
>>>>> +
>>>>> + priv->client = client;
>>>>> + priv->cdef = cdef;
>>>>> + i2c_set_clientdata(client, priv);
>>>>> +
>>>>> + ret = is31fl32xx_init_regs(priv);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> +
>>>>> + ret = is31fl32xx_parse_dt(dev, priv);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static int is31fl32xx_remove(struct i2c_client *client)
>>>>> +{
>>>>> + struct is31fl32xx_priv *priv = i2c_get_clientdata(client);
>>>>> +
>>>>> + return is31fl32xx_reset_regs(priv);
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * i2c-core requires that id_table be non-NULL, even though
>>>>> + * it is not used for DeviceTree based instantiation.
>>>>> + */
>>>>> +static const struct i2c_device_id is31fl31xx_id[] = {
>>>>> + {},
>>>>> +};
>>>>> +
>>>>> +MODULE_DEVICE_TABLE(i2c, is31fl31xx_id);
>>>>> +
>>>>> +static struct i2c_driver is31fl32xx_driver = {
>>>>> + .driver = {
>>>>> + .name = "is31fl32xx",
>>>>> + .of_match_table = of_is31fl31xx_match,
>>>>> + },
>>>>> + .probe = is31fl32xx_probe,
>>>>> + .remove = is31fl32xx_remove,
>>>>> + .id_table = is31fl31xx_id,
>>>>> +};
>>>>> +
>>>>> +module_i2c_driver(is31fl32xx_driver);
>>>>> +
>>>>> +MODULE_AUTHOR("David Rivshin <drivshin@...worx.com>");
>>>>> +MODULE_DESCRIPTION("ISSI IS31FL32xx LED driver");
>>>>> +MODULE_LICENSE("GPL v2");
>>>>>
>
>
>
--
Best regards,
Jacek Anaszewski
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